Outage Performance and Diversity Analysis for Multi-antenna Multi-relay Networks

The performance of multi-antenna multi-relay cooperative system is investigated in this paper. Two relaying strategies, i.e., reactive and proactive strategies are analyzed with the Amplify-and-Forward (AF) and Decode-and-Forward (DF) protocols. We derive the Cumulative Distribution Function (CDF) of the received Signal-to-Noise Ratio (SNR) at the destination, which is used to calculate the exact outage probability, for both AF and DF protocols. According to these results, we conclude that a cooperative network which composes K relays each equipped with n, antennas can achieve maximal order-(2n,K+1) diversity gain, by proper processing at relays and destination. Furthermore, the performance comparison is given, in terms of outage probability. These two strategies outperform each other in different scenarios in AF protocol, whilst proactive strategy is always better than its counterpart in DF protocol. According to these results, the optimal power allocation schemes among relay nodes are also presented, with reasonable power constraint.