Unified Sum-BER Performance Analysis of AF MIMO Beamforming in Two-Way Relay Networks

Unified performance analysis is carried out for amplify-and-forward (AF) multiple-input-multiple-output (MIMO) beamforming (BF) two-way relay networks in Rayleigh fading with five different relaying protocols including two novel protocols for better performance. As a result, a novel closed-form sum-bit error rate (BER) expression is presented in a unified expression for all protocols. A new closed-form high signal-to-noise-ratio (SNR) performance is also obtained in a single expression, and an analytical high-SNR gap expression between the five protocols is provided. We compare the performance of the five relaying protocols with respect to sum-BER with appropriately normalized rate and power, and show that the proposed protocol with four time slots outperforms other protocols when transmit powers from two sources are sufficiently different, and the one with three time slots dominates other protocols when multiple relay antennas are used, at high-SNR.