1 research outputs found
Opportunistic Relaying for Space-Time Coded Cooperation with Multiple Antenna Terminals
We consider a wireless relay network with multiple antenna terminals over
Rayleigh fading channels, and apply distributed space-time coding (DSTC) in
amplify-and-forward (A&F) mode. The A&F scheme is used in a way that each relay
transmits a scaled version of the linear combination of the received symbols.
It turns out that, combined with power allocation in the relays, A&F DSTC
results in an opportunistic relaying scheme, in which only the best relay is
selected to retransmit the source's space-time coded signal. Furthermore,
assuming the knowledge of source-relay CSI at the source node, we design an
efficient power allocation which outperforms uniform power allocation across
the source antennas. Next, assuming M-PSK or M-QAM modulations, we analyze the
performance of the proposed cooperative diversity transmission schemes in a
wireless relay networks with the multiple-antenna source and destination. We
derive the probability density function (PDF) of the received SNR at the
destination. Then, the PDF is used to determine the symbol error rate (SER) in
Rayleigh fading channels. We derived closed-form approximations of the average
SER in the high SNR scenario, from which we find the diversity order of system
RminfNs;Ndg, where R, Ns, and Nd are the number of the relays, source antennas,
and destination antennas, respectively. Simulation results show that the
proposed system obtain more than 6 dB gain in SNR over A&F MIMO DSTC for BER
10^{-4}, when R = 2, Ns = 2, and Nd = 1