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Journal of Information Science and Engineering, Vol.19 No.6, pp.1041-1057 (November 2003)

A Modified Approach to Determine the Most Appropriate
Spreading Codes for a DS/CDMA System with
Exponentially Weighted Despreading Sequences

Cerbrail Ciftlikli and Ibrahim Develi
Department of Electronic Engineering
Erciyes University
38039, Kayseri, Turkey

Exponential chip weighting waveform used in a direct sequence/code division multiple access (DS/CDMA) receiver is an effective method to reject multiple access interference (MAI). Recently, we introduced a strategy to determine the most appropriate spreading codes (MASC) which might be used as references in a given code set for a DS/CDMA system employing exponentially weighted despreading sequences. In the strategy it was shown that lower bit error rates might be achieved when the MASC, which were differentiated by the strategy, are used as references. The main limitation of the strategy was the requirement for dividing a code set into sub-sets to distinguish the resultant MASC. In this study, we present a modified approach that eliminates this requirement and also simplifies the determination of the MASC by ignoring one of the calculations, which was taken into consideration in the previous strategy on the features of the spreading codes in a given code set. Numerical results show that the MASC for a given code set can be detected simply and precisely by using the proposed approach.

Keywords: spread spectrum communications, DS/CDMA systems, optimal code selection, multiple access interference, weighted despreading sequences

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Received April 16, 2002; revised November 15, 2002; accepted March 10, 2003.
Communicated by Chi Sung Laih.