Alternate AF MIMO Relaying Systems with Full Inter-Relay Interference Cancellation

This paper considers amplify-and-forward (AF), multiple-input multiple-output (MIMO), two-hop relay systems in which the inter-relay interference (IRI), if not mitigated, may limit performance. In these systems with half-duplex relays, through TDMA scheduling, the wireless medium in both hops is always utilized through the simultaneous transmission of one of the sources and one of the relays which in turn leads to IRI. By representing IRI with the recursive term(s) and exploiting opportunistic listening, this interference is fully removed at the receiver(s) using limited channel state information (CSI) from both hops. As presented in this paper, the proposed MIMO IRI cancellation is applicable to cellular and ad-hoc wireless networks and could work with an arbitrary number of antennas provided that the number of antennas at the corresponding relays and the receivers is the same. We analyze the diversity gain and the multiplexing gain through simulations to verify the good performance of the proposed algorithm.