Twin-cell detection (TCD): A code acquisition scheme in the presence of fractional doppler frequency offset

As a novel code-acquisition scheme, the twin-cell detection (TCD) is proposed for the acquisition in time of spread-spectrum codes in the presence of fractional Doppler frequency offset (FDFO). When the FDFO exists, the correlation peak that is used for detection during the acquisition process is split into two neighboring peaks with smaller magnitudes, which results in a considerable degradation in the overall acquisition performance of conventional schemes. In the TCD, the decision variable for detection is formed by combining two consecutive correlator outputs so that the influence of the reduction in the correlation peak due to the FDFO can be alleviated. The numerical results show that the TCD can offer a better mean-time-to-synchronization performance than the conventional scheme based on the cell-by-cell detection.