Medium Access Control protocols for ad hoc wireless networks : A survey
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paper_title: A Review of Current Routing Protocols for Ad-Hoc Mobile Wireless Networks

paper_content:

An ad hoc mobile network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. In order to facilitate communication within the network, a routing protocol is used to discover routes between nodes. The primary goal of such an ad hoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. Route construction should be done with a minimum of overhead and bandwidth consumption. This article examines routing protocols for ad hoc networks and evaluates these protocols based on a given set of parameters. The article provides an overview of eight different protocols by presenting their characteristics and functionality, and then provides a comparison and discussion of their respective merits and drawbacks.
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paper_title: Ad hoc mobile wireless networks : protocols and systems

paper_content:

About The Author. Preface. Acknowledgments. Quotes & Words of Wisdom. 1. Introduction to Wireless Networks. Evolution of Mobile Cellular Networks. Global System for Mobile Communications (GSM). General Packet Radio Service (GPRS). Personal Communications Services (PCSs). Wireless LANs (WLANS). Universal Mobile Telecommunications System (UMTS). IMT2000. IS-95, cdmaOne and cdma2000 Evolution. Organization of this Book. 2. Origins Of Ad Hoc: Packet Radio Networks. Introduction. Technical Challenges. Architecture of PRNETs. Components of Packet Radios. Routing in PRNETs. Route Calculation. Pacing Techniques. Media Access in PRNETs. Flow Acknowledgments in PRNETs. Conclusions. 3. Ad Hoc Wireless Networks. What Is an Ad Hoc Network? Heterogeneity in Mobile Devices. Wireless Sensor Networks. Traffic Profiles. Types of Ad Hoc Mobile Communications. Types of Mobile Host Movements. Challenges Facing Ad Hoc Mobile Networks. Conclusions. 4. Ad Hoc Wireless Media Access Protocols. Introduction. Problems in Ad Hoc Channel Access. Receiver-Initiated MAC Protocols. Sender-Initiated MAC Protocols. Existing Ad Hoc MAC Protocols. MARCH: Media Access with Reduced Handshake. Conclusions. 5. Overview of Ad Hoc Routing Protocols. Table-Driven Approaches. Destination Sequenced Distance Vector (DSDV). Wireless Routing Protocol (WRP). Cluster Switch Gateway Routing (CSGR). Source-Initiated On-Demand Approaches. Ad Hoc On-Demand Distance Vector Routing (AODV). Dynamic Source Routing (DSR). Temporally Ordered Routing Algorithm (TORA). Signal Stability Routing (SSR). Location-Aided Routing (LAR). Power-Aware Routing (PAR). Zone Routing Protocol (ZRP). Source Tree Adaptive Routing (STAR). Relative Distance Microdiversity Routing (RDMAR). Conclusions. 6. Associativity-Based Long-Lived Routing. A New Routing Paradigm. Associativity-Based Long-Lived Routing. ABR Protocol Description. Conclusions. 7. Implementation Of Ad Hoc Mobile Networks. Introduction. ABR Protocol Implementation in Linux. Experimentation and Protocol Performance. Important Deductions. Conclusions. 8. Communication Performance of Ad Hoc Networks. Introduction. Performance Parameters of Interest. Route Discovery (RD) Time. End-to-End Delay (EED) Performance. Communication Throughput Performance. Packet Loss Performance. Route Reconfiguration/Repair Time. TCP/IP-Based Applications. Conclusions. 9. Energy Conservation: Power Life Issues. Introduction. Power Management. Advances in Device Power Management. Advances in Protocol Power Management. Power Conservation by Mobile Applications. Periodic Beaconing On Battery Life. Standalone Beaconing. HF Beaconing with Neighboring Nodes. Comparison of HF Beaconing with and without Neighbors. LF Beaconing with Neighboring Nodes. Comparison of LF Beaconing with and without Neighbors. Deductions. Conclusions. 10. Ad Hoc Wireless Multicast Routing. Multicasting in Wired Networks. Multicast Routing in Mobile Ad Hoc Networks. Existing Ad Hoc Multicast Routing Protocols. ABAM: Associativity-Based Ad Hoc Multicast. Comparisons of Multicast Routing Protocols. Conclusions. 11. TCP Over Ad Hoc. Introduction to TCP. Versions of TCP. Problems Facing TCP in Wireless Last-Hop. Problems Facing TCP in Wireless Ad Hoc. Approaches to TCP over Ad Hoc. Conclusion. 12. Internet & Ad Hoc Service Discovery. Resource Discovery in the Internet. Service Location Protocol (SLP) Architecture. SLPv2 Packet Format. Jini. Salutation Protocol. Simple Service Discovery Protocol (SSDP). Service Discovery for Ad Hoc. Ad Hoc Service Location Architectures. Conclusions. 13. BLUETOOTH TECHNOLOGY. Bluetooth Specifications. Bluetooth Architectures. Bluetooth Protocols. Bluetooth Service Discovery. Bluetooth MAC. Bluetooth Packet Structure. Bluetooth Audio. Bluetooth Addressing. Bluetooth Limitations. Bluetooth Implementation. Conclusions. 14. WIRELESS APPLICATION PROTOCOL (WAP). The WAP Forum. The WAP Service Model. The WAP Protocol Architecture. The WWW Programming Model. The WAP Programming Model. Conclusions. 15. Ad Hoc Nomadic Mobile Applications. In the Office. While Traveling. Arriving Home. In the Car. Shopping Malls. The Modern Battlefield. Car-to-Car Mobile Communications. Mobile Collaborative Applications. Location/Context Based Mobile Services. Conclusions. 16. Conclusions and The Future. Pervasive Computing. Motorola PIANO Project. UC Berkeley Sensor Networks: Smart Dust. EPFL Terminodes/Large-Scale Networks. 802.15 PANs and 802.16 Wireless MANs. Ad Hoc Everywhere? Glossary of Terms. References. Index.
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paper_title: On some challenges and design choices in ad-hoc communications

paper_content:

Ad-hoc networks are network architectures that can be rapidly (ideally immediately) deployed and that do not need to rely on pre-existing infrastructure. The salient feature of this breed of networks is that they can operate in different and differing propagation and network operational conditions, which cannot be predicted during the network design stage. We discuss some of the challenges and choices that need to be made while designing an ad-hoc network. In particular, we address the following three issues: hierarchical vs. flat network architectures, proactive vs. reactive (on demand) routing protocols vs. a hybrid approach, and sensing-based vs. dialog-based medium access control.
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paper_title: Ad hoc mobile wireless networks : protocols and systems

paper_content:

About The Author. Preface. Acknowledgments. Quotes & Words of Wisdom. 1. Introduction to Wireless Networks. Evolution of Mobile Cellular Networks. Global System for Mobile Communications (GSM). General Packet Radio Service (GPRS). Personal Communications Services (PCSs). Wireless LANs (WLANS). Universal Mobile Telecommunications System (UMTS). IMT2000. IS-95, cdmaOne and cdma2000 Evolution. Organization of this Book. 2. Origins Of Ad Hoc: Packet Radio Networks. Introduction. Technical Challenges. Architecture of PRNETs. Components of Packet Radios. Routing in PRNETs. Route Calculation. Pacing Techniques. Media Access in PRNETs. Flow Acknowledgments in PRNETs. Conclusions. 3. Ad Hoc Wireless Networks. What Is an Ad Hoc Network? Heterogeneity in Mobile Devices. Wireless Sensor Networks. Traffic Profiles. Types of Ad Hoc Mobile Communications. Types of Mobile Host Movements. Challenges Facing Ad Hoc Mobile Networks. Conclusions. 4. Ad Hoc Wireless Media Access Protocols. Introduction. Problems in Ad Hoc Channel Access. Receiver-Initiated MAC Protocols. Sender-Initiated MAC Protocols. Existing Ad Hoc MAC Protocols. MARCH: Media Access with Reduced Handshake. Conclusions. 5. Overview of Ad Hoc Routing Protocols. Table-Driven Approaches. Destination Sequenced Distance Vector (DSDV). Wireless Routing Protocol (WRP). Cluster Switch Gateway Routing (CSGR). Source-Initiated On-Demand Approaches. Ad Hoc On-Demand Distance Vector Routing (AODV). Dynamic Source Routing (DSR). Temporally Ordered Routing Algorithm (TORA). Signal Stability Routing (SSR). Location-Aided Routing (LAR). Power-Aware Routing (PAR). Zone Routing Protocol (ZRP). Source Tree Adaptive Routing (STAR). Relative Distance Microdiversity Routing (RDMAR). Conclusions. 6. Associativity-Based Long-Lived Routing. A New Routing Paradigm. Associativity-Based Long-Lived Routing. ABR Protocol Description. Conclusions. 7. Implementation Of Ad Hoc Mobile Networks. Introduction. ABR Protocol Implementation in Linux. Experimentation and Protocol Performance. Important Deductions. Conclusions. 8. Communication Performance of Ad Hoc Networks. Introduction. Performance Parameters of Interest. Route Discovery (RD) Time. End-to-End Delay (EED) Performance. Communication Throughput Performance. Packet Loss Performance. Route Reconfiguration/Repair Time. TCP/IP-Based Applications. Conclusions. 9. Energy Conservation: Power Life Issues. Introduction. Power Management. Advances in Device Power Management. Advances in Protocol Power Management. Power Conservation by Mobile Applications. Periodic Beaconing On Battery Life. Standalone Beaconing. HF Beaconing with Neighboring Nodes. Comparison of HF Beaconing with and without Neighbors. LF Beaconing with Neighboring Nodes. Comparison of LF Beaconing with and without Neighbors. Deductions. Conclusions. 10. Ad Hoc Wireless Multicast Routing. Multicasting in Wired Networks. Multicast Routing in Mobile Ad Hoc Networks. Existing Ad Hoc Multicast Routing Protocols. ABAM: Associativity-Based Ad Hoc Multicast. Comparisons of Multicast Routing Protocols. Conclusions. 11. TCP Over Ad Hoc. Introduction to TCP. Versions of TCP. Problems Facing TCP in Wireless Last-Hop. Problems Facing TCP in Wireless Ad Hoc. Approaches to TCP over Ad Hoc. Conclusion. 12. Internet & Ad Hoc Service Discovery. Resource Discovery in the Internet. Service Location Protocol (SLP) Architecture. SLPv2 Packet Format. Jini. Salutation Protocol. Simple Service Discovery Protocol (SSDP). Service Discovery for Ad Hoc. Ad Hoc Service Location Architectures. Conclusions. 13. BLUETOOTH TECHNOLOGY. Bluetooth Specifications. Bluetooth Architectures. Bluetooth Protocols. Bluetooth Service Discovery. Bluetooth MAC. Bluetooth Packet Structure. Bluetooth Audio. Bluetooth Addressing. Bluetooth Limitations. Bluetooth Implementation. Conclusions. 14. WIRELESS APPLICATION PROTOCOL (WAP). The WAP Forum. The WAP Service Model. The WAP Protocol Architecture. The WWW Programming Model. The WAP Programming Model. Conclusions. 15. Ad Hoc Nomadic Mobile Applications. In the Office. While Traveling. Arriving Home. In the Car. Shopping Malls. The Modern Battlefield. Car-to-Car Mobile Communications. Mobile Collaborative Applications. Location/Context Based Mobile Services. Conclusions. 16. Conclusions and The Future. Pervasive Computing. Motorola PIANO Project. UC Berkeley Sensor Networks: Smart Dust. EPFL Terminodes/Large-Scale Networks. 802.15 PANs and 802.16 Wireless MANs. Ad Hoc Everywhere? Glossary of Terms. References. Index.
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paper_title: A Review of Current Routing Protocols for Ad-Hoc Mobile Wireless Networks

paper_content:

An ad hoc mobile network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. In order to facilitate communication within the network, a routing protocol is used to discover routes between nodes. The primary goal of such an ad hoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. Route construction should be done with a minimum of overhead and bandwidth consumption. This article examines routing protocols for ad hoc networks and evaluates these protocols based on a given set of parameters. The article provides an overview of eight different protocols by presenting their characteristics and functionality, and then provides a comparison and discussion of their respective merits and drawbacks.
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paper_title: Medium access control protocols for multimedia traffic in wireless networks

paper_content:

This article presents a survey on medium access control protocols for multimedia traffic in wireless networks. A basic overview of MAC protocol concepts is presented, and a framework is developed on which to base qualitative comparisons. The MAC protocols covered include third-generation TDMA and CDMA schemes intended for use in a single-hop wireless system. The operation of each protocol is explained, and its advantages and disadvantages ore presented. Finally, a qualitative comparative outline of the discussed protocols is provided, based on multimedia traffic requirements.
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paper_title: Ad hoc mobile wireless networks : protocols and systems

paper_content:

About The Author. Preface. Acknowledgments. Quotes & Words of Wisdom. 1. Introduction to Wireless Networks. Evolution of Mobile Cellular Networks. Global System for Mobile Communications (GSM). General Packet Radio Service (GPRS). Personal Communications Services (PCSs). Wireless LANs (WLANS). Universal Mobile Telecommunications System (UMTS). IMT2000. IS-95, cdmaOne and cdma2000 Evolution. Organization of this Book. 2. Origins Of Ad Hoc: Packet Radio Networks. Introduction. Technical Challenges. Architecture of PRNETs. Components of Packet Radios. Routing in PRNETs. Route Calculation. Pacing Techniques. Media Access in PRNETs. Flow Acknowledgments in PRNETs. Conclusions. 3. Ad Hoc Wireless Networks. What Is an Ad Hoc Network? Heterogeneity in Mobile Devices. Wireless Sensor Networks. Traffic Profiles. Types of Ad Hoc Mobile Communications. Types of Mobile Host Movements. Challenges Facing Ad Hoc Mobile Networks. Conclusions. 4. Ad Hoc Wireless Media Access Protocols. Introduction. Problems in Ad Hoc Channel Access. Receiver-Initiated MAC Protocols. Sender-Initiated MAC Protocols. Existing Ad Hoc MAC Protocols. MARCH: Media Access with Reduced Handshake. Conclusions. 5. Overview of Ad Hoc Routing Protocols. Table-Driven Approaches. Destination Sequenced Distance Vector (DSDV). Wireless Routing Protocol (WRP). Cluster Switch Gateway Routing (CSGR). Source-Initiated On-Demand Approaches. Ad Hoc On-Demand Distance Vector Routing (AODV). Dynamic Source Routing (DSR). Temporally Ordered Routing Algorithm (TORA). Signal Stability Routing (SSR). Location-Aided Routing (LAR). Power-Aware Routing (PAR). Zone Routing Protocol (ZRP). Source Tree Adaptive Routing (STAR). Relative Distance Microdiversity Routing (RDMAR). Conclusions. 6. Associativity-Based Long-Lived Routing. A New Routing Paradigm. Associativity-Based Long-Lived Routing. ABR Protocol Description. Conclusions. 7. Implementation Of Ad Hoc Mobile Networks. Introduction. ABR Protocol Implementation in Linux. Experimentation and Protocol Performance. Important Deductions. Conclusions. 8. Communication Performance of Ad Hoc Networks. Introduction. Performance Parameters of Interest. Route Discovery (RD) Time. End-to-End Delay (EED) Performance. Communication Throughput Performance. Packet Loss Performance. Route Reconfiguration/Repair Time. TCP/IP-Based Applications. Conclusions. 9. Energy Conservation: Power Life Issues. Introduction. Power Management. Advances in Device Power Management. Advances in Protocol Power Management. Power Conservation by Mobile Applications. Periodic Beaconing On Battery Life. Standalone Beaconing. HF Beaconing with Neighboring Nodes. Comparison of HF Beaconing with and without Neighbors. LF Beaconing with Neighboring Nodes. Comparison of LF Beaconing with and without Neighbors. Deductions. Conclusions. 10. Ad Hoc Wireless Multicast Routing. Multicasting in Wired Networks. Multicast Routing in Mobile Ad Hoc Networks. Existing Ad Hoc Multicast Routing Protocols. ABAM: Associativity-Based Ad Hoc Multicast. Comparisons of Multicast Routing Protocols. Conclusions. 11. TCP Over Ad Hoc. Introduction to TCP. Versions of TCP. Problems Facing TCP in Wireless Last-Hop. Problems Facing TCP in Wireless Ad Hoc. Approaches to TCP over Ad Hoc. Conclusion. 12. Internet & Ad Hoc Service Discovery. Resource Discovery in the Internet. Service Location Protocol (SLP) Architecture. SLPv2 Packet Format. Jini. Salutation Protocol. Simple Service Discovery Protocol (SSDP). Service Discovery for Ad Hoc. Ad Hoc Service Location Architectures. Conclusions. 13. BLUETOOTH TECHNOLOGY. Bluetooth Specifications. Bluetooth Architectures. Bluetooth Protocols. Bluetooth Service Discovery. Bluetooth MAC. Bluetooth Packet Structure. Bluetooth Audio. Bluetooth Addressing. Bluetooth Limitations. Bluetooth Implementation. Conclusions. 14. WIRELESS APPLICATION PROTOCOL (WAP). The WAP Forum. The WAP Service Model. The WAP Protocol Architecture. The WWW Programming Model. The WAP Programming Model. Conclusions. 15. Ad Hoc Nomadic Mobile Applications. In the Office. While Traveling. Arriving Home. In the Car. Shopping Malls. The Modern Battlefield. Car-to-Car Mobile Communications. Mobile Collaborative Applications. Location/Context Based Mobile Services. Conclusions. 16. Conclusions and The Future. Pervasive Computing. Motorola PIANO Project. UC Berkeley Sensor Networks: Smart Dust. EPFL Terminodes/Large-Scale Networks. 802.15 PANs and 802.16 Wireless MANs. Ad Hoc Everywhere? Glossary of Terms. References. Index.
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paper_title: Packet Switching in Radio Channels: Part I -- Carrier sense multiple-access modes and their throughput-delay characteristics

paper_content:

