Distributed beamforming approach to full-duplex relay in multiuser MIMO transmission

In this paper, we propose a distributed beamforming approach to full-duplex relay (FDR) in multiuser multiple-input multiple-output (MIMO) relaying systems. In the proposed scheme, each mobile station (MS) and relay station (RS) performs distributed transmit beamforming and receive combining to suppress the self-interference at the RS as well as the multiuser interference at the MS´s, while the base station (BS) performs zero-forcing beamforming with water-filling power allocation. Using the channel reciprocity between the uplink and downlink in time division duplex (TDD) systems, the distributed beamforming is realized in an iterative way without the need for additional information exchange among nodes. Numerical results are presented to verify that the proposed scheme provides substantial performance improvement compared with the half-duplex relay (HDR).