A Frequency-Domain Feature-Based Self-Interference Cancellation Method for In-Band Full-Duplex Communications in Inter-Tower Communication Networks

As a hot research topic for next-generation broadcasting systems, enhancements to In-band Distribution Links (IDL) and the Inter-Tower Communications Network (ITCN) have attracted significant attention. With its significant advantages in spectrum efficiency and inter-tower wireless connectivity, the In-Band Full-Duplex (IBFD) technique has become a much-needed solution for Single-Frequency Network (SFN) signal backhaul, network synchronization and control, and emergency alert information distribution. However, the self-interference resulting from the local transmitter signal loop-back is the primary bottleneck impacting the performance of the IBFD technique, and the non-linear distortion caused by the high-power amplifier further complicates the cancellation of the self-interference. This paper proposes a full-duplex self-interference cancellation (SIC) method. Based on radio frequency (RF) reference signals and short-term learning via phase search and tracking, combined with prior knowledge of Advanced Television Standards Committee (ATSC) 3.0 signals, this method achieves good SIC performance with low complexity. Simulation results show that the proposed method achieves a good SIC gain of up to 46 dB in digital domain cancellation. With analog pre-cancellation and other co-channel interference mitigation techniques, 60+ dB total SIC cancellation can be achieved for ITCN applications. Meanwhile, the simulation results also show that this method can effectively address phase jitter and signal distortion caused by the distributed parameters of hardware devices and environmental variations.