Radio communication is considered as a method for providing remote terminal access to computers. Digital byte streams from each terminal are partitioned into packets (blocks) and transmitted in a burst mode over a shared radio channel. When many terminals operate in this fashion, transmissions may conflict with and destroy each other. A means for controlling this is for the terminal to sense the presence of other transmissions; this leads to a new method for multiplexing in a packet radio environment: carrier sense multiple access (CSMA). Two protocols are described for CSMA and their throughput-delay characteristics are given. These results show the large advantage CSMA provides as compared to the random ALOHA access modes.
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paper_title: Medium access control in a network of ad hoc mobile nodes with heterogeneous power capabilities

paper_content:

MAC layer protocols for wireless ad hoc networks typically assume that the network is homogeneous with respect to the transmit power capability of individual nodes in the network. The IEEE 802.11 MAC protocol has been popular for use in ad hoc networks. We investigate the performance of this protocol when it is used in a network with nodes that transmit at various power levels. We show that overall throughput is lower than the throughput of a network in which all nodes transmit at identical power levels. In addition, low power nodes have a disadvantage in accessing the medium due to higher levels of interference from the high power nodes. We consider propagating the control messages generated by a node wishing to initiate communication to distant nodes so that they may forbear transmissions for some time, thereby allowing clear access to the initiating node. We find that the overhead incurred due to the additional message transmissions outweighs the potential gain achieved by propagating these messages. This indicates that the signalling mechanism used in the IEEE 802.11 standard or the variants thereof are not sufficient to alleviate the loss in throughput and the lack of fairness engendered by networks that are heterogeneous with regard to the transmit power capabilities of individual nodes.
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paper_title: Multichannel CSMA with signal power-based channel selection for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, using multiple channels and a distributed channel selection scheme. The proposed protocol divides the available bandwidth into N channels where the transmitting station selects an appropriate channel for packet transmission. The selection criterion is based on the interference power measurements on the channels. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions.
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paper_title: Receiver-initiated busy-tone multiple access in packet radio networks

paper_content:

The ALOHA and Carrier Sense Multiple Access (CSMA) protocols have been proposed for packet radio networks (PRN). However, CSMA/CD which gives superior performance and has been successful applied in local area networks cannot be readily applied in PRN since the locally generated signals will overwhelm a remote transmission, rendering it impossible to tell whether a collision has occurred or not. In addition, CSMA and CSMA/CD suffer from the “hidden node” problem in a multihop PRN. In this paper, we develop the Receiver-Initiated Busy-Tone Multiple Access Protocol to resolve these difficulties. Both fully connected and multihop networks are studied. The busy tone serves as an acknowledgement and prevents conflicting transmissions from other nodes, including “hidden nodes”.
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paper_title: Floor acquisition multiple access (FAMA) for packet-radio networks

paper_content:

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
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paper_title: Distributed fair scheduling in a wireless LAN

paper_content:

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling , it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmission such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.
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paper_title: Performance considerations for slotted spread-spectrum random-access networks with directional antennas

paper_content:

The throughput/delay performance of certain types of spread spectrum random-access (SSRA) networks employing directional antennas is considered. The use of directional antennas in the receiving sites to improve the network performance is presented and analyzed. The basic idea is to reduce the contention of the users (transmitters) by dividing the coverage area into different regions; at the receiving site, a single directional antenna is aimed at one region, so that transmissions from different regions do not interface with each other. In addition to the reduction of the multiuser interference, the directional antennas allow for different classifications, in different regions, of the users according to their physical and link level parameters. The throughput improvement is substantial for heavy-traffic conditions, and the gains are further amplified if the number of available receivers is increased. Numerical results for performance comparison with the case receivers using omnidirectional antennas are also included. >
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paper_title: Design challenges for energy-constrained ad hoc wireless networks

paper_content:

Ad hoc wireless networks enable new and exciting applications, but also pose significant technical challenges. In this article we give a brief overview of ad hoc wireless networks and their applications with a particular emphasis on energy constraints. We then discuss advances in the link, multiple access, network, and application protocols for these networks. We show that cross-layer design of these protocols is imperative to meet emerging application requirements, particularly when energy is a limited resource.
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paper_title: Medium access control in a network of ad hoc mobile nodes with heterogeneous power capabilities

paper_content:

MAC layer protocols for wireless ad hoc networks typically assume that the network is homogeneous with respect to the transmit power capability of individual nodes in the network. The IEEE 802.11 MAC protocol has been popular for use in ad hoc networks. We investigate the performance of this protocol when it is used in a network with nodes that transmit at various power levels. We show that overall throughput is lower than the throughput of a network in which all nodes transmit at identical power levels. In addition, low power nodes have a disadvantage in accessing the medium due to higher levels of interference from the high power nodes. We consider propagating the control messages generated by a node wishing to initiate communication to distant nodes so that they may forbear transmissions for some time, thereby allowing clear access to the initiating node. We find that the overhead incurred due to the additional message transmissions outweighs the potential gain achieved by propagating these messages. This indicates that the signalling mechanism used in the IEEE 802.11 standard or the variants thereof are not sufficient to alleviate the loss in throughput and the lack of fairness engendered by networks that are heterogeneous with regard to the transmit power capabilities of individual nodes.
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paper_title: Energy efficiency of media access protocols for mobile data networks

paper_content:

As mobile terminals are powered by a finite battery source, energy constraints play a major role in the design of wireless communications systems. In this letter, based on a general analytical framework, we study the energy efficiency of a class of multiple access schemes, using the average number of correctly transmitted packets for a given amount of allocated energy as an appropriate metric. We show that a good choice of the protocol rules can significantly improve the energy efficiency.
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paper_title: An energy efficient MAC protocol for wireless LANs

paper_content:

This paper presents an optimization of the power saving mechanism in the Distributed Coordination Function (DCF) in the IEEE 802.11 standard. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up for a duration called the ATIM window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has a significant impact on energy saving and throughput achieved by the nodes. This paper proposes an adaptive mechanism to dynamically choose a suitable ATIM window size. We also allow the nodes to stay awake for only a fraction of the beacon interval following the ATIM window. On the other hand, IEEE 802.11 DCF mode requires the nodes to stay awake either for the entire beacon interval following the ATIM window or none at all. Simulation results show that the proposed approach outperforms the IEEE 802.11 power saving mechanism in terms of throughput and the amount of energy consumed.
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paper_title: QoS in Mobile Ad Hoc Networks

paper_content:

A mobile ad hoc network (MANET) consists of mobile nodes communicating over wireless channels. Routing in MANETs is very challenging due to the random mobility of nodes and unreliability of wireless channels. Therefore most of the existing routing algorithms make only the best effort to find routes for communication but do not provide any performance guarantee. Because of the widespread use of MANETs in real-time applications, it becomes pertinent to provide deterministic network behavior. Quality of Service (QoS) aims to shape the network behavior and provide performance guarantees. In this work, a novel heuristic called Advanced-Optimised Link State Routing (A-OLSR) protocol is designed to provide QoS. It functions by enhancing the connectivity of nodes and establishing more stable routes as compared to standard best-effort Optimised Link State Routing (OLSR) protocol. The simulation results show that A-OLSR provides lower delay, reduces energy consumption and achieves higher throughput without introducing any additional routing overhead as compared to the standard OLSR and it's variants-A$$'$$?-OLSR and A$$''$$??-OLSR. The results also show that A-OLSR provides scalability since it's performance remains consistent with the increasing size of network.
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paper_title: A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks

paper_content:

The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This paper considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an "on-demand" style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit) some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
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paper_title: IEEE 802.11 e contention-based channel access (EDCF) performance evaluation

paper_content:

IEEE 802.11 e medium access control (MAC) is an emerging supplement to the IEEE 802.11 wireless local area network (WLAN) standard to support quality-of-service (QoS). The 802.11e MAC is based on both centrally-controlled and contention-based channel accesses. In this paper, we evaluate the contention-based channel access mechanism, called enhanced distributed coordination function (EDCF), in comparison with the 802.11 legacy MAC. The ECDF provides differentiated channel access to frames with different priorities. We also consider an optional feature of the EDCF, called contention-free burst (CFB), which allows multiple MAC frame transmissions during a single transmission opportunity (TXOP). Through our simulation study, we conclude that the EDCF can provide differentiated channel access for different traffic types. Furthermore, the CFB is found to enhance the EDCF performance by increasing the overall system throughput and achieving more acceptable streaming quality in terms of frame losses and delays.
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paper_title: Design algorithms for multihop packet radio networks with multiple directional antennas stations

paper_content:

A protocol called the simple tone sense (STS) protocol is designed for multihop packet radio networks (PRNs) with multiple directional antennas stations. The protocol can minimize transmission interference by using a group of tones to identify the active neighbors. A variation of the STS protocol called the variable power tone sense (VPTS) protocol is also designed to further reduce interference. Algorithms for assigning tones and for determining the orientation and broadcasting angles of the directional antennas are designed. Design examples are given. Simulation result shows that the STS protocol gives better throughput-delay performance than the busy-tone multiple access protocol, especially when the traffic is heavy. The VPTS protocol gives still better throughput-delay performance than the STS protocol. >
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paper_title: Hop-reservation multiple access (HRMA) for ad-hoc networks

paper_content:

A new multichannel MAC protocol called hop-reservation multiple access (HRMA) for wireless ad-hoc networks (multi-hop packet radio networks) is introduced, specified and analyzed. HRMA is based on simple half-duplex, very slow frequency-hopping spread spectrum (FHSS) radios and takes advantage of the time synchronization necessary for frequency-hopping. HRMA allows a pair of communicating nodes to reserve a frequency hop using a reservation and handshake mechanism that guarantee collision-free data transmission in the presence of hidden terminals. We analyze the throughput achieved in HRMA for the case of a hypercube network topology assuming variable-length packets, and compare it against the multichannel slotted ALOHA protocol, which represents the current practice of MAC protocols in commercial ad-hoc networks based on spread spectrum radios, such as Metricom's Ricochet system. The numerical results show that HRMA can achieve much higher throughput than multichannel slotted ALOHA within the traffic-load ranges of interest, especially when the average packet length is large compared to the duration of a dwell time in the frequency hopping sequence, in which case the maximum throughput of HRMA is close to the maximum possible value.
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paper_title: Channel access scheduling in Ad Hoc networks with unidirectional links

paper_content:

A new family of collision-free channel access protocols for ad hoc networks with unidirectional links is introduced. These protocols are based on a distributed contention resolution algorithm that operates at each node based on the list of direct contenders (one-hop neighbors or incident links) and indirect interferences (two-hop neighbors and related links). Depending on the activation scheme (node activation or link activation), a network node uses the identifiers of its neighbors one and two hops away to elect deterministically one or multiple winners for channel access in each contention context (e.g., a time slot or a frequency band). The protocols are shown to be fair and capable of achieving maximum utilization of the channel bandwidth. The delay and throughput characteristics of the channel access protocols is studied by simulations.
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paper_title: Unidirectional links prove costly in wireless ad hoc networks

paper_content:

Most, of t,he routing algorithms for ad hoc net,works assume t,hat all wireless links are bidirect,ional. In realit,y, some links may be unidirect.ional. The presence of such links can jeopardize t,he performance of t,he existing dist,ance vect.or rout.ing algorit.hms. In this paper we show t,hat, dist.ance vector based rout,ing prot.ocols t,hat, account for unidirectional links will require nodes t.o exchange O(n2) informat.ion with each other, where n is t.he number of nodes in t,he nebwork. We also present. modifications to dist,ance vector based routing algorithms to make t,hem work in ad hoc netsworks wit.h unidirectional links.
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paper_title: Providing a bidirectional abstraction for unidirectional ad hoc networks

paper_content:

Several routing protocols for mobile ad hoc networks work efficiently only in bidirectional networks. Unidirectional links may exist in a real network due to variations in transmission power of different nodes, noise or other signal propagation phenomena, and heterogeneity in the transmission hardware of nodes in the network. We introduce a sub-layer called sub routing layer, SRL, between the network and the MAC layer to provide a bidirectional abstraction of the unidirectional network to the routing protocols. We present a scalable and efficient way to provide this abstraction by finding and maintaining multi-hop reverse routes to each unidirectional link. We simulate SRL and a modified version of AODV (ad hoc on demand distance vector) that uses SRL to route packets in a unidirectional network. We observed that with SRL, the packet delivery of AODV in unidirectional networks increases substantially. Further our simulations indicate that reverse routes are often only a few hops long and hence the overhead of using SRL is very low.
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paper_title: Ad hoc mobile wireless networks : protocols and systems

paper_content:

About The Author. Preface. Acknowledgments. Quotes & Words of Wisdom. 1. Introduction to Wireless Networks. Evolution of Mobile Cellular Networks. Global System for Mobile Communications (GSM). General Packet Radio Service (GPRS). Personal Communications Services (PCSs). Wireless LANs (WLANS). Universal Mobile Telecommunications System (UMTS). IMT2000. IS-95, cdmaOne and cdma2000 Evolution. Organization of this Book. 2. Origins Of Ad Hoc: Packet Radio Networks. Introduction. Technical Challenges. Architecture of PRNETs. Components of Packet Radios. Routing in PRNETs. Route Calculation. Pacing Techniques. Media Access in PRNETs. Flow Acknowledgments in PRNETs. Conclusions. 3. Ad Hoc Wireless Networks. What Is an Ad Hoc Network? Heterogeneity in Mobile Devices. Wireless Sensor Networks. Traffic Profiles. Types of Ad Hoc Mobile Communications. Types of Mobile Host Movements. Challenges Facing Ad Hoc Mobile Networks. Conclusions. 4. Ad Hoc Wireless Media Access Protocols. Introduction. Problems in Ad Hoc Channel Access. Receiver-Initiated MAC Protocols. Sender-Initiated MAC Protocols. Existing Ad Hoc MAC Protocols. MARCH: Media Access with Reduced Handshake. Conclusions. 5. Overview of Ad Hoc Routing Protocols. Table-Driven Approaches. Destination Sequenced Distance Vector (DSDV). Wireless Routing Protocol (WRP). Cluster Switch Gateway Routing (CSGR). Source-Initiated On-Demand Approaches. Ad Hoc On-Demand Distance Vector Routing (AODV). Dynamic Source Routing (DSR). Temporally Ordered Routing Algorithm (TORA). Signal Stability Routing (SSR). Location-Aided Routing (LAR). Power-Aware Routing (PAR). Zone Routing Protocol (ZRP). Source Tree Adaptive Routing (STAR). Relative Distance Microdiversity Routing (RDMAR). Conclusions. 6. Associativity-Based Long-Lived Routing. A New Routing Paradigm. Associativity-Based Long-Lived Routing. ABR Protocol Description. Conclusions. 7. Implementation Of Ad Hoc Mobile Networks. Introduction. ABR Protocol Implementation in Linux. Experimentation and Protocol Performance. Important Deductions. Conclusions. 8. Communication Performance of Ad Hoc Networks. Introduction. Performance Parameters of Interest. Route Discovery (RD) Time. End-to-End Delay (EED) Performance. Communication Throughput Performance. Packet Loss Performance. Route Reconfiguration/Repair Time. TCP/IP-Based Applications. Conclusions. 9. Energy Conservation: Power Life Issues. Introduction. Power Management. Advances in Device Power Management. Advances in Protocol Power Management. Power Conservation by Mobile Applications. Periodic Beaconing On Battery Life. Standalone Beaconing. HF Beaconing with Neighboring Nodes. Comparison of HF Beaconing with and without Neighbors. LF Beaconing with Neighboring Nodes. Comparison of LF Beaconing with and without Neighbors. Deductions. Conclusions. 10. Ad Hoc Wireless Multicast Routing. Multicasting in Wired Networks. Multicast Routing in Mobile Ad Hoc Networks. Existing Ad Hoc Multicast Routing Protocols. ABAM: Associativity-Based Ad Hoc Multicast. Comparisons of Multicast Routing Protocols. Conclusions. 11. TCP Over Ad Hoc. Introduction to TCP. Versions of TCP. Problems Facing TCP in Wireless Last-Hop. Problems Facing TCP in Wireless Ad Hoc. Approaches to TCP over Ad Hoc. Conclusion. 12. Internet & Ad Hoc Service Discovery. Resource Discovery in the Internet. Service Location Protocol (SLP) Architecture. SLPv2 Packet Format. Jini. Salutation Protocol. Simple Service Discovery Protocol (SSDP). Service Discovery for Ad Hoc. Ad Hoc Service Location Architectures. Conclusions. 13. BLUETOOTH TECHNOLOGY. Bluetooth Specifications. Bluetooth Architectures. Bluetooth Protocols. Bluetooth Service Discovery. Bluetooth MAC. Bluetooth Packet Structure. Bluetooth Audio. Bluetooth Addressing. Bluetooth Limitations. Bluetooth Implementation. Conclusions. 14. WIRELESS APPLICATION PROTOCOL (WAP). The WAP Forum. The WAP Service Model. The WAP Protocol Architecture. The WWW Programming Model. The WAP Programming Model. Conclusions. 15. Ad Hoc Nomadic Mobile Applications. In the Office. While Traveling. Arriving Home. In the Car. Shopping Malls. The Modern Battlefield. Car-to-Car Mobile Communications. Mobile Collaborative Applications. Location/Context Based Mobile Services. Conclusions. 16. Conclusions and The Future. Pervasive Computing. Motorola PIANO Project. UC Berkeley Sensor Networks: Smart Dust. EPFL Terminodes/Large-Scale Networks. 802.15 PANs and 802.16 Wireless MANs. Ad Hoc Everywhere? Glossary of Terms. References. Index.
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paper_title: A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks

paper_content:

In a mobile ad-hoc networks (MANET), one essential issue is medium access control (MAC) which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing work is dedicated to using multiple channels and power control to improve the performance of MANET. We investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: it follows an "on-demand" style to assign channels to mobile hosts; the number of channels required is independent of the network topology and degree; it flexibly adapts to host mobility; no form of clock synchronization is required; and power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol.
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paper_title: Real-time traffic over the IEEE 802.11 medium access control layer

paper_content:

This paper proposes multiple access procedures to transport real-time traffic over IEEE 802.11 wireless local area networks (LANs). As currently defined, the IEEE 802.11 standard supports real-time traffic by switching from its normal, distributed access mode — carrier sense multiple access/collision avoidance (CSMA/CA) — to a centralized one. The centralized mode severely constrains the operation of wireless LANs and provides inadequate performance. Our proposed procedures, on the other hand, are totally distributed and can be overlaid on CSMA/CA. They use the carrier sense capabilities of the network interfaces and require only the ability to jam the channel with pulses of energy of specified duration. The resulting scheme guarantees priority to real-time traffic and provides round-robin service and bounded access delays to real-time stations. This paper examines the behavior of the new access techniques to derive conditions under which they can be considered stable. In addition, it presents simulation results that assess the impact of these access procedures on the average delay of data packets. The simulations are also used to provide estimates of the number of real-time stations that can be supported under various network operating conditions.
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paper_title: A multichannel CSMA MAC protocol with receiver-based channel selection for multihop wireless networks

paper_content:

We propose a CSMA-based medium access control protocol for multihop wireless networks that uses multiple channels and a dynamic channel selection method. The proposed protocol uses one control channel and N data channels, where N is independent of the number of nodes in the network. The source uses an exchange of control packets on the control channel to decide on the best channel to send the data packet on. Channel selection is based on maximizing the signal-to-interference plus noise ratio at the receiver. We present performance evaluations obtained from simulations that demonstrate the effectiveness of the proposed protocol.
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paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
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paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
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paper_title: A power control MAC protocol for ad hoc networks

paper_content:

This paper presents a power control MAC protocol based on the IEEE 802.11 standard. Several researchers have proposed a simple modification of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS-CTS and DATA-ACK. Specifically, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that this scheme can degrade network throughput and can result in higher energy consumption than using IEEE 802.11 without power control. We propose an improved power control protocol which does not degrade throughput and yields energy saving.
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paper_title: Slotted ALOHA multihop packet radio networks with directional antennas

paper_content:

The use of directional antennas in multihop packet radio networks using slotted ALOHA access is considered. Tractable approximations to the network performance in terms of expected forward progress are derived. Results show that packet collisions can be strongly reduced already with moderate gain antennas to allow for a substantial increase in network performance.
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paper_title: A QoS enabled MAC protocol for multi-hop ad hoc wireless networks

paper_content:

A medium access control (MAC) technique for multi-hop wireless networks with quality of service (QoS) assurance is introduced The proposed protocol deals with most of the hidden node problems in a multi-hop environment and also provides service differentiation for various types of traffic: real-time constant bit rate (CBR) traffic, real-time variable bit rate (VBR) traffic, and non-real-time datagram traffic, by guaranteeing bounded delay for real-time traffic, at the same time avoiding lockout of datagram traffic. It uses a distributed mechanism of scheduling and reserving the channel access for real-time sessions. Transmission of datagram or starting packet of a new realtime session is granted only after checking the reservation such that they do not affect the scheduled ongoing real-time sessions. The protocol has been implemented and tested using the VINT Network Simulator 2 (NS2). The performance evaluation and comparison confirm the improved QoS features and multimedia support compared to various existing QoS enabled MAC protocols.
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paper_title: A MAC protocol for mobile ad hoc networks using directional antennas

paper_content:

We propose a medium access control (MAC) protocol for an ad hoc network of mobile wireless terminals that are equipped with multiple directional antennas. Use of directional antennas in ad hoc networks can largely reduce the radio interference, thereby improving the packet throughput. However, the main problem of using directional antennas in such networks is due to the dynamic nature of the network caused by frequent node movements. This gives rise to problems such as locating and tracking during random channel access. The MAC protocol presented in this paper proposes a solution to these problems without the help of additional hardware. Results obtained from detailed computer simulations demonstrate the performance improvement obtained with the proposed scheme.
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paper_title: Low power link and access protocols for wireless multimedia networks

paper_content:

Energy efficiency is a critical issue in wireless networks since the battery life of mobile terminals is limited to only a few hours. One of the goals of protocol development for wireless networks should be power efficiency in mobile terminals. This paper addresses the design of link level and medium access protocols (MACs) for this environment, with the objective of power conservation, in addition to the traditional design goals of maximizing channel utilization and minimizing latency. We consider a local area wireless asynchronous transfer mode (ATM) network supporting virtual circuits and multimedia traffic. A taxonomy of access protocols with respect to power conservation is presented. A comparison of access protocols for wireless networks from a power management perspective is presented. Access protocols such as 802.11, DSA++, and others are considered in the comparison.
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paper_title: Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks

paper_content:

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of powersaving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multihop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.
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paper_title: Soft reservation multiple access with priority assignment (SRMA/PA): a novel MAC protocol for QoS-guaranteed integrated services in mobile ad-hoc networks

paper_content:

A new medium access control (MAC) protocol-soft reservation multiple access with priority assignment (SRMA/PA) protocol-is introduced for supporting the integrated services of real-time and non-real-time applications in mobile ad-hoc networks. The SRMA/PA protocol allows the distributed nodes to contend for and reserve time slots with a RTS/CTS-like "collision-avoidance" handshake and "soft reservation" mechanism augmented with distributed and dynamic access priority control, which virtually achieves capability of the distributed scheduling to guarantee the QoS requirements of the integrated services. We have demonstrated via simulation studies that the multiplexing gain can be significantly improved without much compromising the system complexity. We also have shown that the proposed back-off mechanism designed for the delay-constrained services is useful for further improving the channel utilization.
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paper_title: On the performance of ad hoc networks with beamforming antennas

paper_content:

Beamforming antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. We present a broad-based examination of this potential, focusing on exploiting the longer ranges as well as the reduced interference that beamforming antennas can provide. We consider a number of enhancements to a convectional ad hoc network system, and evaluation the impact of each enhancement using simulation. Such enhancements include "aggressive" and "conservative" channel access models for beamforming antennas, link power control, and directional neighbor discovery. Our simulations are based on detailed modeling on detailed modeling of steered as well as swiched beams using antenna patterns of varying gains, and a realistic radio and propagation model. For the scenarios studied, our results show that beamforming can yield a 28% to 118% (depending upon the density) improvement in throughput, and up to a factor-of-28 reduction in delay. Our study also tells us which mechanisms are likely to be more effective and under what conditions, which in turn identifies areas where future research is neede
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paper_title: Using Directional Antennas for Medium Access Control in Ad Hoc Networks

paper_content:

A composition for use in the treatment for developing seedless fleshy berry of grapes. By treating the flower bunches of a grape tree with a composition containing gibberellin and cyclic 3',5'-adenylic acid in the form of an aqueous solution, it became possible to make seedless fleshy berry from grape trees belonging to varieties other than Delaware, namely belonging to Campbell-Arley, Berry A, Niagara, Kyoho, etc., from which seedless fleshy berry cannot be made by the conventional treatment with gibberellin.
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paper_title: MACA-BI (MACA By Invitation) - A Wireless MAC Protocol for High Speed ad hoc Networking

paper_content:

This paper introduces a new wireless MAC protocol, MACA-BI (MACA by invitation). The protocol is a simplified version of the well known MACA (multiple access collision avoidance) based on the request to send/clear to send (RTS/CTS) handshake. The clear to send (CTS) control message is retained, while the request to send (RTS) part of the RTS/CTS handshake is suppressed. MACA-BI, preserving the data collision free property, is more robust than MACA to problems such as protocol failures (control packet collision and corruption) and finite turn-around time. Analytic results for a 1 Mbps single-hop far-field wireless network, and simulation results for a 10 Mbps multi-hop near-field ATM wireless indoor network, show that MACA-BI outperforms other multiple access protocols in high speed, steady traffic environments (e.g. ATM VBR and CBR) and where the propagation delay can be neglected (typically indoor).
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paper_title: A power controlled multiple access protocol for wireless packet networks

paper_content:

Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
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paper_title: A survey on quality-of-service support for mobile ad hoc networks

paper_content:

The general field of mobile ad hoc networking is still in its infancy. Particularly, the challenge of providing Quality-of-Service (QoS) support for ad hoc networks is an open problem and remains relatively uncharted territory. Providing a complete QoS solution for the ad hoc networking environment requires the interaction and cooperation of several components. These components include: (1) a QoS routing protocol, (2) a resource reservation scheme and (3) a QoS capable medium access control (MAC) layer. In this paper, we present a survey of the current research that has addressed each of these components in the context of ad hoc networks. This work is intended to provide a broad and comprehensive view of the various components and protocols required to provide QoS support in computer networks, focusing primarily on ad hoc networks. First, we introduce the unique characteristics of mobile ad hoc networks, which distinguishing this new network architecture from traditional infrastructured wired and wireless networks (i.e. cellular-based networks). We also discuss the impact of these characteristics on QoS provisioning. Next, we describe the first QoS model proposed for mobile ad hoc networks and its relationship to QoS models proposed for the Internet. We then present a review of the proposed algorithms for each QoS component (e.g. QoS routing, resource reservation and the MAC layer). Copyright © 2002 John Wiley & Sons, Ltd.
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paper_title: Quality-of-service in ad hoc carrier sense multiple access wireless networks

paper_content:

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.
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paper_title: A multichannel CSMA MAC protocol for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, sometimes also called ad hoc networks. The CSMA protocol divides the available bandwidth into several channels and selects an idle channel randomly for packet transmission. It also employs a notion of "soft" channel reservation as it gives preference to the channel that was used for the last successful transmission. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions. We also show that the use of channel reservation provides better performance than multichannel CSMA with purely random idle channel selection.
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paper_title: Floor acquisition multiple access (FAMA) for packet-radio networks

paper_content:

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
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paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
---
paper_title: MACA-BI (MACA By Invitation) - A Wireless MAC Protocol for High Speed ad hoc Networking

paper_content:

This paper introduces a new wireless MAC protocol, MACA-BI (MACA by invitation). The protocol is a simplified version of the well known MACA (multiple access collision avoidance) based on the request to send/clear to send (RTS/CTS) handshake. The clear to send (CTS) control message is retained, while the request to send (RTS) part of the RTS/CTS handshake is suppressed. MACA-BI, preserving the data collision free property, is more robust than MACA to problems such as protocol failures (control packet collision and corruption) and finite turn-around time. Analytic results for a 1 Mbps single-hop far-field wireless network, and simulation results for a 10 Mbps multi-hop near-field ATM wireless indoor network, show that MACA-BI outperforms other multiple access protocols in high speed, steady traffic environments (e.g. ATM VBR and CBR) and where the propagation delay can be neglected (typically indoor).
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paper_title: An Efficient Packet Sensing MAC Protocol for Wireless Networks

paper_content:

The Group Allocation Multiple Access with Packet-Sensing (GAMA-PS) protocol for scheduling real-time and datagram traffic in a wireless LAN is specified and analyzed. By maintaining a dynamically-sized cycle that changes in length depending on the amount of network traffic, GAMA-PS is able to efficiently control channel access while ensuring that there are no collisions of data packets. Each cycle contains a contention period and a group-transmission period; a station with data to send competes for membership in the “transmission group” by using packet sensing to successfully complete an RTS/CTS message exchange during the contention period. Once a station is a member of the transmission group, it is able to transmit a collision-free data packet during each cycle; as long as a station has data to send, it maintains its position in the group.
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paper_title: Design challenges for energy-constrained ad hoc wireless networks

paper_content:

Ad hoc wireless networks enable new and exciting applications, but also pose significant technical challenges. In this article we give a brief overview of ad hoc wireless networks and their applications with a particular emphasis on energy constraints. We then discuss advances in the link, multiple access, network, and application protocols for these networks. We show that cross-layer design of these protocols is imperative to meet emerging application requirements, particularly when energy is a limited resource.
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paper_title: Energy efficiency of media access protocols for mobile data networks

paper_content:

As mobile terminals are powered by a finite battery source, energy constraints play a major role in the design of wireless communications systems. In this letter, based on a general analytical framework, we study the energy efficiency of a class of multiple access schemes, using the average number of correctly transmitted packets for a given amount of allocated energy as an appropriate metric. We show that a good choice of the protocol rules can significantly improve the energy efficiency.
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paper_title: An energy efficient MAC protocol for wireless LANs

paper_content:

This paper presents an optimization of the power saving mechanism in the Distributed Coordination Function (DCF) in the IEEE 802.11 standard. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up for a duration called the ATIM window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has a significant impact on energy saving and throughput achieved by the nodes. This paper proposes an adaptive mechanism to dynamically choose a suitable ATIM window size. We also allow the nodes to stay awake for only a fraction of the beacon interval following the ATIM window. On the other hand, IEEE 802.11 DCF mode requires the nodes to stay awake either for the entire beacon interval following the ATIM window or none at all. Simulation results show that the proposed approach outperforms the IEEE 802.11 power saving mechanism in terms of throughput and the amount of energy consumed.
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paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
---
paper_title: A power control MAC protocol for ad hoc networks

paper_content:

This paper presents a power control MAC protocol based on the IEEE 802.11 standard. Several researchers have proposed a simple modification of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS-CTS and DATA-ACK. Specifically, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that this scheme can degrade network throughput and can result in higher energy consumption than using IEEE 802.11 without power control. We propose an improved power control protocol which does not degrade throughput and yields energy saving.
---
paper_title: Low power link and access protocols for wireless multimedia networks

paper_content:

Energy efficiency is a critical issue in wireless networks since the battery life of mobile terminals is limited to only a few hours. One of the goals of protocol development for wireless networks should be power efficiency in mobile terminals. This paper addresses the design of link level and medium access protocols (MACs) for this environment, with the objective of power conservation, in addition to the traditional design goals of maximizing channel utilization and minimizing latency. We consider a local area wireless asynchronous transfer mode (ATM) network supporting virtual circuits and multimedia traffic. A taxonomy of access protocols with respect to power conservation is presented. A comparison of access protocols for wireless networks from a power management perspective is presented. Access protocols such as 802.11, DSA++, and others are considered in the comparison.
---
paper_title: Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks

paper_content:

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of powersaving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multihop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.
---
paper_title: A power controlled multiple access protocol for wireless packet networks

paper_content:

Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
---
paper_title: Floor acquisition multiple access (FAMA) for packet-radio networks

paper_content:

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
---
paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
---
paper_title: An energy efficient MAC protocol for wireless LANs

paper_content:

This paper presents an optimization of the power saving mechanism in the Distributed Coordination Function (DCF) in the IEEE 802.11 standard. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up for a duration called the ATIM window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has a significant impact on energy saving and throughput achieved by the nodes. This paper proposes an adaptive mechanism to dynamically choose a suitable ATIM window size. We also allow the nodes to stay awake for only a fraction of the beacon interval following the ATIM window. On the other hand, IEEE 802.11 DCF mode requires the nodes to stay awake either for the entire beacon interval following the ATIM window or none at all. Simulation results show that the proposed approach outperforms the IEEE 802.11 power saving mechanism in terms of throughput and the amount of energy consumed.
---
paper_title: Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks

paper_content:

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of powersaving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multihop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.
---
paper_title: An energy efficient MAC protocol for wireless LANs

paper_content:

This paper presents an optimization of the power saving mechanism in the Distributed Coordination Function (DCF) in the IEEE 802.11 standard. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up for a duration called the ATIM window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has a significant impact on energy saving and throughput achieved by the nodes. This paper proposes an adaptive mechanism to dynamically choose a suitable ATIM window size. We also allow the nodes to stay awake for only a fraction of the beacon interval following the ATIM window. On the other hand, IEEE 802.11 DCF mode requires the nodes to stay awake either for the entire beacon interval following the ATIM window or none at all. Simulation results show that the proposed approach outperforms the IEEE 802.11 power saving mechanism in terms of throughput and the amount of energy consumed.
---
paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
---
paper_title: A power control MAC protocol for ad hoc networks

paper_content:

This paper presents a power control MAC protocol based on the IEEE 802.11 standard. Several researchers have proposed a simple modification of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS-CTS and DATA-ACK. Specifically, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that this scheme can degrade network throughput and can result in higher energy consumption than using IEEE 802.11 without power control. We propose an improved power control protocol which does not degrade throughput and yields energy saving.
---
paper_title: Distributed power control in ad-hoc wireless networks

paper_content:

Mobile ad-hoc networking involves peer-to-peer communication in a network with a dynamically changing topology. Achieving energy efficient communication in such a network is more challenging than in cellular networks since there is no centralized arbiter such as a base station that can administer power management. We propose and evaluate a power control loop, similar to those commonly found in cellular CDMA networks, for ad-hoc wireless networks. We use a comprehensive simulation infrastructure consisting of group mobility, group communication and terrain blockage models. A major focus of research in ad-hoc wireless networking is to reduce energy consumption because the wireless devices are envisioned to have small batteries and be incapable of energy scavenging. We show that this power control loop reduces energy consumption per transmitted byte by 10-20%. Furthermore, we show that it increases overall throughput by 15%.
---
paper_title: Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks

paper_content:

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of powersaving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multihop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.
---
paper_title: Minimum energy mobile wireless networks

paper_content:

We describe a distributed position-based network protocol optimized for minimum energy consumption in mobile wireless networks that support peer-to-peer communications. Given any number of randomly deployed nodes over an area, we show that a simple local optimization scheme executed at each node guarantees strong connectivity of the entire network and attains the global minimum energy solution for the stationary case. Due to its localized nature, this protocol proves to be self-reconfiguring and stays close to the minimum energy solution when applied to the case of mobile nodes. Our simulations verify its performance.
---
paper_title: Topology control of multihop wireless networks using transmit power adjustment

paper_content:

We consider the problem of adjusting the transmit powers of nodes in a multihop wireless network (also called an ad hoc network) to create a desired topology. We formulate it as a constrained optimization problem with two constraints-connectivity and biconnectivity, and one optimization objective-maximum power used. We present two centralized algorithms for use in static networks, and prove their optimality. For mobile networks, we present two distributed heuristics that adaptively adjust node transmit powers in response to topological changes and attempt to maintain a connected topology using minimum power. We analyze the throughput, delay, and power consumption of our algorithms using a prototype software implementation, an emulation of a power-controllable radio, and a detailed channel model. Our results show that the performance of multihop wireless networks in practice can be substantially increased with topology control.
---
paper_title: Distributed topology control for power efficient operation in multihop wireless ad hoc networks

paper_content:

The topology of wireless multihop ad hoc networks can be controlled by varying the transmission power of each node. We propose a simple distributed algorithm where each node makes local decisions about its transmission power and these local decisions collectively guarantee global connectivity. Specifically, based on the directional information, a node grows it transmission power until it finds a neighbor node in every direction. The resulting network topology increases the network lifetime by reducing the transmission power and reduces traffic interference by having low node degrees. Moreover, we show that the routes in the multihop network are efficient in power consumption. We give an approximation scheme in which the power consumption of each route can be made arbitrarily close to the optimal by carefully choosing the parameters. Simulation results demonstrate significant performance improvements.
---
paper_title: Resource-limited energy-efficient wireless multicast of session traffic

paper_content:

Addresses the impact of resource limitations on the operation and performance of the broadcasting and multicasting schemes developed for infrastructureless wireless networks in our earlier studies (2000, 2001). These schemes, which provide energy-efficient operation for source-initiated session traffic, were previously studied without fully accounting for such limitations. We discuss the "node-based" nature of the all-wireless medium and demonstrate that improved performance can be obtained when such properties are exploited by networking algorithms. Our broadcast and multicast algorithms involve the joint choice of transmitter power and tree construction, and thus depart from the conventional approach that makes design choices at each layer separately. We indicate how the impact of limited frequency resources can be addressed. Alternative schemes are developed for frequency assignment, and their performance is compared under different levels of traffic load, while also incorporating the impact of limited transceiver resources.
---
paper_title: Span: an energy-efficient coordination algorithm for topology maintenance in ad hoc wireless networks

paper_content:

This paper presents Span, a power saving technique for multi-hop ad hoc wireless networks that reduces energy consumption without significantly diminishing the capacity or connectivity of the network. Span builds on the observation that when a region of a sharedchannel wireless network has a sufficient density of nodes, only a small number of them need be on at any time to forward traffic for active connections. Span is a distributed, randomized algorithm where nodes make local decisions on whether to sleep, or to join a forwarding backbone as a coordinator. Each node bases its decision on an estimate of how many of its neighbors will benefit from it being awake, and the amount of energy available to it. We give a randomized algorithm where coordinators rotate with time, demonstrating how localized node decisions lead to a connected, capacity-preserving global topology. Improvement in system lifetime due to Span increases as the ratio of idle-to-sleep energy consumption increases. Our simulations show that with a practical energy model, system lifetime of an 802.11 network in power saving mode with Span is a factor of two better than without. Additionally, Span also improves communication latency and capacity.
---
paper_title: Low power link and access protocols for wireless multimedia networks

paper_content:

Energy efficiency is a critical issue in wireless networks since the battery life of mobile terminals is limited to only a few hours. One of the goals of protocol development for wireless networks should be power efficiency in mobile terminals. This paper addresses the design of link level and medium access protocols (MACs) for this environment, with the objective of power conservation, in addition to the traditional design goals of maximizing channel utilization and minimizing latency. We consider a local area wireless asynchronous transfer mode (ATM) network supporting virtual circuits and multimedia traffic. A taxonomy of access protocols with respect to power conservation is presented. A comparison of access protocols for wireless networks from a power management perspective is presented. Access protocols such as 802.11, DSA++, and others are considered in the comparison.
---
paper_title: On the construction of energy-efficient broadcast and multicast trees in wireless networks

paper_content:

The wireless networking environment presents formidable challenges to the study of broadcasting and multicasting problems. After addressing the characteristics of wireless networks that distinguish them from wired networks, we introduce and evaluate algorithms for tree construction in infrastructureless, all-wireless applications. The performance metric used to evaluate broadcast and multicast trees is energy-efficiency. We develop the broadcast incremental power algorithm, and adapt it to multicast operation as well. This algorithm exploits the broadcast nature of the wireless communication environment, and addresses the need for energy-efficient operation. We demonstrate that our algorithm provides better performance than algorithms that have been developed for the link-based, wired environment.
---
paper_title: A power controlled multiple access protocol for wireless packet networks

paper_content:

Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
---
paper_title: Multichannel CSMA with signal power-based channel selection for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, using multiple channels and a distributed channel selection scheme. The proposed protocol divides the available bandwidth into N channels where the transmitting station selects an appropriate channel for packet transmission. The selection criterion is based on the interference power measurements on the channels. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions.
---
paper_title: Receiver-initiated busy-tone multiple access in packet radio networks

paper_content:

The ALOHA and Carrier Sense Multiple Access (CSMA) protocols have been proposed for packet radio networks (PRN). However, CSMA/CD which gives superior performance and has been successful applied in local area networks cannot be readily applied in PRN since the locally generated signals will overwhelm a remote transmission, rendering it impossible to tell whether a collision has occurred or not. In addition, CSMA and CSMA/CD suffer from the “hidden node” problem in a multihop PRN. In this paper, we develop the Receiver-Initiated Busy-Tone Multiple Access Protocol to resolve these difficulties. Both fully connected and multihop networks are studied. The busy tone serves as an acknowledgement and prevents conflicting transmissions from other nodes, including “hidden nodes”.
---
paper_title: Packet Switching in Radio Channels: Part I -- Carrier sense multiple-access modes and their throughput-delay characteristics

paper_content:

Radio communication is considered as a method for providing remote terminal access to computers. Digital byte streams from each terminal are partitioned into packets (blocks) and transmitted in a burst mode over a shared radio channel. When many terminals operate in this fashion, transmissions may conflict with and destroy each other. A means for controlling this is for the terminal to sense the presence of other transmissions; this leads to a new method for multiplexing in a packet radio environment: carrier sense multiple access (CSMA). Two protocols are described for CSMA and their throughput-delay characteristics are given. These results show the large advantage CSMA provides as compared to the random ALOHA access modes.
---
paper_title: A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks

paper_content:

The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This paper considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an "on-demand" style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit) some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
---
paper_title: Hop-reservation multiple access (HRMA) for ad-hoc networks

paper_content:

A new multichannel MAC protocol called hop-reservation multiple access (HRMA) for wireless ad-hoc networks (multi-hop packet radio networks) is introduced, specified and analyzed. HRMA is based on simple half-duplex, very slow frequency-hopping spread spectrum (FHSS) radios and takes advantage of the time synchronization necessary for frequency-hopping. HRMA allows a pair of communicating nodes to reserve a frequency hop using a reservation and handshake mechanism that guarantee collision-free data transmission in the presence of hidden terminals. We analyze the throughput achieved in HRMA for the case of a hypercube network topology assuming variable-length packets, and compare it against the multichannel slotted ALOHA protocol, which represents the current practice of MAC protocols in commercial ad-hoc networks based on spread spectrum radios, such as Metricom's Ricochet system. The numerical results show that HRMA can achieve much higher throughput than multichannel slotted ALOHA within the traffic-load ranges of interest, especially when the average packet length is large compared to the duration of a dwell time in the frequency hopping sequence, in which case the maximum throughput of HRMA is close to the maximum possible value.
---
paper_title: A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks

paper_content:

In a mobile ad-hoc networks (MANET), one essential issue is medium access control (MAC) which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing work is dedicated to using multiple channels and power control to improve the performance of MANET. We investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: it follows an "on-demand" style to assign channels to mobile hosts; the number of channels required is independent of the network topology and degree; it flexibly adapts to host mobility; no form of clock synchronization is required; and power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol.
---
paper_title: A multichannel CSMA MAC protocol with receiver-based channel selection for multihop wireless networks

paper_content:

We propose a CSMA-based medium access control protocol for multihop wireless networks that uses multiple channels and a dynamic channel selection method. The proposed protocol uses one control channel and N data channels, where N is independent of the number of nodes in the network. The source uses an exchange of control packets on the control channel to decide on the best channel to send the data packet on. Channel selection is based on maximizing the signal-to-interference plus noise ratio at the receiver. We present performance evaluations obtained from simulations that demonstrate the effectiveness of the proposed protocol.
---
paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
---
paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
---
paper_title: A multichannel CSMA MAC protocol for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, sometimes also called ad hoc networks. The CSMA protocol divides the available bandwidth into several channels and selects an idle channel randomly for packet transmission. It also employs a notion of "soft" channel reservation as it gives preference to the channel that was used for the last successful transmission. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions. We also show that the use of channel reservation provides better performance than multichannel CSMA with purely random idle channel selection.
---
paper_title: Receiver-initiated busy-tone multiple access in packet radio networks

paper_content:

The ALOHA and Carrier Sense Multiple Access (CSMA) protocols have been proposed for packet radio networks (PRN). However, CSMA/CD which gives superior performance and has been successful applied in local area networks cannot be readily applied in PRN since the locally generated signals will overwhelm a remote transmission, rendering it impossible to tell whether a collision has occurred or not. In addition, CSMA and CSMA/CD suffer from the “hidden node” problem in a multihop PRN. In this paper, we develop the Receiver-Initiated Busy-Tone Multiple Access Protocol to resolve these difficulties. Both fully connected and multihop networks are studied. The busy tone serves as an acknowledgement and prevents conflicting transmissions from other nodes, including “hidden nodes”.
---
paper_title: Packet Switching in Radio Channels: Part I -- Carrier sense multiple-access modes and their throughput-delay characteristics

paper_content:

Radio communication is considered as a method for providing remote terminal access to computers. Digital byte streams from each terminal are partitioned into packets (blocks) and transmitted in a burst mode over a shared radio channel. When many terminals operate in this fashion, transmissions may conflict with and destroy each other. A means for controlling this is for the terminal to sense the presence of other transmissions; this leads to a new method for multiplexing in a packet radio environment: carrier sense multiple access (CSMA). Two protocols are described for CSMA and their throughput-delay characteristics are given. These results show the large advantage CSMA provides as compared to the random ALOHA access modes.
---
paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
---
paper_title: Multichannel CSMA with signal power-based channel selection for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, using multiple channels and a distributed channel selection scheme. The proposed protocol divides the available bandwidth into N channels where the transmitting station selects an appropriate channel for packet transmission. The selection criterion is based on the interference power measurements on the channels. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions.
---
paper_title: A multichannel CSMA MAC protocol for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, sometimes also called ad hoc networks. The CSMA protocol divides the available bandwidth into several channels and selects an idle channel randomly for packet transmission. It also employs a notion of "soft" channel reservation as it gives preference to the channel that was used for the last successful transmission. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions. We also show that the use of channel reservation provides better performance than multichannel CSMA with purely random idle channel selection.
---
paper_title: A design concept for reliable mobile radio networks with frequency hopping signaling

paper_content:

The design of a packet radio network must reflect the operational requirements and environmental constraints to which it is subject. In this paper, we outline those features that distinguish the High Frequency (HF) Intra Task Force (ITF) Network from other packet radio networks, and we present a design concept for this network that encompasses organizational structure, waveform design, and channel access. Network survivability is achieved through the use of distributed network control and frequency hopping spread-spectrum signaling. We demonstrate how the execution of the fully distributed Linked Cluster Algorithm can enable a network to reconfigure itself when it is affected by connectivity changes such as those resulting from jamming. Additional resistance against jamming is provided by frequency hopping, which leads naturally to the use of code division mutiple access (CDMA) techniques that permit the simultaneous successful transmission by several users. Distributed algorithms that exploit CDMA properties have been developed to schedule contention-free transmissions for much of the channel access in this network. Contention-based channel access protocols can also be implemented in conjunction with the Linked Cluster network structure. The design concept presented in this paper provides a high degree of survivability and flexibility, to accommodate changing environmental conditions and user demands.
---
paper_title: Hop-reservation multiple access (HRMA) for ad-hoc networks

paper_content:

A new multichannel MAC protocol called hop-reservation multiple access (HRMA) for wireless ad-hoc networks (multi-hop packet radio networks) is introduced, specified and analyzed. HRMA is based on simple half-duplex, very slow frequency-hopping spread spectrum (FHSS) radios and takes advantage of the time synchronization necessary for frequency-hopping. HRMA allows a pair of communicating nodes to reserve a frequency hop using a reservation and handshake mechanism that guarantee collision-free data transmission in the presence of hidden terminals. We analyze the throughput achieved in HRMA for the case of a hypercube network topology assuming variable-length packets, and compare it against the multichannel slotted ALOHA protocol, which represents the current practice of MAC protocols in commercial ad-hoc networks based on spread spectrum radios, such as Metricom's Ricochet system. The numerical results show that HRMA can achieve much higher throughput than multichannel slotted ALOHA within the traffic-load ranges of interest, especially when the average packet length is large compared to the duration of a dwell time in the frequency hopping sequence, in which case the maximum throughput of HRMA is close to the maximum possible value.
---
paper_title: The role of spread spectrum in packet radio networks

paper_content:

This paper is devoted to an examination of the key features of spread-spectrum signaling in packet radio networks. The multiple-access capability, capture, and anti-multipath capability of spread spectrum are the principal topics, and the basic features of spread spectrum that enable it to provide these capabilities are illustrated. The interaction between the spread-spectrum signaling and the network protocols is discussed. Methods for performance evaluation are reviewed, and analytical results on the multiple-access capability of spread spectrum are presented.
---
paper_title: An energy efficient MAC protocol for wireless LANs

paper_content:

This paper presents an optimization of the power saving mechanism in the Distributed Coordination Function (DCF) in the IEEE 802.11 standard. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called beacon intervals. At the start of each beacon interval, each node in the power saving mode periodically wakes up for a duration called the ATIM window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the beacon interval. The size of the ATIM window has a significant impact on energy saving and throughput achieved by the nodes. This paper proposes an adaptive mechanism to dynamically choose a suitable ATIM window size. We also allow the nodes to stay awake for only a fraction of the beacon interval following the ATIM window. On the other hand, IEEE 802.11 DCF mode requires the nodes to stay awake either for the entire beacon interval following the ATIM window or none at all. Simulation results show that the proposed approach outperforms the IEEE 802.11 power saving mechanism in terms of throughput and the amount of energy consumed.
---
paper_title: A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks

paper_content:

The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This paper considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an "on-demand" style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit) some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
---
paper_title: A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks

paper_content:

In a mobile ad-hoc networks (MANET), one essential issue is medium access control (MAC) which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing work is dedicated to using multiple channels and power control to improve the performance of MANET. We investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: it follows an "on-demand" style to assign channels to mobile hosts; the number of channels required is independent of the network topology and degree; it flexibly adapts to host mobility; no form of clock synchronization is required; and power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol.
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paper_title: A multichannel CSMA MAC protocol with receiver-based channel selection for multihop wireless networks

paper_content:

We propose a CSMA-based medium access control protocol for multihop wireless networks that uses multiple channels and a dynamic channel selection method. The proposed protocol uses one control channel and N data channels, where N is independent of the number of nodes in the network. The source uses an exchange of control packets on the control channel to decide on the best channel to send the data packet on. Channel selection is based on maximizing the signal-to-interference plus noise ratio at the receiver. We present performance evaluations obtained from simulations that demonstrate the effectiveness of the proposed protocol.
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paper_title: Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks

paper_content:

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of powersaving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multihop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.
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paper_title: A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks

paper_content:

The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This paper considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an "on-demand" style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit) some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
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paper_title: A multi-channel MAC protocol with power control for multi-hop mobile ad hoc networks

paper_content:

In a mobile ad-hoc networks (MANET), one essential issue is medium access control (MAC) which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing work is dedicated to using multiple channels and power control to improve the performance of MANET. We investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: it follows an "on-demand" style to assign channels to mobile hosts; the number of channels required is independent of the network topology and degree; it flexibly adapts to host mobility; no form of clock synchronization is required; and power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol.
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paper_title: Performance considerations for slotted spread-spectrum random-access networks with directional antennas

paper_content:

The throughput/delay performance of certain types of spread spectrum random-access (SSRA) networks employing directional antennas is considered. The use of directional antennas in the receiving sites to improve the network performance is presented and analyzed. The basic idea is to reduce the contention of the users (transmitters) by dividing the coverage area into different regions; at the receiving site, a single directional antenna is aimed at one region, so that transmissions from different regions do not interface with each other. In addition to the reduction of the multiuser interference, the directional antennas allow for different classifications, in different regions, of the users according to their physical and link level parameters. The throughput improvement is substantial for heavy-traffic conditions, and the gains are further amplified if the number of available receivers is increased. Numerical results for performance comparison with the case receivers using omnidirectional antennas are also included. >
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paper_title: Design algorithms for multihop packet radio networks with multiple directional antennas stations

paper_content:

A protocol called the simple tone sense (STS) protocol is designed for multihop packet radio networks (PRNs) with multiple directional antennas stations. The protocol can minimize transmission interference by using a group of tones to identify the active neighbors. A variation of the STS protocol called the variable power tone sense (VPTS) protocol is also designed to further reduce interference. Algorithms for assigning tones and for determining the orientation and broadcasting angles of the directional antennas are designed. Design examples are given. Simulation result shows that the STS protocol gives better throughput-delay performance than the busy-tone multiple access protocol, especially when the traffic is heavy. The VPTS protocol gives still better throughput-delay performance than the STS protocol. >
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paper_title: Slotted ALOHA multihop packet radio networks with directional antennas

paper_content:

The use of directional antennas in multihop packet radio networks using slotted ALOHA access is considered. Tractable approximations to the network performance in terms of expected forward progress are derived. Results show that packet collisions can be strongly reduced already with moderate gain antennas to allow for a substantial increase in network performance.
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paper_title: A MAC protocol for mobile ad hoc networks using directional antennas

paper_content:

We propose a medium access control (MAC) protocol for an ad hoc network of mobile wireless terminals that are equipped with multiple directional antennas. Use of directional antennas in ad hoc networks can largely reduce the radio interference, thereby improving the packet throughput. However, the main problem of using directional antennas in such networks is due to the dynamic nature of the network caused by frequent node movements. This gives rise to problems such as locating and tracking during random channel access. The MAC protocol presented in this paper proposes a solution to these problems without the help of additional hardware. Results obtained from detailed computer simulations demonstrate the performance improvement obtained with the proposed scheme.
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paper_title: On the performance of ad hoc networks with beamforming antennas

paper_content:

Beamforming antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. We present a broad-based examination of this potential, focusing on exploiting the longer ranges as well as the reduced interference that beamforming antennas can provide. We consider a number of enhancements to a convectional ad hoc network system, and evaluation the impact of each enhancement using simulation. Such enhancements include "aggressive" and "conservative" channel access models for beamforming antennas, link power control, and directional neighbor discovery. Our simulations are based on detailed modeling on detailed modeling of steered as well as swiched beams using antenna patterns of varying gains, and a realistic radio and propagation model. For the scenarios studied, our results show that beamforming can yield a 28% to 118% (depending upon the density) improvement in throughput, and up to a factor-of-28 reduction in delay. Our study also tells us which mechanisms are likely to be more effective and under what conditions, which in turn identifies areas where future research is neede
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paper_title: Using Directional Antennas for Medium Access Control in Ad Hoc Networks

paper_content:

A composition for use in the treatment for developing seedless fleshy berry of grapes. By treating the flower bunches of a grape tree with a composition containing gibberellin and cyclic 3',5'-adenylic acid in the form of an aqueous solution, it became possible to make seedless fleshy berry from grape trees belonging to varieties other than Delaware, namely belonging to Campbell-Arley, Berry A, Niagara, Kyoho, etc., from which seedless fleshy berry cannot be made by the conventional treatment with gibberellin.
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paper_title: Topology control of multihop wireless networks using transmit power adjustment

paper_content:

We consider the problem of adjusting the transmit powers of nodes in a multihop wireless network (also called an ad hoc network) to create a desired topology. We formulate it as a constrained optimization problem with two constraints-connectivity and biconnectivity, and one optimization objective-maximum power used. We present two centralized algorithms for use in static networks, and prove their optimality. For mobile networks, we present two distributed heuristics that adaptively adjust node transmit powers in response to topological changes and attempt to maintain a connected topology using minimum power. We analyze the throughput, delay, and power consumption of our algorithms using a prototype software implementation, an emulation of a power-controllable radio, and a detailed channel model. Our results show that the performance of multihop wireless networks in practice can be substantially increased with topology control.
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paper_title: Medium access control in a network of ad hoc mobile nodes with heterogeneous power capabilities

paper_content:

MAC layer protocols for wireless ad hoc networks typically assume that the network is homogeneous with respect to the transmit power capability of individual nodes in the network. The IEEE 802.11 MAC protocol has been popular for use in ad hoc networks. We investigate the performance of this protocol when it is used in a network with nodes that transmit at various power levels. We show that overall throughput is lower than the throughput of a network in which all nodes transmit at identical power levels. In addition, low power nodes have a disadvantage in accessing the medium due to higher levels of interference from the high power nodes. We consider propagating the control messages generated by a node wishing to initiate communication to distant nodes so that they may forbear transmissions for some time, thereby allowing clear access to the initiating node. We find that the overhead incurred due to the additional message transmissions outweighs the potential gain achieved by propagating these messages. This indicates that the signalling mechanism used in the IEEE 802.11 standard or the variants thereof are not sufficient to alleviate the loss in throughput and the lack of fairness engendered by networks that are heterogeneous with regard to the transmit power capabilities of individual nodes.
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paper_title: Channel access scheduling in Ad Hoc networks with unidirectional links

paper_content:

A new family of collision-free channel access protocols for ad hoc networks with unidirectional links is introduced. These protocols are based on a distributed contention resolution algorithm that operates at each node based on the list of direct contenders (one-hop neighbors or incident links) and indirect interferences (two-hop neighbors and related links). Depending on the activation scheme (node activation or link activation), a network node uses the identifiers of its neighbors one and two hops away to elect deterministically one or multiple winners for channel access in each contention context (e.g., a time slot or a frequency band). The protocols are shown to be fair and capable of achieving maximum utilization of the channel bandwidth. The delay and throughput characteristics of the channel access protocols is studied by simulations.
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paper_title: Distributed topology control for power efficient operation in multihop wireless ad hoc networks

paper_content:

The topology of wireless multihop ad hoc networks can be controlled by varying the transmission power of each node. We propose a simple distributed algorithm where each node makes local decisions about its transmission power and these local decisions collectively guarantee global connectivity. Specifically, based on the directional information, a node grows it transmission power until it finds a neighbor node in every direction. The resulting network topology increases the network lifetime by reducing the transmission power and reduces traffic interference by having low node degrees. Moreover, we show that the routes in the multihop network are efficient in power consumption. We give an approximation scheme in which the power consumption of each route can be made arbitrarily close to the optimal by carefully choosing the parameters. Simulation results demonstrate significant performance improvements.
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paper_title: Unidirectional links prove costly in wireless ad hoc networks

paper_content:

Most, of t,he routing algorithms for ad hoc net,works assume t,hat all wireless links are bidirect,ional. In realit,y, some links may be unidirect.ional. The presence of such links can jeopardize t,he performance of t,he existing dist,ance vect.or rout.ing algorit.hms. In this paper we show t,hat, dist.ance vector based rout,ing prot.ocols t,hat, account for unidirectional links will require nodes t.o exchange O(n2) informat.ion with each other, where n is t.he number of nodes in t,he nebwork. We also present. modifications to dist,ance vector based routing algorithms to make t,hem work in ad hoc netsworks wit.h unidirectional links.
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paper_title: Providing a bidirectional abstraction for unidirectional ad hoc networks

paper_content:

Several routing protocols for mobile ad hoc networks work efficiently only in bidirectional networks. Unidirectional links may exist in a real network due to variations in transmission power of different nodes, noise or other signal propagation phenomena, and heterogeneity in the transmission hardware of nodes in the network. We introduce a sub-layer called sub routing layer, SRL, between the network and the MAC layer to provide a bidirectional abstraction of the unidirectional network to the routing protocols. We present a scalable and efficient way to provide this abstraction by finding and maintaining multi-hop reverse routes to each unidirectional link. We simulate SRL and a modified version of AODV (ad hoc on demand distance vector) that uses SRL to route packets in a unidirectional network. We observed that with SRL, the packet delivery of AODV in unidirectional networks increases substantially. Further our simulations indicate that reverse routes are often only a few hops long and hence the overhead of using SRL is very low.
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paper_title: QoS in Mobile Ad Hoc Networks

paper_content:

A mobile ad hoc network (MANET) consists of mobile nodes communicating over wireless channels. Routing in MANETs is very challenging due to the random mobility of nodes and unreliability of wireless channels. Therefore most of the existing routing algorithms make only the best effort to find routes for communication but do not provide any performance guarantee. Because of the widespread use of MANETs in real-time applications, it becomes pertinent to provide deterministic network behavior. Quality of Service (QoS) aims to shape the network behavior and provide performance guarantees. In this work, a novel heuristic called Advanced-Optimised Link State Routing (A-OLSR) protocol is designed to provide QoS. It functions by enhancing the connectivity of nodes and establishing more stable routes as compared to standard best-effort Optimised Link State Routing (OLSR) protocol. The simulation results show that A-OLSR provides lower delay, reduces energy consumption and achieves higher throughput without introducing any additional routing overhead as compared to the standard OLSR and it's variants-A$$'$$?-OLSR and A$$''$$??-OLSR. The results also show that A-OLSR provides scalability since it's performance remains consistent with the increasing size of network.
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paper_title: Supporting Service Differentiation in Wireless Packet Networks Using Distributed Control

paper_content:

This paper investigates differentiated services in wireless packet networks using a fully distributed approach that supports service differentiation, radio monitoring, and admission control. While our proposal is generally applicable to distributed wireless access schemes, we design, implement, and evaluate our framework within the context of existing wireless technology. Service differentiation is based on the IEEE 802.11 distributed coordination function (DCF) originally designed to support best-effort data services. We analyze the delay experienced by a mobile host implementing the IEEE 802.11 DCF and derive a closed-form formula. We then extend the DCF to provide service differentiation for delay-sensitive and best-effort traffic based on the results from the analysis. Two distributed estimation algorithms are proposed. These algorithms are evaluated using simulation, analysis, and experimentation. A virtual MAC (VMAC) algorithm passively monitors the radio channel and estimates locally achievable service levels. The VMAC estimates key MAC level statistics related to service quality such as delay, delay variation, packet collision, and packet loss. We show the efficiency of the VMAC algorithm through simulation and consider significantly overlapping cells and highly bursty traffic mixes. In addition, we implement and evaluate the VMAC in an experimental differentiated services wireless testbed. A virtual source (VS) algorithm utilizes the VMAC to estimate application-level service quality. The VS allows application parameters to be tuned in response to dynamic channel conditions based on "virtual delay curves." We demonstrate through simulation that when these distributed victual algorithms are applied to the admission control of the radio channel then a globally stable state can be maintained without the need for complex centralized radio resource management.
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paper_title: A survey on quality-of-service support for mobile ad hoc networks

paper_content:

The general field of mobile ad hoc networking is still in its infancy. Particularly, the challenge of providing Quality-of-Service (QoS) support for ad hoc networks is an open problem and remains relatively uncharted territory. Providing a complete QoS solution for the ad hoc networking environment requires the interaction and cooperation of several components. These components include: (1) a QoS routing protocol, (2) a resource reservation scheme and (3) a QoS capable medium access control (MAC) layer. In this paper, we present a survey of the current research that has addressed each of these components in the context of ad hoc networks. This work is intended to provide a broad and comprehensive view of the various components and protocols required to provide QoS support in computer networks, focusing primarily on ad hoc networks. First, we introduce the unique characteristics of mobile ad hoc networks, which distinguishing this new network architecture from traditional infrastructured wired and wireless networks (i.e. cellular-based networks). We also discuss the impact of these characteristics on QoS provisioning. Next, we describe the first QoS model proposed for mobile ad hoc networks and its relationship to QoS models proposed for the Internet. We then present a review of the proposed algorithms for each QoS component (e.g. QoS routing, resource reservation and the MAC layer). Copyright © 2002 John Wiley & Sons, Ltd.
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paper_title: A Review of Current Routing Protocols for Ad-Hoc Mobile Wireless Networks

paper_content:

An ad hoc mobile network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. In order to facilitate communication within the network, a routing protocol is used to discover routes between nodes. The primary goal of such an ad hoc network routing protocol is correct and efficient route establishment between a pair of nodes so that messages may be delivered in a timely manner. Route construction should be done with a minimum of overhead and bandwidth consumption. This article examines routing protocols for ad hoc networks and evaluates these protocols based on a given set of parameters. The article provides an overview of eight different protocols by presenting their characteristics and functionality, and then provides a comparison and discussion of their respective merits and drawbacks.
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paper_title: QoS in Mobile Ad Hoc Networks

paper_content:

A mobile ad hoc network (MANET) consists of mobile nodes communicating over wireless channels. Routing in MANETs is very challenging due to the random mobility of nodes and unreliability of wireless channels. Therefore most of the existing routing algorithms make only the best effort to find routes for communication but do not provide any performance guarantee. Because of the widespread use of MANETs in real-time applications, it becomes pertinent to provide deterministic network behavior. Quality of Service (QoS) aims to shape the network behavior and provide performance guarantees. In this work, a novel heuristic called Advanced-Optimised Link State Routing (A-OLSR) protocol is designed to provide QoS. It functions by enhancing the connectivity of nodes and establishing more stable routes as compared to standard best-effort Optimised Link State Routing (OLSR) protocol. The simulation results show that A-OLSR provides lower delay, reduces energy consumption and achieves higher throughput without introducing any additional routing overhead as compared to the standard OLSR and it's variants-A$$'$$?-OLSR and A$$''$$??-OLSR. The results also show that A-OLSR provides scalability since it's performance remains consistent with the increasing size of network.
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paper_title: INSIGNIA: IN-BAND SIGNALING SUPPORT FOR QOS IN MOBILE AD HOC NETWORKS

paper_content:

Vaporous alkylene oxides are polymerized by passage over catalysts at elevated temperatures. Alkaline catalysts, such as caustic potash, caustic soda and the oxides or hydroxides of the other alkali metals are suitable for the preparation of highly polymerized wax-like products, which may be liquid or solid, while acid-reacting substances, such as sodium bisulphate, aluminium sulphate, or mixtures of these with small amounts of sulphuric acid or with diluents such as sodium sulphate, or acid phosphates, are suitable catalysts for the preparation of dioxane and its homologues. The temperatures of working lie between 40 DEG -200 DEG C., the range 100-160 DEG C. being preferred. In the examples, (1) ethylene oxide vapour is led over anhydrous caustic soda at the rate of 0,1-0,4 gram per second per litre of catalyst, the catalyst being situated in a vertical iron tube which is maintained at 120-130 DEG C., this temperature regulation being effected by means of a jacket containing a suitable liquid, e.g. ethylene glycol. Cooling in the reaction chamber is also aided by the use of excess of ethylene oxide, which passes out at the lower end of the tube and is returned to the process. The liquid formed is collected in a closed receiver, where it solidifies to a waxy or horn-like mass. This may be freed from enclosed caustic potash by dissolving it in benzene, filtering and evaporating. (2) Anhydrous sodium bisulphate is substituted for the caustic soda of the previous example, and the ethylene oxide passed over it, the vapours condensed and returned to the process. After about 24 hours, the condensate is fractionated, yielding unchanged ethylene oxide, dioxane and a small amount of acetaldehyde ethylene acetal (3) Propylene oxide is passed over anhydrous potassium hydroxide as in example (1). The product is a viscous liquid which is insoluble in water but soluble in most organic solvents, including alcohol, ether, and aromatic hydrocarbons. (4) Propylene oxide is passed over a catalyst consisting of 1 part of sodium bisulphate mixed with 3 parts of anhydrous sodium sulphate. From the issuing vapours, a crude dimethyl dioxane consisting mainly of 2,5 dimethyl dioxane is condensed, distilled in vacuo under reduced pressure, then fractionally distilled.
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paper_title: QoS routing in ad hoc wireless networks

paper_content:

The emergence of nomadic applications have generated a lot of interest in wireless network infrastructures which support multimedia services. We propose a bandwidth routing algorithm for multimedia support in a multihop wireless network. This network can be interconnected to wired networks (e.g. ATM or the Internet) or stand alone. Our bandwidth routing includes bandwidth calculation and reservation schemes. Under such a routing algorithm, we can derive a route to satisfy the bandwidth requirement for the QoS constraint. At a source node, the bandwidth information can be used to decide to accept a new call or not immediately. This is specially important to carry out a fast handoff when interconnecting to an ATM backbone infrastructure. It enables an efficient call admission control. The simulation results show that the bandwidth routing algorithm is very useful in extending the ATM virtual circuit service to the wireless network. Different types of QoS traffic can be integrated in such a dynamic radio network with high performance.
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paper_title: SWAN: service differentiation in stateless wireless ad hoc networks

paper_content:

We propose SWAN, a stateless network model which uses distributed control algorithms to deliver service differentiation in mobile wireless ad hoc networks in a simple, scalable and robust manner. We use rate control for UDP and TCP best-effort traffic, and sender-based admission control for UDP real-time traffic. SWAN uses explicit congestion notification (ECN) to dynamically regulate admitted real-time traffic in the face of network dynamics brought on by mobility or traffic overload conditions. We use the term "soft" real-time services to indicate that real-time sessions could be regulated or dropped due to mobility or excessive traffic overloading at mobile wireless routers. SWAN is designed to limit such conditions, however. A novel aspect of SWAN is that it does not require the support of a QOS-capable MAC. Rather, soft real-time services are built using existing best effort wireless MAC technology. Simulation, analysis, and results from an experimental wireless testbed show that real-time applications experience low and stable delays under various multi-hop, traffic and mobility conditions. The wireless testbed and ns-2 simulator source code are available from the Web (comet.columbia.edu/swan).
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paper_title: A flexible quality of service model for mobile ad-hoc networks

paper_content:

Quality of service (QoS) support in mobile ad-hoc networks (MANETs) is a challenging task. Most of the proposals in the literature only address certain aspects of the QoS support, e.g., QoS routing, QoS medium access control (MAC) and resource reservation. However, none of them proposes a QoS model for MANETs. Meanwhile, two QoS models have been proposed for the Internet, viz., the integrated services (IntServ) model and the differentiated services (DiffServ) model, but these models are aimed for wired networks. In this paper, we propose a flexible QoS model for MANETs (FQMM) which considers the characteristics of MANETs and combines the high quality QoS of IntServ and service differentiation of Diff-Serv. Salient features of FQMM include: dynamics roles of nodes, hybrid provisioning and adaptive conditioning. Preliminary simulation results show that FQMM achieves better performance in terms of throughput and service differentiation than the best-effort model.
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paper_title: Distributed fair scheduling in a wireless LAN

paper_content:

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling , it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmission such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.
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paper_title: Medium access control protocols for multimedia traffic in wireless networks

paper_content:

This article presents a survey on medium access control protocols for multimedia traffic in wireless networks. A basic overview of MAC protocol concepts is presented, and a framework is developed on which to base qualitative comparisons. The MAC protocols covered include third-generation TDMA and CDMA schemes intended for use in a single-hop wireless system. The operation of each protocol is explained, and its advantages and disadvantages ore presented. Finally, a qualitative comparative outline of the discussed protocols is provided, based on multimedia traffic requirements.
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paper_title: IEEE 802.11 e contention-based channel access (EDCF) performance evaluation

paper_content:

IEEE 802.11 e medium access control (MAC) is an emerging supplement to the IEEE 802.11 wireless local area network (WLAN) standard to support quality-of-service (QoS). The 802.11e MAC is based on both centrally-controlled and contention-based channel accesses. In this paper, we evaluate the contention-based channel access mechanism, called enhanced distributed coordination function (EDCF), in comparison with the 802.11 legacy MAC. The ECDF provides differentiated channel access to frames with different priorities. We also consider an optional feature of the EDCF, called contention-free burst (CFB), which allows multiple MAC frame transmissions during a single transmission opportunity (TXOP). Through our simulation study, we conclude that the EDCF can provide differentiated channel access for different traffic types. Furthermore, the CFB is found to enhance the EDCF performance by increasing the overall system throughput and achieving more acceptable streaming quality in terms of frame losses and delays.
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paper_title: Adaptive Clustering for Mobile Wireless Networks

paper_content:

This paper describes a self-organizing, multihop, mobile radio network which relies on a code-division access scheme for multimedia support. In the proposed network architecture, nodes are organized into nonoverlapping clusters. The clusters are independently controlled, and are dynamically reconfigured as the nodes move. This network architecture has three main advantages. First, it provides spatial reuse of the bandwidth due to node clustering. Second, bandwidth can be shared or reserved in a controlled fashion in each cluster. Finally, the cluster algorithm is robust in the face of topological changes caused by node motion, node failure, and node insertion/removal. Simulation shows that this architecture provides an efficient, stable infrastructure for the integration of different types of traffic in a dynamic radio network.
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paper_title: Multicluster, mobile, multimedia radio network

paper_content:

A multi-cluster, multi-hop packet radio network architecture for wireless adaptive mobile information systems is presented. The proposed network supports multimedia traffic and relies on both time division and code division access schemes. This radio network is not supported by a wired infrastructure as conventional cellular systems are. Thus, it can be instantly deployed in areas with no infrastructure at all. By using a distributed clustering algorithm, nodes are organized into clusters. The clusterheads act as local coordinators to resolve channel scheduling, perform power measurement/control, maintain time division frame synchronization, and enhance the spatial reuse of time slots and codes. Moreover, to guarantee bandwidth for real time traffic, the architecture supports virtual circuits and allocates bandwidth to circuits at call setup time. The network is scalable to large numbers of nodes, and can handle mobility. Simulation experiments evaluate the performance of the proposed scheme in static and mobile environments.
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paper_title: Real-time traffic over the IEEE 802.11 medium access control layer

paper_content:

This paper proposes multiple access procedures to transport real-time traffic over IEEE 802.11 wireless local area networks (LANs). As currently defined, the IEEE 802.11 standard supports real-time traffic by switching from its normal, distributed access mode — carrier sense multiple access/collision avoidance (CSMA/CA) — to a centralized one. The centralized mode severely constrains the operation of wireless LANs and provides inadequate performance. Our proposed procedures, on the other hand, are totally distributed and can be overlaid on CSMA/CA. They use the carrier sense capabilities of the network interfaces and require only the ability to jam the channel with pulses of energy of specified duration. The resulting scheme guarantees priority to real-time traffic and provides round-robin service and bounded access delays to real-time stations. This paper examines the behavior of the new access techniques to derive conditions under which they can be considered stable. In addition, it presents simulation results that assess the impact of these access procedures on the average delay of data packets. The simulations are also used to provide estimates of the number of real-time stations that can be supported under various network operating conditions.
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paper_title: A QoS enabled MAC protocol for multi-hop ad hoc wireless networks

paper_content:

A medium access control (MAC) technique for multi-hop wireless networks with quality of service (QoS) assurance is introduced The proposed protocol deals with most of the hidden node problems in a multi-hop environment and also provides service differentiation for various types of traffic: real-time constant bit rate (CBR) traffic, real-time variable bit rate (VBR) traffic, and non-real-time datagram traffic, by guaranteeing bounded delay for real-time traffic, at the same time avoiding lockout of datagram traffic. It uses a distributed mechanism of scheduling and reserving the channel access for real-time sessions. Transmission of datagram or starting packet of a new realtime session is granted only after checking the reservation such that they do not affect the scheduled ongoing real-time sessions. The protocol has been implemented and tested using the VINT Network Simulator 2 (NS2). The performance evaluation and comparison confirm the improved QoS features and multimedia support compared to various existing QoS enabled MAC protocols.
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paper_title: Soft reservation multiple access with priority assignment (SRMA/PA): a novel MAC protocol for QoS-guaranteed integrated services in mobile ad-hoc networks

paper_content:

A new medium access control (MAC) protocol-soft reservation multiple access with priority assignment (SRMA/PA) protocol-is introduced for supporting the integrated services of real-time and non-real-time applications in mobile ad-hoc networks. The SRMA/PA protocol allows the distributed nodes to contend for and reserve time slots with a RTS/CTS-like "collision-avoidance" handshake and "soft reservation" mechanism augmented with distributed and dynamic access priority control, which virtually achieves capability of the distributed scheduling to guarantee the QoS requirements of the integrated services. We have demonstrated via simulation studies that the multiplexing gain can be significantly improved without much compromising the system complexity. We also have shown that the proposed back-off mechanism designed for the delay-constrained services is useful for further improving the channel utilization.
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paper_title: Quality-of-service in ad hoc carrier sense multiple access wireless networks

paper_content:

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.
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paper_title: IEEE 802.11 e contention-based channel access (EDCF) performance evaluation

paper_content:

IEEE 802.11 e medium access control (MAC) is an emerging supplement to the IEEE 802.11 wireless local area network (WLAN) standard to support quality-of-service (QoS). The 802.11e MAC is based on both centrally-controlled and contention-based channel accesses. In this paper, we evaluate the contention-based channel access mechanism, called enhanced distributed coordination function (EDCF), in comparison with the 802.11 legacy MAC. The ECDF provides differentiated channel access to frames with different priorities. We also consider an optional feature of the EDCF, called contention-free burst (CFB), which allows multiple MAC frame transmissions during a single transmission opportunity (TXOP). Through our simulation study, we conclude that the EDCF can provide differentiated channel access for different traffic types. Furthermore, the CFB is found to enhance the EDCF performance by increasing the overall system throughput and achieving more acceptable streaming quality in terms of frame losses and delays.
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paper_title: Supporting Service Differentiation in Wireless Packet Networks Using Distributed Control

paper_content:

This paper investigates differentiated services in wireless packet networks using a fully distributed approach that supports service differentiation, radio monitoring, and admission control. While our proposal is generally applicable to distributed wireless access schemes, we design, implement, and evaluate our framework within the context of existing wireless technology. Service differentiation is based on the IEEE 802.11 distributed coordination function (DCF) originally designed to support best-effort data services. We analyze the delay experienced by a mobile host implementing the IEEE 802.11 DCF and derive a closed-form formula. We then extend the DCF to provide service differentiation for delay-sensitive and best-effort traffic based on the results from the analysis. Two distributed estimation algorithms are proposed. These algorithms are evaluated using simulation, analysis, and experimentation. A virtual MAC (VMAC) algorithm passively monitors the radio channel and estimates locally achievable service levels. The VMAC estimates key MAC level statistics related to service quality such as delay, delay variation, packet collision, and packet loss. We show the efficiency of the VMAC algorithm through simulation and consider significantly overlapping cells and highly bursty traffic mixes. In addition, we implement and evaluate the VMAC in an experimental differentiated services wireless testbed. A virtual source (VS) algorithm utilizes the VMAC to estimate application-level service quality. The VS allows application parameters to be tuned in response to dynamic channel conditions based on "virtual delay curves." We demonstrate through simulation that when these distributed victual algorithms are applied to the admission control of the radio channel then a globally stable state can be maintained without the need for complex centralized radio resource management.
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paper_title: Real-time traffic over the IEEE 802.11 medium access control layer

paper_content:

This paper proposes multiple access procedures to transport real-time traffic over IEEE 802.11 wireless local area networks (LANs). As currently defined, the IEEE 802.11 standard supports real-time traffic by switching from its normal, distributed access mode — carrier sense multiple access/collision avoidance (CSMA/CA) — to a centralized one. The centralized mode severely constrains the operation of wireless LANs and provides inadequate performance. Our proposed procedures, on the other hand, are totally distributed and can be overlaid on CSMA/CA. They use the carrier sense capabilities of the network interfaces and require only the ability to jam the channel with pulses of energy of specified duration. The resulting scheme guarantees priority to real-time traffic and provides round-robin service and bounded access delays to real-time stations. This paper examines the behavior of the new access techniques to derive conditions under which they can be considered stable. In addition, it presents simulation results that assess the impact of these access procedures on the average delay of data packets. The simulations are also used to provide estimates of the number of real-time stations that can be supported under various network operating conditions.
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paper_title: Quality-of-service in ad hoc carrier sense multiple access wireless networks

paper_content:

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.
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paper_title: Real-time traffic over the IEEE 802.11 medium access control layer

paper_content:

This paper proposes multiple access procedures to transport real-time traffic over IEEE 802.11 wireless local area networks (LANs). As currently defined, the IEEE 802.11 standard supports real-time traffic by switching from its normal, distributed access mode — carrier sense multiple access/collision avoidance (CSMA/CA) — to a centralized one. The centralized mode severely constrains the operation of wireless LANs and provides inadequate performance. Our proposed procedures, on the other hand, are totally distributed and can be overlaid on CSMA/CA. They use the carrier sense capabilities of the network interfaces and require only the ability to jam the channel with pulses of energy of specified duration. The resulting scheme guarantees priority to real-time traffic and provides round-robin service and bounded access delays to real-time stations. This paper examines the behavior of the new access techniques to derive conditions under which they can be considered stable. In addition, it presents simulation results that assess the impact of these access procedures on the average delay of data packets. The simulations are also used to provide estimates of the number of real-time stations that can be supported under various network operating conditions.
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paper_title: Quality-of-service in ad hoc carrier sense multiple access wireless networks

paper_content:

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.
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paper_title: Floor acquisition multiple access (FAMA) for packet-radio networks

paper_content:

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
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paper_title: Distributed fair scheduling in a wireless LAN

paper_content:

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling , it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmission such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.
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paper_title: A QoS enabled MAC protocol for multi-hop ad hoc wireless networks

paper_content:

A medium access control (MAC) technique for multi-hop wireless networks with quality of service (QoS) assurance is introduced The proposed protocol deals with most of the hidden node problems in a multi-hop environment and also provides service differentiation for various types of traffic: real-time constant bit rate (CBR) traffic, real-time variable bit rate (VBR) traffic, and non-real-time datagram traffic, by guaranteeing bounded delay for real-time traffic, at the same time avoiding lockout of datagram traffic. It uses a distributed mechanism of scheduling and reserving the channel access for real-time sessions. Transmission of datagram or starting packet of a new realtime session is granted only after checking the reservation such that they do not affect the scheduled ongoing real-time sessions. The protocol has been implemented and tested using the VINT Network Simulator 2 (NS2). The performance evaluation and comparison confirm the improved QoS features and multimedia support compared to various existing QoS enabled MAC protocols.
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paper_title: Distributed fair scheduling in a wireless LAN

paper_content:

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling , it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmission such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.
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paper_title: Achieving MAC layer fairness in wireless packet networks

paper_content:

Link-layer fairness models that have been proposed for wireline and packet cellular networks cannot be generalized for shared channel wireless networks because of the unique characteristics of the wireless channel, such as location-dependent contention, inherent conflict between optimizing channel utilization and achieving fairness, and the absence of any centralized control. In this paper, we propose a general analytical framework that captures the unique characteristics of shared wireless channels and allows the modeling of a large class of system-wide fairness models via the specification of per-flow utility functions. We show that system-wide fairness can be achieved without explicit global coordination so long as each node executes a contention resolution algorithm that is designed to optimize its local utility function. We present a general mechanism for translating a given fairness model in our framework into a corresponding contention resolution algorithm . Using this translation, we derive the backoff algorithm for achieving proportional fairness in wireless shared channels, and compare the fairness properties of this algorithm with both the ideal proportional fairness objective, and state-of-the-art backoff-based contention resolution algorithms. We believe that the two aspects of the proposed framework, i.e. the ability to specify arbitrary fairness models via local utility functions, and the ability to automatically generate local contention resolution mechanisms in response to a given utility function, together provide the path for achieving flexible service differentiation in future shared channel wireless networks.
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paper_title: A self-clocked fair queueing scheme for broadband applications

paper_content:

An efficient fair queueing scheme which is feasible for broadband implementation is proposed and its performance is analyzed. The author defines fairness in a self-contained manner, eliminating the need for the hypothetical fluid-flow reference system used in the present state of art and thereby removing the associated computational complexity. The scheme is based on the adoption of an internally generated virtual time as the index of work progress, hence the name self-clocked fair queueing. The author proves that the scheme possesses the desired fairness property and is nearly optimal, in the sense that the maximum permissible disparity among the normalized services offered to the backlogged sessions is never more than two times the corresponding figure in any packet-based queueing system. >
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paper_title: Floor acquisition multiple access (FAMA) for packet-radio networks

paper_content:

A family of medium access control protocols for single-channel packet radio networks is specified and analyzed. These protocols are based on a new channel access discipline called floor acquisition multiple access (FAMA), which consists of both carrier sensing and a collision-avoidance dialogue between a source and the intended receiver of a packet. Control of the channel (the floor) is assigned to at most one station in the network at any given time, and this station is guaranteed to be able to transmit one or more data packets to different destinations with no collision with transmissions from other stations. The minimum length needed in control packets to acquire the floor is specified as a function of the channel propagation time. The medium access collision avoidance (MACA) protocol proposed by Karn and variants of CSMA based on collision avoidance are shown to be variants of FAMA protocols when control packets last long enough compared to the channel propagation delay. The throughput of FAMA protocols is analyzed and compared with the throughput of non-persistent CSMA. This analysis shows that using carrier sensing as an integral part of the floor acquisition strategy provides the benefits of MACA in the presence of hidden terminals, and can provide a throughput comparable to, or better than, that of non-persistent CSMA when no hidden terminals exist.
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paper_title: Distributed fair scheduling in a wireless LAN

paper_content:

Fairness is an important issue when accessing a shared wireless channel. With fair scheduling , it is possible to allocate bandwidth in proportion to weights of the packet flows sharing the channel. This paper presents a fully distributed algorithm for fair scheduling in a wireless LAN. The algorithm can be implemented without using a centralized coordinator to arbitrate medium access. The proposed protocol is derived from the Distributed Coordination Function in the IEEE 802.11 standard. Simulation results show that the proposed algorithm is able to schedule transmission such that the bandwidth allocated to different flows is proportional to their weights. An attractive feature of the proposed approach is that it can be implemented with simple modifications to the IEEE 802.11 standard.
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paper_title: Performance considerations for slotted spread-spectrum random-access networks with directional antennas

paper_content:

The throughput/delay performance of certain types of spread spectrum random-access (SSRA) networks employing directional antennas is considered. The use of directional antennas in the receiving sites to improve the network performance is presented and analyzed. The basic idea is to reduce the contention of the users (transmitters) by dividing the coverage area into different regions; at the receiving site, a single directional antenna is aimed at one region, so that transmissions from different regions do not interface with each other. In addition to the reduction of the multiuser interference, the directional antennas allow for different classifications, in different regions, of the users according to their physical and link level parameters. The throughput improvement is substantial for heavy-traffic conditions, and the gains are further amplified if the number of available receivers is increased. Numerical results for performance comparison with the case receivers using omnidirectional antennas are also included. >
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paper_title: Medium access control in a network of ad hoc mobile nodes with heterogeneous power capabilities

paper_content:

MAC layer protocols for wireless ad hoc networks typically assume that the network is homogeneous with respect to the transmit power capability of individual nodes in the network. The IEEE 802.11 MAC protocol has been popular for use in ad hoc networks. We investigate the performance of this protocol when it is used in a network with nodes that transmit at various power levels. We show that overall throughput is lower than the throughput of a network in which all nodes transmit at identical power levels. In addition, low power nodes have a disadvantage in accessing the medium due to higher levels of interference from the high power nodes. We consider propagating the control messages generated by a node wishing to initiate communication to distant nodes so that they may forbear transmissions for some time, thereby allowing clear access to the initiating node. We find that the overhead incurred due to the additional message transmissions outweighs the potential gain achieved by propagating these messages. This indicates that the signalling mechanism used in the IEEE 802.11 standard or the variants thereof are not sufficient to alleviate the loss in throughput and the lack of fairness engendered by networks that are heterogeneous with regard to the transmit power capabilities of individual nodes.
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paper_title: A new multi-channel MAC protocol with on-demand channel assignment for multi-hop mobile ad hoc networks

paper_content:

The wireless mobile ad hoc network (MANET) architecture has received a lot of attention recently. This paper considers the access of multiple channels in a MANET with multi-hop communication behavior. We point out several interesting issues when using multiple channels. We then propose a new multi-channel MAC protocol, which is characterized by the following features: (i) it follows an "on-demand" style to assign channels to mobile hosts, (ii) the number of channels required is independent of the network topology and degree, (iii) it flexibly adapts to host mobility and only exchanges few control messages to achieve channel assignment and medium access, and (iv) no clock synchronization is required. Compared to existing protocols, some assign channels to hosts statically (thus a host will occupy a channel even when it has no intention to transmit) some require a number of channels which is a function of the maximum connectivity, and some necessitate a clock synchronization among all hosts in the MANET. Extensive simulations are conducted to evaluate the proposed protocol.
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paper_title: Design algorithms for multihop packet radio networks with multiple directional antennas stations

paper_content:

A protocol called the simple tone sense (STS) protocol is designed for multihop packet radio networks (PRNs) with multiple directional antennas stations. The protocol can minimize transmission interference by using a group of tones to identify the active neighbors. A variation of the STS protocol called the variable power tone sense (VPTS) protocol is also designed to further reduce interference. Algorithms for assigning tones and for determining the orientation and broadcasting angles of the directional antennas are designed. Design examples are given. Simulation result shows that the STS protocol gives better throughput-delay performance than the busy-tone multiple access protocol, especially when the traffic is heavy. The VPTS protocol gives still better throughput-delay performance than the STS protocol. >
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paper_title: Hop-reservation multiple access (HRMA) for ad-hoc networks

paper_content:

A new multichannel MAC protocol called hop-reservation multiple access (HRMA) for wireless ad-hoc networks (multi-hop packet radio networks) is introduced, specified and analyzed. HRMA is based on simple half-duplex, very slow frequency-hopping spread spectrum (FHSS) radios and takes advantage of the time synchronization necessary for frequency-hopping. HRMA allows a pair of communicating nodes to reserve a frequency hop using a reservation and handshake mechanism that guarantee collision-free data transmission in the presence of hidden terminals. We analyze the throughput achieved in HRMA for the case of a hypercube network topology assuming variable-length packets, and compare it against the multichannel slotted ALOHA protocol, which represents the current practice of MAC protocols in commercial ad-hoc networks based on spread spectrum radios, such as Metricom's Ricochet system. The numerical results show that HRMA can achieve much higher throughput than multichannel slotted ALOHA within the traffic-load ranges of interest, especially when the average packet length is large compared to the duration of a dwell time in the frequency hopping sequence, in which case the maximum throughput of HRMA is close to the maximum possible value.
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paper_title: Real-time traffic over the IEEE 802.11 medium access control layer

paper_content:

