Self-Interference Cancelation for Two-way MIMO Relay Network Based on Channel Independent Precoding

In two-way relay network, it brings the additional self-interference when improving the spectrum effectiveness. This paper considers the self-interference cancellation for amplify-and-forward multi-input multi-output (MIMO) two-way relay network. In order to cancel the residual self-interference with the imperfect channel estimation, a blind interference cancelation scheme (BIC) based on channel independent precoding is proposed. In the new scheme, the transmit data blocks at source node are precoded using row-space-mapping，with the target signal subspace and self-interference signal subspace established that is independent of MIMO channel state information (CSI), which can cancel the self-interference and decouple the target signal without CSI. On this basis, we design the optimal precoding matrix to maximum effective signal-to-noise ratio, derive the close-form expression of achievable sum rate and analysis the effect of channel estimation error under different scheme on achievable sum rate. Simulation results present that the new scheme can cancel the residual self-interference with different channel estimation error. The detectability and capacity both perform better compared to self-interference schemes based on channel estimation.