Coarse Symbol Timing Synchronization Improved Algorithm for CMMB Mobile TV

ABSTRACT

There are some multipath and frequency offset in wireless transmission environment, in order to determine the correct starting position of each OFDM symbol, CMMB system must achieve accurate symbol synchronization for sending and receiving data, making FFT data transform window position in receiver consistent with IFFT window position in sender. This paper combined the specific frame structure of CMMB standard protocol, analyzed some influences of symbol synchronization timing errors in system, discussed the traditional ML (Maximum Likelihood) algorithm, the non data aided algorithm and the reverse conjugate symmetry direct algorithm, and based on the characteristics of these algorithm, proposed a coarse symbol timing synchronization improved algorithm according to CMMB mobile TV, the feasibility of this algorithm is verified in AWGN and multipath channel. Simulation results show that the performance of improved algorithm is better, there is no multi-peak of ML algorithm, and don’t worry about appearing “lat roof” phenomenon like no data aided algorithm, and it also eliminates adjacent peak interference of the reverse conjugate symmetry direct algorithm, this algorithm is not limited by SNR, even in bad multipath channel condition, the approximate starting position of symbol can be estimated.

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