Synchronization Algorithm For Ofdm Systems Based On Chaotic Training Sequence

Due to its frequency-selective fading channels resistance, highfrequency available rate and anti-narrow-band performance, OFDMbecomes a hot topic in communication technology. In this paper,theoretical analysis and computer simulation are adopted to study thesynchronization technology of OFDM system, including the generation oftraining sequence, timing synchronization, frequency offset estimation,system design and algorithm analysis.According to the analysis and comparison of the balance, run-length,correlation and peak-to-average ratio (in OFDM systems) from 4different pseudo random sequence, the feasibility of taking chaoticsequences as the training sequences is proved. Besides, the high securityof chaotic sequences ensures the great importance of their application.A new algorithm of system time synchronization by trainingsequence is proposed. Only one training sequence is needed whichensures the simple construction and low spending. It can conquer theambiguous flat top and multi-peaks, and has a high precision. Thesynchronization algorithm shows a strong robust of carrierfrequency-offset as well as anti multi-path interference. Timingsynchronization is accomplished in time domain in one time whichdecreases the difficulty of frequency-offset estimation, and it is suitablenot only for small sub carrier systems, but also for systems with a greatdeal sub carriers.A new algorithm of frequency-offset estimation is proposed. Thetraining sequence is same as the one used in timing synchronization, andeliminates the decline of transmission efficiency caused by differentsequences. It moves the high complexity and low precision. The proposedfrequency-offset estimation scheme is finished in time domain, whichexpedites speed of frequency compensation. The frequency estimationdomain is extended.An OFDM transmission system is designed, and system simulations are conduced with different channels mode. Simulation results show thatthe system has many features, such as stability, strong robust, low biterror rate and easy realization.