Relay techniques in MIMO wireless networks

Abstract

Using multiple terminals each of which is equipped with multiple antennas to relay messages is a promising technique to improve the capacity of wireless networks. In this paper, we propose two relay schemes for multiple-input and multiple-output (MIMO) wireless networks: 1) ZF-P-QR scheme: it conducts zero forcing (ZF) processing on the backward channel and QR decomposition (QRD) on the forward channel in conjunction with phase control, and 2) QR-P-ZF scheme: it conducts QRD on the backward channel and ZF on the forward channel in conjunction with phase control. The ergodic capacities of the proposed schemes are compared to those of previously proposed relay schemes, as well as that of direct communication under path-loss environments with various relay node configurations. It's shown that the ZF-P-QR and the QR-P-ZF schemes outperform the previously proposed relay schemes when the relay nodes are located close to the source and destination nodes, respectively. It is also found out that the relay schemes can achieve higher capacity than direct communication when the source and destination nodes are in non line of sight propagation environments and are separated by large distances.