March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Issue:
Date:
Location:
Draft Magenta Book, Issue 1.1
March 2014
Not Applicable
This document has been approved for publication by the Consultative Committee for Space
Data Systems (CCSDS). The procedure for review and authorization of CCSDS documents is detailed in the Procedures Manual for the Consultative Committee for Space Data
Systems .
This document is published and maintained by:
CCSDS Secretariat
Office of Space Communication (Code M-3)
National Aeronautics and Space Administration
Washington, DC 20546, USA
CCSDS 131.1-R-0.1 Page i March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially established by the management of its members. The Committee meets periodically to address data systems problems that are common to all participants, and to formulate sound technical solutions to these problems. Inasmuch as participation in the CCSDS is completely voluntary, the results of Committee actions are termed Recommendations and are not in themselves considered binding on any Agency.
CCSDS Recommendations take two forms: Recommended Standards that are prescriptive and are the formal vehicles by which CCSDS Agencies create the standards that specify how elements of their space mission support infrastructure shall operate and interoperate with others; and Recommended Practices that are more descriptive in nature and are intended to provide general guidance about how to approach a particular problem associated with space mission support. This Recommended Practice is issued by, and represents the consensus of, the CCSDS members. Endorsement of this Recommended Practice is entirely voluntary and does not imply a commitment by any Agency or organization to implement its recommendations in a prescriptive sense.
No later than five years from its date of issuance, this Recommended Practice will be reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Practice is issued, existing
CCSDS-related member Practices and implementations are not negated or deemed to be non-
CCSDS compatible. It is the responsibility of each member to determine when such Practices or implementations are to be modified. Each member is, however, strongly encouraged to direct planning for its new Practices and implementations towards the later version of the
Recommended Practice.
CCSDS 131.1-R-0.1 Page ii March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
This document is a CCSDS recommended practice for using variable coded modulation
(VCM) together with any CCSDS recommended channel codes, such as those described in
Ref. [1], [2], or [3], or other channel codes. It was contributed to CCSDS by NASA.
Through the process of normal evolution, it is expected that expansion, deletion, or modification of this document may occur. This Experimental Specification is therefore subject to CCSDS document management and change control procedures, which are defined in the Procedures Manual for the Consultative Committee for Space Data Systems . Current versions of CCSDS documents are maintained at the CCSDS Web site: http://www.ccsds.org/
Questions relating to the contents or status of this document should be addressed to the
CCSDS Secretariat at the address indicated on page i.
CCSDS 131.1-R-0.1 Page iii March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
At time of publication, the active Member and Observer Agencies of the CCSDS were:
Member Agencies
–
Agenzia Spaziale Italiana (ASI)/Italy.
–
British National Space Centre (BNSC)/United Kingdom.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
–
Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)/Germany.
– European Space Agency (ESA)/Europe.
–
Federal Space Agency (FSA)/Russian Federation.
–
Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
–
Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
Observer Agencies
–
Austrian Space Agency (ASA)/Austria.
–
Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
–
Centro Tecnico Aeroespacial (CTA)/Brazil.
–
Chinese Academy of Sciences (CAS)/China.
–
Chinese Academy of Space Technology (CAST)/China.
–
Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
–
Danish National Space Center (DNSC)/Denmark.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
–
European Telecommunications Satellite Organization (EUTELSAT)/Europe.
–
Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
–
Institute of Space Research (IKI)/Russian Federation.
–
KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
–
MIKOMTEK: CSIR (CSIR)/Republic of South Africa.
–
Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
–
National Oceanic and Atmospheric Administration (NOAA)/USA.
–
National Space Organization (NSPO)/Taiwan.
–
Naval Center for Space Technology (NCST)/USA.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
–
Swedish Space Corporation (SSC)/Sweden.
–
United States Geological Survey (USGS)/USA.
CCSDS 131.1-R-0.1 Page iv March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Document Title
CCSDS
131.5-M-1.1
Variable Coded Modulation
Protocol, Recommended Practice,
Issue 1, Draft 1
Date Status
March 2014 Current draft
CCSDS 131.1-R-0.1 Page v March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Section Page
1 INTRODUCTION.......................................................................................................... 1-1
1.1
BACKGROUND .................................................................................................... 1-1
1.2
PURPOSE AND SCOPE ........................................................................................ 1-1
1.3
NOMENCLATURE ............................................................................................... 1-1
1.3.1
NORMATIVE TEXT ................................................................................. 1-1
1.3.2
INFORMATIVE TEXT .............................................................................. 1-2
1.4
DEFINITIONS........................................................................................................ 1-2
1.4.1
DEFINITIONS FROM THE OPEN SYSTEM INTERCONNECTION
(OSI) BASIC REFERENCE MODEL ....................................................... 1-2
1.4.2
DEFINITION OF CADU ........................................................................... 1-2
1.5
CONVENTIONS .................................................................................................... 1-2
1.6
REFERENCES ....................................................................................................... 1-3
2 OVERVIEW ................................................................................................................... 2-1
2.1
ARCHITECTURE .................................................................................................. 2-1
2.2
SLICER ................................................................................................................... 2-1
3 VARIABLE CODED MODULATION PROTOCOL ................................................ 3-1
3.1
PHYSICAL LAYER FRAME STRUCTURE ....................................................... 3-1
3.2
FRAME MARKER (FM) ....................................................................................... 3-1
3.2.1
FM OF LENGTH 256 BITS ....................................................................... 3-1
3.2.2
FM OF LENGTH 26 BITS ......................................................................... 3-2
3.3
FRAME DESCRIPTOR (FD) ................................................................................ 3-2
3.4
VCM MODE TABLES .......................................................................................... 3-4
3.4.1
VCM MODE TABLE FOR CCSDS TURBO AND LDPC CODES ......... 3-5
3.4.2
VCM MODE TABLE FOR CCSDS SCCC ............................................... 3-6
3.4.3
VCM MODE TABLE FOR CCSDS DVB-S2 CODES ............................. 3-7
3.4.4
USER-SPECIFIED VCM MODE TABLE ................................................ 3-8
3.5
PILOT INSERTION ............................................................................................... 3-8
3.5.1
PILOT BLOCKS OF LENGTH P = 36 SYMBOLS ................................ 3-8
3.5.2
DVB-S2 ........................... ОШИБКА! ЗАКЛАДКА НЕ ОПРЕДЕЛЕНА.
