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WO2008126047A1 - Modulation codée en treillis avec protection d'erreur inégale - Google Patents

Modulation codée en treillis avec protection d'erreur inégale Download PDF

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Publication number
WO2008126047A1
WO2008126047A1 PCT/IB2008/051398 IB2008051398W WO2008126047A1 WO 2008126047 A1 WO2008126047 A1 WO 2008126047A1 IB 2008051398 W IB2008051398 W IB 2008051398W WO 2008126047 A1 WO2008126047 A1 WO 2008126047A1
Authority
WO
WIPO (PCT)
Prior art keywords
bit
bits
constellation
bit set
symbol constellation
Prior art date
Application number
PCT/IB2008/051398
Other languages
English (en)
Inventor
Seyed-Alireza Seyedi-Esfahani
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2008126047A1 publication Critical patent/WO2008126047A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/25—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM]
    • H03M13/256—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] with trellis coding, e.g. with convolutional codes and TCM
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/25—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM]
    • H03M13/258—Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] with turbo codes, e.g. Turbo Trellis Coded Modulation [TTCM]
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/35—Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
    • H03M13/356—Unequal error protection [UEP]
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/63—Joint error correction and other techniques
    • H03M13/635—Error control coding in combination with rate matching
    • H03M13/6362—Error control coding in combination with rate matching by puncturing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0059—Convolutional codes
    • H04L1/006—Trellis-coded modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/007—Unequal error protection

