Digital self-interference cancellation under nonideal RF components: Advanced algorithms and measured performance

This paper addresses digital self-interference cancellation in a full-duplex radio under the distortion of practical RF components. Essential self-interference signal models under different RF imperfections are first presented, and then used to formulate widely linear, nonlinear and augmented nonlinear digital canceler structures. Furthermore, a general parameter estimation procedure based on least squares is laid out. Digital cancellation with actual measured self-interference signals is then performed using all the presented methods. To ensure a realistic scenario, the used transmitter has realistic levels of I/Q imbalance, and is also utilizing a highly nonlinear low-cost power amplifier. Furthermore, a realistic RF canceler is incorporated in the measurements, and both shared-antenna and dual-antenna based devices are measured and experimented. The obtained results indicate that only a digital canceler structure capable of modeling all the essential impairments is able to suppress the self-interference close to the receiver noise floor.