Low Overhead Phase Rotation Schemes for Relay Selection in Two-Way DF Relay Networks
Han Wang, Pengfei Wang, Qisong Li, Ruohan Cao, Fangwei Zhang · 2018
Phase rotation (PR) aided Max-Min relay selection (RS) can achieve full diversity gains in two-way decode-and-forward relay networks. The pre-processing associated with the conventional PR scheme requires explicit feedback of the channel's effective angle (EA), which imposes extra system overhead. In this letter, we propose two novel low-overhead PR schemes that do not require full knowledge of the channel's EA, namely, the limited-feedback PR (LF-PR) scheme and the blind PR (B-PR) scheme. The LF-PR scheme partially pre-mitigates the negative effect of channel fading. The impact of quantization precision on the achievable performance with the LF-PR scheme is also analyzed. In order to further reduce system overhead, B-PR adopts a symbol extension and an offline-designed PR sequence to create multiple-path transmission at the source for each symbol. Both the LF-PR and B-PR schemes perform well with Max-Min RS and achieve the full diversity gain.