Research And Validation On Key Technologies Of 2×2 Co-frequency Co-time Full Duplex Rf Front-end

Since the spectrum resources has became scarce, Co-frequency Co-time Full Duplex mode, which is based on Time Division Duplex mode and Frequency Division Duplex mode, is created to double the spectrum efficiency of those traditional duplex modes, in which neither up nor down link data is distinguished by different time slots or frequency bands. However, when transmitting and receiving signals at the same time slots and frequency bands, local receiver is strongly affected by local transmitted singal, which is called self-interference.Currently, there are three types of technologies to cancel the self-interference: antenna interference cancellation、radio frequency interference cancellation、digital interference cancellation. This thesis focuses on the RF front-end of a 2T2 R LTE communication system in Co-frequency Co-time Full Duplex mode, including RF transreceiver and self-interference rebuilding and cancelling.Firstly, the key technologies of RF transreceiver and self-interference cancellor are analyzed. Common transreceiver structures are introduced by comparing their advantages and disadvantages. Self-interference cancellation technologies are also discussed. Key parameters of this RF front-end’s transreceiver and self-interference cancellor are analyzed and given according to the 3GPP LTE standards.Secondly, the RF front-end’s plan is built under those given parameters. Structures are selected to achieve the transreceiver’s two transmitters, two receivers, two feedback and two local oscillators. Direct RF interference cancellation technology is applied in 4?4channels to rebuild and cancel the transmitting interference signal and its multipath signal. Meanwhile, power detection is added as the feedback of cancellation.Again, both the transreceiver and interference cancellor are devicely realized by estimating parameter indexes and analyzing some crucial devices.Finally, after testing the transreceiver and interference cancellor with LTE signal, 43 dB for RF cancellation and 75 dB for RF+antenna cancellation are achieved, by which this RF front-end’s availablity is verified.This thesis achieves a considerable amount of interference cancellation applied on LTE communication system, which improves spectrum efficiency and provide stheoretical and engineering reference for the further MIMO application.