A simple cooperative diversity method based on network path selection (2006)

by A Bletsas, A Khisti, D P Reed, A Lippman
Venue:IEEE J. Selec. Areas Commun
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Multiple-antenna cooperative wireless systems: A diversity multiplexing tradeoff perspective

by Melda Yuksel, Elza Erkip , 2007
"... We consider a general multiple-antenna network with multiple sources, multiple destinations, and multiple relays in terms of the diversity–multiplexing tradeoff (DMT). We examine several subcases of this most general problem taking into account the processing capability of the relays (half-duplex o ..."
Abstract - Cited by 70 (3 self) - Add to MetaCart
We consider a general multiple-antenna network with multiple sources, multiple destinations, and multiple relays in terms of the diversity–multiplexing tradeoff (DMT). We examine several subcases of this most general problem taking into account the processing capability of the relays (half-duplex or full-duplex), and the network geometry (clustered or nonclustered). We first study the multiple-antenna relay channel with a full-duplex relay to understand the effect of increased degrees of freedom in the direct link. We find DMT upper bounds and investigate the achievable performance of decode-and-forward (DF), and compress-and-forward (CF) protocols. Our results suggest that while DF is DMT optimal when all terminals have one antenna each, it may not maintain its good performance when the degrees of freedom in the direct link are increased, whereas CF continues to perform optimally. We also study the multiple-antenna relay channel with a half-duplex relay. We show that the half-duplex DMT behavior can significantly be different from the full-duplex case. We find that CF is DMT optimal for half-duplex relaying as well, and is the first protocol known to achieve the half-duplex relay DMT. We next study the multiple-access relay channel (MARC) DMT. Finally, we investigate a system with a single source–destination pair and multiple relays, each node with a single antenna, and show that even under the ideal assumption of full-duplex relays and a clustered network, this virtual multiple-input multiple-output (MIMO) system can never fully mimic a real MIMO DMT. For cooperative systems with multiple sources and multiple destinations the same limitation remains in effect.

Energy-efficient cooperative relaying over fading channels with simple relay selection

by Ritesh Madan, Neelesh Mehta, Andreas Molisch, Jin Zhang - in EEE Global Telecommunications Conference (GLOBECOM , 2006
"... We consider a cooperative wireless network where a set of nodes cooperate to relay in parallel the information from a source to a destination using a decode-and-forward approach. The source broadcasts the data to the relays, some or all of which cooperatively beamform to forward the data to the dest ..."
Abstract - Cited by 60 (16 self) - Add to MetaCart
We consider a cooperative wireless network where a set of nodes cooperate to relay in parallel the information from a source to a destination using a decode-and-forward approach. The source broadcasts the data to the relays, some or all of which cooperatively beamform to forward the data to the destination. We generalize the standard approaches for cooperative communications in two key respects: (i)we explicitly model and factor in the cost of acquiring channel state information (CSI), and (ii)we consider more general selection rules for the relays and compute the optimal one among them. In particular, we consider simple relay selection and outage criteria that exploit the inherent diversity of relay networks and satisfy a mandated outage constraint. These criteria include as special cases serveral relay selection criteria proposed in the literature. We obtain expressions for the total energy consumption for general relay selection and outage criteria for the non-homogeneous case, in which different relay links have different mean channel power gains, and the homogeneous case, in which the relay links statistics are identical. We characterize the structure of the optimal transmission scheme. Numerical results show that the cost of training and feedback of CSI is significant. The optimal strategy is to use a varying subset (and number) or relay nodes to cooperatively beamform at any given time. Depending on the relative location of the relays, the source, and the destination, numerical computations show energy savings of about 16 % when an optimal relay selection rule is used. We also study the impact of shadowing correlation on the energy consumption for a cooperative relay network.
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Performance analysis of cooperative diversity wireless networks over Nakagami-m fading channel,”

by Salama Ikki , Member, IEEE Mohamed H Ahmed - IEEE Commun. Lett., , 2007
"... Abstract-This letter analyzes the performance of cooperative diversity wireless networks using amplify-and-forward relaying over independent, non-identical, Nakagami-m fading channels. The error rate and the outage probability are determined using the moment generating function (MGF ) of the total ..."
Abstract - Cited by 55 (3 self) - Add to MetaCart
Abstract-This letter analyzes the performance of cooperative diversity wireless networks using amplify-and-forward relaying over independent, non-identical, Nakagami-m fading channels. The error rate and the outage probability are determined using the moment generating function (MGF ) of the total signal-tonoise-ratio (SN R) at the destination. Since it is hard to find a closed form for the probability density function (P DF ) of the total SN R, we use an approximate value instead. We first derive the P DF and the MGF of the approximate value of the total SN R. Then, the MGF is used to determine the error rate and the outage probability. We also use simulation to verify the analytical results. Results show that the derived error rate and outage probability are tight lower bounds particularly at medium and high SN R. Index Terms-Average error rate, outage probability, cooperative diversity, amplify-and-forward, Nakagami-m fading.

