A Modified Genetic Algorithm for Multiuser Detection in DS/CDMA Systems

Mahrokh G. SHAYESTEH  Mohammad B. MENHAJ  Babak G. NOBARY  

IEICE TRANSACTIONS on Communications   Vol.E86-B   No.8   pp.2377-2388
Publication Date: 2003/08/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
code division multiple access (CDMA),  genetic algorithms (GAs),  multiuser detection,  multiple access interference (MAI),  near-far effect,  

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Multiple access interference and near-far effect cause the performance of the conventional single user detector in DS/CDMA systems to degrade. Due to high complexity of the optimum multiuser detector, suboptimal multiuser detectors with less complexity and reasonable performance have received considerable attention. In this paper we apply the classic and a new modified genetic algorithm for multiuser detection of DS/CDMA signals. It is shown that the classic genetic algorithm (GA) reaches an error floor at high signal to noise ratios (SNR) while the performance of proposed modified GA is much better than the classic one and is comparable to the optimum detector with much less complexity. The results hold true for AWGN and fading channels. We also describe another GA called as meta GA to find the optimum parameters of the modified GA. We compare the performance of proposed method with the other detectors used in CDMA.