Research On Key Front-end Technologies Of 220GHz Frequency Division Multiplexing Communication System

With the formal commercialization of 5G,the overall vision of 6G will be further expanded and upgraded.As one of the options of 6G communication,terahertz wireless communication technology has the characteristics of ultra-high bandwidth,high security,low environmental noise and so on,which fits the requirements of future wireless communication.There are still many problems to be solved in terahertz wireless communication.How to realize full duplex is one of them.In order to solve this problem,this thesis studies the 220 GHz frequency division multiplexing communication system,and designs,processes and tests the key front-end components required by it.Based on the communication architecture,frequency division multiplexing is selected to divide different channels,so as to achieve frequency division full duplex communication.Based on the half-wavelength coupling structure,two terahertz diplexers are developed to divide the communication channel and filter the mirror frequency.Through the combination of "field" and "path" simulation,this paper designs a harmonic mixer which can work at the local frequency of 216 GHz and 204 GHz.In view of the low center frequency baseband signal in terahertz mirror frequency superheterodyne communication system is difficult to filter out the problem,this thesis puts forward using the secondary inverter communication architecture,through mixer will move to baseband signal c-band improve baseband signal center frequency,makes at terahertz frequencies of mirror frequency difference,further by terahertz duplexer can mirror frequency filter.The above work has established a good foundation for terahertz full duplex communication system.After experimental verification,the insertion loss of the 220 GHz duplexer is less than 0.8d B in the same band 197-203 and 207-213 ghz passband range,and the rejection is 32 d B and 38 d B at 208.1 and 220.1ghz.The frequency conversion loss of 204 GHz and216GHz is less than 10.5d B in the range of 20 GHz RF bandwidth.The performance of terahertz diplexer and harmonic mixer is good,both meet the system requirements.Through the above devices combined with the baseband platform and antenna required by the communication system,a 220 Ghz full-duplex communication system with a realtime communication rate of 10.4Gbps and communication distance of 15 m was built.The communication results show that the constellation diagram of the two receivers is clearly visible,the SNR is higher than 22 d B,and the bit error rate is less than 8-9.The communication effect is good,and high-definition 4K video can be transmitted in real time without lag.