Design and Analysis of Wideband Self-Interference Cancellation for Full-Duplex Wireless Networks

This paper proposes a wideband self-interference cancellation scheme for beyond 5G full-duplex communications. Especially, optical components are explored to achieve efficient wideband RF cancellation. We use a fiber array to form multiple independent tunable delay lines for a low-complexity and low-cost design. The processing and implementation details are given, and its performance is evaluated with practical concerns (e.g., inaccurate hardware measurements and tuning speed). Then, a nonlinear digital canceller is utilised to generate a replicate of the received baseband digitised self-interference signal along with the nonlinear effects induced by the power amplifier. The relationship between RF and digital cancellation is explored, and an appropriate RF cancellation amount is given based on this. Simulation results illustrate that more than 30 dB of RF cancellation can be achieved within 400 MHz bandwidth centred at 2.5 GHz, and the residual self-interference is brought to close the noise floor by the nonlinear digital canceller with practical transceiver nonlinearity and distortions.