Research On MIMO Technology And Implementation Of MIMO In LTE Downlink

With the development of data services such as the real-time multimedia communications and the high-speed INTERNET access, enhancing data rate and bandwidth efficiency has become a pressing problem. MIMO (Multiple-Input Multiple-Output, Multiple Input Multiple Output) wireless communications technology can use multi-path fading entironment effectively and improve the link reliability and system capacity without increasing the bandwidth. So it become popular on the research of communications on domestic and international at present.High-throughput, low latency and low-cost is the three basic requirements of 4G network development. And the goal of LTE is to meet these three requirements. LTE adopts a series of key technologies to achieve this goal, such as using OFDM / MIMO technology to achieve high data throughput,and the targets of its upstream and downstream throughput are not less than 50Mbps and 100Mbps.This paper introduces the MIMO technology and the LTE network system structure, key technologies and frame structure firstly.The main application of MIMO in LTE is layer mapping and precoding.Than analyzing and simulating the channel capacity of MIMO system and carry out the theoretical expression of channel capacity of SISO, SIMO, MISO, MIMO systems, and giving a simulation results for different system channel capacity under the conditions of slow Rayleigh fading channel.In the LTE downlink focused analyzing the detected algorithm of MIMO.Depending on the existing algorithm,this paper proposes a simplified BLAST optimal order detected algorithm based on MMSE. The performance of various algorithms are compared to verify that the simplified algorithm can reduce computational complexity and save storage space resources without affecting the algorithm performance. Finally,paper explains the LTE downlink physical channel design and processing, analyses a variety of algorithms in the downlink such as channel estimation and interference noise power measurement,and achieve the MIMO decoding module, that is, with 2T2R and rank of 2 of pre-coding matrix of MCW decoding in the DSP system.