On Cancellation Capability of Full-Duplex RF Self-Interference Cancellation Schemes

In this work, we study the self-interference cancellation (SIC) capability of two basic radio frequency (RF) SIC schemes: auxiliary antenna cancellation and multireconstruction-path (MRP) cancellation (including particular two-reconstruction-path balun cancellation), and derive their cancellation capability in detail. Theoretical results show that auxiliary antenna cancellation capability and balun cancellation capability are related to the ratio of bandwidth to carrier frequency, the latter is further related to an angle ratio; that is, the ratio of the angle between the self-interference vector and the first fixed delay vector to the angle between the two fixed delay vectors, and common MRP cancellation capability is essentially related to the channel response of self-interference and the canceller frequency response. Numerical results confirm a perhaps obvious intuition: MRP cancellation outplays auxiliary antenna cancellation to cancel self-interference, especially when multiple self-interference paths exist, and MRP cancellation with more reconstruction paths achieves higher cancellation capability.