Spatial Modulation in Full-Duplex Relaying

In this letter, we consider a multiple-input multiple-output (MIMO) source-relay-destination network, where the relay is a full-duplex MIMO transceiver (FD-MIMO) and uses spatial modulation (SM). We propose a transmission protocol for this system, where the source beamforms to the relay antennas that are not used for transmission, while the remaining antennas in the relay forward the previously decoded information using SM to the destination. We derive the analytical expressions for the bit error rate of the FD-MIMO relaying system. We show from the analytical results and simulations that our proposed FD-MIMO system outperforms the one that uses V-BLAST at relay. This performance advantage is due to the availability of more antennas at the relay dedicated to reception and the use of a lower order quadratic-amplitude modulation in SM, when compared with V-BLAST.