KARAGIANNIDIS G.: ‘Performance analysis of single relay selection in Rayleigh fading

by Diomidis S. Michalopoulos, Student Member, George K. Karagiannidis, Senior Member - IEEE Trans. Wirel. Commun
"... Abstract—We provide closed-form expressions for the outage and bit error probability (BEP) of uncoded, threshold-based opportunistic relaying (OR) and selection cooperation (SC), at arbitrary signal to noise ratios (SNRs) and number of available relays, assuming decode-and-forward relays and Rayleig ..."
Abstract - Cited by 49 (3 self) - Add to MetaCart
Abstract—We provide closed-form expressions for the outage and bit error probability (BEP) of uncoded, threshold-based opportunistic relaying (OR) and selection cooperation (SC), at arbitrary signal to noise ratios (SNRs) and number of available relays, assuming decode-and-forward relays and Rayleigh fad-ing channels. Numerical results demonstrate that SC performs slightly better in terms of outage probability; in terms of BEP, both systems may outperform one another, depending on the SNR threshold that determines the set of relays that participate in the forwarding process. Index Terms—Cooperative diversity, fading channels. I.
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Energy-efficient cooperative communication based on power control and selective single-relay in wireless sensor networks

by Zhong Zhou, Student Member, Shengli Zhou, Jun-hong Cui, Shuguang Cui - IEEE Trans. Wireless Commun , 2008
"... Abstract—Cooperative communication with single relay selection is a simple but effective communication scheme for energyconstrained networks. In this paper, we propose a novel selective single-relay cooperative scheme, combining selective-relay cooperative communication with physical-layer power con ..."
Abstract - Cited by 35 (0 self) - Add to MetaCart
Abstract—Cooperative communication with single relay selection is a simple but effective communication scheme for energyconstrained networks. In this paper, we propose a novel selective single-relay cooperative scheme, combining selective-relay cooperative communication with physical-layer power control. Based on the MAC-layer RTS-CTS signaling, a set of potential relays compute individually the required transmission power to participate in the cooperative communication, and compete within a window of fixed length. The “best ” relay is selected in a distributed fashion with minimum signaling overhead. We derive power-control solutions corresponding to two policies on relay selection: One is to minimize the energy consumption per data packet, and the other is to maximize the network lifetime. Our numerical and simulation results confirm that the proposed scheme achieves significant energy savings and prolongs the network lifetime considerably. Index Terms—Selective relay cooperation, energy efficiency, wireless sensor networks, power control. I.
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Distributed cooperative MAC for multi-hop wireless networks

by Hangguan Shan , Weihua Zhuang , Zongxin Wang - IEEE Commun. Mag , 2009
"... Abstract: This article investigates distributed cooperative medium access control (MAC) protocol design for multi-hop wireless networks. Cooperative communication has been proposed recently as an effective way to mitigate channel impairments. With cooperation, single-antenna mobile terminals in ..."
Abstract - Cited by 35 (8 self) - Add to MetaCart
Abstract: This article investigates distributed cooperative medium access control (MAC) protocol design for multi-hop wireless networks. Cooperative communication has been proposed recently as an effective way to mitigate channel impairments. With cooperation, single-antenna mobile terminals in a multi-user environment share antennas from other mobiles to generate a virtual multiple-antenna system that achieves more reliable communication with a higher diversity gain. However, more mobiles conscribed for one communication induces inevitably complex medium access interactions, especially in multi-hop wireless ad hoc networks. To improve the network throughput and diversity gain simultaneously, we investigate the issues and challenges in designing an efficient MAC scheme for such networks. Furthermore, based on IEEE 802.11 DCF, a cross-layer designed cooperative MAC protocol is proposed. The MAC scheme adapts to the channel condition and payload length.
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Voluntary energy harvesting relays and selection in cooperative wireless networks

by Bhargav Medepally, Neelesh B. Mehta, Senior Member - IEEE Trans. Wireless Commun , 2010
"... Abstract—The use of energy harvesting (EH) nodes as coop-erative relays is a promising and emerging solution in wireless systems such as wireless sensor networks. It harnesses the spatial diversity of a multi-relay network and addresses the vexing problem of a relay’s batteries getting drained in fo ..."
Abstract - Cited by 33 (5 self) - Add to MetaCart
Abstract—The use of energy harvesting (EH) nodes as coop-erative relays is a promising and emerging solution in wireless systems such as wireless sensor networks. It harnesses the spatial diversity of a multi-relay network and addresses the vexing problem of a relay’s batteries getting drained in forwarding information to the destination. We consider a cooperative system in which EH nodes volunteer to serve as amplify-and-forward relays whenever they have sufficient energy for transmission. For a general class of stationary and ergodic EH processes, we intro-duce the notion of energy constrained and energy unconstrained relays and analytically characterize the symbol error rate of the system. Further insight is gained by an asymptotic analysis that considers the cases where the signal-to-noise-ratio or the number of relays is large. Our analysis quantifies how the energy usage at an EH relay and, consequently, its availability for relaying, depends not only on the relay’s energy harvesting process, but also on its transmit power setting and the other relays in the system. The optimal static transmit power setting at the EH relays is also determined. Altogether, our results demonstrate how a system that uses EH relays differs in significant ways from one that uses conventional cooperative relays. Index Terms—Energy harvesting, relays, selection, cooperative systems, diversity methods, modulation, fading channels, amplify-and-forward, energy storage, wireless sensor networks. I.
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Optimal relay assignment for cooperative communications

