Comparison of channel estimation schemes for MIMO two-way relaying systems

In this paper, we investigate the performance of two-way amplify-and-forward (AF) MIMO relaying systems with different channel estimation schemes. Two channel estimation schemes, named cascaded channel estimation and individual channel estimation, are considered. In the first scheme, the cascaded source-relay-destination links are estimated at the two users, and no channel estimation is need at the relay station. In the individual scheme, the channels from the users to the relay are estimated at the relay station, and then the estimated CSIs are feed-forward to the two users, while the channels from the relay to the users are estimated at the two users, respectively. The mean square error (MSE) and bit-error-rate (BER) performance of these two schemes are compared through numerical simulations. The simulation results show that the individual scheme outperforms the cascaded scheme in various cases.