Wireless sensor networks: a survey
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paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
paper_title: Next century challenges: scalable coordination in sensor networks

paper_content:

Networked sensors-those that coordinate amongst themselves to achieve a larger sensing task-will revolutionize information gathering and processing both in urban environments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured differently from traditional network applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor network coordination. In this paper, we describe localized algorithms, and then discuss directed diffusion, a simple communication model for describing localized algorithms.
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paper_title: Adaptive protocols for information dissemination in wireless sensor networks

paper_content:

In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.
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paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
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paper_title: DataSpace—querying and monitoring deeply networked collections in physical space

paper_content:

In this article we introduce a new conception of three-dimensional DataSpace, which is physical space enhanced by connectivity to the network. DataSpace is addressed geographically as opposed to the current logical addressing scheme of the Internet. Here, a local area network is replaced by a room, a street, a mountaintop, and so on. Billions of objects populate DataSpace, each aware of its own geographic location. These objects move through DataSpace, and produce and locally store their own data. They can be selectively queried, monitored, and controlled based on their properties. We propose two architectures for DataSpace. We describe mechanisms to use the network as a DataSpace engine in order to perform querying and monitoring operation in a highly scalable way.
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paper_title: Querying the physical world

paper_content:

In the next decade, millions of sensors and small-scale mobile devices will integrate processors, memory, and communication capabilities. Networks of devices will be widely deployed for monitoring applications. In these new applications, users need to query very large collections of devices in an ad hoc manner. Most existing systems rely on a centralized system for collecting device data. These systems lack flexibility because data is extracted in a predefined way. Also, they do not scale to a large number of devices because large volumes of raw data are transferred. In our new concept of a device database system, distributed query execution techniques are applied to leverage the computing capabilities of devices, and to reduce communication. We define an abstraction that allows us to represent a device network as a database and we describe how distributed query processing techniques are applied in this new context.
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paper_title: Detecting Critical Scales in Fragmented Landscapes

paper_content:

We develop methods for quantifying habitat connectivity at multiple scales and assigning conservation priority to habitat patches based on their contribution to connectivity. By representing the habitat mosaic as a mathematical "graph," we show that percolation theory can be used to quantify connectivity at multiple scales from empirical landscape data. Our results indicate that connectivity of landscapes is highly scale dependent, exhibiting a marked transition at a characteristic distance and varying significantly for organisms with different dispersal behavior. More importantly, we show that the sensitivity and importance of landscape pattern is also scale dependent, peaking at scales associated with the percolation transition. In addition, the sensitivity analysis allows us to identify critical "stepping stone" patches that, when removed from the landscape, cause large changes in connectivity.
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paper_title: Scalable coordination for wireless sensor networks: Selfconfiguring localization systems

paper_content:

Pervasive networks of micro-sensors and actuators offer to revolutionize the ways in which we understand and construct complex physical systems. Sensor networks must be scalable, long-lived and robust systems, overcoming energy limitations and a lack of pre-installed infrastructure. We explore three themes in the design of self-configuring sensor networks: tuning density to trade operational quality against lifetime; using multiple sensor modalities to obtain robust measurements; and exploiting fixed environmental characteristics. We illustrate these themes through the problem of localization, which is a key building block for sensor systems that itself requires coordination.
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paper_title: ASCENT: adaptive self-configuring sensor networks topologies

paper_content:

Advances in microsensor and radio technology enable small but smart sensors to be deployed for a wide range of environmental monitoring applications. The low-per node cost allows these wireless networks of sensors and actuators to be densely distributed. The nodes in these dense networks coordinate to perform the distributed sensing and actuation tasks. Moreover, as described in this paper, the nodes can also coordinate to exploit the redundancy provided by high density so as to extend overall system lifetime. The large number of nodes deployed in this systems preclude manual configuration, and the environmental dynamics precludes design-time preconfiguration. Therefore, nodes have to self-configure to establish a topology that provides communication under stringent energy constraints. ASCENT builds on the notion that, as density increases, only a subset of the nodes is necessary to establish a routing forwarding backbone. In ASCENT, each node assesses its connectivity and adapts its participation in the multihop network topology based on the measured operating region. This paper motivates and describes the ASCENT algorithm and presents analysis, simulation, and experimental measurements. We show that the system achieves linear increase in energy savings as a function of the density and the convergence time required in case of node failures while still providing adequate connectivity.
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paper_title: Energy efficient protocols for low duty cycle wireless microsensor networks

paper_content:

Emerging distributed wireless microsensor networks will enable the reliable and fault tolerant monitoring of the environment. Such microsensors are required to operate for years from a small energy source, while maintaining a reliable communication link to the base station. The design of energy-aware communication protocols can have a dramatic impact on the network lifetime for such applications. A detailed communication energy model, obtained from measurements, is introduced that incorporates the non-ideal behavior of the physical layer electronics. This includes the start-up energy cost of the RF transceiver, which dominates energy dissipation for short packet sizes. Using this model, various communication layer protocols are explored for asymmetrical sensor networks such as machine monitoring. The paper also proposes the use of a variable bandwidth allocation scheme that exploits spatial distribution of sensors.
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paper_title: Diagnosis of sensor networks

paper_content:

As sensor nodes are embedded into physical environments and becoming integral parts of our daily lives, sensor networks will become the important nerve systems that monitor and actuate our physical environments. We define the process of monitoring the status of a sensor network and figuring out the problematic sensor nodes sensor network diagnosis. However, the high sensor node-to-manager ratio makes it extremely difficult to pay special attention to any individual node. In addition, the response implosion problem, which occurs when a high volume of incoming replies triggered by diagnosis queries cause the central diagnosing node to become a bottleneck, is one major obstacle to be overcome. We describe approaches to addressing the response implosion problem in sensor network diagnosis. We also present simulation experiments on the performance of these approaches, and discuss presentation schemes for diagnostic results.
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paper_title: Upper bounds on the lifetime of sensor networks

paper_content:

We ask a fundamental question concerning the limits of energy efficiency of sensor networks-what is the upper bound on the lifetime of a sensor network that collects data from a specified region using a certain number of energy-constrained nodes? The answer to this question is valuable for two main reasons. First, it allows calibration of real world data-gathering protocols and an understanding of factors that prevent these protocols from approaching fundamental limits. Secondly, the dependence of lifetime on factors like the region of observation, the source behavior within that region, basestation location, number of nodes, radio path loss characteristics, efficiency of node electronics and the energy available on a node, is exposed. This allows architects of sensor networks to focus on factors that have the greatest potential impact on network lifetime. By employing a combination of theory and extensive simulations of constructed networks, we show that in all data gathering scenarios presented, there exist networks which achieve lifetimes equal to or >95% of the derived bounds. Hence, depending on the scenario, our bounds are either tight or near-tight.
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paper_title: Power efficient organization of wireless sensor networks

paper_content:

