Investigations On Interference Coordination Technologies For LTE-A Networks

Interference coordination techniques in LTE-A networks attracted much interest-ing.Conventionally,interference coordination is solved by frequency division or time division multiplexing techniques.ABS(Almost Blank Sub-frame),CRE(Cell Range Expansion),CA(Carrier Aggregation),CoMP(Coordinated Multipoint Processing)techniques are proposed to mitigate inter-cell interference of users on the edge of cells in LTE-A systems.CoMP based interference coordination techniques are worthy fur-ther study.Interference coordinating techniques in CoMP scenarios in LTE-A systems are studied in this thesis,with focus on the user selection based interference coordination algorithms with coordinated beam-forming.User scheduling algorithms and coordinated beamforming techniques in single cell and CoMP scenarios are studied in chapter 3.Novel three-cell coordinated SU-MIMO user scheduling algorithm(CS-ORT Algorithm)and lower complexity versions(CS-ORT-Ⅰ and CS-ORT-Ⅱ Algorithms)to constrain inter-cell interferences and exploit MUD based on orthogonality metrics are proposed to deal with three-cell CoMP SU-MIMO user scheduling.Cells determine scheduling users successively to avoid the exhaustive search in CS-ORT-Ⅰ and stop searching when orthogonality met-ric under a certain threshold in CS-ORT-Ⅱ.Simulation results show that the algo-rithms and lower complexity versions improve the perfonnance of cell-edge users in the three-cell CoMP scenario,and scheduling fairness are obtained.CS-SVD and CS-SVD-Ⅰ algorithm proposed afterwards are similar to CS-ORT and CS-ORT-Ⅰ algo-rithm.Chapter 4 focuses on the multi-user MIMO user scheduling algorithm in single cell and the CoMP scenario.The traditional multi-user MIMO system usually aims to suppress the intra-cell inter-user interference and maximize the multiuser diversity gain.Under the CoMP scenario,some coordinated multi-user scheduling algorithms for collaborative multi-user MIMO system in two-cell and three-cell case are pro-posed.In this thesis,improved algorithms taking advantage of typical single-cell scheduling algorithms such as SUS are proposed for three-cell CoMP multi-user MIMO user scheduling,namely,CSM(COMP-SUS-MODIFIED),CSC(COMP-SUS-CANDRESTRICTED),CoSIF(COMP-SUS-IUIFIRST),CoSVD(COMP-SVD)algorithm etc.The simulation results show that the proposed algo-rithms can effectively improve the performance of cell-edge users.