Cooperative Linear Combining on Quantize-Forward Relay Channel with M-Ary Phase Shift Keying

This work considers quantize-forward (QF) relay channels with M-ary phase shift keying at the source and q-bit uniform phase quantization at the relay. A cooperative linear combining (CLC) detection which linearly combines the received signals at the destination is proposed in the QF relay channel by deriving an equivalent signal-to-noise ratio for the source-relay-destination link. Furthermore, the proposed detection is simplified by approximating Q function in two directions: small q and large q. The CLC detection and its simplified version are also extended to multi-relay channels. Simulation results verify that the CLC and simplified CLC detections achieve reasonable performance with less complexity than the maximum-likelihood detection. It demonstrates that applying (log2 M+2)-bit uniform phase quantization at the relay and the simplified CLC detection at the destination can be an appropriate choice in terms of performance, complexity, and memory.