Composite CDMA—a statistical mechanics analysis


Code division multiple access (CDMA) in which the spreading code assignment to users contains a random element has recently become a cornerstone of CDMA research. The random element in the construction is particularly attractive as it provides robustness and flexibility in utilizing multiaccess channels, whilst not making significant sacrifices in terms of transmission power. Random codes are generated from some ensemble; here we consider the possibility of combining two standard paradigms, sparsely and densely spread codes, in a single composite code ensemble. The composite code analysis includes a replica symmetric calculation of performance in the large system limit, and investigation of finite systems through a composite belief propagation algorithm. A variety of codes are examined with a focus on the high multi-access interference regime. We demonstrate scenarios both in the large size limit and for finite systems in which the composite code has typical performance exceeding those of sparse and dense codes at equivalent signal to noise ratio.

Publication DOI:
Divisions: College of Engineering & Physical Sciences
College of Engineering & Physical Sciences > Systems analytics research institute (SARI)
Additional Information: © 2009 IOP Publishing Ltd and SISSA
Uncontrolled Keywords: random graphs,networks,disordered systems,source and channel coding
Publication ISSN: 1742-5468
Last Modified: 15 Apr 2024 07:09
Date Deposited: 11 Dec 2012 14:24
Full Text Link: http://iopscien ... 2009/05/P05015/
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2009-05-21
Authors: Raymond, Jack
Saad, David (ORCID Profile 0000-0001-9821-2623)



Version: Published Version

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