Wireless sensor networks have emerged recently as an effective way of monitoring remote or inhospitable physical environments. One of the major challenges in devising such networks lies in the constrained energy and computational resources available to sensor nodes. These constraints must be taken into account at all levels of the system hierarchy. The deployment of sensor nodes is the first step in establishing a sensor network. Since sensor networks contain a large number of sensor nodes, the nodes must be deployed in clusters, where the location of each particular node cannot be fully guaranteed a priori. Therefore, the number of nodes that must be deployed in order to completely cover the whole monitored area is often higher than if a deterministic procedure were used. In networks with stochastically placed nodes, activating only the necessary number of sensor nodes at any particular moment can save energy. We introduce a heuristic that selects mutually exclusive sets of sensor nodes, where the members of each of those sets together completely cover the monitored area. The intervals of activity are the same for all sets, and only one of the sets is active at any time. The experimental results demonstrate that by using only a subset of sensor nodes at each moment, we achieve a significant energy savings while fully preserving coverage.
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paper_title: Scientific data visualization and biological diversity: new tools for spatializing multimedia observations of species and ecosystems

paper_content:

Abstract Current knowledge of the biodiversity of protected ecosystems is often limited to museum collection specimen data, outdated or cursory inventories and anecdotal accounts. Beyond the inventory of biological diversity comes the need to monitor changes of many parameters and at many scales, and the need to incorporate this knowledge into an accessible information system for biodiversity management planning and conservation education. This paper briefly describes our continuing research efforts to develop new ways to collect, analyze, organize and distribute biodiversity data.
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paper_title: An integrated architecture for cooperative sensing networks

paper_content:

Distributed sensor networks (DSNs) consisting of many small, low-cost, spatially dispersed, communicating nodes have been proposed for many applications, such as area surveillance and environmental monitoring. Trends in integrated electronics, such as better performance-to-cost ratios, low-power radios, and microelectromechanical systems (MEMS) sensors, now allow the construction of sensor nodes with signal processing, wireless communications, power sources and synchronization, all packaged into inexpensive miniature devices. If these devices can be easily deployed and self-integrated into a system, they promise great benefits in providing real-time information about environmental conditions. Intelligent sensor nodes function much like individual ants that, when formed into a network, cooperatively accomplish complex tasks and provide capabilities greater than the sum of the individual parts. The paper discusses several technical challenges that must be overcome to fully realize the viability of the DSN concept in realistic application scenarios.
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paper_title: An Overview of the Implications of Global Change for Natural and Managed Terrestrial Ecosystems

paper_content:

Global change is the net effect of individual and interactive effects of changes in land use, atmospheric composition, biological diversity, and climate. A synthesis of the past six years' activities of the Global Change and Terrestrial Ecosystems project of the IGBP (International Geosphere-Biosphere Programme) deals with global change effects as ecosystem responses and living with global change. Ecosystem responses are considered in terms of changes in function and vegetation composition/structure. Field experiments of elevated CO 2 effects on aboveground biomass show, on average, a positive effect on biomass, ranging from -20% to +80%. Some early predictions of CO 2 effects (C 3 vs. C 4 plants, N-fixers, C:N in litter) are not generally supported, and it is necessary to consider the interactive effects of changes in CO 2 , temperature, and nitrogen. Dynamic global vegetation models involving transient changes show that biomes will not shift as intact entities. Significant changes in vegetation, especially in high latitudes, are likely over the next century, and changes in disturbance regimes will be most important. Based on forecast changes in land use, vegetation structure, and ecosystem physiology, the terrestrial biosphere will probably become a source rather than a sink for carbon over the next century.
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paper_title: The mobile patient: wireless distributed sensor networks for patient monitoring and care

paper_content:

The concept of a three layer distributed sensor network for patient monitoring and care is introduced. The envisioned network has a leaf node layer (consisting of patient sensors), an intermediate node layer (consisting of the supervisory processor residing with each patient) and the root node processor (residing at a central monitoring facility). The paradigm has the capability of dealing with the bandwidth bottleneck at the wireless patient-root node link and the processing bottleneck at the central processor or root node of the network.
---
paper_title: Scalable coordination for wireless sensor networks: Selfconfiguring localization systems

paper_content:

Pervasive networks of micro-sensors and actuators offer to revolutionize the ways in which we understand and construct complex physical systems. Sensor networks must be scalable, long-lived and robust systems, overcoming energy limitations and a lack of pre-installed infrastructure. We explore three themes in the design of self-configuring sensor networks: tuning density to trade operational quality against lifetime; using multiple sensor modalities to obtain robust measurements; and exploiting fixed environmental characteristics. We illustrate these themes through the problem of localization, which is a key building block for sensor systems that itself requires coordination.
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paper_title: An instrumentation system for the remote monitoring of changes in functional health status of the elderly at home

paper_content:

There is a rapidly developing interest in the creative use of information, instrumentation and communications technology for the nonconstrained monitoring of physiological and health variables at home. Evidence for this interest are major research programs in Europe, such as the Technology Initiative for Disabled and Elderly People (TIDE), and the European Prototype for Integrated Care (EPIC), initiated under the general umbrella of the Advanced Informatics in Medicine (AIM) program which has as a major theme the application of Telematics Systems in Health Care. Here, the authors discuss the design and implementation of instrumentation modules for monitoring the interaction between the elderly participant and his or her living environment to assess changes in functional health status. The objectives of the first data collection phase are to develop individualised templates of functional health status and to use knowledge based systems to identify changes which may indicate a deterioration of health and a reduced capacity for coping with the demands of day to day living. This is a major interdisciplinary study involving biomedical design engineers, computer scientists (medical AI) and community medicine specialists. Preliminary data are presented on the results of a small pilot project and a major field trial involving over 75 households. >
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paper_title: Use computerized systems to cut adverse drug events: report

paper_content:

Computerized monitoring systems can reduce the number of medication errors and prevent many adverse drug events (ADEs), a new report indicates. In addition, the systems can save hospitals as much as US$500 000 annually in direct costs, not including liability costs or the cost of injuries to
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paper_title: Remote Continuous Physiological Monitoring in the Home

paper_content:

As part of a larger study we established a remote physiological monitoring network to investigate cardiorespiratory function during sleep in 400 infants in their homes. The objective of the study was to link measurements made at three weeks and three months of age with detailed measurements of maternal and fetal nutrition during pregnancy and subsequent outcome (growth, development and cardiorespiratory diseases). Five infants per night were monitored anywhere within a radius of 10 miles (16 km) of the remote hub. Of 800 overnight studies on 64 (of 400) infants, 99 were completed. Options allowed downloading data from monitor memory as well as review (on- and off-line) from the infants' or nurses' homes, the hub and the Oxford telemonitoring centre. The reasons for these measurements being made at home were to ensure physiological accuracy and to reduce cost. The network was effectively run by local community nurses; with the exception of the size and cost of the monitors, it had all the elements of a remote primary-care clinical service.
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paper_title: Fully automated biosignal acquisition in daily routine through 1 month

paper_content:

With the goal of keeping people healthy and active, long-term at-home measurement of physiological function during daily life is valuable, and is attempted in this study. As a first trial of at-home measurements, a fully automated physiological data acquisition system was developed. This system contains unconstrained physiological parameter monitors: an ECG monitor for use during bathing, a bed temperature monitor, and a weight monitor located in the toilet seat. It also contains a computer with data acquisition programs and a data format rule. Unconstrained physiological parameter monitors and fully automatic measurement procedures provide data acquisition non-invasively and without the subject's awareness. This system has been proved by an experiment involving measurement over one month of a healthy male subject (aged 29 years) in laboratory-based facilities. The system functioned for one month of data acquisition with no operator involved. The system may be used for home health monitoring of patients and also of healthy subjects.
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paper_title: PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking

paper_content:

Technology advances have made it conceivable to build and deploy dense wireless networks of heterogeneous nodes collecting and disseminating wide ranges of environmental data. Applications of such sensor and monitoring networks include smart homes equipped with security, identification, and personalization systems; intelligent assembly systems; warehouse inventory control; interactive learning toys; and disaster mitigation. The opportunities emerging from this technology give rise to new definitions of distributed computing and the user interface. Crucial to the success of these ubiquitous networks is the availability of small, lightweight, low-cost network elements, which the authors call PicoNodes. The authors present a configurable architecture that enables these opportunities to be efficiently realized in silicon. They believe that this energy-conscious system design and implementation methodology will lead to radio nodes that are two orders of magnitude more efficient than existing solutions.
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paper_title: Ubiquitous sensing for smart and aware environments

paper_content:

As computing technology continues to become increasingly pervasive and ubiquitous, we envision the development of environments that can sense what we are doing and support our daily activities. In this article, we outline our efforts toward building such environments and discuss the importance of a sensing and signal-understanding infrastructure that leads to awareness of what is happening in an environment and how it can best be supported. Such an infrastructure supports both high- and low-end data transmission and processing, while allowing for detailed interpretation, modeling and recognition from sensed information. We are currently prototyping several aware environments to aid in the development and study of such sensing and computation in real-world settings.
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paper_title: Component-Based Software Systems for Smart Environments

paper_content:

The article focuses on the role component-based software may play in realizing smart environments. A scenario describes a future smart environment in a university campus setting. The scenario illustrates how software components might contribute to the various phases of development, deployment and use of smart environments. Key research areas identified include: development of component frameworks, component interface standards, addressing schemes, and protocols.
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paper_title: Final report on the inter-agency workshop on research issues for smart environments

paper_content:

Presents the final report summarizing some of the major outcomes of the July 25-26 DARPA/NIST/NSF inter-agency workshop on smart environments, which took place on the campus of Georgia Tech. in the College of Computing. We are beginning to see a proliferation of small, portable information appliances for individuals and powerful sensors that can be embedded and networked in environments. As we attempt to compose these devices into sophisticated, an hoc and cooperative computational and communications structures, significant research issues arise, from both technological and human-centered perspectives. The purpose of this workshop was to identify those issues from two distinct perspectives: human-centered: what can and should we expect for human interaction within a smart environment? Technology-centered: what new requirements do smart environments place on technology infrastructure, specifically networking infrastructure? What new advances in programming or system construction must accompany this paradigm shift? We summarize findings from breakout discussions representing these two perspectives. We then summarize discussions of inter-disciplinary research issues and the need for effective testbeds for researching smart environments.
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paper_title: Sensor-Based Information Appliances

paper_content:

Using the existing home infrastructure based on open industry standards, we will be able to integrate the home network with external networks to easily manage home devices, both locally and remotely. The advent of pervasive computing marks an urgent need for a new generation of intelligent sensing agents and information appliances. It will also demand environments for resource management of broad applications involving loosely coupled, event-driven, diverse information appliances. It is suggested that the development of intelligent sensing agents and sensor-based information appliances will spread pervasive technology to a multitude of human activities such as mining and manufacturing, security, transportation, sports, and health care. The topics discussed also include management of heterogeneous functions and networking technologies.
---
paper_title: Next century challenges: scalable coordination in sensor networks

paper_content:

Networked sensors-those that coordinate amongst themselves to achieve a larger sensing task-will revolutionize information gathering and processing both in urban environments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured differently from traditional network applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor network coordination. In this paper, we describe localized algorithms, and then discuss directed diffusion, a simple communication model for describing localized algorithms.
---
paper_title: Scalable coordination for wireless sensor networks: Selfconfiguring localization systems

paper_content:

Pervasive networks of micro-sensors and actuators offer to revolutionize the ways in which we understand and construct complex physical systems. Sensor networks must be scalable, long-lived and robust systems, overcoming energy limitations and a lack of pre-installed infrastructure. We explore three themes in the design of self-configuring sensor networks: tuning density to trade operational quality against lifetime; using multiple sensor modalities to obtain robust measurements; and exploiting fixed environmental characteristics. We illustrate these themes through the problem of localization, which is a key building block for sensor systems that itself requires coordination.
---
paper_title: Energy efficient protocols for low duty cycle wireless microsensor networks

paper_content:

Emerging distributed wireless microsensor networks will enable the reliable and fault tolerant monitoring of the environment. Such microsensors are required to operate for years from a small energy source, while maintaining a reliable communication link to the base station. The design of energy-aware communication protocols can have a dramatic impact on the network lifetime for such applications. A detailed communication energy model, obtained from measurements, is introduced that incorporates the non-ideal behavior of the physical layer electronics. This includes the start-up energy cost of the RF transceiver, which dominates energy dissipation for short packet sizes. Using this model, various communication layer protocols are explored for asymmetrical sensor networks such as machine monitoring. The paper also proposes the use of a variable bandwidth allocation scheme that exploits spatial distribution of sensors.
---
paper_title: PicoRadio: Ad-hoc wireless networking of ubiquitous low-energy sensor/monitor nodes

paper_content:

One of the most compelling challenges of the next decade is the solution of the "last meter" problem, which extends the network into the end-user data-collection and monitoring devices. This paper discusses the challenges and opportunities of a "PicoRadio Network" that supports the assembly of an an-hoc wireless network of meso-scale, low-cost and low-energy sensor and monitor nodes.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: The Cricket location-support system

paper_content:

This paper presents the design, implementation, and evaluation of Cricket , a location-support system for in-building, mobile, location-dependent applications. It allows applications running on mobile and static nodes to learn their physical location by using listeners that hear and analyze information from beacons spread throughout the building. Cricket is the result of several design goals, including user privacy, decentralized administration, network heterogeneity, and low cost. Rather than explicitly tracking user location, Cricket helps devices learn where they are and lets them decide whom to advertise this information to; it does not rely on any centralized management or control and there is no explicit coordination between beacons; it provides information to devices regardless of their type of network connectivity; and each Cricket device is made from off-the-shelf components and costs less than U.S. $10. We describe the randomized algorithm used by beacons to transmit information, the use of concurrent radio and ultrasonic signals to infer distance, the listener inference algorithms to overcome multipath and interference, and practical beacon configuration and positioning techniques that improve accuracy. Our experience with Cricket shows that several location-dependent applications such as in-building active maps and device control can be developed with little effort or manual configuration.
---
paper_title: An integrated architecture for cooperative sensing networks

paper_content:

Distributed sensor networks (DSNs) consisting of many small, low-cost, spatially dispersed, communicating nodes have been proposed for many applications, such as area surveillance and environmental monitoring. Trends in integrated electronics, such as better performance-to-cost ratios, low-power radios, and microelectromechanical systems (MEMS) sensors, now allow the construction of sensor nodes with signal processing, wireless communications, power sources and synchronization, all packaged into inexpensive miniature devices. If these devices can be easily deployed and self-integrated into a system, they promise great benefits in providing real-time information about environmental conditions. Intelligent sensor nodes function much like individual ants that, when formed into a network, cooperatively accomplish complex tasks and provide capabilities greater than the sum of the individual parts. The paper discusses several technical challenges that must be overcome to fully realize the viability of the DSN concept in realistic application scenarios.
---
paper_title: PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking

paper_content:

