Efficient hybrid relaying schemes with limited feedback

Abstract

We noticed that in a relay system, the assumption of global Channel State Information (CSI) knowledge is unrealistic and normally, only the receiver but not the transmitter side has CSI knowledge. In this paper, we analyzed, with receive CSI, the performance of hybrid relaying scheme in the half-duplex relay channel in terms of the outage probability and expected throughput, where the relay switches between decode-and-forward (DF) and compress-and-forward (CF) modes adaptively according to the current channel realizations. Moreover, since the original CF technique requires global CSI at the relay to calculate the optimal compression rate, we established a restricted feedback link to convey extremely limited CSI (only 3 bits in our results) from the destination to the relay and develop a more practical hybrid relaying scheme. Simulation results revealed that the hybrid relaying scheme with restricted feedback outperforms DF especially when the link between source and relay is of low quality.