A DS-CDMA code acquisition scheme robust to residual code phase offset variation

In this paper, we first investigate the effect of residual code phase offset on the direct-sequence code-division multiple-access code acquisition scheme using a noncoherent matched filter receiver. We then propose a new code acquisition scheme that is robust to the variation of the residual code phase offset and outperforms the conventional scheme. When the code phase offset normalized to the chip duration between two sequences is within the advancing step size, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset when the noise is absent. Based on this observation, we propose a new code acquisition scheme and investigate the performance of the scheme. The proposed code acquisition scheme is analyzed in an additive white Gaussian noise and multiple-access interference environment. Finally, numerical results are given to show that the proposed scheme is more robust to the variation of the residual code phase offset and has better performance than the conventional scheme on average.