Performance benefits of fractional sampling in the initial code synchronization for the wireless access of 3G mobile communications

The paper addresses algorithms for the initial code synchronization of the W-CDMA wireless access infrastructure. Conventional non-coherent algorithms of sequential cell search usually operate at the chip rate. We match the conventional power detector procedure, based on one sample chip, to the fractional technique operating at twice the chip rate. In our analysis, we have used the constant false alarm rate procedure, often employed to perform effective tests. The benefits of using fractional chip sampling on the mean acquisition time are twofold: code acquisition denotes improved cross-correlation accuracy; timing error results are half those of the conventional technique. Slot synchronization error rate has been evaluated for various wireless channels (pedestrian and vehicular scenarios). The possible disturbing effect of further base stations has been also examined. The obtained results evidence a significant realtime saving of the mean acquisition time in the presence of typical pedestrian and vehicular scenarios.