Unified relaying structure for the MIMO relay network

The MIMO relay network, with multiple relay nodes and the amplify-and-forward relaying strategy, is focused in this paper. The MIMO relay network would provide an excellent information service with high data rate and ubiquitous coverage. But the performance of the MIMO relay network is heavily dependent on the diversity gain brought by the use of multiple relay nodes, which is denoted as the multi-relays gain. The signal relaying scheme adopted by relay nodes is the key to exploit the multi-relays gain. There are many research results on the signal relaying scheme of MIMO relay network, such as AF, ZF, SVD, MF, MMSE relaying schemes. But previous literatures didn't give a comprehensive reason on the causing of multi-relays gain in different relaying schemes. In this paper, a space rotation method is proposed to exploit the causing of multi-relays gain in MIMO relay network. On this basis, a unified relaying structure is given out, which should be satisfied at relay nodes in order to obtain the multi-relays gain. Furthermore, we use the unified relaying structure to analyze the performance of the existing relaying schemes, and a new ASVD relaying scheme is designed for the MIMO relay network which is analogous to the SVD relaying scheme. Numerical results have verified the validity of the unified relaying structure and the ASVD relaying scheme is superior to existing relaying schemes in the capacity.