EN 16603-50-01:2014

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
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

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

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
• 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 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

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

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

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

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

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

Figure 4-2: Coding, randomization and synchronization (2) SIST EN 16603-50-01:2015

a. Soft bit decisions with at least 3-bit quantization shall be used for the decoder. b. The frame synchronization defined in clause 8 shall be used. c. If differential encoding (i.e. conversion from NRZ-L to NRZ-M) is used at the sending end, the conversions should be as follows:  the conversion is performed at the input to the convolutional encoder;  the corresponding conversion at the receiving end from NRZ-M to NRZ-L is performed at the output of the convolutional decoder. SIST EN 16603-50-01:2015

modulo 2 s2(t) = i(t) + i(t−2) + i(t−3) + i(t−5) + i(t−6) + 1 modulo 2 where the equations use modulo 2 addition, and s1 is the first output symbol, s2 is the second output symbol and i(t) is the input information at time t. NOTE 2 An encoder block diagram is shown in Figure 5-1. NOTE 3 The output symbol sequence is: C1(1), ____,C2(1), C1(2), ____,C2(2). . . . Table 5-1: Basic convolutional code characteristics Characteristic Value Nomenclature Convolutional code with maximum-likelihood (Viterbi) decoding Code rate 1/2 bit per symbol Constraint length 7 bits Connection vectors G1 = 1111001 (171 octal); G2 = 1011011 (133 octal) Symbol inversion On output path of G2
Figure 5-1: Convolutional encoder block diagram 5.4 Punctured convolutional code a. The punctured convolutional code shall have the characteristics shown in Table 5-2.
NOTE 1 A single code rate of 2/3, 3/4, 5/6 or 7/8 is selected when it provides the appropriate level of error correction and symbol rate for a given service or data rate. NOTE 2 Figure 5-2 depicts the punctured encoding scheme. NOTE 3 The punctured convolutional code does not include the symbol inverter associated with G2 in the rate 1/2 code defined above. b. The puncturing patterns for each of the punctured convolutional code rates shall be the patterns defined in Table 5-3. SIST EN 16603-50-01:2015

Figure 5-2: Punctured encoder block diagram Table 5-3: Puncture code patterns for convolutional codes Puncturing pattern (a) Code rate Output sequence (b) C1: 1 0 C2: 1 1 2/3 C1(1) C2(1) C2(2) . C1: 1 0 1 C2: 1 1 0 3/4 C1(1) C2(1) C2(2) C1(3) . C1: 1 0 1 0 1 C2: 1 1 0 1 0 5/6 C1(1) C2(1) C2(2) C1(3) C2(4) C1(5) . C1: 1 0 0 0 1 0 1 C2: 1 1 1 1 0 1 0 7/8 C1(1) C2(1) C2(2) C2(3) C2(4) C1(5) C2(6) C1(7) . (a)
1 = transmitted symbol 0 = non-transmitted symbol (b)
C1(t), C2(t) denote values at bit time t
forward error correction capability in a burst-noise channel with an extremely low undetected error rate. This means that the decoder can reliably indicate whether it can make the proper corrections or not. For this reason, when telemetry transfer frames are used, ECSS-E-ST-50-03 does not specify the use of a cyclic redundancy check (CRC) field to validate the frame when this Reed-Solomon Code is used. The Reed-Solomon error correction and detection presupposes correct frame synchronization. The Reed-Solomon frame validation can only deliver a valid frame if the frame is correctly synchronized. If a frame is not correctly synchronized, then the Reed-Solomon decoder can perform a meaningless error correction of the frame and deliver it as valid. The reliability of the Reed-Solomon error correction and detection depends on the correct operation of the pseudo-randomization defined in clause 9. If frames are
• randomized and then not derandomized, or • not randomized and then derandomized, then the Reed-Solomon decoder can perform meaningless error correction of a frame and deliver it as valid. In particular, this can happen when the Reed-Solomon interleaving depth, I, is 5. The Reed-Solomon coding, by itself, cannot guarantee sufficient channel symbol transitions to keep receiver symbol synchronizers in lock. The pseudo-randomizer defined in clause 9 can be used to increase the symbol transition density. 6.2 General a. For Reed-Solomon coding, the frame synchronization defined in clause 8 shall be used. NOTE
The reliability of the Reed-Solomon code depends on proper codeblock synchronization b. To provide additional coding gain, the Reed-Solomon code may be concatenated with one of the convolutional codes defined in clause 5.
Used this way, the Reed-Solomon code is the outer code, while the convolutional code is the inner code. Figure 4-2 shows the order of the codes at the sending and receiving ends. 6.3 Specification 6.3.1 Parameters and general characteristics The Reed-Solomon code shall have the following parameters and general characteristics: • J = 8, where J is the number of bits per R-S symbol. • E = 16, where E is the Reed-Solomon error correction capability, in symbols, within an R-S codeword. • J, E, and I (the depth of interleaving) are independent parameters. • n = 2J−1 = 255, where n is the number of symbols per R-S codeword. • 2E is the number of parity check symbols in each codeword. Therefore there are 32 parity check R-S symbols in each 255-symbol codeword. • k = n−2E, where k is the number of information symbols in each codeword. Therefore there are 223 information R-S symbols in each 255-symbol codeword. NOTE
The specified Reed-Solomon code is a systematic code and results in a systematic codeblock. 6.3.2 Generator polynomials a. The Reed-Solomon code shall have the following field generator polynomial over GF(2): F(x) = x8 + x7 + x2 + x + 1 b. The Reed-Solomon code shall have the following code generator polynomial over GF(28), where F(α) = 0: ∏∑+−===−=EEjEiiijxGxxg1271282011)()(α
NOTE 1 α11 is a primitive element in GF(28). NOTE 2 For E=16, F(x) and g(x) characterize a (255,223) Reed-Solomon code. NOTE 3 Each coefficient of the code generator polynomial can be represented as a power of α or as a binary polynomial in α of degree less than 8, where F(α) = 0 (i.e. α is one of the roots of the field generator polynomial F(x)). The two representations are given in Annex B. SIST EN 16603-50-01:2015

d 5,1d1,2
. . .
d 5,2 . . .
d1,k
. . .
d 5,k
[2E ×
5 ] then the output is the same sequence with the [2E ×
5] filled by the [2E × 5] check symbols as shown below: p1,1
. . .
p 5,1 . . .
p1,2E
. . .
p
5,2Ewhere d i,1 d
i,2 . . .
d i,k
p i,1Error! Bookmark not defined. . . .
p
i,2Eis the R-S codeword produced by the ith encoder. If q virtual fill symbols (see clause 6.3.6) are used in each codeword, then replace k by (k−q) in this functional description. SIST EN 16603-50-01:2015

Figure 6-1: Functional representation of R-S interleaving 6.3.5 Reed-Solomon codeblock partitioning The R-S codeblock is partitioned as shown in Figure 6-2. The attached sync marker used with R-S coding is a 32-bit pattern specified in clause 8 as an aid to synchronization. It precedes the transmitted codeblock. Frame synchronizers are therefore set to expect a marker at every transmitted codeblock + 32 bits. The telemetry transfer frame is defined in ECSS-E-ST-50-03. When used with R-S coding, only specified lengths can be contained within the codeblock’s data space. See Annex C for the maximum lengths, not including the 32-bit attached sync marker. The Reed-Solomon check symbols consist of the trailing 2EI symbols (2EIJ bits) of the codeblock. For example, when E=16 and I=5, then the length occupied by the check symbols is always 1280 bits. The transmitted codeblock consists of the telemetry transfer frame (without the 32-bit sync marker) and R-S check symbols, which is the received data entity physically fed into the R-S decoder. For example, when E=16, k=223 and I=5, the length of the transmitted codeblock is 10 200 bits, unless virtual fill is used. If virtual fill is used, the length of the transmitted codeblock is reduced by the length of the virtual fill. A description of the use of virtual fill is provided in clause 6.3.6. The logical codeblock is the logical data entity operated upon by the R-S decoder. It can have a different length than the transmitted codeblock because it accounts for the amount of virtual fill that was introduced. For example, when E=16, k=223 and I=5, the logical codeblock always appears to be exactly 10 200 bits in length. SIST EN 16603-50-01:2015

Figure 6-2: Reed-Solomon codeblock partitioning 6.3.6 Shortened codeblock length 6.3.6.1 Overview In a systematic block code, a codeword can be divided into an information part and a parity (check) part. If the information part is k symbols long, a shortened code is created by taking only s (s < k) information symbols as input, appending a fixed string of length k−s and then encoding in the normal way. This fixed string is called virtual fill. Since the fill is a predetermined sequence of symbols, it is not transmitted over the channel, resulting in a shortened codeblock length. Thus the length of the transmitted codeblock is reduced by the length of the virtual fill. At the receiving end, the decoder appends the same fill sequence before decoding. The transmitted codeblock together with the virtual fill forms the logical codeblock. Figure 6-2 illustrates the transmitted codeblock and the logical codeblock. Shortening the transmitted codeblock length in this way changes the overall performance to a degree dependent on the amount of virtual fill used. Since it incorporates no virtual fill, the maximum codeblock length provides full performance. 6.3.6.2 General a. A shortened codeblock length may be used to accommodate frame lengths smaller than the maximum. b. Virtual fill shall be inserted only in integer multiples of 8I bits. c. The virtual fill shall not change in length during a mission phase. d. Virtual fill shall be inserted only at the beginning of the codeblock (i.e. after the attached sync marker but before the beginning of the transmitted codeblock). e. Virtual fill shall not be transmitted. NOTE
Virtual fill is used to logically complete the codeblock. SIST EN 16603-50-01:2015

As virtual fill in a codeblock is increased (at a specific bit rate), the number of codeblocks per unit time increases. 6.3.6.3 Use of virtual fill Since
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