Research On Transceiver Modeling And Self-Interference Cancellation Algorithm

With the official commercial use of 5G in 2019,China has officially entered the 5G era.The rapid development of communication technology has led to social progress and the improvement of people's quality of life.Therefore,improving the speed and quality of wireless communication technology is the direction and goal that our researchers have been pursuing.However,the spectrum resources are limited,and people's demand for communication will inevitably cause the continuous reduction of spectrum resources.Compared with the general duplex technology,the full duplex technology can save half of the time-frequency resources,which is a good way to improve the spectrum efficiency.However,the problem of self-interference is inevitable in the full duplex system.The self-interference signal has a great impact on the system performance.How to eliminate the self-interference signal of full duplex system is the focus of this paper.In this paper,full duplex transceiver system and self-interference cancellation technology are studied.The main work is as follows.(1)The structure model and baseband equivalent model of transceiver are established.For the full duplex transceiver system,the mathematical model of each signal component and transmission signal is established;(2)A generalized linear elimination method for nonlinear signals is proposed.The formula derivation and quantitative analysis are carried out for each signal component of the full duplex transceiver model,and the ADC input and output signal strength is studied.Then the self-interference signal under the influence of nonlinear signal is considered,and the generalized linear elimination scheme is used.The simulation results show that the performance is significantly improved compared with the linear elimination scheme.(3)An adaptive algorithm based on LMS(least mean square)improved step size is proposed to eliminate the self-interference.Compared with the traditional adaptive algorithm,the algorithm improves the convergence speed and the effect of self-interference signal eliminatio n.(4)The influence of I/Q imbalance and other non-ideal factors on the elimination effect of digital self-interference signal is analyzed.The estimation and compensation algorithms of I/Q unbalanced signals are proposed at the transmitter and receiver respectively,and the simulation and hardware implementation are carried out to improve the self-interference elimination effect of full duplex system.