Patent ID: 6377614
Filing Date: 2002-04-23
Classification: H04B

Abstract:
A spreading code synchronization circuit in a receiver in a spread-spectrum mobile communication system, comprising:a synchronization acquisition unit performing a sliding correlation of a received signal and a spreading code by varying a phase of the spreading code over a range of synchronization positions within a sliding correlation window, thereby obtaining an acquisition list of synchronization positions with correlation power values exceeding an acquisition threshold; a positive number of synchronization tracking units, each activated by provision of an assigned synchronization position and, while active, tracking a synchronization position of said spreading code with said received signal, starting from said assigned synchronization position; and an assignment control unit coupled to said synchronization acquisition unit and said synchronization tracking units, selecting from said acquisition list a candidate list of synchronization positions mutually separated by at least a predetermined phase difference, and performing a tracked synchronization position exclusion process of comparing the synchronization positions on said candidate list with synchronization positions already being tracked by active synchronization tracking units, and removing from said candidate list those synchronization positions that are separated by less than a predetermined threshold from the synchronization positions already being tracked, an assignable synchronization position selection process of selecting, as assignable synchronization positions, a number of most strongly correlated synchronization positions from the synchronization positions remaining on said candidate list, an idle tracking unit check process of selecting inactive synchronization tracking units as assignable synchronization tracking units, a duplicate tracking check process of comparing the synchronization positions being tracked by the active synchronization tracking units, and if a plurality of said synchronization tracking units are tracking substantially identical synchronization positions, selecting all but one of said plurality of synchronization tracking units as assignable synchronization tracking units, a low power check process of selecting active synchronization tracking units tracking synchronization positions with low correlation power as assignable synchronization tracking units, a reassignment process of assigning the assignable synchronization positions selected in said assignable synchronization position selection process to the assignable synchronization tracking units selected in said idle tracking unit check process, said duplicate tracking check process, and said low power check process, and a window adjustment process of selecting the sliding correlation window to be used next by said synchronization acquisition unit.