A Study On EICIC Schemes Based On Almost Blank Subframes

Heterogeneous Networks(HetNets)deployments,combining a variety of different cell sizes,are considered in order to enhance the coverage and capacity of cellular system.At the same time,this multi-layer structure also brings inter-cell interference.The use of Enhanced Inter-Cell Interference Coordinaton(eICIC)techniques such as Almost Blank Subframes(ABS)which is a time domain technique has been introduced in HetNets to protect the small cells from high interferences.However,this is done at the expense of lower macrocell user capacities.The majority of the proposed sulutions limit reconfiguring the number of ABS,but few works have focused on the enhancement of the ABS scheme itself.The thesis discusses on the inter-cell interference coordination technologies and also introduces the existing problems with solutions,including a dynamic algorithm based on classical ABS,the LP-ABS scheme and the proportional fairness concept.Then the thesis presents a novel scheme that exploits jointly the frequency,time and power dimensions for interference mitigation.Simulation results have shown that the novel scheme can increase throughput for macrocell users without generating severe interference to the small cell usersThis thesis has made great efforts on enhancing ABS management based on the novel scheme.Through improving the algorithms,optimizing the different parameters involved in the proposed scheme,reserving a number of resources in the frequency domain especially devoted to the Cell Range Expansion(CRE)users,and allowing macrocell transmisssions in the ABS subframes with a restricted transmit power,the enhanced scheme increase the macrocell user capacity,while keeping the interference in the small cells in very low level.By simulations and comparisons with the LP-ABS and the novel scheme,it has been proved that the enhanced scheme presents higher capacity gains without convicting the small cell users to severe interference.