Research On Interference Alignment Algorithms For Full Duplex MIMO Systems

Full-duplex(FD)multiple-input and multiple-output(MIMO)technology can significantly improve the communication quality of wireless links as well as bring significant spectrum efficiency gains.But the bi-directional communication mode with the same frequency at the same time also causes more complex interference problems.As an effective interference management strategy for interference-limited systems,interference alignment(IA)technology has attracted much attention in recent years,the research of IA technology in FD MIMO system is of great significance to promote the development of FD MIMO technology.This thesis focuses on the research of IA technology in different scenarios of FD MIMO system.The contents can be concluded as follow.Research on IA algorithm in interference channel(IC)of multiuser FD MIMO.Facing the shortage of IA feasibility and analysis of the degree of freedom as well as the lack of IA algorithm design in FD MIMO-IC model,the degrees of freedom in FD/HD MIMO-IC model with the existence of both half-duplex(HD)transmission pair and FD transmission pair are firstly analyzed from different aspects(The conclusions obtained are applicable to FD MIMO-IC model).Then,the degrees of freedom of FD MIMO-IC FD / HD MIMO-IC and HD MIMO-IC are analyzed and compared.At last,the centralized iterative IA algorithm and the distributed iterative IA algorithm are proposed on the premise of the finite dynamic range between the two ends of FD MIMO-IC model.In the centralized iterative IA algorithm,the available mutual information of FD MIMO-IC model is firstly derived.Then the precoder is designed in the form of one-sided iterative IA algorithm by maximizing the available mutual information.Finally,the combining matrix is designed based on the minimum mean square error criterion.The advantages and disadvantages of the proposed algorithm are investigated through numerical simulation,both theoretical analysis and numerical analysis show that FD MIMO technology has excellent capabilities to increase spectrum efficiency.Research on IA algorithm in multiuser multi-cell FD MIMO.In view of the complex interference problem in multicell multiuser FD MIMO model,the closed-form IA algorithm and the iterative IA are respectively proposed.Firstly,based on the IA feasibility analysis of multi-cell multi-user FD MIMO model,a many-to-one closed direct IA algorithm is proposed,which effectively eliminates the uplink and downlink inter-cell interference and inter-user interference of the uplink cell and downlink cell.Then the objective function is constructed to minimize the residual interference of the uplink user to the downlink user,and by constructing the auxiliary function of the downlink user's inner receiving matrix,the objective function is transformed into a cost function related only to the uplink user pre-coding matrix.Furthermore,the one-sided iterative IA algorithm based on Riemann embedded submanifold is used to optimize the precoding matrix.Finally,the effectiveness of the proposed algorithm is verified by numerical simulation and theoretical analysis.