Technology advances have made it conceivable to build and deploy dense wireless networks of heterogeneous nodes collecting and disseminating wide ranges of environmental data. Applications of such sensor and monitoring networks include smart homes equipped with security, identification, and personalization systems; intelligent assembly systems; warehouse inventory control; interactive learning toys; and disaster mitigation. The opportunities emerging from this technology give rise to new definitions of distributed computing and the user interface. Crucial to the success of these ubiquitous networks is the availability of small, lightweight, low-cost network elements, which the authors call PicoNodes. The authors present a configurable architecture that enables these opportunities to be efficiently realized in silicon. They believe that this energy-conscious system design and implementation methodology will lead to radio nodes that are two orders of magnitude more efficient than existing solutions.
---
paper_title: A new architecture for distributed sensor integration

paper_content:

The authors propose a versatile architecture for a distributed sensor network which consists of a multilevel network with the nodes (processing element/sensor pairs) at each level interconnected as a de Bruijn network. They show that this multilevel network has reasonable fault tolerance, admits simple and decentralized routing, and offers easy extensibility. They model information from sensors as real-valued intervals and state an interesting property related to information integration in the presence of faults. Using this property, the search for a fault is narrowed down to two potentially faulty sensors or communication links. In a distributed environment, information has to be integrated from temporally close signals in the presence of imperfect clocks in a distributed environment. The results of past research in this area are used to state various relationships between the clocks of the processing elements in the network for proper information integration. >
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paper_title: Optimal design of fault tolerant sensor networks

paper_content:

The selection of measurements is one of the most important problems in the design of process instrumentation. This paper deals with the design of sensor networks such that the observability of the variables, which are necessary for the process control, remains satisfied in the presence of sensor failures. Pseudo-minimal and minimal sensor sets are organized into an oriented graph which contains all the possible reconfiguration paths for which those variables remain observable. A bottom-up analysis of this graph allows one to compute reliability functions which evaluate the robustness of the observability property with respect to sensor failures. The design of optimal sensor networks thus resumes to finding pseudo-minimal sensor sets such that the mean time before losing the observability property is larger than a pre-defined value.
---
paper_title: Scalable coordination for wireless sensor networks: Selfconfiguring localization systems

paper_content:

Pervasive networks of micro-sensors and actuators offer to revolutionize the ways in which we understand and construct complex physical systems. Sensor networks must be scalable, long-lived and robust systems, overcoming energy limitations and a lack of pre-installed infrastructure. We explore three themes in the design of self-configuring sensor networks: tuning density to trade operational quality against lifetime; using multiple sensor modalities to obtain robust measurements; and exploiting fixed environmental characteristics. We illustrate these themes through the problem of localization, which is a key building block for sensor systems that itself requires coordination.
---
paper_title: Energy efficient protocols for low duty cycle wireless microsensor networks

paper_content:

Emerging distributed wireless microsensor networks will enable the reliable and fault tolerant monitoring of the environment. Such microsensors are required to operate for years from a small energy source, while maintaining a reliable communication link to the base station. The design of energy-aware communication protocols can have a dramatic impact on the network lifetime for such applications. A detailed communication energy model, obtained from measurements, is introduced that incorporates the non-ideal behavior of the physical layer electronics. This includes the start-up energy cost of the RF transceiver, which dominates energy dissipation for short packet sizes. Using this model, various communication layer protocols are explored for asymmetrical sensor networks such as machine monitoring. The paper also proposes the use of a variable bandwidth allocation scheme that exploits spatial distribution of sensors.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Sensor-Based Information Appliances

paper_content:

Using the existing home infrastructure based on open industry standards, we will be able to integrate the home network with external networks to easily manage home devices, both locally and remotely. The advent of pervasive computing marks an urgent need for a new generation of intelligent sensing agents and information appliances. It will also demand environments for resource management of broad applications involving loosely coupled, event-driven, diverse information appliances. It is suggested that the development of intelligent sensing agents and sensor-based information appliances will spread pervasive technology to a multitude of human activities such as mining and manufacturing, security, transportation, sports, and health care. The topics discussed also include management of heterogeneous functions and networking technologies.
---
paper_title: PicoRadio: Ad-hoc wireless networking of ubiquitous low-energy sensor/monitor nodes

paper_content:

One of the most compelling challenges of the next decade is the solution of the "last meter" problem, which extends the network into the end-user data-collection and monitoring devices. This paper discusses the challenges and opportunities of a "PicoRadio Network" that supports the assembly of an an-hoc wireless network of meso-scale, low-cost and low-energy sensor and monitor nodes.
---
paper_title: PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking

paper_content:

Technology advances have made it conceivable to build and deploy dense wireless networks of heterogeneous nodes collecting and disseminating wide ranges of environmental data. Applications of such sensor and monitoring networks include smart homes equipped with security, identification, and personalization systems; intelligent assembly systems; warehouse inventory control; interactive learning toys; and disaster mitigation. The opportunities emerging from this technology give rise to new definitions of distributed computing and the user interface. Crucial to the success of these ubiquitous networks is the availability of small, lightweight, low-cost network elements, which the authors call PicoNodes. The authors present a configurable architecture that enables these opportunities to be efficiently realized in silicon. They believe that this energy-conscious system design and implementation methodology will lead to radio nodes that are two orders of magnitude more efficient than existing solutions.
---
paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: SPINS: security protocols for sensor networks

paper_content:

Wireless sensor networks will be widely deployed in the near future. While much research has focused on making these networks feasible and useful, security has received little attention. We present a suite of security protocols optimized for sensor networks: SPINS. SPINS has two secure building blocks: SNEP and μTESLA. SNEP includes: data confidentiality, two-party data authentication, and evidence of data freshness. μTESLA provides authenticated broadcast for severely resource-constrained environments. We implemented the above protocols, and show that they are practical even on minimal hardware: the performance of the protocol suite easily matches the data rate of our network. Additionally, we demonstrate that the suite can be used for building higher level protocols.
---
paper_title: Wireless integrated network sensors (WINS): distributed in situ sensing for mission and flight systems

paper_content:

Wireless Integrated Network Sensors (WINS) form a new distributed information technology of combined sensor, actuator, and processing systems. WINS distributed nodes form autonomous, self-organized, wireless sensing and control networks. WINS nodes include microsensors, signal processing, computation and low power wireless networking. WINS enable distributed measurements for applications ranging from aerospace system condition monitoring to distributed environmental science monitoring. This paper will discuss the enabling technology advances of WINS for mission and flight system in situ sensing. This will include the complete set of technologies, from new MEMS devices through information technology. Finally, a new WINS generation, GlobalWINS, will be described. GlobalWINS has been developed for planetary-wide distribution of science instruments.
---
paper_title: Minimum-energy mobile wireless networks revisited

paper_content:

We propose a protocol that, given a communication network, computes a subnetwork such that, for every pair $(u,v)$ of nodes connected in the original network, there is a minimum-energy path between $u$ and $v$ in the subnetwork (where a minimum-energy path is one that allows messages to be transmitted with a minimum use of energy). The network computed by our protocol is in general a subnetwork of the one computed by the protocol given in [13]. Moreover, our protocol is computationally simpler. We demonstrate the performance improvements obtained by using the subnetwork computed by our protocol through simulation.
---
paper_title: PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking

paper_content:

Technology advances have made it conceivable to build and deploy dense wireless networks of heterogeneous nodes collecting and disseminating wide ranges of environmental data. Applications of such sensor and monitoring networks include smart homes equipped with security, identification, and personalization systems; intelligent assembly systems; warehouse inventory control; interactive learning toys; and disaster mitigation. The opportunities emerging from this technology give rise to new definitions of distributed computing and the user interface. Crucial to the success of these ubiquitous networks is the availability of small, lightweight, low-cost network elements, which the authors call PicoNodes. The authors present a configurable architecture that enables these opportunities to be efficiently realized in silicon. They believe that this energy-conscious system design and implementation methodology will lead to radio nodes that are two orders of magnitude more efficient than existing solutions.
---
paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
paper_title: Exposure in wireless Ad-Hoc sensor networks

paper_content:

Wireless ad-hoc sensor networks will provide one of the missing connections between the Internet and the physical world. One of the fundamental problems in sensor networks is the calculation of coverage. Exposure is directly related to coverage in that it is a measure of how well an object, moving on an arbitrary path, can be observed by the sensor network over a period of time. In addition to the informal definition, we formally define exposure and study its properties. We have developed an efficient and effective algorithm for exposure calculation in sensor networks, specifically for finding minimal exposure paths. The minimal exposure path provides valuable information about the worst case exposure-based coverage in sensor networks. The algorithm works for any given distribution of sensors, sensor and intensity models, and characteristics of the network. It provides an unbounded level of accuracy as a function of run time and storage. We provide an extensive collection of experimental results and study the scaling behavior of exposure and the proposed algorithm for its calculation.
---
paper_title: A transmission control scheme for media access in sensor networks

paper_content:

We study the problem of media access control in the novel regime of sensor networks, where unique application behavior and tight constraints in computation power, storage, energy resources, and radio technology have shaped this design space to be very different from that found in traditional mobile computing regime. Media access control in sensor networks must not only be energy efficient but should also allow fair bandwidth allocation to the infrastructure for all nodes in a multihop network. We propose an adaptive rate control mechanism aiming to support these two goals and find that such a scheme is most effective in achieving our fairness goal while being energy efficient for both low and high duty cycle of network traffic.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: A low-power low-voltage transceiver architecture suitable for wireless distributed sensors network

paper_content:

A broad range of new high-volume consumer applications require the availability of low-power, battery operated, wireless microsystems. These systems should conciliate a sufficient battery lifetime with reduced overall dimensions (including antenna), low cost and versatility. The design of such systems highlights many tradeoffs between performances, cost and power consumption. These considerations led our group to choose a direct-conversion scheme for a distributed sensors application. The key blocks for this architecture have been realized and measured in a 0.5 /spl mu/m CMOS technology, validating this approach. From these results, the total power consumption of a receiver operating in the 433 MHz ISM band is expected as low as 1.4 mW, under 1.2 V supply, for a sensitivity of -100 dBm and a 20 kbit/s data rate. The transmitter provides 9 dBm output power under the same supply voltage, with a 35% efficiency.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: A low-power low-voltage transceiver architecture suitable for wireless distributed sensors network

paper_content:

A broad range of new high-volume consumer applications require the availability of low-power, battery operated, wireless microsystems. These systems should conciliate a sufficient battery lifetime with reduced overall dimensions (including antenna), low cost and versatility. The design of such systems highlights many tradeoffs between performances, cost and power consumption. These considerations led our group to choose a direct-conversion scheme for a distributed sensors application. The key blocks for this architecture have been realized and measured in a 0.5 /spl mu/m CMOS technology, validating this approach. From these results, the total power consumption of a receiver operating in the 433 MHz ISM band is expected as low as 1.4 mW, under 1.2 V supply, for a sensitivity of -100 dBm and a 20 kbit/s data rate. The transmitter provides 9 dBm output power under the same supply voltage, with a 35% efficiency.
---
paper_title: Comparing algorithm for dynamic speed-setting of a low-power CPU

paper_content:

To take advantage of the full potential of ubiquitous computing, we will need systems which minimize powerconsumption. Weiser et al. and others have suggested that this may be accomplished by a CPU which dynamically changes speed and voltage, thereby saving energy by spreading run cycles into idle time. Here we continue this research, using a simulation to compare a number of policies for dynamic speed-setting. Our work clarifies a fundamental power vs. delay tradeoff, as well as the role of prediction and of smoothing in dynamic speed-setting policies. We conclude that success seemingly depends more on simple smoothing algorithms than on sophisticated prediction techniques, but defer to the replication of these results on future variable-speed systems.
---
paper_title: Reducing processor power consumption by improving processor time management in a single-user operating system

paper_content:

The CPU is one of the major power consumers in a portable computer, and considerable power can be saved by turning off the CPU when it is not doing useful work. In Apple’s MacOS, however, idle time is often converted to busy waiting, and generally it is very hard to tell when no useful computation is occurring. In this paper, we suggest several heuristic techniques for identifying this condition, and for temporarily putting the CPU in a low-power state. These techniques include turning off the processor when all processes are blocked, turning off the processor when processes appear to be busy waiting, and extending real time process sleep periods. We use trace-driven simulation, using processor run interval traces, to evaluate the potential energy savings and performance impact. We find that these techniques save considerable amounts of processor energy (as much as 66%), while having very little performance impact (less than 2% increase in run time). Implementing the proposed strategies should increase battery lifetime by approximately 20% relative to Apple’s current CPU power management strategy, since the CPU and associated logic are responsible for about 32% of power use; similar techniques should be applicable to operating systems with similar behavior.
---
paper_title: Scheduling for reduced CPU energy

paper_content:

The energy usage of computer systems is becoming more important, especially for battery operated systems. Displays, disks, and cpus, in that order, use the most energy. Reducing the energy used by displays and disks has been studied elsewhere; this paper considers a new method for reducing the energy used by the cpu. We introduce a new metric for cpu energy performance, millions-of-instructions-per-joule (MIPJ). We examine a class of methods to reduce MIPJ that are characterized by dynamic control of system clock speed by the operating system scheduler. Reducing clock speed alone does not reduce MIPJ, since to do the same work the system must run longer. However, a number of methods are available for reducing energy with reduced clock-speed, such as reducing the voltage [Chandrakasan et al 1992][Horowitz 1993] or using reversible [Younis and Knight 1993] or adiabatic logic [Athas et al 1994]. What are the right scheduling algorithms for taking advantage of reduced clock-speed, especially in the presence of applications demanding ever more instructions-per-second? We consider several methods for varying the clock speed dynamically under control of the operating system, and examine the performance of these methods against workstation traces. The primary result is that by adjusting the clock speed at a fine grain, substantial CPU energy can be saved with a limited impact on performance.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Dynamic power management in wireless sensor network

paper_content:

An effective method of dynamic power management,based on wavelet and Kalman analysis,is proposed to extend life of wireless sensor network by making economical use of energy.Wavelet,Kalman filter and AR are used to forecast the time when next event will happen,and the state in which wireless sensor should lie is decided based on the time.Total energy consumption is decreased under fraction of event missed as low as posible.Experimental results show the method is effective.
---
paper_title: Dynamic voltage scaling techniques for distributed microsensor networks

paper_content:

Distributed microsensor networks promise a versatile and robust platform for remote environment monitoring. Crucial to long system lifetimes for these microsensors are algorithms and protocols that provide the option of trading quality for energy savings. Dynamic voltage scaling on the sensor node's processor enables energy savings from these scalable algorithms. We demonstrate dynamic voltage scaling on the beginnings of a sensor node prototype, which currently consists of a commercial processor, a digitally adjustable DC-DC regulator, and a power-aware operating system.
---
paper_title: The simulation and evaluation of dynamic voltage scaling algorithms

paper_content:

