Research On The Synchronization Of MIMO-OFDM System In The Fourth Generation

With the development of wireless mobile communications,People made ever-increasing demands for the transfer rate and system capacity of wireless communications system,However,the limited spectrum resource constraints become a bottleneck in the development of mobile communications,Therefore,to ensure the premise of reliable transmission,how to improve spectrum efficiency in the field of wireless communications become the focus of the study subjects.In this area,OFDM technology and MIMO technology has aroused extensive attention from experts and scholars.The combination of MIMO and OFDM techniques is regarded as one of the best transmission method in the future wireless broadband communication.It not only solves the problems of multi-path fading channel and bandwidth efficiency well,but also enlarges the system capacity and achieves highly reliable transmission.Therefore, MIMO-OFDM has become the first choice of core program in 4G technology, however,timing synchronization and frequency synchronization are the key effects which influence the performance of OFDM system.This paper introduces the synchronization algorithms in SISO/MIMO-OFDM systems thoroughly and comprehensively,the main contents of the dissertation are expressed as follows:Firstly,the basic theory of SISO-OFDM system is introduced,and the errors of timing synchronization and frequency synchronization are deducted.Secondly,the typical timing synchronization algorithms based on training sequence and cyclic prefix are detailed and compared,some improved algorithms based on cyclic prefix are also presented,simulations results illustrate the performance of algorithms.Thirdly,the frequency synchronization algorithms based on training sequence, cyclic prefix and pilots in frequency domain are detailed,some simulation results illustrate the performance of algorithms.Fourthly,MIMO-OFDM system structure and signal model are introduced, synchronization error model and preamble configuration are discussed.Several typical synchronization schemes in MIMO-OFDM systems are detailed.Finally,a new MIMO-OFDM preamble configuration based on IEEE 802.11a and an optimized synchronization schemes based on correlation are presented,some simulation resulted are also presented.