CS-CDMA/CP with ZCZ Codes from an M-Sequence and Its Performance for Downlink Transmission over a Multipath Fading Channel

Nalin S. WEERASINGHE  Chenggao HAN  Takeshi HASHIMOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.6   pp.1204-1213
Publication Date: 2007/06/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.6.1204
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Spread Spectrum Technologies and Applications
zero correlation zone (ZCZ) code,  M-sequence,  CS-CDMA/CP,  multi-user interference,  PAPR,  

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Convolutional spreading CDMA with cyclic prefix (CS-CDMA/CP) is a multiuser interference-free (MUI-free) CDMA scheme proposed for multipath channels based on the convolution between user data and zero correlation zone (ZCZ) code, and its characteristics depend on the employed ZCZ codes. Although ternary ZCZ codes have more sequences than binary ZCZ codes in general, transmitted signal with ternary ZCZ codes give a slightly higher peak-to-average power ratio (PAPR). In this paper we propose the use of periodic ZCZ codes generated from an M-sequence which not only provides the same user capacity as ternary ZCZ codes but allows more design flexibility. Simulation results show that the new ZCZ code shows stronger robustness against an imperfect transmitter with clipping and enjoys better BER performances when used in CS-CDMA/CP compared to the conventional DS-CDMA with MRC-RAKE.