Outage Minimized Full-Duplex Multiantenna DF Relaying With CSI Uncertainty

Multiantenna full-duplex (FD) relaying, as a promising solution for future wireless communications, has received many attentions. In this paper, focusing on FD decode-and-forward relaying with only partial channel state information available, we are interested in the relay beamforming optimization from an outage probability minimization perspective. Due to the implicit outage probability objective function, it is rather hard to find an optimal solution directly. To overcome this obstacle, we first obtain an explicit form of the outage probability, which involves intricate Marcum Q-functions. Based on the derived objective, we find out the optimal relay receive and transmit beamforming directions, which turns out to be the maximum-ratio combining/maximum-ratio transmission strategy. Then, we rigourously prove that the optimal relay transmit power is the unique solution to a strictly quasi-concave problem and, hence, can be efficiently determined. The performance advantage of the proposed optimal design over conventional schemes is validated via simulations.