Impacts of Attenuators on Analog Self-interference Cancellation in Full Duplex Radios

In the wireless co-time and co-frequency full-duplex (CCFD) systems, the self-interference must be cancelled in analog domain before quantization. However, the performance of analog self-interference cancellation (ASIC) is affected by the key components, such as the attenuator. To solve this problem, the convergence characteristics of the analog self-interference cancellation (ASIC) is analyzed and the self-interference cancellation ratio (SICR) expression is derived firstly in this paper. Secondly, the impacts of the accuracy and response time of the attenuator on the ASIC performance are further investigated, and the corresponding closed expressions are concluded based on the obtained SICR expression. Finally, simulation results under different scenarios demonstrate the validity of theoretical analysis.