Bounds on Aperiodic Autocorrelation and Crosscorrelation of Binary LCZ/ZCZ Sequences

Daiyuan PENG  Pingzhi FAN  Naoki SUEHIRO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E88-A   No.12   pp.3636-3644
Publication Date: 2005/12/01
Online ISSN: 
DOI: 10.1093/ietfec/e88-a.12.3636
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Spread Spectrum Technologies and Applications
aperiodic correlation functions,  binary sequences,  generalized orthogonality,  LCZ sequences,  low bound,  ZCZ sequences,  

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In order to eliminate the co-channel and multi-path interference of quasi-synchronous code division multiple access (QS-CDMA) systems, spreading sequences with low or zero correlation zone (LCZ or ZCZ) can be used. The significance of LCZ/ZCZ to QS-CDMA systems is that, even there are relative delays between the transmitted spreading sequences due to the inaccurate access synchronization and the multipath propagation, the orthogonality (or quasi-orthogonality) between the transmitted signals can still be maintained, as long as the relative delay does not exceed certain limit. In this paper, several lower bounds on the aperiodic autocorrelation and crosscorrelation of binary LCZ/ZCZ sequence set with respect to the family size, sequence length and the aperiodic low or zero correlation zone, are derived. The results show that the new bounds are tighter than previous bounds for the LCZ/ZCZ sequences.