Effect of Non-Resolvable Multipath on Full-Duplex Self-Interference Cancellation

In full-duplex multipath self-interference (SI), each of the resolvable multipath SI components consists of a group of non-resolvable (NR) components with similar delays. Since the transceiver cannot distinguish the NR components in reality, the canceller can only generate the approximate constructed SI to imperfectly cancel the received SI. This leads to residual SI remaining. This paper analyzes the effect of the NR components on the SI cancellation, and proposes a practical scheme to eliminate the residual SI caused by the NR components. First, a closed-form expression of the residual SI is obtained. Next, the average power of the residual SI and the SI cancellation ratio are derived to characterize the effect of NR components on SI cancellation in the multipath SI channel. Last, a switch scheme is proposed to eliminate the residual SI.