Approach to blind estimation of PN spreading sequence in lower SNR DS/SS signals
Tianqi Zhang · 2005
An approach was developed using covariance matrix accumulation and the Karhunen-Loeve (K-L) transformation for DS/SS signals to blindly estimate the pseudo noise (PN) sequence in low signal to noise ratio (SNR) DS/SS signals. The parameters of the DS/SS signals (such as the period and chip interval of the PN sequence) need to be known. The received signals were divided into vectors based on the PN sequence period with the starting point of the division being randomized points uniformly distributed in a PN sequence period. Then the covariance matrix of the signal vectors was analyzed using the K-L transformation. The PN sequence of the DS/SS signals was then blindly estimated from the main component eigenvector. The estimated PN sequence can be used to calculate the DS/SS signal despreading without the PN sequence. Theoretical analyses and test results show that the approach is very robust, working well on SNR below -20 dB in normal circumstances.