Study Of Interference Cancellation Technology In LTE/LTE-A System

In order to satisfy the requirements of high data rate, low delay and high-speedmobility for the next generation wireless communication systems,3GPP proposed LTEand LTE-A. However, the MSI in-cell and the ICI is still a bottleneck of restrictingimprove system performance. So, research on the interference cancellation technologyof LTE/LTE-A system has attached considerable significance.For the MSI in-cell, MIMO detection algorithm is the main method to solve thisproblem. In this paper we firstly research and analyze several traditional detectionalgorithms of MIMO system, the BER performance and calculation complexity areanalyzed and contrasted based on the analysis of various algorithm principle, to providethe theory basis for the subsequent improving algorithm. For the complexity oftraditional sphere decoding algorithm is still relatively high problem in MIMO system.To solve the above difficult problems, some improvements are made based on the detailanalysis of the principle of the sphere decoding algorithm. In this paper, a novel variableradius sphere decoding is proposed, namely Golden Section sphere decoding(GS-SD).We introduce a golden section search algorithm to accelerate the convergencerate of the original algorithm. Thus it greatly reduces the complexity of the algorithm.Because the initial search radius has a great effect on the complexity of sphere decodingalgorithm, we has made further improvement to GS-SD algorithm in the paper, themethod of determining the initial radius based on MMSE solution is introduced tofurther reduce the complexity of GS-SD algorithm.For ICI, we firstly analyze and compare three ICI suppression techniques inTD-LTE system:(1) Inter-Cell Interference randomization;(2) Inter-Cell Interferencecancellation;(3) Inter-Cell Interference coordination/avoid. Since the Inter-CellInterference in LTE system is so severe that the existing interference suppressiontechniques fail to resolve the low spectrum efficiency problem of the edge users，LTE-Aintroduced the CoMP scheme to cope with the problem. This paper focuses on theanalysis of JP precoding method of CoMP. Simulation and analysis BD and BD-SVDprecoding, verify the JP precoding methods are effective for Inter-Cell Interferencecancellation in LTE-A system.