Self-Interference Cancellation With Frequency Offset and Nonlinear Distortion Suppression for Cooperative Jamming Communications

Abstract

Cooperative jamming is envisioned as a key technique to enhance the wireless secrecy. With the help of a cooperative node, confidential communications are ensured by emitting a jamming signal to combat against eavesdropping. Concurrently, this jamming signal also propagates into the legitimate node through the multipath wireless channel, then becomes the self-interference (SI). In this letter, a nonlinear SI cancellation scheme is proposed by jointly taking into account the frequency offset, the power amplifier nonlinearity, and the multipath effect. These practical imperfections induced SI is first formulated based on a memory polynomial model. After a Taylor series expansion to the SI, the time-invariant coefficients from the SI are derived and subsequently estimated to yield a SI cancelling signal. Simulation results show that the proposed scheme has a significant SI cancellation improvement over the current method, and extends the transmit power range to provide a better security performance.