An Augmented Nonlinear Complex LMS for Digital Self-Interference Cancellation in Full-Duplex Direct-Conversion Transceivers

摘要

In future full-duplex communications, the cancellation of self-interference(SI) arising from hardware nonidealities, will play an important role in thedesign of mobile-scale devices. To this end, we introduce an optimal digital SIcancellation solution for shared-antenna-based direct-conversion transceivers(DCTs). To establish that the underlying widely linear signal model is notadequate for strong transmit signals, the impacts of various circuitimperfections, including power amplifier (PA) distortion, frequency-dependentI/Q imbalances, quantization noise and thermal noise, on the performance of theconventional augmented complex least mean square (ACLMS) based SI canceller,are analyzed. In order to achieve a sufficientsignal-to-noise-plus-interference ratio (SNIR) when the nonlinear SI componentsare not negligible, we propose an augmented nonlinear CLMS (ANCLMS) based SIcanceller for a joint cancellation of both the linear and nonlinear SIcomponents by virtue of a widely-nonlinear model fit. A rigorous mean and meansquare performance evaluation is conducted to justify the performanceadvantages of the proposed scheme over the conventional ACLMS solution.Simulations on orthogonal frequency division multiplexing (OFDM)-based wirelesslocal area network (WLAN) standard compliant waveforms support the analysis.