Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
On Source Decoding Based on Finite-Bandwidth Soft Information
KTH, School of Electrical Engineering (EES), Communication Theory.
KTH, School of Electrical Engineering (EES), Communication Theory.ORCID iD: 0000-0002-7926-5081
2005 (English)In: 2005 IEEE International Symposium on Information Theory (ISIT), 2005, 87-91 p.Conference paper, Published paper (Refereed)
Abstract [en]

Designing a communication system using joint source-channel coding in general makes it possible to achieve a better performance than when the source and channel codes are designed separately, especially under strict delay-constraints. The majority of work done in joint source-channel coding uses a discrete channel model, corresponding to an analog channel in conjunction with a hard decision modulation scheme. The performance of such a system can however be improved by using soft decision modulation. The main cost is a higher decoding complexity. An alternative is to quantize the soft information and store the pre-calculated soft decision values in a lookup table. In this paper we propose new methods for quantizing soft channel information, to be used in conjunction with soft-decision source decoding. We achieve a performance close to that of a system using unquantized soft information.

Place, publisher, year, edition, pages
2005. 87-91 p.
Keyword [en]
Bandwidth, Communication channels (information theory), Communication systems, Computational complexity, Decoding, Modulation, Decoding complexity, Soft information, Source-channel coding, Strict delay-constraints
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-8449DOI: 10.1109/ISIT.2005.1523298ISI: 000234713800019Scopus ID: 2-s2.0-33749452421ISBN: 0-7803-9151-9 (print)OAI: oai:DiVA.org:kth-8449DiVA: diva2:13773
Note
QC 20100920Available from: 2008-05-15 Created: 2008-05-15 Last updated: 2011-10-14Bibliographically 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.
Series
Trita-EE, ISSN 1653-5146 ; 2008:028
Keyword
source coding, channel coding, joint source-channel coding, bandwidth expansion, distributed source coding, multiple description coding, soft decoding
National Category
Telecommunications
Identifiers
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
Opponent
Supervisors
Note
QC 20100920Available from: 2008-05-15 Created: 2008-05-15 Last updated: 2010-09-20Bibliographically approved
2. Source-channel coding for wireless networks
Open this publication in new window or tab >>Source-channel coding for wireless networks
2006 (English)Licentiate 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 two particular areas in joint source–channel coding are studied: multiple description coding (MDC) and soft decoding. 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 modification 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, 2006. vi, 31 p.
Series
Trita-EE, ISSN 1653-5146 ; 2006:009
Keyword
Source coding, channel coding, joint source-channel coding, multiple description coding, soft decoding, permutation codes
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-3912 (URN)
Presentation
2006-04-11, Sal Q2, KTH, Osquldas väg 10, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101124Available from: 2006-04-07 Created: 2006-04-07 Last updated: 2010-11-24Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Skoglund, Mikael

Search in DiVA

By author/editor
Wernersson, NiklasSkoglund, Mikael
By organisation
Communication Theory
Telecommunications

Search outside of DiVA

GoogleGoogle Scholar

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 55 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf