SIST EN 16603-50-01:2015
(Main)Space engineering - Space data links - Telemetry synchronization and channel coding
Space engineering - Space data links - Telemetry synchronization and channel coding
This Standard establishes a common implementation of space telemetry channel coding systems.
Several space telemetry channel coding schemes are specified in this Standard. The specification does not attempt to quantify the relative coding gain or the merits of each scheme, nor the design requirements for encoders or decoders. However, some application profiles are discussed in Annex D. Performance data for the coding schemes specified in this Standard can be found in CCSDS 130.1 G 1. Annex G describes the related mission configuration parameters.
Further provisions and guidance on the application of this standard can be found in the following publications:
- ECSS-E-ST-50, Communications, which defines the principle characteristics of communication protocols and related services for all communication layers relevant for space communication (physical- to application-layer), and their basic relationship to each other.
- The handbook ECSS-E-HB-50, Communications guidelines, which provides information about specific implementation characteristics of these protocols in order to support the choice of a certain communications profile for the specific requirements of a space mission.
Users of this present standard are invited to consult these documents before taking decisions on the implementation of the present one.
This standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00.
Raumfahrttechnik - Raumfahrt-Datenübertragung - Telemetriesynchronisation und -kanalkodierung
Ingénierie spatiale - Liaison de données spatiales - Synchronisation et codage canal de la télémesure
La présente norme établit une implémentation courante des systèmes de codage utilisés dans les canaux de télémesure spatiaux.
Elle décrit plusieurs schémas de codage applicables aux canaux de télémesure spatiaux. Cette norme ne prétend quantifier ni le gain de codage relatif ou les avantages de chaque schéma, ni les exigences de conception applicables aux codeurs ou décodeurs. Certains profils d'application sont toutefois présentés à l'Annexe D. Les données relatives aux performances des schémas de codage spécifiés dans la présente norme sont définies dans la spécification CCSDS 130.1 G 1. L'Annexe G décrit les paramètres de configuration de mission associés.
Les publications suivantes contiennent des dispositions et des préconisations supplémentaires concernant l'application de la présente norme :
• l'ECSS-E-ST-50, « Communications », qui définit les principes des protocoles de communication et des services connexes pour toutes les couches de communication spatiale (de la couche physique à la couche applicative), et décrit leurs relations de base ;
• le manuel ECSS-E-HB-50, « Communications guidelines », qui fournit des informations sur les caractéristiques de mise en œuvre de ces protocoles afin d'orienter le choix d'un profil de communication donné compte tenu des exigences particulières d'une mission spatiale.
Les utilisateurs de la présente norme sont invités à consulter ces documents avant de prendre toute décision quant à sa mise en œuvre.
La présente norme peut être adaptée aux caractéristiques et contraintes spécifiques d'un projet spatial, conformément à la norme ECSS-S-ST-00.
Vesoljska tehnika - Vesoljske podatkovne povezave - Telemetrijska sinhronizacija in kodiranje kanalov
Ta standard določa skupno izvedbo vesoljskih telemetričnih sistemov za kodiranje kanalov.
V tem standardu je določenih več vesoljskih telemetričnih shem za kodiranje kanalov. Specifikacija ne poskuša količinsko opredeliti relativnega dobička kodiranja ali prednosti vsake sheme ali zahtev za zasnovo kodirnikov ali dekodirnikov. Vendar so nekateri profili uporabe predstavljeni v dodatku D. Podatki o delovanju za kodirne sheme, določene v tem standardu, je mogoče najti v standardu CCSDS 130.1 G 1. V dodatku G so opisani povezani konfiguracijski parametri misije.
Dodatne določbe in smernice o uporabi tega standarda je mogoče najti v naslednjih publikacijah:
– v standardu ECSS-E-ST-50 (Komunikacije), ki določa glavne značilnosti komunikacijskih protokolov in z njimi povezanih storitev za vse ravni komunikacije, pomembne za vesoljsko komunikacijo (od fizične do aplikacijske ravni), in njihove osnovne medsebojne povezave,
– v priročniku ECSS-E-HB-50 (Komunikacijske smernice), ki zagotavlja informacije o posebnih značilnostih vpeljave teh protokolov za podporo pri izbiri določenega komunikacijskega profila za posebne zahteve vesoljske misije.
Uporabniki obstoječega standarda so vabljeni k ogledu teh dokumentov, preden sprejmejo odločitve o izvajanju trenutnega standarda.
