Blind Estimation of Pseudo-random Sequences of the Carrier Modulated Direct Sequence Spread Spectrum Signals in Asynchronous Uplink System Using Space-Time Complex-ICA

Without the knowledge of the users’ carrier frequency or the channel parameters, this paper proposes a new arithmetic to blind estimate the pseudo-random sequences, based on the space-time complex independent component analysis (ST-CICA), phase lock loop (PLL) and principal component analysis (PCA). The received carrier modulated signals are firstly separated by the ST-CICA, while the multi-path interference, multiple access interference and near-far effect are cancelled. PLL and PCA will be utilized on the separated signal, in order to estimate the pseudo-random sequences, the carrier frequencies and the data of users. This new arithmetic of blind estimation works well in low signal-to-noise ratio (SNR) environment, because of well utilizing of antenna array diversity gain and spreading gain. The performance of blind estimation is analyzed under Gaussian noise. Illustrative simulation examples were provided at last.