Research On Channel Estimation Algorithm In MIMO-OFDM System

In recent years, due to the impact of various high-tech technology, the fourth generation mobile communication technology(4G) develops rapidly, and the core technology of 4G is MIMO-OFDM technology, it has attracted much attention. While this technology still exists some deficiencies, especially when decoding, demodulating or detecting signals, accurate channel state information is needed in the receiver of the MIMO-OFDM system, therefor channel estimation technology is particularly important, so this paper focuses on the channel estimation problem for MIMO-OFDM system.This paper firstly introduces the research backgrounds and significance of the relevant technologies of MIMO-OFDM system including channel estimation, then describes about the wireless channel propagation characteristics and the OFDM model based on pilots and the MIMO model based on Space Time Block Code(STBC). Besides, some traditional channel estimation methods based on pilots are introduced such as Minimum Mean Square Error(MMSE), Least Square(LS) and the semi blind channel estimation such as Least Mean Square(LMS), Recursive Least Square(RLS) then an improved semi blind channel estimation based on RLS is proposed,and simulation results show that the improved RLS algorithm has a better Symbol Error Rate(SER) and Mean Square Error(MSE) performance.After constructing the MIMO-OFDM system based on pilots and Space Frequency Block Code(SFBC) and comparing the STBC and SFBC MIMO-OFDM system, we focus on the research of the Low Rank Adaptive channel estimation algorithm(LRA) based on pilots, and an Improved Low Rank Adaptive channel estimation algorithm(ILRA) has been proposed. At last, we simulate the SER and MSE performance between improved algorithm and some existing low rank algorithms in MIMO-OFDM system. The results show that the ILRA has a better performance and lower complexity.