Two-hop relay channels with limited feedback

In this paper, we consider the layered two-hop relay channel, operating under the linear rotate-and-forward (RF) scheme, where the relays rotate the received signal before its retransmission. In this work, a limited feedback channel is considered between the relays and the destination. The destination finds the optimal rotation vector and feeds it back to the relays. We propose an iterative algorithm to find this optimal rotation vector. The proposed algorithm is shown to have optimal performance with low complexity.