Enhance cell-edge rates by amplify-forward shared relays in dense cellular networks

This paper explores the benefits of deploying multi-antenna half-duplex amplify-and-forward shared relays at the cell-edge to assist the downlink transmission in a multiple-input multiple-output wireless cellular network. We design the relay node to provide extra spatial dimensions to multiple receivers at the same time for interference mitigation and signal enhancement. This paper proposes an efficient algorithm to solve the non-convex problem of jointly optimizing the transmit beamforming and relay combining matrices to a stationary point by extending the celebrated weighted minimum mean squared error (WMMSE) algorithm. We show that the optimized relaying strategy can significantly improve the long-term average rates of cell-edge users in a cellular network, even after accounting for the extra bandwidth required for halfduplex relaying.