Design And Verification Of 5G Millimeter Wave Full Duplex RF Self Interference Cancellation Circuit

With the growth of user business data,the mobile communication system won't support the massive data flow.3GPP(3rd Generation Partnership Project)promoted the5 G mobile communication system to increase network capacity and meet the growing demand for mobile data flow.Commercial frequency bands are already crowded,so people are starting to research new millimeter wave frequency bands.The research of the CCFD(co-time co-frequency full-duplex)technology is of great significance for the improvement of spectrum utilization in the new frequency band.This thesis mainly studies the self-interference signal suppression capability in the radio frequency domain of CCFD communication between base stations under the IAB(Integrated Acess Backhaul)architecture.The main work is as follows:Firstly,this thesis analyzes the self-interference suppression requirement of the 5G CCFD communication system,and then analyzes the theoretical performance of radio frequency self-interference suppression theoretically and simulation.The existing selfinterference suppression technology are: air domain,radio frequency domain and digital domain self-interference suppression.For airspace self-interference suppression,this thesis modeled and analyzed the self-interference channel environment under the phased array antenna to provide the isolation between the transmitting and receiving antennas theoretically.through this it is meaningful to know that the receive element is not saturated;for the RF self-interference suppression,this thesis uses a direct coupled structure,and it is determined through simulation that sixteen reconstruction taps are needed;Then,the indicators of transmitting channel,receiving channel and reconstruction channel are analyzed to provide theoretical guidance for circuit implementation.Secondly,according to the 3GPP(3rd Generation Partnership Project)NR(New Radio)standard and the index requirements put forward by theoretical analysis,the circuit of 5G millimeter-wave CCFD communication is designed and implemented in detail.The link budget is mainly performed on the receiving channel and the reconstruction channel,and the key device parameters are analyzed.Finally,a full-duplex communication platform was built,the RF transmit and receive channel indicators of the platform were tested,and the joint debugging of 5G millimeterwave CCFD communication was completed.The results show that the RF selfinterference suppression suppressed 27 d B self-interference signal under the condition of EIRP of 54 d Bm and 100 MHz signal bandwidth.The thesis designs and implements an RF self-interference suppression module with an operating frequency of 26?27GHz for CCFD of 5G millimeter wave,which provides a certain reference value for the realization of CCFD communication between base stations under the 5G IAB architecture.