Ta standard se lahko prilagodi posameznim lastnostim in omejitvam vesoljskega projekta v skladu s standardom ECSS-S-ST-00.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Vesoljska tehnika - Vesoljske podatkovne povezave - Telemetrijska sinhronizacija in kodiranje kanalovRaumfahrttechnik - Raumfahrt-Datenübertragung - Telemetriesynchronisation und -kanalkodierungIngénierie spatiale - Liaison de données spatiales - Synchronisation et codage canal de la télémesureSpace engineering - Space data links - Telemetry synchronization and channel coding49.140Vesoljski sistemi in operacijeSpace systems and operations33.200Daljinsko krmiljenje, daljinske meritve (telemetrija)Telecontrol. TelemeteringICS:Ta slovenski standard je istoveten z:EN 16603-50-01:2014SIST EN 16603-50-01:2015en01-januar-2015SIST EN 16603-50-01:2015SLOVENSKI
STANDARD
SIST EN 16603-50-01:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16603-50-01
September 2014 ICS 49.140
English version
Space engineering - Space data links - Telemetry synchronization and channel coding
Ingénierie spatiale - Liaison de données spatiales - Synchronisation et codage canal de la télémesure
Raumfahrtproduktsicherung - Raumfahrt-Datenübertragung - Telemetriesynchronisation und
kanalkodierung This European Standard was approved by CEN on 11 April 2014.
CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2014 CEN/CENELEC All rights of exploitation in any form and by any means reserved worldwide for CEN national Members and for CENELEC Members. Ref. No. EN 16603-50-01:2014 E SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 2 Table of contents Foreword . 6 1 Scope . 7 2 Normative references . 8 3 Terms, definitions and abbreviated terms . 9 3.1 Terms from other standards . 9 3.2 Terms specific to the present standard . 9 3.3 Abbreviations . 9 3.4 Conventions. 10 4 Overview . 11 4.1 Introduction . 11 4.2 Coding . 11 4.2.1 Channel codes . 11 4.2.2 Connection vectors . 12 4.3 Convolutional codes . 12 4.4 Reed-Solomon codes . 12 4.5 Concatenated codes . 13 4.6 Turbo codes. 13 4.7 Synchronization and pseudo-randomization . 13 5 Convolutional coding . 16 5.1 Properties . 16 5.2 General . 16 5.3 Basic convolutional code . 17 5.4 Punctured convolutional code . 18 6 Reed-Solomon coding . 20 6.1 Properties . 20 6.2 General . 20 6.3 Specification . 21 6.3.1 Parameters and general characteristics . 21 6.3.2 Generator polynomials . 21 SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 3 6.3.3 Symbol interleaving depth . 22 6.3.4 Symbol interleaving mechanism . 22 6.3.5 Reed-Solomon codeblock partitioning . 23 6.3.6 Shortened codeblock length . 24 6.3.7 Dual basis symbol representation and ordering . 25 6.3.8 Synchronization . 26 6.3.9 Ambiguity resolution . 26 6.4 Reed-Solomon with E=8 . 26 6.4.1 Introduction . 26 6.4.2 General . 27 7 Turbo coding . 28 7.1 Properties . 28 7.2 General . 28 7.3 Specification . 29 7.3.1 General . 29 7.3.2 Parameters and general characteristics . 29 7.3.3 Turbo code permutation . 30 7.3.4 Backward and forward connection vectors . 32 7.3.5 Turbo encoder block . 33 7.3.6 Turbo codeblock specification . 33 7.3.7 Turbo codeblock synchronization . 34 8 Frame synchronization . 35 8.1 Introduction . 35 8.2 The attached sync marker (ASM) . 35 8.2.1 Overview . 35 8.2.2 Encoder side . 36 8.2.3 Decoder side . 36 8.3 ASM bit patterns . 36 8.4 Location of ASM . 37 8.5 Relationship of ASM to Reed-Solomon and turbo codeblocks . 37 8.6 ASM for embedded data stream . 38 8.6.1 Overview . 38 8.6.2 Embedded ASM . 38 9 Pseudo-randomizer . 39 9.1 General . 39 9.1.1 Overview . 39 SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 4 9.1.2 Application . 39 9.2 Pseudo-randomizer description . 39 9.3 Synchronization and application of pseudo-randomizer . 40 9.3.1 Overview . 40 9.3.2 Application . 40 9.4 Sequence specification . 41 Annex A (informative) Transformation between Berlekamp and conventional representations . 43 Annex B (informative) Expansion of Reed-Solomon coefficients . 50 Annex C (informative) Compatible frame lengths . 52 Annex D (informative) Application profiles . 54 Annex E (informative) Changes from ESA-PSS-04-103. 60 Annex F (informative) Differences from CCSDS recommendations . 61 Annex G (informative) Mission configuration parameters . 62 Annex H (informative) Turbo code patent rights . 66 Bibliography . 67
Figures Figure 3-1: Bit numbering convention . 10 Figure 4-1: Coding, randomization and synchronization (1) . 14 Figure 4-2: Coding, randomization and synchronization (2) . 15 Figure 5-1: Convolutional encoder block diagram . 18 Figure 5-2: Punctured encoder block diagram . 19 Figure 6-1: Functional representation of R-S interleaving . 23 Figure 6-2: Reed-Solomon codeblock partitioning . 24 Figure 7-1: Interpretation of permutation . 31 Figure 7-2: Turbo encoder block diagram . 32 Figure 7-3: Turbo codeblocks for code rates 1/2 and 1/4 . 34 Figure 7-4: Turbo codeblock with attached sync marker . 34 Figure 8-1: Format of channel access data unit (CADU) . 35 Figure 8-2 ASM bit pattern for non-turbo-coded data . 36 Figure 8-3: ASM bit pattern for rate 1/2 turbo-coded data . 36 Figure 8-4: ASM bit pattern for rate 1/4 turbo-coded data . 37 Figure 8-5: Embedded ASM bit pattern . 38 SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 5 Figure 9-1: Pseudo-randomizer configuration . 40 Figure 9-2: Pseudo-randomizer logic diagram . 42 Figure A-1 : Transformational equivalence . 44
