Coordinated downlink precoder design for regenerative multi-user relaying

Regenerative relaying is an efficient method of increasing the achievable capacity and cell coverage. We propose a weighted mean squared error (WMSE) minimization based throughput maximizing precoder design subject to separate sum transmit power constraints for the base station (BS) and relay station (RS). The proposed algorithm is implemented in a distributed manner, thus, further improving the efficiency. We assume a system consisting of a single multi-antenna BS and multi-antenna RS, both of which are serving multiple single-antenna users. We consider a two-stage transmission strategy, in which, at the first stage, BS transmits to the associated users and the RS. At the second stage, the BS and RS transmit to their associated users. It is demonstrated that, with appropriate over-the-air (OTA) signaling, the system performance can be significantly improved.