Algorithm Research And Experimental Platform Design And Implementation Of Polarization Based Self-interference Cancellation In Full Duplex Communications

With the expansion of service scenarios and the corresponding traffic,mobile communication data continues to increase,and the problem of shortage of spectrum resources is becoming increasingly prominent.Therefore,how to improve spectrum efficiency has become one of the research hotspots in mobile communications.Full duplex(FD)is a technology that enables the equipment to transmit and receive signals in the same frequency band simultaneously.Compared with FDD and TDD,it can double the spectral efficiency under ideal conditions,and the basis and key to realize FD is effective self-interference cancellation(SIC)technology.As another signal dimension in addition to the space and time-frequency domains,polarization can be also used for SIC.The existing polarization based SIC algorithms focus on completely eliminating self-interference,and considering that the effective reception of the desired signal is also important in above process.Therefore,it is necessary to research related algorithms.The research work focuses on polarization based SIC algorithm in FD.It is supported by Chinese National Nature Science Foundation Project"Research on Full-duplex Polarization Self-interference Elimination Based on Phase Noise Additive Gaussization(61501050),and Beijing Laboratory of Advanced Information Network Funded Project“5G Full-duplex Communication Prototype System".The main research and achievements are as follows:(1)This thesis reviews the FD and polarization signal processing technology.First,it summarizes the characteristics,advantages and main research directions of FD.Then it introduces the SIC technology by classification,research status and experimental verification in detail.Meanwhile,it introduces the polarization signal processing technology,which lays a theoretical foundation for the subsequent research content.(2)Aiming at the problem of how to receive the desired signal more effectively while performing SIC,this thesis proposes a polarization filtering based SIC algorithm.The algorithm aims at maximizing the output SINR.It guarantees the reception of the desired signal as much as possible while performing SIC by selecting the appropriate receive filtering polarization state,and finally maximizes SINR.Simulation results demonstrate that the SINR gain and achievable rate of the proposed algorithm are greater than or equal to the existing algorithms under the same conditions,and the cancellation performance of the proposed algorithm is relatively less affected by the polarization channel.(3)In order to verify the actual performance of the polarization based SIC algorithm and expand the application of polarization signal processing technology in FD communications,this thesis is based on the polarization FD communication experimental platform,and focuses on the design and implementation of the polarization SIC module.The platform's hardware used USRP and dual-polarized antenna,and software used Lab VIEW.It can implement three kinds of polarization based SIC algorithms including the proposed algorithm.Meanwhile,the actual performance of above algorithms were verified and evaluated by the platform in the experimental scenario environment.The evaluate results show that the proposed algorithm has better achievable rate performance than the existing two algorithms under the same conditions,and the performance of the proposed algorithm is less affected by the communication distance.In the algorithm research of polarization based SIC algorithm,this thesis chooses to maximize the output SINR as the goal,which effectively improves the theoretical performance of SIC in FD communications.And the experimental platform is designed and implemented to verify the actual performance of polarization based SIC.