Joint beamforming and antenna selection for two-way amplify-and-forward MIMO relay networks

A novel joint beamforming and antenna selection strategy is proposed and analyzed for two-way multiple-input multiple-output amplify-and-forward relay networks. Specifically, this strategy selects the optimal transmit precoding and receiver filtering vectors at the two source terminals, and an optimal transmit/receive antenna at the relay terminal based on minimizing the overall outage probability. The performance of this transmission strategy is quantified by first deriving the exact cumulative distribution function of the effective signal-to-noise ratio (SNR), and thereby, evaluating the overall outage probability, its asymptotically exact high SNR approximation and achievable diversity order. For a multiple relay scenario, a joint relay, beamforming, and antenna selection strategy is proposed and analyzed as well. Interestingly, our selection strategies are optimal in the sense of the overall outage probability, and hence, in the sense of achievable diversity order as well.