Tables Table 5-1: Basic convolutional code characteristics . 17 Table 5-2: Punctured convolutional code characteristics . 19 Table 5-3: Puncture code patterns for convolutional codes . 19 Table 7-1: Specified information block lengths . 30 Table 7-2: Codeblock lengths (measured in bits) . 30 Table 7-3: Parameters k1 and k2 for specified information block lengths . 31 Table 7-4: Forward connection vectors . 32 Table 8-1: ASM bit patterns in hexadecimal notation . 37 Table A-1 : Equivalence of representations (Part 1 of 4) . 46 Table B-1 : Expansion for E=16 . 50 Table B-2 : Expansion for E=8 . 51 Table C-1 : Maximum frame lengths for E=16 . 53 Table C-2 : Maximum frame lengths for E=8 . 53 Table D-1 : Preferred coding schemes . 56 Table D-2 : Coding gains and bandwidth expansions . 58 Table D-3 : Coding gains for R-S(255, 239) and 4D-8PSK-TCM . 59
SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 6 Foreword This document (EN 16603-50-01:2014) has been prepared by Technical Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN. This standard (EN 16603-50-01:2014) originates from ECSS-E-ST-50-01C. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2015, and conflicting national standards shall be withdrawn at the latest by March 2015. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This document has been developed to cover specifically space systems and has therefore precedence over any EN covering the same scope but with a wider domain of applicability (e.g. : aerospace). According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 7 1 Scope This Standard establishes a common implementation of space telemetry channel coding systems. Several space telemetry channel coding schemes are specified in this Standard. The specification does not attempt to quantify the relative coding gain or the merits of each scheme, nor the design requirements for encoders or decoders. However, some application profiles are discussed in Annex D. Performance data for the coding schemes specified in this Standard can be found in CCSDS 130.1-G-1. Annex G describes the related mission configuration parameters. Further provisions and guidance on the application of this standard can be found in the following publications: • ECSS-E-ST-50, Communications, which defines the principle characteristics of communication protocols and related services for all communication layers relevant for space communication (physical- to application-layer), and their basic relationship to each other.
• The handbook ECSS-E-HB-50, Communications guidelines, which provides information about specific implementation characteristics of these protocols in order to support the choice of a certain communications profile for the specific requirements of a space mission. Users of this present standard are invited to consult these documents before taking decisions on the implementation of the present one. This standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00. SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 8 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this ECSS Standard. For dated references, subsequent amendments to, or revisions of any of these publications, do not apply. However, parties to agreements based on this ECSS Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references the latest edition of the publication referred to applies.
EN reference Reference in text Title EN 16601-00-01 ECSS-S-ST-00-01 ECSS system - Glossary of terms SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 9 3 Terms, definitions and abbreviated terms 3.1 Terms from other standards For the purpose of this Standard, the terms and definitions from ECSS-ST-00-01 apply. 3.2 Terms specific to the present standard 3.2.1 category A category of spacecraft having an altitude above the Earth’s surface less than 2 × 106 km 3.2.2 category B category of spacecraft having an altitude above the Earth’s surface equal to, or greater than 2 × 106 km 3.2.3 octet group of eight bits NOTE 1 The numbering for octets within a data structure starts with 0. NOTE 2 Refer to clause 3.4 for the convention for the numbering of bits. 3.2.4 physical channel stream of bits transferred over a space link in a single direction 3.3 Abbreviations For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01and the following apply: Abbreviation Meaning 8PSK phase shift keying of eight states AOS advanced orbiting systems APP a posteriori probability ASM attached sync marker SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 10 AWGN additive white Gaussian noise BER bit error rate BPSK binary phase shift keying CADU channel access data unit CCSDS Consultative Committee for Space Data Systems CRC cyclic redundancy check FER frame error rate GF(n) Galois field consisting of exactly n elements GMSK Gaussian minimum shift keying MSB most significant bit MS/S mega symbols per second NRZ-L non-return to zero level NRZ-M non-return to zero mark QPSK quadrature phase shift keying R-S Reed-Solomon TCM trellis-coded modulation
3.4 Conventions 3.4.1 bit 0, bit 1, bit N−1 To identify each bit in an N-bit field, the first bit in the field to be transferred (i.e. the most left justified in a graphical representation) is defined as bit 0; the following bit is defined as bit 1 and so on up to bit N−1.
