Understanding the impact of phase noise on active cancellation in wireless full-duplex

Practical designs of wireless full-duplex are made feasible by reducing self-interference via active and passive methods. However, extending the range to long-range communication remains a challenge, primarily due to residual self-interference even after a combination of active cancellation and passive suppression methods is employed. In this paper, we study the factor that limits the amount of active cancellation in current designs of full-duplex. Through an experiment, we show that phase noise in the local oscillator limits the amount of active cancellation of the self-interference signal. Analysing the design proposed by [1, 2] in detail, we show that modifying the quality of the local oscillator can significantly increase the amount of active cancellation in full-duplex systems.