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Polyphase Scrambled Walsh Codes for Zero-Correlation Zone Extension in QS-CDMA

TitlePolyphase Scrambled Walsh Codes for Zero-Correlation Zone Extension in QS-CDMA
Publication TypeJournal Article
Year of Publication2012
AuthorsChoi, K., and H. Liu
JournalIEEE Communications Letters
Pagination429 - 431
Date Published04/2012
Keywordsorthogonal spreading codes, quasi-synchronous CDMA, scrambling, zero-correlation zone (ZCZ)

Polyphase complex scrambling patterns are designed to extend the zero-correlation zone (ZCZ) of a family of user spreading sequences, called properly scrambled Walsh-Hadamard (PSW) codes, recently proposed for quasi-synchronous (QS) code-division multiple-access systems. The merits of the binary (ZCZ equals 2) and quadri-phase (ZCZ equals 4) PSW codes over the existing QS spreading codes are still retained in the proposed polyphase PSW codes. Scrambling patterns for the case of ZCZ of 8 are derived first. Then, the scrambling pattern design rules are generalized for greater ZCZs and a structured procedure to generate polyphase PSW codes for any ZCZ is developed. Finally, the cross-correlation properties of the proposed spreading codes are evaluated.

Short TitleIEEE Commun. Lett.