Figure 3-1: Bit numbering convention 3.4.2 most significant bit When an N-bit field is used to express a binary value (such as a counter), the most significant bit is the first bit of the field, i.e. bit 0 (see Figure 3-1). SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 11 4 Overview 4.1 Introduction Telemetry channel coding is a method of processing data that is sent from a source to a destination so that distinct messages are created that are easily distinguishable from one another and thus enable reconstruction of the data with low error probability, thus improve the performance of the channel. 4.2 Coding 4.2.1 Channel codes A channel code is the set of rules that specify the transformation of elements of a source alphabet to elements of a code alphabet. The elements of the source alphabet and of the code alphabet are called symbols.
Depending on the code, the symbols can consist of one or more bits. The source symbols are also called information symbols. The code symbols are called channel symbols when they are the output of the last or only code applied during the encoding process. Block encoding is a one-to-one transformation of sequences of length k source symbols to sequences of length n code symbols. The length of the encoded sequence is greater than the source sequence, so n> k.
The ratio k/n is the code rate, which can be defined more generally as the average ratio of the number of binary digits at the input of an encoder to the number of binary digits at its output. A codeword of an (n,k) block code is one of the sequences of n code symbols in the range of the one-to-one transformation. A codeblock of an (n,k) block code is a sequence of n channel symbols which are produced as a unit by encoding a sequence of k information symbols. The codeblock is decoded as a unit and, if successful, delivers a sequence of k information symbols. A systematic code is one in which the input information sequence appears in unaltered form as part of the output codeword. A transparent code has the property that complementing the input of the encoder or decoder results in complementing the output. SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 12 4.2.2 Connection vectors Convolutional and turbo coding use connection vectors.
A forward connection vector is a vector which specifies one of the parity checks computed by the shift register(s) in the encoder. For a shift register with s stages, a connection vector is an s-bit binary number. A bit equal to "1" in position i (counted from the left) indicates that the output of the ith stage of the shift register is used in computing that parity check. In turbo coding, a backward connection vector is a vector which specifies the feedback to the shift registers in the encoder. For a shift register with s stages, a backward connection vector is an s-bit binary number. A bit equal to "1" in position i (counted from the left) indicates that the output of the ith stage of the shift register is used in computing the feedback value, except for the leftmost bit which is ignored. 4.3 Convolutional codes A convolutional code is a code in which a number of output symbols are produced for each input information bit. Each output symbol is a linear combination of the current input bit as well as some or all of the previous k−1 bits, where k is the constraint length of the code. The constraint length is the number of consecutive input bits that are used to determine the value of the output symbols at any time. The rate 1/2 convolutional code is specified in clause 5. Depending on performance requirements, this code can be used alone.
For telecommunication channels that are constrained by bandwidth and cannot accommodate the increase in bandwidth caused by the basic convolutional code, clause 5 also specifies a punctured convolutional code which has the advantage of a smaller bandwidth expansion.