by Yi Shi, Sushant Sharma, Y. Thomas Hou, Sastry Kompella - in Proc. ACM MobiHoc , 2008
"... Recently, cooperative communications, in the form of keeping each node with a single antenna and having a node exploit a relay node’s antenna, is shown to be a promising approach to achieve spatial di-versity. Under this communication paradigm, the choice of relay node plays a significant role in th ..."
Abstract - Cited by 28 (4 self) - Add to MetaCart
Recently, cooperative communications, in the form of keeping each node with a single antenna and having a node exploit a relay node’s antenna, is shown to be a promising approach to achieve spatial di-versity. Under this communication paradigm, the choice of relay node plays a significant role in the overall system performance. In this paper, we study the relay node assignment problem in a net-work environment, where multiple source-destination pairs com-pete for the same pool of relay nodes in the network. The main contribution of this paper is the development of a polynomial time algorithm to solve this problem. A key idea in this algorithm is a “linear marking ” mechanism, which is able to offer a linear com-plexity for each iteration. We give a formal proof of optimality for this algorithm. We also show several attractive properties associ-ated with this algorithm.
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PHY-layer fairness in amplify and forward cooperative diversity systems

by Diomidis S. Michalopoulos, Student Member, George K. Karagiannidis, Senior Member - IEEE Trans. Wireless Commun , 2008
"... Abstract — We deal with the concept of physical-layer fairness in amplify and forward cooperative diversity systems, which reflects the need for equally allocating the consumed power among the relays. To this end, we propose a method which utilizes knowledge on both the instantaneous and average cha ..."
Abstract - Cited by 28 (0 self) - Add to MetaCart
Abstract — We deal with the concept of physical-layer fairness in amplify and forward cooperative diversity systems, which reflects the need for equally allocating the consumed power among the relays. To this end, we propose a method which utilizes knowledge on both the instantaneous and average channel conditions in order to encompass this concept, by attributing a weight coefficient to each relay depending on its average channel state and then selecting the relay with the best instantaneous “weighted ” channel conditions. We also provide a performance analysis of the proposed scheme that includes an analytical expression for the outage probability, together with a closed form one in the high signal-to-noise-ratio (SNR) regime. Through the latter expression, the average Symbol Error Probability (ASEP) for high SNRs is also derived. Numerical results demonstrate that, for small number of available relays or for high SNRs, the performance of the proposed scheme resembles that of the “best relay selection ” scheme, in terms of outage probability and ASEP, despite maintaining the average power consumptions equal. Index Terms — Cooperative diversity, Fading channels. I.

1 Protocol Design and Throughput Analysis for Multi-user Cognitive Cooperative Systems

by Ioannis Krikidis, J. Nicholas Laneman, John Thompson, Steve Mclaughlin , 2009
"... This paper deals with protocol design for cognitive cooperative systems with many secondary users. In contrast with previous cognitive configurations, the channel model considered assumes a cluster of secondary users which perform both a sensing process for transmitting opportunities and can relay d ..."
Abstract - Cited by 28 (3 self) - Add to MetaCart
This paper deals with protocol design for cognitive cooperative systems with many secondary users. In contrast with previous cognitive configurations, the channel model considered assumes a cluster of secondary users which perform both a sensing process for transmitting opportunities and can relay data for the primary user. Appropriate relaying improves the throughput of the primary users and can increase the transmission opportunities for the cognitive users. Based on different multi-access protocols, the schemes investigated enable relaying either between the primary user and a selected secondary user or between two selected secondary users. This collaboration can be a simple distributed multipleinput single-output transmission of the primary data or a simultaneous transmission of primary and secondary data using dirty-paper coding (DPC). The parametrization of DPC as well as its combination with opportunistic relay selection yields an interesting trade-off between the primary and the secondary performance which is investigated by theoretical and simulation results under the perspective of a desired primary throughput. The proposed protocols are studied from a networking point of view and the stable throughput for primary and secondary users is derived based on the principles of queueing theory. Index Terms analysis.