The reduction of energy consumption in microprocessors can be accomplished without impacting the peak performance through the use of dynamic voltage scaling (DVS). This approach varies the processor voltage under software control to meet dynamically varying performance requirements. This paper presents a foundation for the simulation and analysis of DVS algorithms. These algorithms are applied to a benchmark suite specifically targeted for PDA devices.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Next century challenges: scalable coordination in sensor networks

paper_content:

Networked sensors-those that coordinate amongst themselves to achieve a larger sensing task-will revolutionize information gathering and processing both in urban environments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured differently from traditional network applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor network coordination. In this paper, we describe localized algorithms, and then discuss directed diffusion, a simple communication model for describing localized algorithms.
---
paper_title: Random, Ephemeral Transaction Identifiers in dynamic sensor networks

paper_content:

Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale, highly distributed systems of small, wireless, low-power unattended sensors and actuators. We explore the use of Random, Ephemeral TRansaction Identifiers (RETRI) in such systems, and contrast it with the typical design philosophy of using static identifiers in roles such as node addressing or efficient data naming. Instead of using statically assigned identifiers that are guaranteed to be unique, nodes randomly select probabilistically unique identifiers for each new transaction. We show how this randomized scheme can significantly improve the system's energy efficiency in contexts where that efficiency is paramount, such as energy-constrained wireless sensor networks. Benefits are realized if the typical data size is small compared to the size of an identifier, and the number of transactions seen by an individual node is small compared to the number of nodes that exist in the entire system. Our scheme is designed to scale well: identifier sizes grow with a system's density not its overall size. We quantify these benefits using an analytic model that predicts our scheme's efficiency. We also describe an implementation as applied to packet fragmentation and an experiment that validates our model.
---
paper_title: SPINS: security protocols for sensor networks

paper_content:

Wireless sensor networks will be widely deployed in the near future. While much research has focused on making these networks feasible and useful, security has received little attention. We present a suite of security protocols optimized for sensor networks: SPINS. SPINS has two secure building blocks: SNEP and μTESLA. SNEP includes: data confidentiality, two-party data authentication, and evidence of data freshness. μTESLA provides authenticated broadcast for severely resource-constrained environments. We implemented the above protocols, and show that they are practical even on minimal hardware: the performance of the protocol suite easily matches the data rate of our network. Additionally, we demonstrate that the suite can be used for building higher level protocols.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Dynamic power management in wireless sensor network

paper_content:

An effective method of dynamic power management,based on wavelet and Kalman analysis,is proposed to extend life of wireless sensor network by making economical use of energy.Wavelet,Kalman filter and AR are used to forecast the time when next event will happen,and the state in which wireless sensor should lie is decided based on the time.Total energy consumption is decreased under fraction of event missed as low as posible.Experimental results show the method is effective.
---
paper_title: Protocols for self-organization of a wireless sensor network

paper_content:

We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the nodes.
---
paper_title: PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking

paper_content:

Technology advances have made it conceivable to build and deploy dense wireless networks of heterogeneous nodes collecting and disseminating wide ranges of environmental data. Applications of such sensor and monitoring networks include smart homes equipped with security, identification, and personalization systems; intelligent assembly systems; warehouse inventory control; interactive learning toys; and disaster mitigation. The opportunities emerging from this technology give rise to new definitions of distributed computing and the user interface. Crucial to the success of these ubiquitous networks is the availability of small, lightweight, low-cost network elements, which the authors call PicoNodes. The authors present a configurable architecture that enables these opportunities to be efficiently realized in silicon. They believe that this energy-conscious system design and implementation methodology will lead to radio nodes that are two orders of magnitude more efficient than existing solutions.
---
paper_title: Adaptive protocols for information dissemination in wireless sensor networks

paper_content:

In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.
---
paper_title: Energy-efficient communication protocol for wireless microsensor networks

paper_content:

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.
---
paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
paper_title: Random, Ephemeral Transaction Identifiers in dynamic sensor networks

paper_content:

Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale, highly distributed systems of small, wireless, low-power unattended sensors and actuators. We explore the use of Random, Ephemeral TRansaction Identifiers (RETRI) in such systems, and contrast it with the typical design philosophy of using static identifiers in roles such as node addressing or efficient data naming. Instead of using statically assigned identifiers that are guaranteed to be unique, nodes randomly select probabilistically unique identifiers for each new transaction. We show how this randomized scheme can significantly improve the system's energy efficiency in contexts where that efficiency is paramount, such as energy-constrained wireless sensor networks. Benefits are realized if the typical data size is small compared to the size of an identifier, and the number of transactions seen by an individual node is small compared to the number of nodes that exist in the entire system. Our scheme is designed to scale well: identifier sizes grow with a system's density not its overall size. We quantify these benefits using an analytic model that predicts our scheme's efficiency. We also describe an implementation as applied to packet fragmentation and an experiment that validates our model.
---
paper_title: Instrumenting the world with wireless sensor networks

paper_content:

Pervasive micro-sensing and actuation may revolutionize the way in which we understand and manage complex physical systems: from airplane wings to complex ecosystems. The capabilities for detailed physical monitoring and manipulation offer enormous opportunities for almost every scientific discipline, and it will alter the feasible granularity of engineering. We identify opportunities and challenges for distributed signal processing in networks of these sensing elements and investigate some of the architectural challenges posed by systems that are massively distributed, physically-coupled, wirelessly networked, and energy limited.
---
paper_title: Adaptive protocols for information dissemination in wireless sensor networks

paper_content:

In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.
---
paper_title: Energy-efficient communication protocol for wireless microsensor networks

paper_content:

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.
---
paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
---
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: Minimum-energy mobile wireless networks revisited

paper_content:

We propose a protocol that, given a communication network, computes a subnetwork such that, for every pair $(u,v)$ of nodes connected in the original network, there is a minimum-energy path between $u$ and $v$ in the subnetwork (where a minimum-energy path is one that allows messages to be transmitted with a minimum use of energy). The network computed by our protocol is in general a subnetwork of the one computed by the protocol given in [13]. Moreover, our protocol is computationally simpler. We demonstrate the performance improvements obtained by using the subnetwork computed by our protocol through simulation.
---
paper_title: Protocols for self-organization of a wireless sensor network

paper_content:

We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the nodes.
---
paper_title: Adaptive protocols for information dissemination in wireless sensor networks

paper_content:

In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.
---
paper_title: Energy-efficient communication protocol for wireless microsensor networks

paper_content:

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.
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paper_title: Directed diffusion: a scalable and robust communication paradigm for sensor networks

paper_content:

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.
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paper_title: A transmission control scheme for media access in sensor networks

paper_content:

We study the problem of media access control in the novel regime of sensor networks, where unique application behavior and tight constraints in computation power, storage, energy resources, and radio technology have shaped this design space to be very different from that found in traditional mobile computing regime. Media access control in sensor networks must not only be energy efficient but should also allow fair bandwidth allocation to the infrastructure for all nodes in a multihop network. We propose an adaptive rate control mechanism aiming to support these two goals and find that such a scheme is most effective in achieving our fairness goal while being energy efficient for both low and high duty cycle of network traffic.
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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: Intelligent medium access for mobile ad hoc networks with busy tones and power control

paper_content:

In a mobile ad-hoc networks (MANETs), one essential issue is how to increase channel utilization while avoiding the hidden-terminal and the exposed-terminal problems. Several MAC protocols, such as RTS (request to send)/CTS (clear to send) based and busy tone-based schemes, have been proposed to alleviate these problems. In this paper, we explore the possibility of combining the concept of power control with the RTS/CTS-based and busy tone-based protocols to further increase channel utilization. A sender will use an appropriate power level to transmit its packets so as to increase the possibility of channel reuse. The possibility of using discrete, instead of continuous, power levels is also discussed. Through analyses and simulations, we demonstrate the advantage of our new MAC protocol. This, together with the extra benefits such as saving battery energy and reducing co-channel interference, does show a promising direction to enhance the performance of MANETs.
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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: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
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paper_title: Minimum-energy mobile wireless networks revisited

paper_content:

We propose a protocol that, given a communication network, computes a subnetwork such that, for every pair $(u,v)$ of nodes connected in the original network, there is a minimum-energy path between $u$ and $v$ in the subnetwork (where a minimum-energy path is one that allows messages to be transmitted with a minimum use of energy). The network computed by our protocol is in general a subnetwork of the one computed by the protocol given in [13]. Moreover, our protocol is computationally simpler. We demonstrate the performance improvements obtained by using the subnetwork computed by our protocol through simulation.
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paper_title: Protocols for self-organization of a wireless sensor network

paper_content:

We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the nodes.
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paper_title: Dynamic power management in wireless sensor network

paper_content:

An effective method of dynamic power management,based on wavelet and Kalman analysis,is proposed to extend life of wireless sensor network by making economical use of energy.Wavelet,Kalman filter and AR are used to forecast the time when next event will happen,and the state in which wireless sensor should lie is decided based on the time.Total energy consumption is decreased under fraction of event missed as low as posible.Experimental results show the method is effective.
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paper_title: Adaptive frame length control for improving wireless link throughput, range, and energy efficiency

paper_content:

Wireless network links are characterized by rapidly time varying channel conditions and battery energy limitations at the wireless mobile user nodes. Therefore static link control techniques that make sense in comparatively well behaved wired links do not necessarily apply to wireless links. New adaptive link layer control techniques are needed to provide robust and energy efficient operation even in the presence of orders of magnitude variations in bit error rates and other radio channel conditions. For example, research has advocated adaptive link layer techniques such as adaptive error control, channel state dependent protocols, and variable spreading gain. We explore dynamic sizing of the MAC layer frame, the atomic unit that is sent through the radio channel. A trade-off exists between the desire to reduce the header and physical layer overhead by making frames large, and the need to reduce frame error rates in the noisy channel by using small frame lengths. Clearly the optimum depends on the channel conditions. Through analysis supported by physical measurements with Lucent's WaveLAN radio we show that adaptive sizing of the MAC layer frame in the presence of varying channel noise indeed has a large impact on the user seen throughput (goodput). In addition, we show how that adaptive frame length control can be exploited to improve the energy efficiency for a desired level of goodput, and to extend the usable radio range with graceful throughput degradation. We describe the implementation of the adaptive MAC frame length control mechanism in combination with adaptive hybrid FEC/ARQ error control in a reconfigurable wireless link layer packet processing architecture for a low-power adaptive wireless multimedia node.
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paper_title: Energy-efficient link layer for wireless microsensor networks

paper_content:

Wireless microsensors are being used to form large, dense networks for the purposes of long-term environmental sensing and data collection. Unfortunately these networks are typically deployed in remote environments where energy sources are limited. Thus, designing fault-tolerant wireless microsensor networks with long system lifetimes can be challenging. By applying energy-efficient techniques at all levels of the system hierarchy, system lifetime can be extended. In this paper, energy-efficient techniques that adapt underlying communication parameters will be presented in the context of wireless microsensor networks. In particular, the effect of adapting link and physical layer parameters, such as output transmit power and error control coding, on system energy consumption will be examined.
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paper_title: Power-aware communication for mobile computers

paper_content:

The mobile community has focused on techniques for reducing energy consumption for mobile hosts. These power management techniques typically target communication devices such as wireless network interfaces, aiming to reduce usage, and thus energy consumption, of the particular device itself. We observe that optimization of a single device's energy consumption, without considering the effect of the strategy on the rest of the machine, can have negative consequences. We propose power management techniques addressing mobile host communications that encompass all components of a mobile host in an effort to optimize the total energy consumption. Specifically, we propose runtime adaptation of communication parameters in order to minimize the energy consumed during active data transfer. Information about the network environment is used to drive such adaptations in an effort to compensate for the effect of a dynamic service from the wireless communication device on the energy consumed during data transfer. Our results show that power management can often be achieved while maintaining the QoS provided to the application.
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paper_title: Evaluation of an adaptive power and error control algorithm for wireless systems

paper_content:

We study the performance of a unified power control and forward error correction control algorithm for mobile radio systems that attempts to maximize system capacity and minimize transmitter power utilization while satisfying user defined quality of service constraints. The algorithm is distributed, with each individual transmitter-receiver pair determining its own operating point with respect to power and error control parameters. Simulation results from a cellular system with mobile users show that this unified algorithm outperforms the schemes that use power control alone.
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paper_title: Error Control and Energy Consumption in Communications for Nomadic Computing

paper_content:

We consider the problem of communications over a wireless channel in support of data transmissions from the perspective of small portable devices that must rely on limited battery energy. We model the channel outages as statistically correlated errors. Classic ARQ strategies are found to lead to a considerable waste of energy, due to the large number of transmissions. The use of finite energy sources in the face of dependent channel errors leads to new protocol design criteria. As an example, a simple probing scheme, which slows down the transmission rate when the channel is impaired, is show? to be more energy efficient, with a slight loss in throughput. A modified scheme that yields slightly better performance but requires some additional complexity is also studied. Some references on the modeling of battery cells are discussed to highlight the fact that battery charge capacity is strongly influenced by the available "relaxation time" between current pulses. A formal approach that can track complex models for power sources, including dynamic charge recovery, is also developed.
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paper_title: On the analysis of UWB communication channels

paper_content:

Ultra-wideband (UWB) communication systems have been proposed for use in dense multipath or shadowed environments. Given the bandwidth of the signals involved, traditional signal processing techniques are often not applicable to the analysis of UWB waveforms. In particular, many array signal processing techniques for determining the angle-of-arrival which make use of a narrowband assumption are not suitable. An iterative algorithm for the UWB channel characterization is proposed and a discussion is initiated.
---
paper_title: Energy-efficient link layer for wireless microsensor networks

paper_content:

Wireless microsensors are being used to form large, dense networks for the purposes of long-term environmental sensing and data collection. Unfortunately these networks are typically deployed in remote environments where energy sources are limited. Thus, designing fault-tolerant wireless microsensor networks with long system lifetimes can be challenging. By applying energy-efficient techniques at all levels of the system hierarchy, system lifetime can be extended. In this paper, energy-efficient techniques that adapt underlying communication parameters will be presented in the context of wireless microsensor networks. In particular, the effect of adapting link and physical layer parameters, such as output transmit power and error control coding, on system energy consumption will be examined.
---
paper_title: All-digital impulse radio for MUI/ISI-resilient multiuser communications over frequency-selective multipath channels

paper_content:

Impulse radio (IR) is an ultra-wideband system with attractive features for baseband asynchronous multiple access (MA), multimedia services, and tactical wireless communications. Implemented with analog components, the continuous-time IRMA model utilizes pulse-position modulation (PPM) and random time-hopping codes to alleviate multipath effects and suppress multiuser interference (MUI). We introduce a novel continuous-time multiple input multiple output (MIMO) PPM-IRMA scheme, and derive its discrete-time equivalent model. Relying on a time-division-duplex access protocol and orthogonal user codes, we design composite linear and non-linear receivers for the downlink. The linear step eliminates MUI deterministically and accounts for frequency-selective multipath, while a maximum likelihood (ML) receiver performs symbol detection.
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paper_title: Multipath characteristics of impulse radio channels

paper_content:

We investigate the multipath characteristics of the impulse radios (IR) which have drawn much attention for future high-speed wireless communication services. For this objective, we observe the characteristics of bit error rates through computer simulations for the deterministic two-path model and the statistical indoor multipath model of Saleh and Valenzuela (1987). The simulation results indicate that the performance of the IR system depends on the time-delay differences between the multipath components, the path gains, the time interval in the PPM, and the reference signal waveform. It is also observed that the reference signal waveform used in the AWGN channel can not be applicable to the multipath channel.
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paper_title: Impulse radio multipath characteristics and diversity reception

paper_content:

Delay-and-sum beamforming is applied to both ideal and measured ultra-wideband (UWB) signals. The results of propagation measurements are also used directly to estimate the performance of an UWB communication system and to characterize design tradeoffs.
---
paper_title: Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

paper_content:

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring long-term, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energy-constrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols.
---
paper_title: Low-power direct-sequence spread-spectrum modem architecture for distributed wireless sensor networks

paper_content:

Emerging CMOS and MEMS technologies enable the implementation of a large number of wireless distributed microsensors that can be easily and rapidly deployed to form highly redundant, self-configuring, and ad hoc sensor networks. To facilitate ease of deployment, these sensors should operate on battery for extended periods of time. A particular challenge in maintaining extended battery lifetime lies in achieving communications with low power. This paper presents a direct-sequence spread-spectrum modem architecture that provides robust communications for wireless sensor networks while dissipating very low power. The modem architecture has been verified in an FPGA implementation that dissipates only 33 mW for both transmission and reception. The implementation can be easily mapped to an ASIC technology with an estimated power performance of less than 1 row.
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paper_title: Performance of equicorrelated ultra-wideband pulse-position-modulated signals in the indoor wireless impulse radio channel

paper_content:

Impulse radio (IR) is a spread spectrum (SS) wireless technique in which ultra-wideband (UWB) communication waveforms that consist of trains of time-shifted subnanosecond pulses are modulated to convey information exclusively in the relative time position of the pulses. In this paper we describe the construction of equally correlated (EC) pulse position modulation (PPM) signals, using trains of binary time-shift-keyed UWB subnanosecond pulses. The performance of the EC UWB PPM signals in the indoor IR channel with detection using a Rake receiver is analyzed.
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Title: Wireless Sensor Networks: A Survey

Section 1: Introduction
Description 1: This section provides an overview of wireless sensor networks, their components, advantages over traditional sensors, unique features, and application areas.

Section 2: Sensor networks applications
Description 2: This section discusses various application areas for wireless sensor networks, including military, environmental, health, home, and other commercial applications.

Section 3: Military applications
Description 3: This section explores the integration of sensor networks in military command, control, communications, intelligence, surveillance, reconnaissance, and targeting systems.

Section 4: Environmental applications
Description 4: This section highlights the role of sensor networks in monitoring environmental conditions, including tracking wildlife, detecting forest fires, and mapping bio-complexity.

Section 5: Health applications
Description 5: This section addresses the usage of sensor networks in health applications, such as patient monitoring, drug administration, and interfaces for the disabled.

Section 6: Home applications
Description 6: This section delves into home automation and smart environments facilitated by wireless sensor networks.

Section 7: Other commercial applications
Description 7: This section outlines the commercial applications of sensor networks, including inventory management, vehicle tracking, and interactive museums.

Section 8: Factors influencing sensor network design
Description 8: This section reviews the various factors that influence the design of sensor networks, including fault tolerance, scalability, production costs, hardware constraints, and power consumption.

Section 9: Fault tolerance
Description 9: This section examines the reliability and fault tolerance of sensor networks and how they sustain functionalities despite sensor node failures.

Section 10: Scalability
Description 10: This section discusses the scalability of sensor networks and their ability to handle large numbers of nodes.

Section 11: Production costs
Description 11: This section assesses the importance of production costs and the feasibility of sensor networks based on the cost per node.

Section 12: Hardware constraints
Description 12: This section provides a detailed overview of the hardware components of sensor nodes, including sensing, processing, transceiver, and power units.

Section 13: Sensor network topology
Description 13: This section describes the topology of sensor networks, covering pre-deployment, post-deployment, and additional node deployment phases.

Section 14: Environment
Description 14: This section discusses the various environments in which sensor nodes operate and their deployment in challenging conditions.

Section 15: Transmission media
Description 15: This section examines the types of transmission media used in sensor networks, such as radio, infrared, and optical media.

Section 16: Power consumption
Description 16: This section analyzes the power consumption issues in sensor networks and explores energy-efficient communication and data processing techniques.

Section 17: Sensor networks communication architecture
Description 17: This section provides an overview of the communication architecture of sensor networks, including the protocol stack and management planes for power, mobility, and task management.

Section 18: Application layer
Description 18: This section explores potential application layer protocols for sensor networks, including sensor management, task assignment, and data dissemination.

Section 19: Sensor management protocol
Description 19: This section describes the sensor management protocol which provides software operations for administering sensor networks.

Section 20: Task assignment and data advertisement protocol
Description 20: This section introduces the protocol for disseminating user interest and advertising available data in sensor networks.

Section 21: Sensor query and data dissemination protocol
Description 21: This section discusses the sensor query and data dissemination protocol for issuing and responding to queries within the sensor network.

Section 22: Open research issues
Description 22: This section identifies open research issues in sensor networks, including MAC protocols, error control, hardware design, and physical layer challenges.

Section 23: Transport layer
Description 23: This section highlights the need for transport layer protocols in sensor networks and the challenges associated with end-to-end communication.

Section 24: Network layer
Description 24: This section reviews various network layer protocols proposed for sensor networks to ensure efficient data routing.

Section 25: Data link layer
Description 25: This section details the responsibilities of the data link layer, including medium access control and error control strategies.

Section 26: Medium access control
Description 26: This section discusses different medium access control protocols for sensor networks and their approaches to power conservation and efficiency.

Section 27: Power saving modes of operation
Description 27: This section examines the power-saving modes of operation for sensor nodes and the importance of efficient power management.

Section 28: Error control
Description 28: This section reviews error control techniques for sensor networks, emphasizing the use of forward error correction to maintain link reliability.

Section 29: Physical layer
Description 29: This section focuses on frequency selection, carrier frequency generation, modulation schemes, and energy-efficient signal transmission for sensor networks.

Section 30: Conclusion
Description 30: This section summarizes the key points discussed in the survey and emphasizes the importance and future prospects of wireless sensor networks.