A Review on Cooperative Communication Protocols in Wireless World
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paper_title: Cooperative Communications and Networking: Technologies and System Design

paper_content:

Review of Wireless Communications and MIMO Techniques.- Two-User Cooperative Transmission Schemes.- Cooperative Transmission Schemes with Multiple Relays.- Fundamental Limits of Cooperative and Relay Network.- Cooperative Communications with Multiple Sources.- Cooperation Relaying in OFDM and MIMO Systems.- Medium Access Control in Cooperative Networks.- Networking and Cross-Layer Issues in Cooperative Networks.
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paper_title: User cooperation diversity—Part I: System description

paper_content:

Mobile users' data rate and quality of service are limited by the fact that, within the duration of any given call, they experience severe variations in signal attenuation, thereby necessitating the use of some type of diversity. In this two-part paper, we propose a new form of spatial diversity, in which diversity gains are achieved via the cooperation of mobile users. Part I describes the user cooperation strategy, while Part II (see ibid., p.1939-48) focuses on implementation issues and performance analysis. Results show that, even though the interuser channel is noisy, cooperation leads not only to an increase in capacity for both users but also to a more robust system, where users' achievable rates are less susceptible to channel variations.
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paper_title: Cooperative diversity in wireless networks: Efficient protocols and outage behavior

paper_content:

We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.
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paper_title: THREE-TERMINAL COMMUNICATION CHANNELS

paper_content:

Summary The problem of transmitting information in a specified direction over a communication channel with three terminals is considered. Examples are given of the various ways of sending information. Basic inequalities for average mutual information rates are obtained. A coding theorem and weak converse are proved and a necessary and sufficient condition for a positive capacity is derived. Upper and lower bounds on the capacity are obtained, which coincide for channels with symmetric structure.
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paper_title: User cooperation diversity - part II: implementation aspects and performance analysis

paper_content:

For pt.I see ibid., p.1927-38. This is the second of a two-part paper on a new form of spatial diversity, where diversity gains are achieved through the cooperation of mobile users. Part I described the user cooperation concept and proposed a cooperation strategy for a conventional code-division multiple-access (CDMA) system. Part II investigates the cooperation concept further and considers practical issues related to its implementation. In particular, we investigate the optimal and suboptimal receiver design, and present performance analysis for the conventional CDMA implementation proposed in Part I. We also consider a high-rate CDMA implementation and a cooperation strategy when assumptions about the channel state information at the transmitters are relaxed. We illustrate that, under all scenarios studied, cooperation is beneficial in terms of increasing system throughput and cell coverage, as well as decreasing sensitivity to channel variations.
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paper_title: Capacity-approaching turbo coding and iterative decoding for relay channels

paper_content:

In this paper, we design turbo-based coding schemes for relay systems together with iterative decoding algorithms. In the proposed schemes, the source node sends coded information bits to both the relay and the destination nodes, while the relay simultaneously forwards its estimate for the previous coded block to the destination after decoding and re-encoding. The destination observes a superposition of the codewords and uses an iterative decoding algorithm to estimate the transmitted messages. Different from the block-by-block decoding techniques used in the literature, this decoding scheme operates over all the transmitted blocks jointly. Various encoding and decoding approaches are proposed for both single-input single-output and multi-input multi-output systems over several different channel models. Capacity bounds and information-rate bounds with binary inputs are also provided, and it is shown that the performance of the proposed practical scheme is typically about 1.0-1.5 dB away from the theoretical limits, and a remarkable advantage can be achieved over the direct and multihop transmission alternatives.
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paper_title: Energy-efficient antenna sharing and relaying for wireless networks

paper_content:

We develop energy-efficient transmission protocols for wireless networks that exploit spatial diversity created by antenna sharing: coordinated transmission and/or processing by several distributed radios. We focus on single-user transmission and examine several possibilities for the strategy employed by the assisting radio, or relay, including decoding and forwarding as well as amplifying and forwarding. In each case, we develop receivers based upon maximum-likelihood and/or maximum signal-to-noise ratio criteria, relate their structures, and compare their bit-error probability performance by means of analysis and simulations. We cast single-hop and multihop routing into our framework for comparison purposes. All of our antenna sharing protocols offer diversity gains over single-hop and multihop transmission, and our results suggest that low-complexity amplifying and forwarding is energy-efficient in spite of noise amplification at the relay.
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paper_title: Code design for the relay channel and factor graph decoding

paper_content:

Recent information theoretical results have shown a considerable improvement in the performance of communication systems through the use of relaying and cooperation. Despite a collection of strong information theoretical results on the relay channel, there has been almost no attention to real code design for the relay channel. In this paper, we present a powerful modular code design approach for the relay channel and corresponding decoding algorithms based on the factor graph representation of the code. For most of the relay channel conditions, the constructed codes with a low-complexity simple relay protocol outperforms any possible code design for the direct channel by achieving an E/sub b//N/sub 0/ below the minimum required E/sub b//N/sub 0/ of single-link transmission. Moreover, the designed codes achieve a gap of less than 1 dB (at a BER of 10/sup -6/) to the Shannon limit for the relay channel with a code length of only 2 /spl times/ 10/sup 4/ bits.
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paper_title: Selection cooperation in multi-source cooperative networks

paper_content:

In a cooperative network with multiple potential relays and multiple simultaneous transmissions, we present selection cooperation wherein each source pairs with a single "best" relay. We analyze the outage probability of a simple and completely distributed selection scheme, requiring some feedback but no centralization, and show that it outperforms distributed space-time codes for networks with more than three relaying nodes. These gains are due to the more efficient use of power in networks using selection. We suggest two other more complex selection schemes based on increasing system intelligence and centralization, and show that for smaller network sizes their performance improvement over the simple selection scheme is not significant.
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paper_title: Outage Performance of Multi-Antenna Relay Cooperation in the Absence of Direct Link

paper_content:

Cooperation among relays can achieve spatial diversity, which improves the link quality in a wireless network. In this letter, we investigate the performance of an infrastructure based multi-antenna relay network in the absence of a direct link. A closed form expression of outage probability has been derived, when the cooperating relays and destination coherently combine the received signals. The effect of number of relay antennas and relay placement on the system performance have also been studied.
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paper_title: Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks

paper_content:

We develop and analyze space-time coded cooperative diversity protocols for combating multipath fading across multiple protocol layers in a wireless network. The protocols exploit spatial diversity available among a collection of distributed terminals that relay messages for one another in such a manner that the destination terminal can average the fading, even though it is unknown a priori which terminals will be involved. In particular, a source initiates transmission to its destination, and many relays potentially receive the transmission. Those terminals that can fully decode the transmission utilize a space-time code to cooperatively relay to the destination. We demonstrate that these protocols achieve full spatial diversity in the number of cooperating terminals, not just the number of decoding relays, and can be used effectively for higher spectral efficiencies than repetition-based schemes. We discuss issues related to space-time code design for these protocols, emphasizing codes that readily allow for appealing distributed versions.
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paper_title: Performance of two-hop regenerative relay network under correlated nakagami-m fading at multi-antenna relay

paper_content:

Performance of cooperative relaying employing infrastructure based fixed relays having multiple antennas has been investigated. Here, both relay and destination perform maximal ratio combining combining of the signals. Closed form expressions for outage probability and bit error rate have been derived for Nakagami-m fading channels, with integer values of m. The effect of fading correlation among relay antennas and relay positioning on the system performance have also been studied.
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paper_title: Bounds for multihop relayed communications in nakagami-m fading

paper_content:

Abstract— We present closed-form lower bounds for the perfor-mance of multihop transmissions with nonregenerative relays overnot necessarily identically distributed Nakagami- fading chan-nels. The end-to-end signal-to-noise ratio is formulated and upperbounded by using an inequality between harmonic and geometricmeans of positive random variables (RVs). Novel closed-formexpressions are derived for the moment generating function, theprobability density function, and the cumulative distribution func-tion of the product of rational powers of statistically independentGamma RVs. These statistical results are then applied to studyingthe outage probability and the average bit-error probability forphase- and frequency-modulated signaling. Numerical examplescompare analytical and simulation results, verifying the tightnessof the proposed bounds. Index Terms— Average bit-error probability (ABEP), Gammarandom variables (RVs), multihop relayed communications, Nak-agami- fading, outage probability.
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paper_title: Average Error Rate of Multi-Antenna Decode and Forward Cooperative Relay Network

paper_content:

