How do I design a self-interference cancellation system for a full duplex radio?

Designing a self-interference cancellation system for a full-duplex radio enables simultaneous transmission and reception on the same frequency, which requires cancelling the transmitter's signal (the self-interference) at the receiver input by 100-120 dB so that the desired received signal (which may be 80-100 dB weaker than the self-interference) can be demodulated. The cancellation is achieved in three stages: antenna domain cancellation (20-40 dB, using antenna separation, directional coupling, or a circulator to isolate the transmit and receive paths at the antenna; a circulator provides approximately 20 dB isolation; additional isolation is achieved by physical separation of TX and RX antennas with absorptive shielding, or by using antenna cancellation techniques such as placing a cancellation antenna that creates a null at the RX antenna), analog RF cancellation (30-50 dB, using an adaptive analog cancellation circuit that creates a copy of the transmit signal, adjusts its amplitude, phase, and delay to match the self-interference, and subtracts it from the received signal before the LNA; the cancellation circuit uses a multi-tap transversal filter with taps spaced at the delay spread of the self-interference channel, typically 1-10 ns; each tap has adjustable amplitude and phase controlled by a feedback loop), and digital cancellation (30-40 dB, using the known transmitted digital signal to reconstruct and cancel the residual self-interference in the digital domain after the ADC; this requires: knowledge of the transmit signal, estimation of the self-interference channel (including the PA's nonlinear distortion), and digital subtraction of the estimated self-interference from the received digital samples). The total cancellation (sum of all three stages) must reach 100-120 dB to reduce the self-interference below the receiver's noise floor.