A simple carrier frequency detection algorithm for fine compensation of Doppler shift in direct-sequence code division multiple access mobile satellite communications

A simple algorithm is proposed for carrier frequency synchronization after PN code acquisition using FFT (fast Fourier transform) in a direct-sequence code division multiple access mobile satellite communications system. The proposed algorithm shows almost the same performance as the phase differential algorithm under additive white Gaussian noise channel environments. The proposed algorithm, however, largely reduces hardware complexity when a two-dimensional search algorithm is employed for PN code timing acquisition and coarse Doppler shift compensation since the proposed algorithm shares the FFT operator with the two-dimensional search.