A punctured code is a code obtained by deleting some of the parity symbols generated by the convolutional encoder before transmission. There is an increase in the bandwidth efficiency due to puncturing compared to the original code, however the minimum weight (and therefore its error-correcting performance) is less than that of the original code. 4.4 Reed-Solomon codes The Reed-Solomon (R-S) code specified in clause 6 is a powerful burst error correcting code. In addition, the code has the capability of indicating the presence of uncorrectable errors, with an extremely low undetected error rate. The Reed-Solomon code has the advantage of smaller bandwidth expansion than the convolutional code. The Reed-Solomon symbol is a set of J bits that represents an element in the Galois field GF(2J), the code alphabet of a J-bit Reed-Solomon code. For the code specified in clause 6, J = 8 bits per R-S symbol. SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 13 4.5 Concatenated codes Concatenation is the use of two or more codes to process data sequentially, with the output of one encoder used as the input to the next. In a concatenated coding system, the first encoding algorithm that is applied to the data stream is called the outer code. The last encoding algorithm that is applied to the data stream is called the inner code. The data stream that is input to the inner encoder consists of the codewords generated by the outer encoder. To achieve a greater coding gain than the one that can be provided by the convolutional code or Reed-Solomon code alone, a concatenation of the convolutional code as the inner code with the Reed-Solomon code as the outer code can be used for improved performance. This Standard also specifies the concatenation of the Reed-Solomon code with the 4-dimensional 8PSK trellis-coded modulation (4D-8PSK-TCM) defined in ECSS-E-ST-50-05. In this case, the Reed-Solomon code with E=8 is the outer code and the 4D-8PSK-TCM is the inner code. 4.6 Turbo codes A turbo code is a block code formed by combining two component recursive convolutional codes. A turbo code takes as input a block of information bits. The input block is sent unchanged to the first component code and bit-wise interleaved to the second component code. The interleaving process, called the turbo code permutation, is a fixed bit-by-bit permutation of the entire input block. The output is formed by the parity symbols contributed by each component code plus a replica of the information bits. The turbo codes specified in clause 7 can be used to increase the coding gain in cases where the environment tolerates the bandwidth overhead. 4.7 Synchronization and pseudo-randomization The methods for synchronization specified in clause 8 apply to all telemetry channels, coded or uncoded. An attached sync marker (ASM) is attached to the codeblock or transfer frame. The ASM can also be used for resolution of data ambiguity (sense of ‘1’ and ‘0’) if data ambiguity is not resolved by the modulation method used. Successful bit synchronization at the receiving end depends on the incoming signal having a minimum bit transition density. Clause 9 specifies the method of pseudo-randomizing the data to improve bit transition density. Figure 4-1 and Figure 4-2 provide an overview of how pseudo-randomization and synchronization are combined with the different coding options at the sending and receiving end.
At the sending end, the order of convolutional encoding and modulation is dependent on the implementation. At the receiving end, the order of SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 14 demodulation, frame synchronization and convolutional decoding are dependent on the implementation.
The figures do not imply any hardware or software configuration in a real system. When designing a communications system, the system designer usually takes into account radio regulations and modulation standardization requirements from other standards, such as ECSS-E-ST-50-05.
Figure 4-1: Coding, randomization and synchronization (1) SIST EN 16603-50-01:2015
EN 16603-50-01:2014 (E) 15
Figure 4-2: Coding, randomization and synchronization (2) SI
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Vesoljsko inženirstvo - Vesoljske podatkovne povezave - Telemetrijska sinhronizacija in kodiranje kanalovRaumfahrttechnik - Raumfahrt-Datenübertragung - Telemetriesynchronisation und -kanalkodierungIngénierie spatiale - Liaison de données spatiales - Synchronisation et codage canal de la télémesureSpace engineering - Space data links - Telemetry synchronization and channel coding49.140Vesoljski sistemi in operacijeSpace systems and operations33.200Daljinsko krmiljenje, daljinske meritve (telemetrija)Telecontrol. TelemeteringICS:Ta slovenski standard je istoveten z:FprEN 16603-50-01kSIST FprEN 16603-50-01:2014en01-februar-2014kSIST FprEN 16603-50-01:2014SLOVENSKI
STANDARD
kSIST FprEN 16603-50-01:2014
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN 16603-50-01
October 2013 ICS
English version
Space engineering - Space data links - Telemetry synchronization and channel coding
Ingénierie spatiale - Liaison de données spatiales - Synchronisation et codage canal de la télémesure
Raumfahrttechnik - Raumfahrt-Datenübertragung - Telemetriesynchronisation und -kanalkodierung This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/CLC/TC 5.
If this draft becomes a European Standard, CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN and CENELEC in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard. CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2013 CEN/CENELEC All rights of exploitation in any form and by any means reserved worldwide for CEN national Members and for CENELEC Members. Ref. No. FprEN 16603-50-01:2013 E kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 2 Table of contents Foreword . 6 1 Scope . 7 2 Normative references . 8 3 Terms, definitions and abbreviated terms . 9 3.1 Terms from other standards . 9 3.2 Terms specific to the present standard . 9 3.3 Abbreviations . 9 3.4 Conventions. 10 4 Overview . 11 4.1 Introduction . 11 4.2 Coding . 11 4.2.1 Channel codes . 11 4.2.2 Connection vectors . 12 4.3 Convolutional codes . 12 4.4 Reed-Solomon codes . 12 4.5 Concatenated codes . 13 4.6 Turbo codes. 13 4.7 Synchronization and pseudo-randomization . 13 5 Convolutional coding . 16 5.1 Properties . 16 5.2 General . 16 5.3 Basic convolutional code . 17 5.4 Punctured convolutional code . 18 6 Reed-Solomon coding . 20 6.1 Properties . 20 6.2 General . 20 6.3 Specification . 21 6.3.1 Parameters and general characteristics . 21 6.3.2 Generator polynomials . 21 kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 3 6.3.3 Symbol interleaving depth . 22 6.3.4 Symbol interleaving mechanism . 22 6.3.5 Reed-Solomon codeblock partitioning . 23 6.3.6 Shortened codeblock length . 24 6.3.7 Dual basis symbol representation and ordering . 25 6.3.8 Synchronization . 26 6.3.9 Ambiguity resolution . 26 6.4 Reed-Solomon with E=8 . 27 6.4.1 Introduction . 27 6.4.2 General . 27 7 Turbo coding . 28 7.1 Properties . 28 7.2 General . 28 7.3 Specification . 29 7.3.1 General . 29 7.3.2 Parameters and general characteristics . 29 7.3.3 Turbo code permutation . 30 7.3.4 Backward and forward connection vectors . 32 7.3.5 Turbo encoder block . 33 7.3.6 Turbo codeblock specification . 33 7.3.7 Turbo codeblock synchronization . 34 8 Frame synchronization . 35 8.1 Introduction . 35 8.2 The attached sync marker (ASM) . 35 8.2.1 Overview . 35 8.2.2 Encoder side . 36 8.2.3 Decoder side . 36 8.3 ASM bit patterns . 36 8.4 Location of ASM . 37 8.5 Relationship of ASM to Reed-Solomon and turbo codeblocks . 37 8.6 ASM for embedded data stream . 38 8.6.1 Overview . 38 8.6.2 Embedded ASM . 38 9 Pseudo-randomizer . 39 9.1 General . 39 9.1.1 Overview . 39 kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 4 9.1.2 Application . 39 9.2 Pseudo-randomizer description . 39 9.3 Synchronization and application of pseudo-randomizer . 40 9.3.1 Overview . 40 9.3.2 Application . 40 9.4 Sequence specification . 41 Annex A (informative) Transformation between Berlekamp and conventional representations . 43 Annex B (informative) Expansion of Reed-Solomon coefficients . 51 Annex C (informative) Compatible frame lengths . 53 Annex D (informative) Application profiles . 55 Annex E (informative) Changes from ESA-PSS-04-103. 61 Annex F (informative) Differences from CCSDS recommendations . 62 Annex G (informative) Mission configuration parameters . 63 Annex H (informative) Turbo code patent rights . 67 Bibliography . 68
Figures Figure 3-1: Bit numbering convention . 10 Figure 4-1: Coding, randomization and synchronization (1) . 14 Figure 4-2: Coding, randomization and synchronization (2) . 15 Figure 5-1: Convolutional encoder block diagram . 18 Figure 5-2: Punctured encoder block diagram . 19 Figure 6-1: Functional representation of R-S interleaving . 23 Figure 6-2: Reed-Solomon codeblock partitioning . 24 Figure 7-1: Interpretation of permutation . 31 Figure 7-2: Turbo encoder block diagram . 32 Figure 7-3: Turbo codeblocks for code rates 1/2 and 1/4 . 34 Figure 7-4: Turbo codeblock with attached sync marker . 34 Figure 8-1: Format of channel access data unit (CADU) . 35 Figure 8-2 ASM bit pattern for non-turbo-coded data . 36 Figure 8-3: ASM bit pattern for rate 1/2 turbo-coded data . 36 Figure 8-4: ASM bit pattern for rate 1/4 turbo-coded data . 37 Figure 8-5: Embedded ASM bit pattern . 38 kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 5 Figure 9-1: Pseudo-randomizer configuration . 40 Figure 9-2: Pseudo-randomizer logic diagram . 42 Figure A-1 : Transformational equivalence . 44
Tables Table 5-1: Basic convolutional code characteristics . 17 Table 5-2: Punctured convolutional code characteristics . 19 Table 5-3: Puncture code patterns for convolutional codes . 19 Table 7-1: Specified information block lengths . 30 Table 7-2: Codeblock lengths (measured in bits) . 30 Table 7-3: Parameters k1 and k2 for specified information block lengths . 31 Table 7-4: Forward connection vectors . 32 Table 8-1: ASM bit patterns in hexadecimal notation . 37 Table A-1 : Equivalence of representations (Part 1 of 4) . 47 Table B-1 : Expansion for E=16 . 51 Table B-2 : Expansion for E=8 . 52 Table C-1 : Maximum frame lengths for E=16 . 54 Table C-2 : Maximum frame lengths for E=8 . 54 Table D-1 : Preferred coding schemes . 57 Table D-2 : Coding gains and bandwidth expansions . 59 Table D-3 : Coding gains for R-S(255, 239) and 4D-8PSK-TCM . 60
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FprEN 16603-50-01:2013 (E) 6 Foreword This document (FprEN 16603-50-01:2013) has been prepared by Technical Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN (Germany). This document (FprEN 16603-50-01:2013) originates from ECSS-E-ST-50-01C. This document is currently submitted to the Unique Acceptance Procedure. This document has been developed to cover specifically space systems and will therefore have precedence over any EN covering the same scope but with a wider domain of applicability (e.g. : aerospace). kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 7 1 Scope This Standard establishes a common implementation of space telemetry channel coding systems. Several space telemetry channel coding schemes are specified in this Standard. The specification does not attempt to quantify the relative coding gain or the merits of each scheme, nor the design requirements for encoders or decoders. However, some application profiles are discussed in Annex D. Performance data for the coding schemes specified in this Standard can be found in CCSDS 130.1-G-1. Annex G describes the related mission configuration parameters. Further provisions and guidance on the application of this standard can be found in the following publications: • ECSS-E-ST-50, Communications, which defines the principle characteristics of communication protocols and related services for all communication layers relevant for space communication (physical- to application-layer), and their basic relationship to each other.
• The handbook ECSS-E-HB-50, Communications guidelines, which provides information about specific implementation characteristics of these protocols in order to support the choice of a certain communications profile for the specific requirements of a space mission. Users of this present standard are invited to consult these documents before taking decisions on the implementation of the present one. This standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00. kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 8 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this ECSS Standard. For dated references, subsequent amendments to, or revisions of any of these publications, do not apply. However, parties to agreements based on this ECSS Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references the latest edition of the publication referred to applies.
EN reference Reference in text Title EN 16601-00-01 ECSS-S-ST-00-01 ECSS system - Glossary of terms kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 9 3 Terms, definitions and abbreviated terms 3.1 Terms from other standards For the purpose of this Standard, the terms and definitions from ECSS-ST-00-01 apply. 3.2 Terms specific to the present standard 3.2.1 category A category of spacecraft having an altitude above the Earth’s surface less than 2 × 106 km 3.2.2 category B category of spacecraft having an altitude above the Earth’s surface equal to, or greater than 2 × 106 km 3.2.3 octet group of eight bits NOTE 1 The numbering for octets within a data structure starts with 0. NOTE 2 Refer to clause 3.4 for the convention for the numbering of bits. 3.2.4 physical channel stream of bits transferred over a space link in a single direction 3.3 Abbreviations For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01and the following apply: Abbreviation Meaning 8PSK phase shift keying of eight states AOS advanced orbiting systems APP a posteriori probability ASM attached sync marker kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 10 AWGN additive white Gaussian noise BER bit error rate BPSK binary phase shift keying CADU channel access data unit CCSDS Consultative Committee for Space Data Systems CRC cyclic redundancy check FER frame error rate GF(n) Galois field consisting of exactly n elements GMSK Gaussian minimum shift keying MSB most significant bit MS/S mega symbols per second NRZ-L non-return to zero level NRZ-M non-return to zero mark QPSK quadrature phase shift keying R-S Reed-Solomon TCM trellis-coded modulation
3.4 Conventions 3.4.1 bit 0, bit 1, bit N−1 To identify each bit in an N-bit field, the first bit in the field to be transferred (i.e. the most left justified in a graphical representation) is defined as bit 0; the following bit is defined as bit 1 and so on up to bit N−1.
Figure 3-1: Bit numbering convention 3.4.2 most significant bit When an N-bit field is used to express a binary value (such as a counter), the most significant bit is the first bit of the field, i.e. bit 0 (see Figure 3-1). kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 11 4 Overview 4.1 Introduction Telemetry channel coding is a method of processing data that is sent from a source to a destination so that distinct messages are created that are easily distinguishable from one another and thus enable reconstruction of the data with low error probability, thus improve the performance of the channel. 4.2 Coding 4.2.1 Channel codes A channel code is the set of rules that specify the transformation of elements of a source alphabet to elements of a code alphabet. The elements of the source alphabet and of the code alphabet are called symbols.
Depending on the code, the symbols can consist of one or more bits. The source symbols are also called information symbols. The code symbols are called channel symbols when they are the output of the last or only code applied during the encoding process. Block encoding is a one-to-one transformation of sequences of length k source symbols to sequences of length n code symbols. The length of the encoded sequence is greater than the source sequence, so n> k.
The ratio k/n is the code rate, which can be defined more generally as the average ratio of the number of binary digits at the input of an encoder to the number of binary digits at its output. A codeword of an (n,k) block code is one of the sequences of n code symbols in the range of the one-to-one transformation. A codeblock of an (n,k) block code is a sequence of n channel symbols which are produced as a unit by encoding a sequence of k information symbols. The codeblock is decoded as a unit and, if successful, delivers a sequence of k information symbols. A systematic code is one in which the input information sequence appears in unaltered form as part of the output codeword. A transparent code has the property that complementing the input of the encoder or decoder results in complementing the output. kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 12 4.2.2 Connection vectors Convolutional and turbo coding use connection vectors.
A forward connection vector is a vector which specifies one of the parity checks computed by the shift register(s) in the encoder. For a shift register with s stages, a connection vector is an s-bit binary number. A bit equal to "1" in position i (counted from the left) indicates that the output of the ith stage of the shift register is used in computing that parity check. In turbo coding, a backward connection vector is a vector which specifies the feedback to the shift registers in the encoder. For a shift register with s stages, a backward connection vector is an s-bit binary number. A bit equal to "1" in position i (counted from the left) indicates that the output of the ith stage of the shift register is used in computing the feedback value, except for the leftmost bit which is ignored. 4.3 Convolutional codes A convolutional code is a code in which a number of output symbols are produced for each input information bit. Each output symbol is a linear combination of the current input bit as well as some or all of the previous k−1 bits, where k is the constraint length of the code. The constraint length is the number of consecutive input bits that are used to determine the value of the output symbols at any time. The rate 1/2 convolutional code is specified in clause 5. Depending on performance requirements, this code can be used alone.
For telecommunication channels that are constrained by bandwidth and cannot accommodate the increase in bandwidth caused by the basic convolutional code, clause 5 also specifies a punctured convolutional code which has the advantage of a smaller bandwidth expansion.
A punctured code is a code obtained by deleting some of the parity symbols generated by the convolutional encoder before transmission. There is an increase in the bandwidth efficiency due to puncturing compared to the original code, however the minimum weight (and therefore its error-correcting performance) is less than that of the original code. 4.4 Reed-Solomon codes The Reed-Solomon (R-S) code specified in clause 6 is a powerful burst error correcting code. In addition, the code has the capability of indicating the presence of uncorrectable errors, with an extremely low undetected error rate. The Reed-Solomon code has the advantage of smaller bandwidth expansion than the convolutional code. The Reed-Solomon symbol is a set of J bits that represents an element in the Galois field GF(2J), the code alphabet of a J-bit Reed-Solomon code. For the code specified in clause 6, J = 8 bits per R-S symbol. kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 13 4.5 Concatenated codes Concatenation is the use of two or more codes to process data sequentially, with the output of one encoder used as the input to the next. In a concatenated coding system, the first encoding algorithm that is applied to the data stream is called the outer code. The last encoding algorithm that is applied to the data stream is called the inner code. The data stream that is input to the inner encoder consists of the codewords generated by the outer encoder. To achieve a greater coding gain than the one that can be provided by the convolutional code or Reed-Solomon code alone, a concatenation of the convolutional code as the inner code with the Reed-Solomon code as the outer code can be used for improved performance. This Standard also specifies the concatenation of the Reed-Solomon code with the 4-dimensional 8PSK trellis-coded modulation (4D-8PSK-TCM) defined in ECSS-E-ST-50-05. In this case, the Reed-Solomon code with E=8 is the outer code and the 4D-8PSK-TCM is the inner code. 4.6 Turbo codes A turbo code is a block code formed by combining two component recursive convolutional codes. A turbo code takes as input a block of information bits. The input block is sent unchanged to the first component code and bit-wise interleaved to the second component code. The interleaving process, called the turbo code permutation, is a fixed bit-by-bit permutation of the entire input block. The output is formed by the parity symbols contributed by each component code plus a replica of the information bits. The turbo codes specified in clause 7 can be used to increase the coding gain in cases where the environment tolerates the bandwidth overhead. 4.7 Synchronization and pseudo-randomization The methods for synchronization specified in clause 8 apply to all telemetry channels, coded or uncoded. An attached sync marker (ASM) is attached to the codeblock or transfer frame. The ASM can also be used for resolution of data ambiguity (sense of ‘1’ and ‘0’) if data ambiguity is not resolved by the modulation method used. Successful bit synchronization at the receiving end depends on the incoming signal having a minimum bit transition density. Clause 9 specifies the method of pseudo-randomizing the data to improve bit transition density. Figure 4-1 and Figure 4-2 provide an overview of how pseudo-randomization and synchronization are combined with the different coding options at the sending and receiving end.
At the sending end, the order of convolutional encoding and modulation is dependent on the implementation. At the receiving end, the order of kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 14 demodulation, frame synchronization and convolutional decoding are dependent on the implementation.
The figures do not imply any hardware or software configuration in a real system. When designing a communications system, the system designer usually takes into account radio regulations and modulation standardization requirements from other standards, such as ECSS-E-ST-50-05.
Figure 4-1: Coding, randomization and synchronization (1) kSIST FprEN 16603-50-01:2014
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Figure 4-2: Coding, randomization and synchronization (2) kSIST FprEN 16603-50-01:2014
FprEN 16603-50-01:2013 (E) 16 5 Convolutional coding 5.1 Properties Convolutional coding is suitable for channels with predominantly Gaussian noise. The basic convolutional code defined in clause 5.3 is a rate 1/2, constraint-length 7 transparent code. The basic code can be modified by puncturing, which removes some of the symbols before transmission, thus providing lower overhead and lower bandwidth expansion than the original code, but with reduced error correcting performance. The punctured convolutional codes
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