Research On Multi-cell Coordinated Scheduling And Coordinated Beamforming

Coordinated Multi-Point transmission and reception (CoMP), as a key technologyto increase system spectrum efficiency and improve cell-edge users’ performance, hasbeen proposed in3rd Generation Partnership Project (3GPP) Long TermEvolution-Advanced (LTE-A) system.The essence of Coordinated Scheduling and Coordinated Beamforming (CSCB) isa reasonable allocation scheme of space resource composed by multiple antennas andmulti-cells. CSCB avoid scheduling users which suffer inter-cell interference seriouslythrough the information interaction among multi-cells, and reduce interference bycoordinated beamforming further, in order to improve cell-edge users’ performance.However, many factors restrict the application of CSCB, such as signaling designing,backhaul capacity, feedback overhead, and high computational complexity.Aiming to enhance cell-edge users’ performance, we focus on limited feedbacksystem and analyze the interference introduced by channel quantization in zero-forcingcoordinated beamforming, further we propose adaptive bit allocation feedback scheme.Then to solve high computational complexity of designing channel reciprocity basedzero-forcing beamforming vector, first-order perturbation compensation is adopted infrequency and time domain, and the configuration of compensation step in multi-cell isproposed. The following is the content of each chapter:In chapter1, the background of CSCB is introduced, standardization process ofCSCB in3GPP LTE are summarized. Then the existing problems of CSCB and theresearch emphases of this dissertation are pointed out.Chapter2classifies the current coordinated beamforming technology anddiscusses several typical beamforming technology applied in multi-cell in detail,finally their performance is compared and analyzed.In chapter3, for the purpose of minimizing the interference in finite feedbacksystem, we come up with an adaptive feedback bit allocation scheme by analyzing interference introduced by quantization error. We also combine multi-cell greedyscheduling scheme with adaptive feedback scheme. Simulation results show ourfeedback scheme can increase spectral efficiency of cell-edge users compared totraditional feedback scheme.In chapter4, in order to reduce the computational complexity of coordinatedbeamforming, the first-order perturbation compensation for null space of matrixperturbation is adopted in the computation of zero-forcing beamforming vector in timedivision duplex (TDD) system, utilizing the similarity of channel in frequency andtime domain. We also come up with the method of setting perturbation compensationsteps in the environment of multi-cells. Simulation results show that the adaptingmethod of setting perturbation compensation proposed in our paper can increase thecapacity of users compared with traditional schemes in the condition that the totalperturbation steps is fixed.In the last part of the paper, previous research work is summarized, andsuggestions for future research direction are presented combined with the study of thisdissertation.