Definitions

  • This invention pertains to the field of data communication, and more particularly to a system and method of encoding and modulating data for transmission.
  • BER bit error rate
  • N 0 spectral noise density
  • EtZN 0 spectral noise density
  • different portions of the data are more critical to successful operation of the application than other portions.
  • N e.g., 24
  • M M-bit words
  • the MSBs of each of these three words are more critical than the LSBs to achieving an accurate representation of the video signal.
  • errors in the MSBs are more detrimental than errors in the LSBs to successful operation of the video application. Accordingly, it would be desirable to provide a method of communicating data which provides greater error protection for more critical data than it provides to less critical data.
  • a method of transmitting data comprises: separating data bits into a first bit set and a second bit set; and mapping the first and second bit sets to a symbol constellation, where an Euclidian distance in the symbol constellation between valu s in the first bit set is less than an Euclidian distance in the symbol constellation between values for the bits in the second bit set; wherein within each of the first and second bit sets, the bits are mapped to the symbol constellation using trellis-coded modulation.
  • a system for transmitting data bits separated into a first bit set and a second bit set comprises a constellation mapper adapted to map the first and second bit sets into a symbol constellation.
  • a Euclidean distance in the symbol constellation between values for the bits in the first bit set is greater than a Euclidean distance in the symbol constellation between values for the bits in the second bit set.
  • the constellation mapper maps bits to the symbol constellation using trellis-coded modulation.
  • FIG. 1 is a functional block diagram of a transmission system employing trellis coded modulation (TCM).
  • TCM trellis coded modulation
  • FIG. 2 is a symbol constellation produced by the transmission system of FIG. 1.
  • FIG. 3 is a functional block diagram of a transmission system employing unequal data protection (UEP).
  • UEP unequal data protection
  • FIG. 4 is a symbol constellation produced by the transmission system of FIG. 3.
  • FIG. 5 is a functional block diagram of one embodiment of a transmission system employing TCM and UEP.
  • FIG. 6 is a symbol constellation produced by the transmission system of FIG. 5.
  • FIG. 7 compares bit error rate (BER) versus Eb/No performance for a transmission scheme employing UEP, against a transmission scheme employing both TCM and UEP.
  • FIG. 1 is a functional block diagram of one exemplary transmission system 100 employing trellis coded modulation (TCM).
  • System 100 includes trellis (e.g., convolutional) coder 110 and 16-QAM TCM constellation mapper 120.
  • trellis e.g., convolutional
  • system 100 receives a group of data bits ai-a3 and generates one transmission symbol S xy from the three data bits.
  • 16-QAM TCM constellation mapper 120 maps four bits bib 2 b3b 4 to each transmission symbol S xy .
  • trellis coder 110 is a 1 A rate convolutional coder that receives data bit a 3 and generates therefrom bits b 3 and b 4 for 16-QAM TCM constellation mapper 120. Meanwhile, data bits ao and ai are applied directly to 16-QAM TCM constellation mapper 120 as bits bi and b 2 .
  • 16-QAM TCM constellation mapper 120 maps the bits bib 2 transmission symbol S xy based on the level of protection that each bit has received in the encoding process.
  • 16-QAM TCM constellation mapper 120 maps the bits bi and b 2 onto constellation points such that the 0 and 1 values for each bit have a relatively greater Euclidian distance from each other, and maps the bits b 3 and b 4 onto constellation points such that the 0 and 1 values for each bit have a relatively smaller Euclidian distance from each other.
  • the overall protection that each bit receives is increased.
  • FIG. 2 is a symbol constellation 200, produced by the transmission system 100 of FIG. 1. Each constellation point is shown together with the corresponding bits bib 2 b 3 b 4 that map to that point. As can be seen in FIG. 2 the Euclidian distances dbi and db 2 between 0 and 1 values for bits bi and b 2 , respectively - which were not subject to protection by convolutional coder 110 - are both greater than the Euclidian distances db 3 and db 4 between 0 and 1 values for bits b 3 and b 4 , respectively - which were subject to protection by convolutional coder 110.
  • FIG. 3 is a functional block diagram of a transmission system 300 employing unequal data protection (UEP).
  • System 300 includes first and second convolutional coders 310, 315 and first and second 16-QAM UEP constellation mappers 320 and 325.
  • system 300 receives a group of six data bits ai-a 6 and generates two transmission symbols S xlyl and S x2y2 from the six data bits.
  • data bits ai-a 6 are separated into a first bit set comprising ai-a 3 , and a second bit set comprising a 4 -a 6 .
  • the first bit set ai-a 3 comprises data requires a lower level of protection than data in the second bit set a 4 -a 6 .
  • each pixel is represented by three 6-bit words ai-a 6 to represent the red, green and blue levels.
  • the three MSBs a 4 -a 6 of each of these three words are more critical than the three LSBs ai-a 3 to achieving an accurate representation of the video signal.
  • bits a r a 3 may be referred to as "Low Protection” data bits requiring a lower level of protection against error
  • bits a 4 -a 6 may be referred to as "High Protection” data bits requiring a higher level of protection against error.
  • Each 16-QAM UEP constellation mapper 320/325 maps four bits bib 2 b 3 b 4 to a corresponding transmission symbol S xy .
  • the first and second convolutional coders 310, 315 mvolutional coders that receive data bits ai-a3 and a 4 -a6, respectively, and generate therefrom bits bib 2 b 3 b 4 for each of the 16-QAM UEP constellation mappers 320 and 325.
  • first convolutional coder 310 receives the Low Protection data bits ai-a 3 and produces therefrom the bits bib 2 for each of the two 16-QAM UEP constellation mappers 320 and 325.
  • second convolutional coder 315 receives the High Protection data bits a 4 -a6 and produces therefrom the bits b 3 b 4 for each of the two 16-QAM UEP constellation mappers 320 and 325.
