Blind Periodic Estimation of PN Sequence Based on Reprocessing of Power in Multirate DS / CDMA Transmissions.

The blind periodic estimation of the PN sequence in variable-spreading-length(VSL) multirate direct-sequence code division multiple access(DS / CDMA) systems is considered. The method of the reprocessing of the power spectrum which is used to estimate the period of general DS-SS signal is extended to multirate DS / CDMA model. Firstly, the received signal is sampled and its power spectrum is estimated, then Fourier transform is directly used to the power spectrum to modulo and square the value,and so repro? cessing of the power spectrum is obtained. The derivation proves that the power spectrum reprocessing of the multirate DS / CDMA signal will arise varied amplitude sharp pulse with interval equal to the period of these different rates users' PN sequence, accordingly, the periods of the different rates users' PN sequence can be acquired. The computer simulation results show that the method can work well under the lower signal-to-noise ratio(SNR) input signals and it is able to estimate many rates by taking advantage of less data at the same time at -15 dB SNR. [ABSTRACT FROM AUTHOR]