Bandwidth-Efficient Cooperative Relaying Schemes with Multiantenna Relay
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Research Article Bandwidth-Efficient Cooperative Relaying Schemes with Multiantenna Relay Khuong Ho-Van and Tho Le-Ngoc Department of Electrical and Computer Engineering, McGill University, Montreal, QC, Canada H3A 2A7 Correspondence should be addressed to Tho Le-Ngoc, [email protected] Received 1 November 2007; Revised 12 February 2008; Accepted 17 March 2008 Recommended by Hyundong Shin We propose coded cooperative relaying schemes in which all successfully decoded signals from multiple sources are forwarded simultaneously by a multiantenna relay to a common multiantenna destination to increase bandwidth efficiency. These schemes facilitate various retransmission strategies at relay and single-user and multiuser iterative decoding techniques at destination, suitable for trade-offs between performance, latency, and complexity. Simulation results show that the proposed schemes significantly outperform direct transmission under the same transmit power and bandwidth efficiency. Copyright © 2008 K. Ho-Van and T. Le-Ngoc. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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INTRODUCTION
Cooperative relaying has attracted a great deal of attention recently due to its capability of improving performance, increasing system capacity, extending coverage, and so forth [1, 2]. Different signal processing techniques for retransmission and detection at relays and destination for cooperative relaying have been presented. In [3–6], the relays receive signals from sources in one phase and simply amplify or demodulate source signals before forwarding processed signals to the destination in another phase. The destination can use maximum ratio combining in both phases to recover the original information. In [7–11], coded cooperative relaying schemes were proposed, in which the relays decode the source signals and re-encode the decoded information in a different manner as compared to the sources (e.g., the decoded information is interleaved before being reencoded [8]) so that the destination can use code combining techniques such as iterative decoding to recover the original information. Coded cooperative relaying schemes are not only better than those based on repetition coding under various channel conditions [1], but also provide a great degree of flexibility to adapt channel conditions by allowing different code rates and partitions, for example, relayed signal can include just new parity bits [9] or with a fraction of repeated information bits [10].
The cooperative relaying schemes in [2–11] only consider a simple scenario with a source, a relay, and a destination; all are equipped with a single antenna. To increase spatial diversity order as well as cooperation probability between the source and the relay, several multiantenna relays were investigated using the diversity combining schemes in [12]. In general, all schemes in [2–12] reduce dramatically bandwidth efficiency a
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