Cooperative relaying is emerging as a powerful mean of exploiting broadcast nature of the channel to provide diversity gain and improve link performance for single-antenna wireless terminals. In this paper, we investigate the average error performance of cooperative relay network employing infrastructure based fixed relays having multiple antennas. A closed form expression of average error rate for such system has been derived when the relay performs selection combining and destination performs MRC combining of signals. The effect of relay placement on the system performance has also been studied.
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paper_title: Outage performance of two-hop multi-antenna co-operative relaying in rayleigh fading channel

paper_content:

Performance of co-operative relaying employing infrastructure based fixed relays having multiple antennas has been investigated. A closed-form expression of outage probability for such a system has been derived when the relay performs selection combining and the destination performs MRC combining of signals. The effect of relay placement on the system performance has also been studied.
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paper_title: Multiple-User Cooperative Communications Based on Linear Network Coding

paper_content:

We propose a new scheme for cooperative wireless networking based on linear network codes. The network consists of multiple (M ≥ 2) users having independent information to be transmitted to a common basestation (BS), assuming block-fading channels with independent fading for different codewords. The users collaborate in relaying messages. Because of potential transmission errors in links, resulting in erasures, the network topology is dynamic. To efficiently exploit the diversity available by cooperation and time-varying fading, we propose the use of diversity network codes (DNCs) over finite fields. These codes are designed such that the BS is able to rebuild the user information from a minimum possible set of coded blocks conveyed through the dynamic network. We show the existence of deterministic DNCs. We also show that the resulting diversity order using the proposed DNCs is 2 M - 1, which is higher than schemes without network coding or with binary network coding. Numerical results from simulations also show substantial improvement by the proposed DNCs over the benchmark schemes. We also propose simplified versions of the DNCs, which have much lower design complexity and still achieve the diversity order 2 M - 1.
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paper_title: Performance of MRC combining multi-antenna cooperative relay network

paper_content:

Abstract Performance of cooperative relaying employing infrastructure based fixed relays having multiple antennas has been investigated. Employing MGF based approach, closed form expression for outage probability and bit error rate performance of BPSK signal have been derived, when relay and destination are assumed to perform MRC combining of the signals. The effect of relay placement on the system performance has also been studied under different path loss conditions.
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paper_title: Outage probability analysis of a MIMO relay channel with orthogonal space-time block codes

paper_content:

We investigate the performance of a cooperative multiple-input multiple-output (MIMO) relay channel in which the source and relay use the same orthogonal space-time block code (OSTBC) for transmission whereas the relay and destination use maximum-ratio-combining (MRC) for reception. Considering that perfect channel state information is available at the relay and destination, we derive a closed-form expression for the outage probability of the destination signal-to-noise ratio (SNR) in terms of the confluent hypergeometric function of two variables in a Rayleigh flat-fading environment. The validity of the closed-form expression is confirmed with the numerical results.
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paper_title: Optimized Power Allocation for Multiple-Antenna Multiple-Relay Cooperative Communication System

paper_content:

One of the main advantages of relayed communication is that it reduces the necessary transmit power and distributes transmitted power throughout the hops. This implies lower interference to the rest of the network and consequently improves performance of the system. In this paper we investigate optimized power allocation over two-hop multiple antenna fixed relays for a given power budget. Outage probability which is the probability that the link quality falls bellow the certain threshold in a Rayleigh fading channel is used as the performance criterion. It is determined that increasing the number of relays and antennas at each relay increases capacity. The outage probability of threshold maximal ratio combining (T-MRC) and threshold selection combining (T-SC) of the multiple antenna multiple fixed relays is derived. Threshold decode and forward relaying (T-DF), which is more reliable than conventional decode and forward relaying (DF) is considered. Results show that optimizing the allocation of power enhances the system performance, especially in highly unbalanced links. The system with optimized power allocation can outperform the two-hop multiple relay system using uniform power allocation and distributed beamforming at the expense of increased computational complexity.
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paper_title: Performance Analysis of Cooperative Diversity Using Equal Gain Combining (EGC) Technique Over Rayleigh Fading Channels

paper_content:

Cooperative diversity is a promising technology for future wireless networks. In this paper, based on the moment generating function (MGF), we derive exact closed-form expressions for the average bit error rate (BER), the amount of fading (AF), and outage probability (Pout) for cooperative diversity networks with amplify-and-forward relaying over Rayleigh-fading channel using differentially- non-coherent equal gain combining (EGC) technique. We show that this scheme (differentially-non-coherent EGC) achieves a diversity order of 2 at high SNR. The main advantage of this scheme is that it does not need channel state. information of the transmission links at the relay and destination nodes. This feature reduces the design and implementation complexity. Furthermore, we study in this paper the impact of the relay location on the system performance.
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paper_title: Outage probability of multi-hop amplify-and-forward relay systems

paper_content:

The outage probability of multi-hop amplify-and-forward relay systems with multiple relays is analyzed. Previously, the outage probability of the two-hop system with multiple relays had been analyzed. In this paper, that work is generalized by finding results for the outage probability of the multi-hop system, of which the previously found results for the two-hop system are special cases. In the two-hop system, signals from the source are forwarded by the relays to the destination only, whereas in the multi-hop system, signals are forwarded to other relays as well as to the destination. We derive a lower bound, which is extremely tight to the actual outage probability for almost all values of outage probability, and asymptotically tight in the high-SNR region, for all important practical cases. We also derive a high-SNR straight-line approximation that is extremely tight to the actual outage probability at very high SNRs, and often at moderately high SNRs as well, for all important practical cases.
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paper_title: Amplify-and-forward cooperation under interference-limited spatial reuse of the relay slot

paper_content:

Cooperative transmission has emerged as an effective tool to deal with channel impairments. In this work we study the applicability of amplify-and-forward cooperative transmission in the downlink of a TDMA cellular system where idle terminals act as relays. The base station may have a multiple antenna configuration, whereas all terminals are equipped with a single antenna. Although cooperation can be viewed as a virtual MIMO system, it further allows dealing with shadowing and pathloss. In order to improve the spectral efficiency loss incurred by the half-duplex relays, in this work we consider the reuse of the relay time slot by simultaneous transmissions from the active relays in the cell. We are able to model the interfering power received by each destination in that slot. The only system parameters adjusted to control the interference are the number of interfering relay terminals and a cell-wide .target SNR in the relay-destination link. This way, it is shown that cooperative transmission is able to provide significant gains in terms of throughput over the direct transmission under round-robin packet scheduling and uniform distribution of terminals by controlling the rate of each transmission (rate control).
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paper_title: User Cooperation in TDMA Wireless System

paper_content:

AbstractReliability of radio link is limited, owing to path loss, shadowing and multi-path fading. This necessitates the use of a certain type of diversity. In recent years, cooperative diversity has gained considerable attention. Here, wireless nodes cooperate in such a way that they share their antennas and other resources, to create a virtual array through distributed transmission and signal processing. This increases coverage and reduces transmitted power, thereby bringing down co-channel interference, which results in increased system capacity. This paper gives an overview of the state of art of various cooperation schemes and issues related to their implementation.
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paper_title: On the Performance of Selection Relaying

paper_content:

Interest in selection relaying is growing. The recent developments in this area have largely focused on information theoretic analyses such as outage performance. Some of these analyses are accurate only at high SNR regimes. In this paper error rate analyses that are sufficiently accurate over a wide range of SNR regimes are provided. The motivations for this work are that practical systems operate at far lower SNR values than those supported by the high SNR analysis. To enable designers to make informed decisions regarding network design and deployment, it is imperative that system performance is evaluated with a reasonable degree of accuracy over practical SNR regimes. Simulations have been used to corroborate the analytical results, as close agreement between the two is observed.
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paper_title: The Gaussian parallel relay network

paper_content:

We introduce the real, discrete-time Gaussian parallel relay network. This simple network is theoretically important in the context of network information theory. We present upper and lower bounds to capacity and explain where they coincide.
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paper_title: An efficient protocol for realizing cooperative diversity in wireless networks

paper_content:

We develop two variants of an energy-efficient cooperative diversity protocol that combats fading induced by multipath propagation in wireless networks, The underlying techniques build upon the classical relay channel and related work and exploit space diversity available at distributed antennas through coordinated transmission and processing by cooperating radios. While applicable to any wireless setting, these protocols are particularly attractive in ad-hoc or peer-to-peer wireless networks, in which radios are typically constrained to employ a single antenna. Substantial energy-savings resulting from these protocols can lead to reduced battery drain, longer network lifetime, and improved network performance in terms of, e.g., capacity.
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paper_title: Cooperative versus non-cooperative communications

paper_content:

In this paper, we review some of the prominent gains achieved with cooperative communications, a new way of communications, which has found its applications in almost every wireless network, from cellular to sensor networks. Cooperative communications is a way of transmission, where wireless users not only transmit their own information, but also repeat other users' information during its transmission to a common destination. On the other hand, a non-cooperative communications is the classical multiple access channel, where users send directly to a common destination, without repeating for one another. We discuss the achievable rates and error rate performance both for cooperative and non-cooperative communications.
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paper_title: Cooperative diversity in wireless networks: Efficient protocols and outage behavior

paper_content:

We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.
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paper_title: Cooperative strategies and capacity theorems for relay networks

paper_content:

Coding strategies that exploit node cooperation are developed for relay networks. Two basic schemes are studied: the relays decode-and-forward the source message to the destination, or they compress-and-forward their channel outputs to the destination. The decode-and-forward scheme is a variant of multihopping, but in addition to having the relays successively decode the message, the transmitters cooperate and each receiver uses several or all of its past channel output blocks to decode. For the compress-and-forward scheme, the relays take advantage of the statistical dependence between their channel outputs and the destination's channel output. The strategies are applied to wireless channels, and it is shown that decode-and-forward achieves the ergodic capacity with phase fading if phase information is available only locally, and if the relays are near the source node. The ergodic capacity coincides with the rate of a distributed antenna array with full cooperation even though the transmitting antennas are not colocated. The capacity results generalize broadly, including to multiantenna transmission with Rayleigh fading, single-bounce fading, certain quasi-static fading problems, cases where partial channel knowledge is available at the transmitters, and cases where local user cooperation is permitted. The results further extend to multisource and multidestination networks such as multiaccess and broadcast relay channels.
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paper_title: Cooperative Communications and Networking

paper_content:

Presenting the fundamentals of cooperative communications and networking, this book treats the concepts of space, time, frequency diversity and MIMO, with a holistic approach to principal topics where significant improvements can be obtained. Beginning with background and MIMO systems, Part I includes a review of basic principles of wireless communications and space-time diversity and coding. Part II then presents topics on physical layer cooperative communications such as relay channels and protocols, performance bounds, multi-node cooperation, and energy efficiency. Finally, Part III focuses on cooperative networking including cooperative and content-aware multiple access, distributed routing, source-channel coding, and cooperative OFDM. Including end-of-chapter review questions, this text will appeal to graduate students of electrical engineering and is an ideal textbook for advanced courses on wireless communications. It will also be of great interest to practitioners in the wireless communications industry. Presentation slides for each chapter and instructor-only solutions are available at www.cambridge.org/9780521895132.
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paper_title: Cooperative diversity in wireless networks: Efficient protocols and outage behavior

paper_content:

We develop and analyze low-complexity cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals' relaying signals for one another. We outline several strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise ratio (SNR) regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols are efficient in the sense that they achieve full diversity (i.e., second-order diversity in the case of two terminals), and, moreover, are close to optimum (within 1.5 dB) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly at the cost of additional receive hardware. Applicable to any wireless setting, including cellular or ad hoc networks-wherever space constraints preclude the use of physical arrays-the performance characterizations reveal that large power or energy savings result from the use of these protocols.
---
paper_title: Cooperative Communications and Networking

paper_content:

Presenting the fundamentals of cooperative communications and networking, this book treats the concepts of space, time, frequency diversity and MIMO, with a holistic approach to principal topics where significant improvements can be obtained. Beginning with background and MIMO systems, Part I includes a review of basic principles of wireless communications and space-time diversity and coding. Part II then presents topics on physical layer cooperative communications such as relay channels and protocols, performance bounds, multi-node cooperation, and energy efficiency. Finally, Part III focuses on cooperative networking including cooperative and content-aware multiple access, distributed routing, source-channel coding, and cooperative OFDM. Including end-of-chapter review questions, this text will appeal to graduate students of electrical engineering and is an ideal textbook for advanced courses on wireless communications. It will also be of great interest to practitioners in the wireless communications industry. Presentation slides for each chapter and instructor-only solutions are available at www.cambridge.org/9780521895132.
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paper_title: Coded cooperation in wireless communications: space-time transmission and iterative decoding

paper_content:

When mobiles cannot support multiple antennas due to size or other constraints, conventional space-time coding cannot be used to provide uplink transmit diversity. To address this limitation, the concept of cooperation diversity has been introduced, where mobiles achieve uplink transmit diversity by relaying each other's messages. A particularly powerful variation of this principle is coded cooperation. Instead of a simple repetition relay, coded cooperation partitions the codewords of each mobile and transmits portions of each codeword through independent fading channels. This paper presents two extensions to the coded cooperation framework. First, we increase the diversity of coded cooperation in the fast-fading scenario via ideas borrowed from space-time codes. We calculate bounds for the bit- and block-error rates to demonstrate the resulting gains. Second, since cooperative coding contains two code components, it is natural to apply turbo codes to this framework. We investigate the application of turbo codes in coded cooperation and demonstrate the resulting gains via error bounds and simulations.
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paper_title: Cooperative Communications and Networking

paper_content:

Presenting the fundamentals of cooperative communications and networking, this book treats the concepts of space, time, frequency diversity and MIMO, with a holistic approach to principal topics where significant improvements can be obtained. Beginning with background and MIMO systems, Part I includes a review of basic principles of wireless communications and space-time diversity and coding. Part II then presents topics on physical layer cooperative communications such as relay channels and protocols, performance bounds, multi-node cooperation, and energy efficiency. Finally, Part III focuses on cooperative networking including cooperative and content-aware multiple access, distributed routing, source-channel coding, and cooperative OFDM. Including end-of-chapter review questions, this text will appeal to graduate students of electrical engineering and is an ideal textbook for advanced courses on wireless communications. It will also be of great interest to practitioners in the wireless communications industry. Presentation slides for each chapter and instructor-only solutions are available at www.cambridge.org/9780521895132.
---
paper_title: Optimization for Cooperative Sensing in Cognitive Radio Networks

paper_content:

In cognitive radio networks, the secondary users can use the frequency bands when the primary users are not present. Hence secondary users need to constantly sense the presence of the primary users. When the primary users are detected, the secondary users have to vacate that channel. This makes the probability of detection important to the primary users as it indicates their protection level from secondary users. When the secondary users detect the presence of a primary user which is in fact not there, it is referred to as false alarm. The probability of false alarm is important to the secondary users as it determines their usage of an unoccupied channel. Depending on whose interest is of priority, either a targeted probability of detection or false alarm shall be set. After setting one of the probabilities, the other can be optimized through cooperative sensing. In this paper, we show that cooperating all secondary users in the network does not necessary achieve the optimum performance, but instead, it is achieved by cooperating a certain number of users with the highest primary user's signal to noise ratio. Computer simulations have shown that the Pd can increase from 92.03% to 99.88% and Pf can decrease from 6.02% to 0.06% in a network with 200 users.
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paper_title: Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks

paper_content:

We develop and analyze space-time coded cooperative diversity protocols for combating multipath fading across multiple protocol layers in a wireless network. The protocols exploit spatial diversity available among a collection of distributed terminals that relay messages for one another in such a manner that the destination terminal can average the fading, even though it is unknown a priori which terminals will be involved. In particular, a source initiates transmission to its destination, and many relays potentially receive the transmission. Those terminals that can fully decode the transmission utilize a space-time code to cooperatively relay to the destination. We demonstrate that these protocols achieve full spatial diversity in the number of cooperating terminals, not just the number of decoding relays, and can be used effectively for higher spectral efficiencies than repetition-based schemes. We discuss issues related to space-time code design for these protocols, emphasizing codes that readily allow for appealing distributed versions.
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paper_title: Cross-Layer Design for QoS Support in Multihop Wireless Networks

paper_content:

Due to such features as low cost, ease of deployment, increased coverage, and enhanced capacity, multihop wireless networks such as ad hoc networks, mesh networks, and sensor networks that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. Providing efficient quality of service (QoS) support is essential for such networks, as they need to deliver real-time services like video, audio, and voice over IP besides the traditional data service. Various solutions have been proposed to provide soft QoS over multihop wireless networks from different layers in the network protocol stack. However, the layered concept was primarily created for wired networks, and multihop wireless networks oppose strict layered design because of their dynamic nature, infrastructureless architecture, and time-varying unstable links and topology. The concept of cross-layer design is based on architecture where different layers can exchange information in order to improve the overall network performance. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. This paper aims to review the present study on the cross-layer paradigm for QoS support in multihop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. Realizing the new trends for wireless networking, such as cooperative communication and networking, opportunistic transmission, real system performance evaluation, etc., several open issues related to cross-layer design for QoS support over multihop wireless networks are also discussed in the paper.
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paper_title: Cooperative communication in wireless networks

paper_content:

Transmit diversity generally requires more than one antenna at the transmitter. However, many wireless devices are limited by size or hardware complexity to one antenna. Recently, a new class of methods called cooperative communication has been proposed that enables single-antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter that allows them to achieve transmit diversity. This article presents an overview of the developments in this burgeoning field.
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paper_title: Successive interference cancellation for cooperative communication systems

paper_content:

In this paper, we analyze and simulate a successive interference cancellation (SIC) scheme for cooperative communication systems in wireless communication network. In the interference cancellation strategy, co-channel interference (CCI) is mitigated by zero forcing (ZF) or minimum mean square error (MMSE) receivers. Moreover, successive interference cancellation (SIC) with optimal ordering algorithm is applied for rejecting CCI efficiently. And we analyzed and simulated the proposed system performance in Rayleigh fading channel. In order to justify the benefit of the proposed strategy, the overall system performance is illustrated in terms of bit error rate and compared with that of conventional interference cancellation receiver.
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Title: A Review on Cooperative Communication Protocols in Wireless World

Section 1: WORKING PRINCIPLE
Description 1: Describe the foundational ideas behind cooperative communication, including its broadcast nature and relay channels.

Section 2: HISTORICAL BACKGROUND
Description 2: Provide a historical perspective on the development of cooperative communications, including key contributions and concepts like amplify-and-forward, decode-and-forward, and coded cooperation.

Section 3: PREVIOUS WORK
Description 3: Summarize the existing literature on cooperative relaying, covering various studies on capacity analysis, relaying strategies, error performance, and more.

Section 4: BASIC RELAYING PROTOCOLS
Description 4: Describe the fundamental protocols used in cooperative communication, such as Amplify and Forward, Decode and Forward, and Compress and Forward, and their respective pioneers.

Section 5: COOPERATIVE RELAYING TECHNIQUES
Description 5: Discuss different cooperative communication protocols or transmission techniques, including Fixed Cooperation Strategies, Fixed Decode and Forward (Single Relay), Fixed Decode and Forward (Multi Relay), and Other Cooperation Strategies.

Section 6: Adaptive Cooperation Strategies
Description 6: Discuss adaptive relaying protocols designed to enhance bandwidth efficiency, such as Selective DF Relaying and Incremental Relaying.

Section 7: APPLICATIONS
Description 7: Highlight various applications for cooperative relaying strategies, including Virtual Antenna Arrays, Wireless Ad-hoc Networks, Wireless Sensor Networks, and Cooperative Sensing for Cognitive Radio.

Section 8: TRACKS FOR FUTURE WORK
Description 8: Outline potential areas for future research to improve cooperative communication, including system modeling, power optimization, full-duplex relay operation, and spectrum efficiency.

Section 9: CHALLENGES
Description 9: Discuss the challenges and complexities involved in implementing cooperative communication, like complex schedulers, increased overhead, interference, latency, and more channel estimates.

Section 10: CONCLUSIONS
Description 10: Summarize the significance of cooperative communication in improving wireless communication systems' efficiency and reliability, and mention areas not covered in detail that deserve further attention.