Blind Estimation of the Pseudo Noise Sequence and Information Sequence for Long Code Asynchronous DS-CDMA Signal in Multipath Environment

For the problem of long code Direct Sequence-Code Division Multiple Access (DS-CDMA) signal in traditional asynchronous single-channel with multipath effect under low Signal-to-Noise Ratio (SNR), including blind estimation of the Pseudo-Noise (PN) sequence and information sequence, a method using multi-channel synchronous and asynchronous based on parallel factor is proposed. Firstly, the received signal in multipath environment is modeled as a multi-channel receiving model. And then the long code DS-CDMA signal is modeled as the short code DS-CDMA signal with missing data to form the observation missing-data matrix, which is equivalent to a parallel factor model with missing data. Finally, the regularized Alternating Least Squares (ALS) algorithm is applied to decompose the parallel factor, and the PN sequence and information sequence of long code DS-CDMA signals in multipath environment can be further estimated. Simulation results show that the performance of sequences estimation closely relates with the multipath environment, and the estimation error rate of 6 user PN sequences and information sequence is less than 1% under the condition that the Rician factor is equal to 10 and the number of path and channel are 3 and 4 respectively when the SNR is higher than -10 dB.