The Research Of Synchronization Technology For High Speed Wlan

Wireless Local Area Network (WLAN) technology is widely used in computer, smart TV, Internet, mobile devices, and other communication products. It has become the most widely used broadband wireless communication technologies. In recent years, due to the rapid development of mobile Internet, cellular mobile is facing more traffic pressure. In order to alleviate this problem, public WLAN hotspot has been constructed in a large scale. Accompanied by the emergence of this phenomenon, the IEEE released the802.1In standards, it employs the MIMO-OFDM technology, and greatly improves the transmission rate of WLAN system.In the MIMO-OFDM system, synchronization is very important. Only through the ideal synchronization estimation and the compensation for the time and frequency deviation, the MIMO-OFDM systems can receive signals accurately. In this thesis, the existing MIMO-OFDM synchronization algorithm has been analyzed, and based on the leading training sequence structure of802.1In standard, the existing timing synchronization and frequency synchronization algorithms of WLAN system is studied and improved.In the research of timing synchronization algorithm, the reason of the platform caused by16points delay correlation algorithm in frame detecting has been analyzed, and the advantages and disadvantages of the algorithm by changing the correlation length to eliminate the platform has been studied. Aiming at the shortcomings of the existing algorithm, based on the differential delay correlation algorithm, an improved frame detecting algorithm is proposed, which can adapt to the complex multipath fading environment better. In the analysis of symbol timing synchronization algorithm, the training sequence structure and the cyclic shift of the WLAN standard is considered, which cause the interference peak and spurious correlation peak, and the simulation of the improved algorithm shows that this algorithm is significantly improved the precision of time synchronization.In the study of frequency synchronization algorithm, the synchronization algorithm in the time domain has been analyzed, and the factor that impact the estimation range and estimation precision of frequency offset estimation has been studied. This thesis proposes a carrier frequency offset estimation algorithm that combine the time domain estimation and frequency domain estimation. Algorithm in this thesis is mainly divided into:coarse fractional frequency offset estimation in the time domain and the integer frequency offset estimation in the frequency domain, and precise fractional frequency offset estimation in the time domain. The simulation results show that the algorithm effectively improves the estimation range of frequency offset estimation, at the same time reduce the MSE of the frequency offset estimation, improved the performance of the frequency offset estimation.