Research On Interferen Cecancellation With Co-sites

Wireless communication technology has broad application prospects in both military and civilian fields.With the large-scale use of electronic communication equipments,it brings great convenience to people's lives.At the same time,there are two major challenges: First,the conflict between the lack of spectrum resources and the increase in demand for communication services;Second,in the narrow communication platforms,which integrates a large number of electronic communication devices.So the challenges,brought by the co-site interference problem,are becoming more and more severe.The 5th generation wireless systems,namely 5G,adopts full-duplex multiplexing technology and can double the utilization of the existing spectrum.The core challenge of full-duplex multiplexing technology is interference cancellation.In the solution of the co-site interference problem,adaptive interference cancellation technology is one of the effective methods.The core of adaptive interference cancellation technology is the adaptive filter.It adjusts the weight coefficients of the filter iteratively according to some kind of decision criterion.The purpose is to synchronize the amplitude and phase of the output signal with the interference signal.Then through the combiner,the interference signal can be cancelled.So far,there are three aspects for the elimination of co-site interference: the elimination of the antenna end;analog domain offset;digital domain cancellation.This paper focuses on studying the elimination of interference signals in the analog domain.A typical cancellation technique in analog domain,which first needs to couple a reference signal at the transmitter that has a strong correlation with the interference signal.Then the algorithm of interference cancellation adjusts the amplitude and phase of the reference signal to equalize the amplitude and phase in the reference signal.At local receiver,the interference signal can be eliminated.However,in practical applications,there are technical problems that need to be solved in order to accurately adjust the amplitude and phase of the signal.Aiming at the above problems,based on multi-channel interference canceller,a novel pre-adjusting system for self-interference cancellation in analog domain is given.This paper analyzes the functions of each module in the system,and proposes an improved interference cancellation algorithm based on the LMS algorithm.The autocorrelation matrix of the weighted iterative reference signal is the core in this algorithm.Through simulation verification,in the ideal environment,the proposed model can achieve 62.8 d B interference cancellation ratio only in the analog domain,which is better than the basic engineering demand of 22.8 d B.In the non-ideal environment,the interference cancellation ratio is 50.4 d B,which is better than the engineering requirement 10.4 d B.The wireless communication technology is about to enter the 5G era.In the 5G full-duplex communication scenarios,the multi-tapping idea is used to further optimize the interference cancellation model.Considering the multipath interference encountered in actual communication,the model is simulated in the analog domain.Compared with the system before improvement,the interference cancellation ratio is slightly decreased.This is due to the consideration of multipath signals,but it still meets the performance requirements of engineering for the cancellation in analog domain.In terms of convergence speed,the improved system model will increase the speed by more than 30%.In summary,the two improved interference cancellation system models,which are proposed in this paper,have better interference cancellation capabilities and provide reference value for engineering implementation.