Joint optimization of relay-precoders and decoders with partial channel side information in cooperative networks

TLDR

The study jointly optimizes relay precoders and decoders in a cooperative network using full or partial channel side information. The authors analyze three CSI scenarios—full CSI at both destination and relays, full CSI at the destination with partial CSI at relays, and partial CSI at both terminals—to derive optimal relay precoders and decoders. With full CSI, the optimal relay precoder is cooperative beamforming and the decoder is a maximum‑ratio combiner, while under partial CSI the optimal designs reduce to channel selection, leading to substantial performance gains.

Abstract

We jointly optimize the relay-precoders and decoders with full or partial channel side information (CSI) in a cooperative network. Specifically, three different CSI assumptions are considered: 1) full CSI at the destination terminal and the relay terminals; 2) full CSI at the destination terminal and partial CSI at the relay terminals; 3) partial CSI at the destination terminal and the relay terminals. We show that, under the assumption of full CSI at the destination terminal and the relay terminals, the optimum relay-precoder is the cooperative transmission beamforming and the optimum decoder is a maximum ratio combiner. Under the two partial CSI assumptions, the optimum relay-precoders and decoders work in a fashion of channel selection. It is demonstrated that the proposed optimum relay-precoders and decoders improve the performance considerably