DAFT-Domain Interference Cancellation Scheme for Full-Duplex AFDM ISAC System

Integrated sensing and communication (ISAC) plays a pivotal role in sixth generation (6G) wireless communication. In a monostatic ISAC system model, in-band full-duplex (IBFD) is typically used, causing severe self interference (SI). Affine frequency division multiplexing (AFDM) is a candidate waveform for the next-generation wireless communication with a robust characteristic in high-speed mobile environments. In AFDM-based ISAC system operating in IBFD mode, both SI and echo signals significantly affect uplink communication, which are both treated as interference by the uplink signal, with all these signals passing through different channels. In this paper, we propose an interference cancellation (IC) scheme based on frame design in the discrete affine Fourier transform (DAFT) domain. Interference reconstruction and cancellation are added on the basis of the communication link, and ISAC functionalities are realized, including uplink and downlink communication as well as sensing. The simulation results show that the detection probability and normalized mean square error (NMSE) perform well under high signal-to-noise ratio (SNR) of pilot. Particularly, after adopting the proposed IC method, the bit error rate (BER) significantly decreases and approaches the ideal level, which demonstrates the effectiveness of our scheme.