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Nonlinear Coding and Estimation for Correlated Data in Wireless Sensor Networks
KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.ORCID iD: 0000-0002-7926-5081
2009 (English)In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 57, no 10, 2932-2939 p.Article in journal (Refereed) Published
Abstract [en]

The problem of designing simple and energy-efficient nonlinear distributed source-channel codes is considered. By demonstrating similarities between this problem and the problem of bandwidth expansion, a structure for source-channel codes is presented and analyzed. Based on this analysis an understanding about desirable properties for such a system is gained and used to produce an explicit source-channel code which is then analyzed and simulated. One of the main advantages of the proposed scheme is that it is implementable for many sources, contrary to most existing nonlinear distributed source-channel coding systems.

Place, publisher, year, edition, pages
IEEE Communications Society , 2009. Vol. 57, no 10, 2932-2939 p.
Keyword [en]
Source coding, quantization, channel coding, correlation
National Category
URN: urn:nbn:se:kth:diva-8445DOI: 10.1109/TCOMM.2009.10.080230ISI: 000270908700020ScopusID: 2-s2.0-70350614010OAI: diva2:13769
QC 20100917. Uppdaterad från submitted till published (20100917).Available from: 2008-05-15 Created: 2008-05-15 Last updated: 2011-12-27Bibliographically approved
In thesis
1. Source-Channel Coding in Networks
Open this publication in new window or tab >>Source-Channel Coding in Networks
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The aim of source coding is to represent information as accurately as possible using as few bits as possible and in order to do so redundancy from the source needs to be removed. The aim of channel coding is in some sense the contrary, namely to introduce redundancy that can be exploited to protect the information when being transmitted over a nonideal channel. Combining these two techniques leads to the area of joint source-channel coding which in general makes it possible to achieve a better performance when designing a communication system than in the case when source and channel codes are designed separately. In this thesis four particular areas in joint source-channel coding are studied: analog (i.e. continuous) bandwidth expansion, distributed source coding over noisy channels, multiple description coding (MDC) and soft decoding.

A general analog bandwidth expansion code based on orthogonal polynomials is proposed and analyzed. The code has a performance comparable with other existing schemes. However, the code is more general in the sense that it is implementable for a larger number of source distributions.

The problem of distributed source coding over noisy channels is studied. Two schemes are proposed and analyzed for this problem which both work on a sample by sample basis. The first code is based on scalar quantization optimized for a certain channel characteristics. The second code is nonlinear and analog.

Two new MDC schemes are proposed and investigated. The first is based on sorting a frame of samples and transmitting, as side-information/redundancy, an index that describes the resulting permutation. In case that some of the transmitted descriptors are lost during transmission this side information (if received) can be used to estimate the lost descriptors based on the received ones. The second scheme uses permutation codes to produce different descriptions of a block of source data. These descriptions can be used jointly to estimate the original source data. Finally, also the MDC method multiple description coding using pairwise correlating transforms as introduced by Wang et al. is studied. A modi fication of the quantization in this method is proposed which yields a performance gain.

A well known result in joint source-channel coding is that the performance of a communication system can be improved by using soft decoding of the channel output at the cost of a higher decoding complexity. An alternative to this is to quantize the soft information and store the pre-calculated soft decision values in a lookup table. In this thesis we propose new methods for quantizing soft channel information, to be used in conjunction with soft-decision source decoding. The issue on how to best construct finite-bandwidth representations of soft information is also studied.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. viii, 44 p.
Trita-EE, ISSN 1653-5146 ; 2008:028
source coding, channel coding, joint source-channel coding, bandwidth expansion, distributed source coding, multiple description coding, soft decoding
National Category
urn:nbn:se:kth:diva-4751 (URN)978-91-7415-002-5 (ISBN)
Public defence
2008-06-03, F3, KTH, Lindstedtsv 25, Stockholm, 13:15
QC 20100920Available from: 2008-05-15 Created: 2008-05-15 Last updated: 2010-09-20Bibliographically approved

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