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Soft detection and decoding in wideband CDMA systems

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Kettunen, Kimmo
dc.date.accessioned 2012-01-24T14:39:39Z
dc.date.available 2012-01-24T14:39:39Z
dc.date.issued 2003-03-14
dc.identifier.isbn 951-22-6425-0
dc.identifier.issn 1458-6401
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2059
dc.description.abstract A major shift is taking place in the world of telecommunications towards a communications environment where a range of new data services will be available for mobile users. This shift is already visible in several areas of wireless communications, including cellular systems, wireless LANs, and satellite systems. The provision of flexible high-quality wireless data services requires a new approach on both the radio interface specification and the design and the implementation of the various transceiver algorithms. On the other hand, when the processing power available in the receivers increases, more complex receiver algorithms become feasible. The general problem addressed in this thesis is the application of soft detection and decoding algorithms in the wideband code division multiple access (WCDMA) receivers, both in the base stations and in the mobile terminals, so that good performance is achieved but that the computational complexity remains acceptable. In particular, two applications of soft detection and soft decoding are studied: coded multiuser detection in the CDMA base station and improved RAKE-based reception employing soft detection in the mobile terminal. For coded multiuser detection, we propose a novel receiver structure that utilizes the decoding information for multiuser detection. We analyze the performance and derive lower bounds for the capacity of interference cancellation CDMA receivers when using channel coding to improve the reliability of tentative decisions. For soft decision and decoding techniques in the CDMA downlink, we propose a modified maximal ratio combining (MRC) scheme that is more suitable for RAKE receivers in WCDMA mobile terminals than the conventional MRC scheme. We also introduce an improved soft-output RAKE detector that is especially suitable for low spreading gains and high-order modulation schemes. Finally we analyze the gain obtained through the use of Brennan's MRC scheme and our modified MRC scheme. Throughout this thesis Bayesian networks are utilized to develop algorithms for soft detection and decoding problems. This approach originates from the initial stages of this research, where Bayesian networks and algorithms using such graphical models (e.g. the so-called sum-product algorithm) were used to identify new receiver algorithms. In the end, this viewpoint may not be easily noticeable in the final form of the algorithms, mainly because the practical efficiency considerations forced us to select simplified variants of the algorithms. However, this viewpoint is important to emphasize the underlying connection between the apparently different soft detection and decision algorithms described in this thesis. en
dc.format.extent 80, [46]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Report / Helsinki University of Technology, Signal Processing Laboratory en
dc.relation.ispartofseries 38 en
dc.relation.haspart Kettunen, K. and Laakso, T., Iterative multiuser receiver utilizing soft decoding information. Proceedings IEEE International Communications Conference, ICC'99. Vancouver, BC, Canada, June 1999, pages 942-946.
dc.relation.haspart Kettunen, K., Iterative multiuser receiver/decoders with enhanced variance estimation. Proceedings IEEE 49th Vehicular Technology Conference, VTC'99. Houston, Texas, USA, May 1999, pages 2318-2322.
dc.relation.haspart Kettunen, K., Performance of coded multistage detection in correlated Rayleigh channels. Proceedings X European Signal Processing Conference, EUSIPCO-2000. Tampere, Finland, September 2000, pages 565-568.
dc.relation.haspart Kettunen, K., 2001. Enhanced maximal ratio combining scheme for RAKE receivers in WCDMA mobile terminals. IEE Electronics Letters 37, No. 8, pages 522-524.
dc.relation.haspart Kettunen, K. and Lilleberg, J., Decoding metric of downlink CDMA RAKE receivers using bit-interleaved coded modulation. Accepted to Wireless Personal Communications, May 2002.
dc.relation.haspart Kettunen, K., Enhanced maximal ratio combining for RAKE receivers in mobile CDMA terminals. Proceedings 5th Nordic Signal Processing Symposium, NORSIG 2002. On board Hurtigruten, Norway, October 2002, pages 217-221.
dc.subject.other Electrical engineering en
dc.title Soft detection and decoding in wideband CDMA systems en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Electrical and Communications Engineering en
dc.contributor.department Sähkö- ja tietoliikennetekniikan osasto fi
dc.subject.keyword CDMA en
dc.subject.keyword soft detection en
dc.subject.keyword soft decoding en
dc.subject.keyword coded multiuser detection en
dc.subject.keyword RAKE receiver en
dc.subject.keyword sum-product algorithm en
dc.subject.keyword iterative methods en
dc.identifier.urn urn:nbn:fi:tkk-000337
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Signal Processing Laboratory en
dc.contributor.lab Signaalinkäsittelytekniikan laboratorio fi

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