Code acquisition of a DS/CDMA system with imperfect power control for LEO mobile satellite communications

The performance of a parallel acquisition scheme is evaluated for a direct-sequence/code-division-multiple-access (DS/CDMA) system with imperfect power control in a low-Earth-orbit (LEO) mobile satellite environment. The acquisition scheme consists of a parallel matched-filter and an FFT processor. The uplink of the mobile satellite channel is modeled as a shadowed Rician fading channel. The acquisition performance is evaluated in terms of the mean acquisition time. The effect of the power control error is considered in the analysis of the acquisition performance. The acquisition-based capacity is defined and estimated. It is shown that the power control error causes the acquisition to be slower than the case of perfect power control, and for high SNR/chip, the effect of the power control error becomes less significant. The better acquisition performance is achieved for the case of a high elevation angle compared to that of a low elevation angle because the propagation conditions becomes worse as the elevation angle gets lower