Frame synchronization for pilot symbol assisted modulation

One method to reduce the effects of channel fading in mobile communication is the use of pilot symbol assisted modulation (PSAM). In this scheme, known pilot symbols are periodically inserted into the transmitted data symbol stream and then used by the receiver to estimate the channel gain and phase, and to appropriately scale and rotate the receiver decision grid. We introduce a non-coherent synchronizer that uses only the received signal magnitude to form an estimate of the pilot symbol timing. We use decision metrics based on a high SNR approximation of the maximum likelihood ratio and on the Euclidean distance from the pilot sequence. Simulations have been performed using an 11 bit Barker sequence interleaved within each 110 symbol transmitted block. With the fading rate set to 1% of the symbol rate and SNR greater than 10 dB, our simulations show a mean acquisition time within 600 symbols.