Impact of Bi-Directional Relays on the Capacity of Rank-Deficient MIMO Channels
Yueming Cai · Journal of Huaqiao University · 2010
Aiming at the rank-deficient problem of multiple-input-multiple-output(MIMO) channel,the bi-directional relay based on the amplify-and-forward(AF) protocol is used to effectively increase the rank of the MIMO channels via forming the rich scattering environment.Because of bi-directional simultaneous transmission of data between the two nodes,the utilization of the spectral efficiency is increased.Theoretical analysis and simulation results show that compared with the MIMO channels without relay assistant,using bi-directional relays can solve the problem of rank-deficient MIMO channels.Because of using bi-directional relays,it requires half of the number of the time slots compared with the conventional AF relays utilizing the self-interference cancellation detection.The choice of the channel gain matrix adds the threshold restriction to the traditional AF protocol,so the capacity of the channel is improved further.