Research On Key Techniques Of Digital Self-Interference Suppression In Co-time Co-Frequency Full Duplex Systems

Co-frequency and co-time full-duplex?CCFD?system means that the transmitter and receiver can transmit and receive signals at the same time and the same frequency.Compared with traditional wireless communication systems,it has theoretically doubled the spectrum utilization rate,which is essential measures to increase the frequency utilization rate in the future.Nowadays,the rapid development of the wireless communication industry worldwide,especially since the issuance of 5G licenses,the increasing number of wireless devices has made it impossible to stretch the non-renewable radio spectrum resources.Although CCFD system can effectively improve the spectrum utilization rate,the key issue that needs to be solved for its implementation is the suppression of interference from the transmitter to the receiver.For this reason,this paper starts with the interference suppression at the digital end,divides the components in the interference signal,and conducts in-depth research on the key technologies.First of all,this paper briefly introduces the characteristics of digital self-interference suppression.Aiming at the problem of insufficient convergence accuracy of traditional interference suppression algorithms,a new horizontal filter structure is designed by analyzing the shortcomings of traditional horizontal filters.The gradient update process of the LMS algorithm based on the position parameters of the mean square error is a cost function.Simulation analysis shows that the designed algorithm can achieve higher convergence accuracy and anti-quantization noise performance.At the same time,a joint algorithm is designed to improve the convergence accuracy of the algorithm.Secondly,the problem of nonlinear component suppression in the interference signal is explored.Based on the analysis of the signal propagation process in a full-duplex system,a detailed expression of the transmitted signal is given.According to the different processes of nonlinear distortion,the nonlinear distortion is divided into three scenarios,namely:mixed nonlinear distortion,The nonlinear distortion under the power amplifier and the nonlinear distortion under the low-noise amplifier.According to the different characteristics of the three scenes and the corresponding signal expressions,the expressions of the nonlinear distortion suppression are derived,which provides a basis for the implementation of the algorithm.Finally,this paper uses the system parameters commonly used in practice and specifies the frame format of the data,including the pilot position,subcarrier mapping position,and synchronization header generation,etc.The detailed data analysis is presented.Using interference cancellation ratio,residual interference signal power,and ideal bit error rate as indicators,the effects of factors such as quantization noise power,signal transmission power,and channel on the performance of the algorithm are studied.Simulations show that LMS based on position parameters compares with the traditional LMS and RLS algorithm can improve the interference cancellation ratio by 4?25?10dB,and the ideal bit error rate is stable belowe^-3.In terms of nonlinear distortion,this paper separately analyzes two kinds of non-linear non-memory power amplifiers and memory power amplifiers.The distortion model is analyzed and the performance of the nonlinear distortion suppression algorithms corresponding to the three scenes is compared.The simulation results show that the nonlinear LMS algorithm can effectively suppress the nonlinear components in the signal.The main research point of this paper is how to effectively filter the linear and non-linear components of the interference signal in the digital domain.It analyzes the areas where the traditional technology can be improved and designs the algorithm of non-linear distortion suppression.It can be used as a digital self-interference suppression system design.reference.