Studies Of Digital Self-interference Cancellation In Full-duplex Wireless Communication System

With the rapid development of wireless technology, how to improve the utilization of the radio spectrum is a hot of the current wireless communications. FD technology is expected to improve the utilization of spectrum resources, but FD system is faced with serious self-interference. This paper mainly uses digital method to eliminate interference of FD system to improve system performance.This paper first analyzes the self-interference characteristics of FD system, and use full-duplex SISO system as the basic model, combining analog cancellation and digital cancellation to suppress self-interference. And using a piecewise linear approximation method to obtain channel rate gain target function.The results show that the scheme can eliminate some of the self-interference, reduce bit error rate and improve the system capacity.Then, the paper studys the self-interference cancellation schemes of full-duplex MIMO system. By the use of pre-coding elimination and time-domain elimination methods, an optimization model is built with the capacity as the objective function. Transmit power and residual self-interference are the constraints. And proposes a modified scheme that joint design of pre-encoding and timedomain to eliminate the self interference. Simulation results show that the improved schemes outperform the basic pre-coding or time-domain SIC scheme on the reliability and the capacity improvement.Finally, the paper studies the digital self-interference cancellation scheme. The phase noise, nonlinear distortion and quantization noise in the circuit of the transmitter and receiver are analyzed. A copy of the radio frequency self-interference signal is reconstructed by using the auxiliary receiver, which can counteract the impairments of the self interference signal and the transmitter in the digital-domain. Simulation results show that the use of all-digital self-interference method can effectively eliminate self-interference of FD system and improve system performance.