A General Model for Performance Evaluation in DS-CDMA Systems with Variable Spreading Factors

Franco CHIARALUCE  Ennio GAMBI  Giorgia RIGHI  

IEICE TRANSACTIONS on Communications   Vol.E91-B    No.2    pp.466-478
Publication Date: 2008/02/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.2.466
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
direct sequence-spread spectrum,  wideband code division multiple access,  spreading sequences,  multipath,  BER performance,  

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This paper extends previous analytical approaches for the study of CDMA systems to the relevant case of multipath environments where users can operate at different bit rates. This scenario is of interest for the Wideband CDMA strategy employed in UMTS, and the model permits the performance comparison of classic and more innovative spreading signals. The method is based on the characteristic function approach, that allows to model accurately the various kinds of interferences. Some numerical examples are given with reference to the ITU-R M.1225 Recommendations, but the analysis could be extended to different channel descriptions.