Outage Behavior of Multi-Antenna Multi-Relay Non-Regenerative Cooperative Networks

To combat the multipath fading, the array gain is introduced to the cooperative system when multiple antennas is applied at relay nodes. Two cooperative schemes, i.e., the reactive and proactive relaying schemes are studied for the non-regenerative relaying, i.e., the amplify-and-forward (AF) mode. The results show that for a K relays network with each relay equips n_r antennas, both these two schemes can achieve order- (2n_r K+1) diversity. The optimal power allocation scheme among multiple relay nodes is given, which can be viewed as a modified water-filling algorithm, and improves the performance of the reactive scheme. Furthermore, these two schemes show performance gain over each other depending on the aggregate relay power in the AF mode.