Symbol synchronization of the Alamouti space-time block code with the Gardner algorithm

A digital communications receiver requires precise symbol synchronization before the transmitted information can be recovered. Gardner's algorithm is a synchronizer that can acquire and track timing with only two samples per symbol, and it does not require prior carrier synchronization. In this paper, a feed-forward, all-digital version of Gardner's algorithm is presented. It is shown that this synchronizer is effective when used in a wireless Alamouti space-time coded system. Besides retaining its immunity to carrier frequency offset, the algorithm does not require knowledge of the channel gains. Simulation results are presented along with mean-square estimates of the timing error for different values of signal to noise ratio and for staggered and non-staggered pulses.