Cyclostationary Analysis of Analog Least Mean Square Loop for Self-Interference Cancellation in In-Band Full-Duplex Systems

Analog least mean square (ALMS) loop is a promising mechanism to suppress self-interference (SI) in an in-band full-duplex (IBFD) system. In this letter, a general solution for the weighting error function is derived to investigate the performance of the ALMS loop employed in any IBFD system. The solution is then applied to IBFD systems with single carrier and multi-carrier signaling respectively. It is shown that due to the cyclostationary property of the transmitted signal, the weighting error function in the multi-carrier system varies more significantly than that in the single carrier one. Therefore, if the ALMS loop can perfectly mimic the SI channel, SI in the single carrier system can be suppressed to a much smaller level than that in the multi-carrier counterpart.