Abstract:In a wireless digital communication system,a digital receiver was sampled with a fixed system clock.The asynchronous digital inputs may cause symbol time offset.To tackle the issue of symbol timing synchronization,this paper proposed an iterative symbol timing synchronization method by interpolation on autocorrelation coefficients.The proposed method was divided into two steps:coarse timing synchronization and fine timing synchronization.In coarse timing synchronization,the received samples were filtered by a zero-phase filter or a three-phase filter-banks.Then,the autocorrelation coefficients was calculated by using the sliding window autocorrelation of the preamble.When the synchronization threshold was reached,the maximum bin search on autocorrelation coefficients was used to obtain the searching interval for fine timing synchronization.In fine timing synchronization,an iterative method was used in the searching interval.It is necessary to generate the group delay matching filter according to the estimated time offset to compensate the received signal,and the likelihood ratio was calculated by using the least squares approximation function.Finally,the Gaussian interpolation was used to obtain an accurate result.Compared with the traditional methods,the proposed method had a lower computational load in coarse synchronization step.Meanwhile,the iterative searching method was utilized to conveniently provide the precise symbol timing synchronization.Simulation results showed that the proposed method can achieve Cramer-Rao bound at -2 dB with a preamble of 64 symbols in additive white Gaussian noise channel (AWGN);when the SNR was 10 dB and symbol time offset belong to [-1/2~1/2] symbol timing interval,the MSE performance exceed the cosine interpolation method,MMSE interpolation method and polyphase filter-banks method.Also,it worked well in Rayleigh,CCIR moderate channel as well as CCIR bad channel.In conclusion,the proposed method was suitable for wireless digital communication system.The proposed method was suitable for wireless digital communication system.