  • each 16-QAM UEP constellation mapper 320/325 maps the bits bib 2 b 3 b 4 to a corresponding transmission symbol S xy based on the protection level of the bits.
  • each 16-QAM UEP constellation mapper 320/325 maps the bits bi and b 2 generated from the first bit set comprising the Low Protection data bits ai-a 3 , to constellation points such that the 0 and 1 values for each bit have a relatively smaller Euclidian distance from each other, and maps the bits b 3 and b 4 generated from the second bit set comprising the High Protection data bits a 4 -a 6 , to constellation points such that the 0 and 1 values for each bit have a relatively greater Euclidian distance from each other.
  • FIG. 4 is a symbol constellation 400 produced by the transmission system 300 of FIG. 3. Each constellation point is shown together with the corresponding bits bib 2 b 3 b 4 that map to that point. It can be seen that the bits b 3 and b 4 map to the "in-phase" component of the symbol constellation, illustrated by a horizontal axis in FIG. 4. Likewise, it can be seen that the bits bi and b 2 map to the "quadrature" component of the symbol constellation, illustrated by a vertical axis in FIG. 4. In symbol constellation 400, it is assumed that the horizontal distance between adjacent constellation points, 2di, is greater than the vertical distance between adjacent constellation points, 2d 2 .
  • FIG. 5 is a functional block diagram of one embodiment of a transmission system 500 employing trellis coded modulation and unequal error protection.
  • System 500 includes first involutional coders 510, 515 and first and second 16-QAM UEP&TCM constellation mappers 520 and 525.
  • system 500 receives a group of six data bits ai-a 6 and generates two transmission symbols S xlyl and S X2y2 from the six data bits.
  • data bits ai-a 6 are separated into a first bit set comprising ai-a3, and a second bit set comprising a 4 -a 6 .
  • the first bit set ai-a 3 comprises data that requires a lower level of protection than data in the second bit set a 4 -a6. For example, consider a case of video data where each pixel is represented by three 6-bit words ai-a 6 to represent the red, green and blue levels.
  • the three MSBs a 4 -a6 of each of these three words are more critical than the three LSBs ai-a3 to achieving an accurate representation of the video signal.
  • errors in the MSBs a 4 -a 6 are more detrimental than errors in the LSBs ai-a 3 to successful operation of the video application.
  • data bits ai-a 3 may be referred to as "Low Protection” data bits requiring a lower level of protection against error
  • data bits a 4 -a 6 may be referred to as "High Protection" data bits requiring a higher level of protection against error.
  • Each 16-QAM UEP&TCM constellation mapper 520/525 maps four bits bib 2 b 3 b 4 to a corresponding transmission symbol S xy .
  • the first and second convolutional coders 510 and 515 are 1 A rate convolutional coders that receive data bits a3 and a 6 , respectively, and generate therefrom bits b 2 and b 4 , respectively, for both of the two 16-QAM UEP&TCM constellation mappers 520 and 525.
  • first convolutional coder 510 receives the Low Protection data bit a 3 and produces therefrom the bit b 2 for both of the two 16-QAM UEP&TCM constellation mappers 520 and 525.
  • second convolutional coder 515 receives the High Protection data bit a 6 and produces therefrom the bit b 4 for both of the two 16-QAM UEP&TCM constellation mappers 520 and 525.
  • each 16-QAM UEP&TCM constellation mapper 520/525 maps the bits bib 2 b 3 b4 to a corresponding transmission symbol S xy based on the protection level of the bits.
  • each 16-QAM UEP&TCM constellation mapper 520/525 maps the bits bi and b 2 generated from the first bit set comprising the Low Protection bits ai-a 3 , to constellation points such that the 0 and 1 values for each bit have a relatively smaller Euclidian distance from each other, and maps the bits b 3 and b 4 generated from the second bit set comprising the High Protection bits a 4 -a 6 , to constellation points such that the 0 and 1 values for each bit have a relatively greater Euclidian distance from each other. Furthermore, in the system 100, the encoding and mapping of the data bits are not performed independently.
  • 16-QAM UEP&TCM constellation mappers 520/525 map the bits within each bit set to each transmission symbol S xy based on the level of protection that each bit has received in the encoding process. Accordingly, within the first bit set, since bit b 2 is subject to "protection" by convolutional encoder 110 while bit bi is not, 16-QAM UEP&TCM constellation mappers 520/525 map the bits bi and b 2 to constellation points such that the 0 and 1 values for bit bi have a relatively greater Euclidian distance from each other, than the 0 and 1 values for bit b 2 . As a result, the overall protection that each bit receives is increased.
  • FIG. 6 is a symbol constellation 600 produced by the transmission system 500 of FIG. 5. Each constellation point is shown together with the corresponding bits bib 2 b 3 b 4 that map to that point. It can be seen that the bits b 3 and b 4 map to the "in-phase" component of the symbol constellation, illustrated by a horizontal axis in FIG. 6. Likewise, it can be seen that the bits bi and b 2 map to the "quadrature" component of the symbol constellation, illustrated by a vertical axis in FIG. 6. In symbol constellation 600, it is assumed that the horizontal distance between adjacent constellation points, 2di, is greater than the vertical distance between adjacent constellation points, 2d 2 .
  • transmission system 500 protects the High Protection data bits a 4 -a6 to a greater extent compared to the Low Protection data bits ai-a 3 . hin each of the in-phase and quadrature components of the constellation map, the bits are mapped according to a TCM scheme.
  • FIG. 7 compares bit error rate (BER) versus Eb/No performance for a transmission scheme employing UEP, against a transmission scheme employing both TCM and UEP.
  • the transmission scheme employing TCM and UEP produces superior BER performance for both cases.
  • the transmission scheme employing TCM and UEP produces superior BER performance for both High Protected and Low Protection data.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Probability & Statistics with Applications (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Error Detection And Correction (AREA)

Abstract

L'invention concerne un procédé et un système (500) de transmission de données qui séparent des bits de données en un premier ensemble de bits et un second ensemble de bits; et font concorder les premier et second ensembles de bits avec une constellation de symboles, une distance euclidienne dans la constellation de symboles entre des valeurs pour les bits du premier ensemble de bits étant inférieure à une distance euclidienne dans la constellation de symboles entre des valeurs pour les bits du second ensemble de bits, et, à l'intérieur de chacun des premier et second ensembles de bits, les bits étant mis en concordance avec la constellation de symboles à l'aide d'une modulation codée en treillis (520, 525).
PCT/IB2008/051398 2007-04-13 2008-04-11 Modulation codée en treillis avec protection d'erreur inégale WO2008126047A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US91152107P 2007-04-13 2007-04-13
US60/911,521 2007-04-13
US98474107P 2007-11-02 2007-11-02
US60/984,741 2007-11-02

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WO2008126047A1 true WO2008126047A1 (fr) 2008-10-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011095043A1 (fr) * 2010-02-08 2011-08-11 Alcatel-Lucent Shanghai Bell Co., Ltd. Technologie de transmission de multiples flux continus de données intégrés
WO2023072168A1 (fr) * 2021-10-31 2023-05-04 华为技术有限公司 Procédé de traitement d'informations et dispositif de communication

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111030961B (zh) * 2019-12-18 2022-04-05 南京信息工程大学 基于星座结构优化及类蜂巢区域判决的信号调制解调方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050111565A1 (en) * 2003-10-24 2005-05-26 Julien Pons Hierarchical trellis coded modulation
WO2006044427A2 (fr) * 2004-10-13 2006-04-27 Conexant Systems, Inc. Procede et systeme de mise en oeuvre d'un schema de turbo-modulations codees en treillis pour des systemes de communication
WO2006117015A1 (fr) * 2005-05-04 2006-11-09 Matsushita Electric Industrial Co., Ltd. Expansion de l'espace des signaux pour un schema 16 qam

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050111565A1 (en) * 2003-10-24 2005-05-26 Julien Pons Hierarchical trellis coded modulation
WO2006044427A2 (fr) * 2004-10-13 2006-04-27 Conexant Systems, Inc. Procede et systeme de mise en oeuvre d'un schema de turbo-modulations codees en treillis pour des systemes de communication
WO2006117015A1 (fr) * 2005-05-04 2006-11-09 Matsushita Electric Industrial Co., Ltd. Expansion de l'espace des signaux pour un schema 16 qam

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NG S X ET AL: "Turbo-detected unequal protection MPEG-4 wireless video telephony using multi-level coding, trellis coded modulation and space-time trellis coding Capacity approaching codes design and implementation", IEE PROCEEDINGS : COMMUNICATIONS, INSTITUTION OF ELECTRICAL ENGINEERS, GB, vol. 152, no. 6, 9 December 2005 (2005-12-09), pages 1116 - 1124, XP006025748, ISSN: 1350-2425 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011095043A1 (fr) * 2010-02-08 2011-08-11 Alcatel-Lucent Shanghai Bell Co., Ltd. Technologie de transmission de multiples flux continus de données intégrés
US9054839B2 (en) 2010-02-08 2015-06-09 Alcatel Lucent Integrated multi-datastream transmission technology
WO2023072168A1 (fr) * 2021-10-31 2023-05-04 华为技术有限公司 Procédé de traitement d'informations et dispositif de communication

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