Jointly optimal pre- and post-channel equalization and distributed beamforming in asynchronous bi-directional relay networks

Abstract

We consider an asynchronous two-way relay network, consisting of two transceivers and multiple relays, where due to the propagation delays of different transceiver-relay paths being different, inter-symbol- interference (ISI) exists at both transceivers. In this work, pre- and post-channel equalization blocks are used to combat ISI. The mean-squared error of the estimated received signals at both transceivers is minimized under a total transmit power budget by optimally obtaining the transceivers’ powers and relay beamforming weight vectors as well as pre- and post-channel equalizers at the two transceivers. We prove that our proposed approach results in a certain relay selection scheme.