Study On Self-Interference Cancellation Techniques And Reflected Signal Modelling In Wireless IBFD

With the rapid development of mobile internet,wireless spectrum resource will be even scarcer.With in-band full-duplex(IBFD),a wireless terminal is allowed to transmit and receive simultaneously in the same band,which can theoretically double the spectrum efficiency.One of the major challenges of IBFD is the cancellation of self-interference related to signal transmission of wireless terminal and the open issue of channel interferences.The thesis studies the source of self-interference in IBFD systems,and focuses on the self-interference propagation characteristics of the far-field reflected signal.The thesis firstly discusses general structure of wireless communication system,and features of signal sending by separated and shared antenna.Considering the complex shared-antenna wireless transceivers,the thesis analyzes and classifies the self-interference into three categories:leakage interference of isolators or circulators,near-field direct-path interference among multi-antennas and far-field reflected-path interference.The thesis analyzes then the feasibility of technologies in propagation domain,analog domain and digital domain to cancel the reflected-path self-interference.Secondly,by reference to the calculation method of radar echo,this thesis presents a detailed mathematical derivation of desired signal and reflected-path interference signal in a common wireless communication scenario with single a scatter,multiple scatters and LOS path exists of not Specifically,a computational model for random distribution of scatters has been developed.According to the mathematical derivation and model,and by numerical simulation,the thesis finally carries out a set of comparing experiments for different distribution of scatters with and without LOS path.Results show that IBFD terminals surrounded by sparse scatters have relative low-intensity interference which is easy to handle.Furthermore,an extended analysis to narrow corridor scenarios shows that the far-field self-interference is not ignorable when the length of corridor greater than a threshold,40m and 15m,for the desired signal along LOS and non-LOS path,respectively.