Two-Way Relaying With Multi-Antenna Sources: Beamforming and Antenna Selection

The authors propose and analyze two Multiple-Input - Multiple-Output (MIMO) two-way relaying schemes with an amplify-and-forward protocol in Nakagami-m fading channels, where multi-antenna sources communicate via a single-antenna relay. Specifically, they present a new framework for the comparative analysis of beamforming and antenna selection with non-identical fading parameter m in the two source-relay links. To facilitate the comparison, they derive new exact, approximate, and asymptotic expressions for the Sum Symbol Error Rate (SSER) with M-ary Phase-Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM).