Fast Acquisition of PN Sequences in DS-CDMA Systems with Incoherent Demodulator


IEICE TRANSACTIONS on Communications   Vol.E89-B   No.12   pp.3319-3334
Publication Date: 2006/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.12.3319
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
fast acquisition,  PN sequence,  decomposition of sequences,  component sequence,  DS-CDMA,  

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DS-CDMA systems employing long-period PN sequences are becoming a widespread standard of wireless communication systems. However, fast acquisition of long-period PN sequences at a low hardware cost is conventionally a difficult problem. This paper examines a recently proposed fast acquisition algorithm for a class of PN sequences, which includes m and GMW sequences as special cases, under conditions of unknown received RF phase and chip boundary timing. The result shows that under low input (chip) SNR and the required delay estimation accuracy of Tc/Δ, Δ=2,3,…, the mean acquisition time can be considerably reduced compared to other known representative acquisition schemes. Its fast acquisition capability is based on a decomposition of long PN sequences into a number of short ones and achieves a significantly reduced code phase uncertainty of acquisition at relatively small hardware cost, estimated as 2/3 of the equivalent parallel correlators system. It can be applied as a (part of) acquisition scheme of a DS-CDMA system instead of a slow sliding correlator or a costly matched filter schemes.