Self-Interference in Full-Duplex Multi-User MIMO Channels

We consider a multi-user multiple-input multiple-output setup, where full-duplex multi-antenna nodes apply linear beamformers to simultaneously transmit and receive multiple streams over Rician fading channels. The exact first and second positive moments of the residual self-interference (SI), involving the squared norm of a sum of non-identically distributed random variables, are derived in closed-form. The method of moments is hence invoked to provide a Gamma approximation for the residual SI distribution. The proposed theorem holds under arbitrary linear precoder/decoder design, antenna array size, number of information streams, and SI cancellation capability.