Conference Paper

Space Diversity for Multi-antenna Multi-relay Channels

Institute for Digital Communications, School of Engineering and Electronics, University of Edinburgh, EH9 3JL, UK
Conference: Wireless Conference 2006 - Enabling Technologies for Wireless Multimedia Communications (European Wireless), 12th European
Source: IEEE Xplore

ABSTRACT In this paper we analyze the performance of multiple relay channels when multiple antennas are deployed only at relays. We apply two antenna diversity techniques at relays, namely maximum ratio combining (MRC) on receive and transmit beamforming (TB). We show that with K relays the network can be decomposed into K diversity channels each with a different channel gain, and that the signals can be effectively combined at the destination. We assume that the total number of antennas at all relays is fixed at N. If the total transmit power for all relays are the same as for the source and equally distributed among all the relays, the network capacity will be lower bounded by that of N relay channels each with single antenna, and upper bounded by that of single relay channels with N antennas.

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Available from: Halim Yanikomeroglu, Dec 20, 2013
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    • "The proof is omitted due to space limitations; please refer to [15] for details. This lemma implies that, generally, the increased " equal gain combining " gain at the destination cannot compensate for the loss of MRC gain at the relay and TB gain at the destination when K is increased and each m k is reduced, given the power constraint (4). "
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    ABSTRACT: In this letter the performance of multiple relay channels is analyzed for the situation in which multiple antennas are deployed only at the relays. The simple repetition-coded decodeand- forward protocol with two different antenna processing techniques at the relays is investigated. The antenna combining techniques are maximum ratio combining (MRC) for reception and transmit beamforming (TB) for transmission. It is shown that these distributed antenna combining techniques can exploit the full spatial diversity of the relay channels regardless of the number of relays and antennas at each relay, and offer significant power gain over distributed space-time coding techniques.
    IEEE Transactions on Communications 03/2008; 57. DOI:10.1109/TCOMM.2009.03.070081 · 1.98 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper we analyze the performance of multiple relay channels when multiple antennas are deployed only at relays. Specifically, we investigate the simple repetition-coded decode-and-forward protocol and apply two antenna combining techniques at relays, namely maximum ratio combining (MRC) on receive and transmit beamforming (TB). We assume that the total number of antennas at all relays is fixed to N. With a reasonable power constraint at the relays, we show that the antenna combining techniques can exploit the full spatial diversity of the relay channels and can achieve the same diversity multiplexing tradeoff as achieved by more complex space-time distributed coding techniques, such as those proposed by Laneman and Womell (2003).
    Communications, 2007. ICC '07. IEEE International Conference on; 07/2007
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    ABSTRACT: In this paper we study the threshold decode and forward (T-DF) fixed relays network with beamforming, which is more reliable than conventional decode and forward (DF) relaying. Deployment of a small number of antennas on fixed relays is easier than on mobile terminals, therefore, the impact of multiple antennas on the outage probability of cooperating fixed relays is considered. Under the total sum power constraint (TSPC) of all relays and also maximum per-relay power constraint (PRPC), the optimum beamforming weights have been found to maximize the received SNR at the destination. It is determined that increasing the number of relays and antennas at each relay increases capacity. The performance of threshold-maximal ratio combining (T-MRC) and threshold-selection combining (T-SC) of the multiple-antenna multiple fixed relays with beamforming is derived. It is observed that the performance of the network with selection combining (SC) configuration is close to the network in which maximal ratio combining (MRC) is used, in addition that it is less complex and less expensive to implement. The outage probability in Rayleigh fading channels is also analyzed.
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