Analysis of Analog Self-Interference Cancellation with Imperfect Channel State Information for Full-Duplex Radios

This paper studies the multi-tap canceller with imperfect self-interference (SI) channel state information (CSI),where the tap coefficients are calculated based on the estimated SI channel. The joint effect of the imperfect channel estimation and reconstruction errors on the estimated SI channel is analyzed in closed form to evaluate the performance of the channelaware canceller. With imperfect SI CSI, the optimal design that minimizes the residual SI power for the canceller should have a consistent tap delay alignment with the channel. With the optimal design, it is demonstrated that the generated response of the canceller is equivalent to the output of a maximum likelihood estimator. Furthermore, the tolerance for the delay alignment errors, i.e., the error between the tap delay of the canceller and that of corresponding taps of the SI channel, is discussed. It is shown that for over 1% tap delay alignment errors, increasing the estimation accuracy of the SI channel contributes little to the cancellation.