This paper proposes multiple access procedures to transport real-time traffic over IEEE 802.11 wireless local area networks (LANs). As currently defined, the IEEE 802.11 standard supports real-time traffic by switching from its normal, distributed access mode — carrier sense multiple access/collision avoidance (CSMA/CA) — to a centralized one. The centralized mode severely constrains the operation of wireless LANs and provides inadequate performance. Our proposed procedures, on the other hand, are totally distributed and can be overlaid on CSMA/CA. They use the carrier sense capabilities of the network interfaces and require only the ability to jam the channel with pulses of energy of specified duration. The resulting scheme guarantees priority to real-time traffic and provides round-robin service and bounded access delays to real-time stations. This paper examines the behavior of the new access techniques to derive conditions under which they can be considered stable. In addition, it presents simulation results that assess the impact of these access procedures on the average delay of data packets. The simulations are also used to provide estimates of the number of real-time stations that can be supported under various network operating conditions.
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paper_title: A multichannel CSMA MAC protocol with receiver-based channel selection for multihop wireless networks

paper_content:

We propose a CSMA-based medium access control protocol for multihop wireless networks that uses multiple channels and a dynamic channel selection method. The proposed protocol uses one control channel and N data channels, where N is independent of the number of nodes in the network. The source uses an exchange of control packets on the control channel to decide on the best channel to send the data packet on. Channel selection is based on maximizing the signal-to-interference plus noise ratio at the receiver. We present performance evaluations obtained from simulations that demonstrate the effectiveness of the proposed protocol.
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paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

paper_content:

In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
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paper_title: Medium Access Control Mechanisms in Mobile Ad Hoc Networks

paper_content:

Medium access control protocol plays an important role in providing fair and efficient allocation of limited bandwidth in wireless LANs. The basic medium access model in the IEEE 802.11 standard, known as DCF (Distributed Coordination Function), is widely used in wireless LANs. Research efforts in wireless multihop networks, where wireless nodes need to forward packets on other’s behalf, try to measure up to or improve upon this standard. This chapter presents an in-depth discussion on the problems with IEEE 802.11, especially those relevant in a multihop network, and discusses various techniques that have been proposed to enhance the channel utilization of multihop wireless networks.
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paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
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paper_title: A power control MAC protocol for ad hoc networks

paper_content:

This paper presents a power control MAC protocol based on the IEEE 802.11 standard. Several researchers have proposed a simple modification of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS-CTS and DATA-ACK. Specifically, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that this scheme can degrade network throughput and can result in higher energy consumption than using IEEE 802.11 without power control. We propose an improved power control protocol which does not degrade throughput and yields energy saving.
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paper_title: Slotted ALOHA multihop packet radio networks with directional antennas

paper_content:

The use of directional antennas in multihop packet radio networks using slotted ALOHA access is considered. Tractable approximations to the network performance in terms of expected forward progress are derived. Results show that packet collisions can be strongly reduced already with moderate gain antennas to allow for a substantial increase in network performance.
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paper_title: A QoS enabled MAC protocol for multi-hop ad hoc wireless networks

paper_content:

A medium access control (MAC) technique for multi-hop wireless networks with quality of service (QoS) assurance is introduced The proposed protocol deals with most of the hidden node problems in a multi-hop environment and also provides service differentiation for various types of traffic: real-time constant bit rate (CBR) traffic, real-time variable bit rate (VBR) traffic, and non-real-time datagram traffic, by guaranteeing bounded delay for real-time traffic, at the same time avoiding lockout of datagram traffic. It uses a distributed mechanism of scheduling and reserving the channel access for real-time sessions. Transmission of datagram or starting packet of a new realtime session is granted only after checking the reservation such that they do not affect the scheduled ongoing real-time sessions. The protocol has been implemented and tested using the VINT Network Simulator 2 (NS2). The performance evaluation and comparison confirm the improved QoS features and multimedia support compared to various existing QoS enabled MAC protocols.
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paper_title: A MAC protocol for mobile ad hoc networks using directional antennas

paper_content:

We propose a medium access control (MAC) protocol for an ad hoc network of mobile wireless terminals that are equipped with multiple directional antennas. Use of directional antennas in ad hoc networks can largely reduce the radio interference, thereby improving the packet throughput. However, the main problem of using directional antennas in such networks is due to the dynamic nature of the network caused by frequent node movements. This gives rise to problems such as locating and tracking during random channel access. The MAC protocol presented in this paper proposes a solution to these problems without the help of additional hardware. Results obtained from detailed computer simulations demonstrate the performance improvement obtained with the proposed scheme.
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paper_title: Dynamic Tuning of the IEEE 802.11 Protocol to Achieve a Theoretical Throughput Limit

paper_content:

In wireless LANs (WLANs), the medium access control (MAC) protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel. In this paper we focus on the efficiency of the IEEE 802.11 standard for WLANs. Specifically, we analytically derive the average size of the contention window that maximizes the throughput, hereafter theoretical throughput limit, and we show that: 1) depending on the network configuration, the standard can operate very far from the theoretical throughput limit; and 2) an appropriate tuning of the backoff algorithm can drive the IEEE 802.11 protocol close to the theoretical throughput limit. Hence we propose a distributed algorithm that enables each station to tune its backoff algorithm at run-time. The performances of the IEEE 802.11 protocol, enhanced with our algorithm, are extensively investigated by simulation. Specifically, we investigate the sensitiveness of our algorithm to some network configuration parameters (number of active stations, presence of hidden terminals). Our results indicate that the capacity of the enhanced protocol is very close to the theoretical upper bound in all the configurations analyzed.
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paper_title: Does the IEEE 802.11 MAC protocol work well in multihop wireless ad hoc networks

paper_content:

The IEEE 802.11 MAC protocol is the standard for wireless LANs; it is widely used in testbeds and simulations for wireless multihop ad hoc networks. However, this protocol was not designed for multihop networks. Although it can support some ad hoc network architecture, it is not intended to support the wireless mobile ad hoc network, in which multihop connectivity is one of the most prominent features. In this article we focus on the following question: can the IEEE 802.11 MAC protocol function well in multihop networks? By presenting several serious problems encountered in an IEEE 802.11-based multihop network and revealing the in-depth cause of these problems, we conclude that the current version of this wireless LAN protocol does not function well in multihop ad hoc networks. We thus doubt whether the WaveLAN-based system is workable as a mobile ad hoc testbed.
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paper_title: On the performance of ad hoc networks with beamforming antennas

paper_content:

Beamforming antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. We present a broad-based examination of this potential, focusing on exploiting the longer ranges as well as the reduced interference that beamforming antennas can provide. We consider a number of enhancements to a convectional ad hoc network system, and evaluation the impact of each enhancement using simulation. Such enhancements include "aggressive" and "conservative" channel access models for beamforming antennas, link power control, and directional neighbor discovery. Our simulations are based on detailed modeling on detailed modeling of steered as well as swiched beams using antenna patterns of varying gains, and a realistic radio and propagation model. For the scenarios studied, our results show that beamforming can yield a 28% to 118% (depending upon the density) improvement in throughput, and up to a factor-of-28 reduction in delay. Our study also tells us which mechanisms are likely to be more effective and under what conditions, which in turn identifies areas where future research is neede
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paper_title: Investigating the energy consumption of a wireless network interface in an ad hoc networking environment

paper_content:

Energy-aware design and evaluation of network protocols requires knowledge of the energy consumption behavior of actual wireless interfaces. But little practical information is available about the energy consumption behavior of well-known wireless network interfaces and device specifications do not provide information in a form that is helpful to protocol developers. This paper describes a series of experiments which obtained detailed measurements of the energy consumption of an IEEE 802.11 wireless network interface operating in an ad hoc networking environment. The data is presented as a collection of linear equations for calculating the energy consumed in sending, receiving and discarding broadcast and point-to-point data packets of various sizes. Some implications for protocol design and evaluation in ad hoc networks are discussed.
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paper_title: Differentiation mechanisms for IEEE 802.11

paper_content:

The IETF is currently working on service differentiation in the Internet. However, in wireless environments where bandwidth is scarce and channel conditions are variable, IP differentiated services are sub-optimal without lower layers' support. We present three service differentiation schemes for IEEE 802.11. The first one is based on scaling the contention window according to the priority of each flow or user. The second one assigns different inter-frame spacings to different users. Finally, the last one uses different maximum frame lengths for different users. We simulate and analyze the performance of each scheme with TCP and UDP flows.
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paper_title: Using Directional Antennas for Medium Access Control in Ad Hoc Networks

paper_content:

A composition for use in the treatment for developing seedless fleshy berry of grapes. By treating the flower bunches of a grape tree with a composition containing gibberellin and cyclic 3',5'-adenylic acid in the form of an aqueous solution, it became possible to make seedless fleshy berry from grape trees belonging to varieties other than Delaware, namely belonging to Campbell-Arley, Berry A, Niagara, Kyoho, etc., from which seedless fleshy berry cannot be made by the conventional treatment with gibberellin.
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paper_title: A power controlled multiple access protocol for wireless packet networks

paper_content:

Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.
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paper_title: Quality-of-service in ad hoc carrier sense multiple access wireless networks

paper_content:

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.
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paper_title: An energy-efficient power control approach for WLANs

paper_content:

In this paper we consider the problem of reducing energy consumption during the transmission phase in WLANs. We found that for a given network configuration, channel characteristics, and packet length, an optimum RF transmission power level exists which assures a minimum energy expenditure for the actually transmitted bit of information. Based on this observation, we present a packet length dependent power control mechanism. We performed discrete event simulations of an IEEE 802.11 LAN in ad hoc mode using a two state Markov channel model. The achieved simulation results indicate a significant potential for energy saving. We also present a workable approach for choosing the most energy-saving RF transmit power level which is based on the perceived packet error rate of a single mobile.
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paper_title: A multichannel CSMA MAC protocol for multihop wireless networks

paper_content:

We describe a new carrier-sense multiple access (CSMA) protocol for multihop wireless networks, sometimes also called ad hoc networks. The CSMA protocol divides the available bandwidth into several channels and selects an idle channel randomly for packet transmission. It also employs a notion of "soft" channel reservation as it gives preference to the channel that was used for the last successful transmission. We show via simulations that this multichannel CSMA protocol provides a higher throughput compared to its single channel counterpart by reducing the packet loss due to collisions. We also show that the use of channel reservation provides better performance than multichannel CSMA with purely random idle channel selection.
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paper_title: Dual Busy Tone Multiple Access (DBTMA) - A Multiple Access Control Scheme for Ad Hoc Networks

paper_content:

In ad hoc networks, the hidden- and the exposed-terminal problems can severely reduce the network capacity on the MAC layer. To address these problems, the ready-to-send and clear-to-send (RTS/CTS) dialogue has been proposed in the literature. However, MAC schemes using only the RTS/CTS dialogue cannot completely solve the hidden and the exposed terminal problems, as pure "packet sensing" MAC schemes are not safe even in fully connected networks. We propose a new MAC protocol, termed the dual busy tone multiple access (DBTMA) scheme. The operation of the DBTMA protocol is based on the RTS packet and two narrow-bandwidth, out-of-band busy tones. With the use of the RTS packet and the receive busy tone, which is set up by the receiver, our scheme completely solves the hidden- and the exposed-terminal problems. The busy tone, which is set up by the transmitter, provides protection for the RTS packets, increasing the probability of successful RTS reception and, consequently, increasing the throughput. This paper outlines the operation rules of the DBTMA scheme and analyzes its performance. Simulation results are also provided to support the analytical results. It is concluded that the DBTMA protocol is superior to other schemes that rely on the RTS/CTS dialogue on a single channel or to those that rely on a single busy tone. As a point of reference, the DBTMA scheme out-performs FAMA-NCS by 20-40% in our simulations using the network topologies borrowed from the FAMA-NCS paper. In an ad hoc network with a large coverage area, DBTMA achieves performance gain of 140% over FAMA-NCS and performance gain of 20% over RI-BTMA.
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paper_title: PAMAS—power aware multi-access protocol with signalling for ad hoc networks

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In this paper we develop a new multiaccess protocol for ad hoc radio networks. The protocol is based on the original MACA protocol with the adition of a separate signalling channel. The unique feature of our protocol is that it conserves battery power at nodes by intelligently powering off nodes that are not actively transmitting or receiving packets. The manner in which nodes power themselves off does not influence the delay or throughput characteristics of our protocol. We illustrate the power conserving behavior of PAMAS via extensive simulations performed over ad hoc networks containing 10-20 nodes. Our results indicate that power savings of between 10% and 70% are attainable in most systems. Finally, we discuss how the idea of power awareness can be built into other multiaccess protocols as well.
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paper_title: A power control MAC protocol for ad hoc networks

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This paper presents a power control MAC protocol based on the IEEE 802.11 standard. Several researchers have proposed a simple modification of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS-CTS and DATA-ACK. Specifically, maximum transmit power is used for RTS-CTS, and the minimum required transmit power is used for DATA-ACK transmissions in order to save energy. However, we show that this scheme can degrade network throughput and can result in higher energy consumption than using IEEE 802.11 without power control. We propose an improved power control protocol which does not degrade throughput and yields energy saving.
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paper_title: Using Directional Antennas for Medium Access Control in Ad Hoc Networks

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A composition for use in the treatment for developing seedless fleshy berry of grapes. By treating the flower bunches of a grape tree with a composition containing gibberellin and cyclic 3',5'-adenylic acid in the form of an aqueous solution, it became possible to make seedless fleshy berry from grape trees belonging to varieties other than Delaware, namely belonging to Campbell-Arley, Berry A, Niagara, Kyoho, etc., from which seedless fleshy berry cannot be made by the conventional treatment with gibberellin.
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Title: Medium Access Control protocols for ad hoc wireless networks: A survey

Section 1: Introduction
Description 1: This section introduces the history and background of ad hoc wireless networks and their significance.

Section 2: Applications
Description 2: This section discusses various applications of ad hoc wireless networks in different scenarios.

Section 3: Important issues
Description 3: This section highlights several critical issues faced in ad hoc wireless networks, including bandwidth limitations, error-prone mediums, and mobility.

Section 4: Need for special MAC protocols
Description 4: This section explains why conventional MAC protocols are not effective in ad hoc wireless networks and the need for specialized MAC protocols.

Section 5: Classification
Description 5: This section provides a detailed classification of different MAC schemes developed for ad hoc wireless networks.

Section 6: Review of non-QoS MAC protocols
Description 6: This section discusses several important contention-based MAC schemes focusing on single channel, receiver-initiated, power-aware, and multiple channel categories.

Section 7: General MAC protocols
Description 7: This section describes mostly single channel MAC protocols and includes specific protocol discussions such as MACA and IEEE 802.11 MAC scheme.

Section 8: Power aware MAC protocols
Description 8: This section discusses MAC protocols designed to conserve power in ad hoc wireless networks.

Section 9: Multiple channel protocols
Description 9: This section reviews MAC protocols that utilize multiple channels to improve performance and reduce collisions.

Section 10: Protocols using directional antennas
Description 10: This section explores MAC protocols that employ directional antennas to enhance spatial reuse and performance.

Section 11: Unidirectional MAC protocols
Description 11: This section covers MAC protocols designed for networks with unidirectional links due to heterogeneous power levels among nodes.

Section 12: QoS-aware MAC protocols
Description 12: This section reviews MAC protocols that provide Quality of Service (QoS) for applications requiring guaranteed bandwidth and delays.

Section 13: Issues affecting QoS
Description 13: This section discusses various issues that affect the provisioning of QoS in ad hoc wireless networks.

Section 14: Review of selected QoS-aware MAC protocols
Description 14: This section reviews significant QoS-aware MAC protocols, highlighting their features and limitations.

Section 15: Summary and future directions
Description 15: This section summarizes the surveyed MAC protocols and outlines potential future research directions in this field.

Section 16: Conclusion
Description 16: This section concludes the survey, summarizing the key findings and observations from the study of MAC protocols for ad hoc wireless networks.