Research On Interference Alignment Of Multicell Multiuser MIMO System

Multiple-Input-Multiple-Output(MIMO),as a key technology in the field of wireless communication,can make full use of space resources and break through the limitation of the capacity of the traditional wireless network.It has the advantages of high transmission reliability,High utilization rate,so it has received extensive attention and research.However,the configuration of multiple antennas in the MIMO system also aggravates the interference at the receiving end.In order to effectively suppress the interference,an interference alignment technique is introduced in the MIMO system.Interference alignment technology is to design a precoding matrix and receiving matrix,and compress the interference into the same subspace at the receiving end,at the same time,to satisfy the expectation that the signal space is orthogonal to the interference space and achieve the purpose of eliminating interference through the receiving matrix.However,the lower feedback rate of the uplink channel makes the current design precoding matrix not necessarily adapt to the current fading channel,resulting in interference leakage at the receiving end,thereby affecting system performance.Therefore,it is of great significance to research the interference alignment technology of MIMO system and the corresponding finite feedback technology.This dissertation focuses on the interference alignment technology and finite feedback technology.The main research results are as follows:The design method of different codebook sets in finite feedback technology has the differences in channel quantization performance and design complexity.The larger the codebook size,the higher the channel quantization accuracy and the higher the complexity of the design.In order to ensure the channel quantization accuracy,reduce the quantization error and reduce the design complexity of the codebook set to meet the requirements of precoding design,this paper proposes a codebook set design scheme based on Principal Component Analysis(PCA)Design a set of codebooks by mapping high-band channel sample points to a low-latitude optimal hyperplane.At the same time,in order to meet the requirements of precoding of transmitter,we can ensure that the receiver's interference is aligned to the same subspace as much as possible to reduce the interference leakage and reduce the computational complexity of solving the optimal precoding matrix.In this paper,The goal is to realize the pre-coding design by quasi-Newton optimization algorithm.The research in this paper shows that the design of codebook based on PCA algorithm can reduce the design complexity of large-size codebook while ensuring the quantization accuracy,meanwhile reduce the codebook dimension and reduce the storage space of codebook.Based on the codebook The precoding matrices of set design effectively compress interference into the same subspace and improve system performance.Simulation results show that the proposed scheme has good performance and effectively improves the total system rate.