Research On Large-scale Array Channel Modeling And Multi-user MIMO Coordinated Scheduling Algorithms

In Long Term Evolution (LTE), the full frequency reuse leads to serious Inter CellInterference (ICI), which is an important limiting factor in the cell average spectralefficiency, especially in the cell edge user spectrum frequency. Subsequent Long TermEvolution Advanced (LTE-A) can effectively solve the spectrum efficiency bottleneckproblem of the cell edge users in LTE. An important technology in LTE-A isCoordinated Multi-point Transmission (CoMP), in which distributed base stationscooperates with each other to complete scheduling and resource allocation, etc.Coordinated scheduling can reduce ICI and observably improve the spectrumefficiency of cell edge users, as a key technology in CoMP.In LTE, the maximum number of transmitting antenna in down link is4, whichincreases to8in LTE-A. We can predict that the increase of antenna number is adevelopment direction of future wireless communication. With the number of antennasincreasing，as the total space of antennas is limited，the mutual coupling betweenantennas can not be ignored. So the modeling analysis of large number antennas isanother research focus.At first, we do research on coordinated scheduling algorithms of recent years inCoMP, on the basis of multiuser scheduling algorithms in single cell. Then wesummarize the current research of coordinated scheduling in recent years, and putforward two new coordinated scheduling algorithms, aiming to further improve thethroughput of the edge users and to reduce the complexity of the algorithm. Secondlythe paper focuses on the influence of antenna mutual coupling on the channelcorrelation and the system throughput. To research on how to place antennas morereasonable, the paper contrasts the capacity of the centralized antenna system anddistributed antenna system. The overview for each chapter is summarized as follows:Chapter1summarizes the research background and research situation of thispaper, this chapter also lists some basic related academic concepts. Also it displays astructure diagram of the dissertation. In chapter2, on the goal of maximizing multi user utility of cooperative system, anew user selection criterion is put forward, aiming to futher improve the spectrumefficiency. Based on the criterion, a greedy coordinated scheduling algorithm isintroduced, the algorithm can effectively improve spectrum efficiency of cell edgeusers. Simulation results show that compared to the Non-CoMP scheme, the proposedscheme increases the cell-edge users’ spectrum efficiency by45.5percent.In chapter3, details of the coordinated scheduling algorithm based on simulatedannealing are introduced. This algorithm uses simulated annealing to select user sets,which can effectively avoid the trap of the local optimum solution. In order to betteranalyse the algorithm, this paper also introduces a successive coordinated schedulingalgorithm，which is local optimal, and shows detailed comparison and analysis ofcomplexity and spectrum efficiency. Numerical results show that the simulatedannealing based algorithm can achieve92.4percent performance of the optimumsolution with low computational complexity.Chapter4studies the MIMO system with large-scale antenna configuration.Firstly the quantitative modeling of antenna array’s mutual coupling effect isresearched. Then we study of the effect of mutual coupling on spatial correlation, andalso answer the question that what is the optimal number of antennas in a fixeddistance. Simulation results show that the optimal number is determined by the totalspace when considered uniform linear array.Chapter5puts forward a distributed antenna system capacity calculation method,using the approximate distribution of chi-square distribution. Secondly we contrast thecapacity of distributed antenna system with distributed antenna systems. In the analysis,we also consider the mutual coupling of antennas in the centralized antenna system.Simulation results show that reasonable layout can decrease the performance losscaused by coupling.In chapter6, the previous research work is summarized. The suggestion for futureresearch direction is also presented.