Key Technologies And Verification Of Nonlinear Interference Suppression In Full-duplex Transceivers

Full duplex technology puts transmitting and receiving at the same time and on the same frequency band,theoretically doubling the frequency efficiency.Typically,the analog self-interference(SI)cancellation is a key technology in the deployment of fullduplex systems.SI signal can be reconstructed by analog SI reconstruction path and subtracted at the receiving end to complete the suppression.However,under high transmission power communication,the nonlinear distortion introduced by the active analog cancellation module becomes more severe due to the non-ideal characteristics of the analog components.Capturing the nonlinear distortion introduced by analog SI reconstruction path requires an Analog-to-Digital Converter(ADC)with a high sampling rate and presents a high computational complexity for the nonlinear modeling.In this thesis,based on the receive loop of full-duplex system,the algorithm to reduce the index requirement of ADC devices at full-duplex receiver is studied and verified as follows.Firstly,a mathematical model for the nonlinear SI introduced in the analog SI reconstruction path is derived.For the nonlinear SI introduced by the active analog cancellation module in the full-duplex system,the nonlinear distortion model in the analog SI reconstruction path is systematically analyzed.Also,the signal model of linear and nonlinear interference in the output of the active analog cancellation module is derived and given.Secondly,the down-sampling nonlinear interference suppression scheme is proposed.Based on the full-duplex architecture with an additional feedback loop,an antialiasing nonlinear component modeling strategy is proposed to construct a reference matrix.It provides the basis for the down-sampling nonlinear SI suppression algorithm.Meanwhile,by analyzing the output of active analog cancellation module,the downsampling nonlinear interference suppression scheme is proposed jointly with linear residual self-interference.Compared to nonlinear interference suppression that requires at least 5x the oversampling of the received signal.The down-sampling algorithm proposed in this thesis can theoretically use 1x sampling rate and reduce the computational complexityThirdly,The ADC nonlinear distortion correction algorithm in frequency domain is proposed.To considering the low power of the signal of interest(SOI)at the receiver in the full-duplex system,the digital domain self-interference theory suppression performance is affected by the dynamic range of ADC devices.The dynamic range of ADCs is limited by the influence of nonlinear characteristics such as intermodulation distortion and harmonic distortion of ADC devices.Based on the focused analysis of the nonlinear distortion within the ADC device,the ADC nonlinear distortion correction scheme in frequency domain is proposed to compensate for the performance loss brought by the hardware non-ideal characteristics.In simulation end testing verification,the twotone signal can achieve a 14.5d B SFDR improvement.This thesis focuses on the full-duplex system receiver side for analog SI reconstruction path down-sampling nonlinear interference suppression and ADC nonlinear distortion issues.The results acquired in this thesis provide a future reference for the application of full duplex technology in 6G wireless communication.