Reacher Of The Differential Correlation Synchronization Algorithom Based On802.11a/g System

The OFDM system is very sensitive to time synchronization deviation, even the small time synchronization deviation can cause severe ICI and ISI. To increase the property of the receiver, we must construct a good time synchronization algorithm with perfect performance. That means the constructed synchronization algorithm should own a relatively low computation complexity, and with the robust performance at the same time. Namely, when the environment parameter varies, the constructed synchronization algorithm can still locate the accurate position of the transmitted frame.The thesis makes a deep study about the current researches about time synchronization algorithm. In the first, the synchronization algorithms are investigated, which are based on the delayed auto-correlation and local cross correlation, carefully. And the theoretical analysis and experiment simulation are analysized mainly. In the second, the thesis does research about the newly differential correlation algorithm which is proposed by Leila Nasraoui. And it mainly focuses on the Brute Force algorithm and Reduced Complexity algorithm, which are based on the differential correlation. The investigation proves that, the synchronization algorithms based on the delayed auto-correlation and local cross-correlation have low computation complexity but good synchronization performance, while the algorithms based on the differential correlation have perfect synchronization performance but low computation complexity.Based on the802.11a/g system, the thesis does research about time synchronization algorithms. Meanwhile, it raises two kind of optimized synchronization algorithms after careful theoretical analysis and experiment simulation.The first improved synchronization algorithm concerns the impact of the noise on time synchronization mainly. And it comes up with the idea of reducing the impact of the noise. With the join of auto-correlation and differential correlation, it firstly employes the delayed auto-correlation to get the coarse position of the transmitted frame with half reduced noise in coarse step. And then the differential correlation will be exploited to achieve the final accurate position of the transmitted frame. Apparently, the computation complexity is lowered further compared with the Reduced Complexity. Also, the simulation results show that it’s with performance of robustness. The second improved synchronization algorithm concerns mainly about the high computation complexity and investigates the performance of the differential correlation with different correlation length. Investigation shows the differential correlation is with good performance of time synchronization, and high computation complexity. And it’s closely related to the correlation length of the differential correlation. Thus, we put forward a new synchronization scheme based on the environment SNR. Namely, we employ different differential correlation length based on the current SNR to finish differential correlation. And finally, the accurate time synchronization is achieved.