LDPC code design for the two-user Gaussian multiple access channel

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dc.citation.epage2844en_US
dc.citation.issueNumber4en_US
dc.citation.spage2833en_US
dc.citation.volumeNumber15en_US
dc.contributor.authorSharifi S.en_US
dc.contributor.authorTanc, A. K.en_US
dc.contributor.authorDuman, T. M.en_US
dc.date.accessioned2018-04-12T10:42:07Z
dc.date.available2018-04-12T10:42:07Z
dc.date.issued2016en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.description.abstractWe study code design for two-user Gaussian multiple access channels (GMACs) under fixed channel gains and under quasi-static fading. We employ low-density parity-check (LDPC) codes with BPSK modulation and utilize an iterative joint decoder. Adopting a belief propagation (BP) algorithm, we derive the PDF of the log-likelihood-ratios (LLRs) fed to the component LDPC decoders. Via examples, it is illustrated that the characterized PDF resembles a Gaussian mixture (GM) distribution, which is exploited in predicting the decoding performance of LDPC codes over GMACs. Based on the GM assumption, we propose variants of existing analysis methods, named modified density evolution (DE) and modified extrinsic information transfer (EXIT). We derive a stability condition on the degree distributions of the LDPC code ensembles and utilize it in the code optimization. Under fixed channel gains, the newly optimized codes are shown to perform close to the capacity region boundary outperforming the existing designs and the off-the-shelf point-to-point (P2P) codes. Under quasi-static fading, optimized codes exhibit consistent improvements upon the P2P codes as well. Finite block length simulations of specific codes picked from the designed ensembles are also carried out and it is shown that optimized codes perform close to the outage limits. © 2015 IEEE.en_US
dc.identifier.doi10.1109/TWC.2015.2511749en_US
dc.identifier.issn1536-1276
dc.identifier.urihttp://hdl.handle.net/11693/36489
dc.language.isoEnglishen_US
dc.publisherInstitute of Electrical and Electronics Engineers Inc.en_US
dc.relation.isversionofhttp://dx.doi.org/10.1109/TWC.2015.2511749en_US
dc.source.titleIEEE Transactions on Wireless Communicationsen_US
dc.subjectCode designen_US
dc.subjectCommon outage capacityen_US
dc.subjectGaussian mixtureen_US
dc.subjectIterative decodingen_US
dc.subjectLow-density parity-check codesen_US
dc.subjectMultiple access channelsen_US
dc.titleLDPC code design for the two-user Gaussian multiple access channelen_US
dc.typeArticleen_US

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