Research And Verification Of Rf Self-interference Suppression Circuit For 2×2 Full Duplex Base Station

The co-time co-frequency full-duplex overcomes the shortcomings of low resource utilization,so that the spectrum efficiency has doubled.The core problem of full-duplex technology is how to suppress the strong self-interference signal,in which RF self-interference suppression is an important method.This paper studies and validates the RF self-interference suppression circuit in combination with the communication mode of two full-duplex base stations.Firstly,the demand and key technology of RF self-interference suppression circuit are analyzed.This paper introduces two methods of RF domain self-interference suppression,and analyzes the influence of delay,amplitude,phase,signal power and reconstruction branch on RF self-interference suppression.Combined with the 3GPP standard,the technical index of the RF self-interference suppression circuit of the full-duplex base station is put forward.According to the technical index,the structure of the two full-duplex base station is given.Secondly,a full-duplex base station RF self-interference suppression circuit scheme is developed.The connection structure of the transceiver channel and the self-interference suppression circuit is determined.The direct coupling RF interference reconstruction scheme is analyzed,and the circuit structure of the delay,amplitude adjustment and phase adjustment of each reconstruction branch is discussed.The power detection and control scheme is determined.Again,the hardware implementation of self-interference suppression circuit is completed.According to the proposed program and technical indicators,select the device to meet the performance requirements;complete the reconstruction of the channel,power detection link structure and key indicators of the budget;determine the control module and power module circuit.Finally,RF self-interference suppression circuit board debugging is completed,test and verify the circuit board performance.Some basic indicators,such as amplitude,phase,delay and inband fluctuation,are measured.The self-interference suppression capability is verified by the 20 MHz bandwidth LTE signal.The results show that the RF self-interference suppression capability is 33 dB,the suppression is 58 dB,with the antenna isolation.The self-interference suppression circuit of this paper can suppress strong self-interference signal.It provides some theoretical and hardware support for the greater bandwidth signal and multi-antenna full-duplex communication.