Research OFDM Synchronization Technologies In Complex Channel Environment

Orthogonal Frequency Division Multiplexing (OFDM) is one of the core technologies toachieve high-speed and reliable wireless data transmission, It has the advantages of hightransmission efficiency, strong anti-jamming capability, and easy to implement. It is suitableto be applied in broadband wireless communication systems, and has become the physicallayer transmission technology adopted by a lot of protocols and standards. And it has a broadapplication prospect.Synchronization is the key technology for a practical OFDM system to address and aprerequisite for the transmission of reliable information. Simple synchronization algorithm isnot suitable for the complex channel environment with multi-path effect and Dopplerfrequency shift extension. The existence of the phenomenon of multi-path transmission makesthe strongest path is not necessarily the first path. The existing timing synchronizationalgorithms based on searching the largest correlation peak usually locate in the strongest pathhaving the instantaneous power. Thus, FFT window position will lag behind. Paths prior tothe strongest path will introduce inter-symbol interference (ISI) and inter-carrier interference(ICI).This paper describes the basic principles and technical characteristics of OFDM. Thepropagation characteristics of wireless channel are analyzed and wireless channel modelingand simulation are studied. Then channel model suitable for the IEEE802.16d systemsimulation is set up. After that, in-depth study of the OFDM synchronization technology isdone, and the performance of the existing typical algorithms and their advantages anddisadvantages are analyzed and compared. On the basis of the wireless channel simulationmodel, aiming at256sub-carriers OFDM system based on IEEE802.16d, a synchronizationscheme are put forward, which makes a good performance in the complex channel conditions.The timing synchronization method in the scheme can correctly synchronize to the first pathin multi-path environments, and the frequency offset estimation algorithm has high estimationaccuracy in the complex channel conditions.