Indoors S-Band 5G CO-Time CO-Frequency Fullduplex RF Circuits Design And Verification

Nowadays,the internet and mobile network services are in rapid growth.New scenarios with high bandwidth and low transmission delay emerge continually while the spectrum resource is in exhaustion.It is a must to raise the spectrum utilization rate to cope with this contradiction.Co-time Co-frequency full-duplex(CCFD)is just such a technique which theoretically doubles the spectrum utilization rate.Based on a indoors S-band 5G CCFD project,this paper focus on its RF circuits design and verification.The specific works are as follows:Firstly,this paper focus on the theoretical basics of RF self-interference cancelation(SIC).Three types of SIC architectures are analyzed.Also,the advantages and disadvantages are analyzed accordingly.Then,The theoretic limits of one-path one-tap,one-path multi-tap and multi-path multi-tap RF SIC abilities are studied based on equation deduction.Secondly,this paper focus on the engineering realization of the RF subsystem of a specific CCFD system.Base on the analysis of the requirements of the whole system,it is divided into two parts which are software defined radio and self-designed RF circuits.The RF circuits are then divided into Tx channel,Rx channel,feedback channel,LO module and rebuild channel and detailed requirements are analyzed accordingly.Then RF circuit budget methods are deducted,including gain,noise and nonlinearity.Each RF circuit part is detailed designed according to the budget method to meet the requirements above.Then the whole system is completed.Thirdly,this paper focus on the test and verification of the designed CCFD system The performance of Tx channel,Rx channel and LO module are tested accordingly.The result shows that the requirements are met.Then the performance of the whole system are tested.The result shows that totally 120dB of SIC is acquired.The RF circuits of a specific 1T1R indoors S-band 5G CCFD system is verified.The working frequency is 2.35-2.55GHz with maxim transmit power 30dBm in 20MHz.120dB of total SIC in which 20dB of RF SIC are achieved.This paper provides certain reference to the evaluation of the performance of CCFD systems.