4 MANAGED PARAMETERS ....................................................................................... 4-1
4.1
OVERVIEW ........................................................................................................... 4-1
ANNEX A INFORMATIVE REFERENCES ................................................................... 4-2
Figure
1-1 BIT NUMBERING CONVENTION ............................................................................ 1-3
CCSDS 131.1-R-0.1 Page vi March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Table
No table of contents entries found.
CCSDS 131.1-R-0.1 Page vii March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
1.1
BACKGROUND
Variable Coded Modulation (VCM) is a method to rapidly switch the channel coding and modulation used during a communications session. After a transmission using one coded modulation, another coded modulation may be used to match dynamic link conditions in near real time. With judicious choice of the coded modulations over time, excess margin can be reduced and total data throughput increased. Such dynamic conditions may arise, for example, because of changes in geometry, weather, interference, launch plumes, and scintillation.
Since VCM is a protocol that lies on top of coding and modulation, it is compatible with a wide variety of channel codes and modulations. Given a numbered list of coded modulations, a VCM protocol provides a mechanism to transition between them in a way that is understandable to the receiver.
CCSDS has recommended three broad classes of channel codes and modulations for use on the space-to-Earth link. The first of these existing standards includes convolutional codes,
Reed-Solomon codes, turbo codes, and low-density parity-check (LDPC) codes [1], to be used with recommended modulations [5]. No VCM protocol is specified in Ref.s [1], [5]. A second Blue Book specifies a set of serially concatenated convolutional codes (SCCCs), together with a set of modulations and a VCM protocol [2]. A third Blue Book specifies a mechanism to communicate CCSDS Transfer Frames using an existing ETSI standard for
Digital Video Broadcasting by satellites (DVB-S2), which uses BCH codes concatenated with LDPC codes [3], [4]. The DVB-S2 standard [4], and thus the CCSDS standard [3], specifies a VCM protocol as well as method for the receiver to monitor quality-of-reception parameters and to communicate this back to the transmitter, as part of an adaptive coded modulation (ACM) protocol.
1.2
PURPOSE AND SCOPE
The purpose of this Recommended Practice is to unify the methods of Ref.s [2], [3], and [4], under a common VCM protocol that is compatible with the existing SCCC VCM protocol [2] and DVB-S2 VCM/ACM protocol [3], [4], and which also can be used with the other
CCSDS recommended channel codes [1] and modulations [5]. The main applications are for space missions needing high data rate telemetry.
1.3
NOMENCLATURE
1.3.1
NORMATIVE TEXT
The following conventions apply throughout this Specification: a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification; b) the word ‘should’ implies an optional, but desirable, specification;
CCSDS 131.1-R-0.1 Page 1-1 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES c) the word ‘may’ implies an optional specification; d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
1.3.2
INFORMATIVE TEXT
In the normative sections of this document, informative text is set off from the normative specifications either in notes or under one of the following subsection headings:
– Overview;
– Background;
– Rationale;
– Discussion.
1.4
DEFINITIONS
1.4.1
DEFINITIONS FROM THE OPEN SYSTEM INTERCONNECTION (OSI)
BASIC REFERENCE MODEL
This Recommended Standard makes use of a number of terms defined in reference [5]. The use of those terms in this Recommended Standard shall be understood in a generic sense, i.e., in the sense that those terms are generally applicable to any of a variety of technologies that provide for the exchange of information between real systems. Those terms are: a) Data Link Layer; b) b) Physical Layer; c) c) service; d) d) service data unit.
1.4.2
DEFINITION OF CADU
The CADU is defined in reference [1]. In this Recommended Practice, CADU only consists in the concatenation of an ASM and a Transfer Frame.
1.5
CONVENTIONS
In this document, the following convention is used to identify each bit in an N -bit field. The first bit in the field to be transmitted (i.e., the most left justified when drawing a figure) is defined to be ‘Bit 0’, the following bit is defined to be ‘Bit 1’, and so on up to ‘Bit
N -1’.
When the field is used to express a binary value (such as a counter), the Most Significant Bit
(MSB) shall be the first transmitted bit of the field, i.e., ‘Bit 0’ (see figure 1-1).
CCSDS 131.1-R-0.1 Page 1-2 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Figure 1-1: Bit Numbering Convention
The convention for matrices differs from that for bit fields. Matrices are indexed beginning with the number ‘1’.
In accordance with standard data-communications practice, data fields are often grouped into
8-bit ‘words’ which conform to the above convention. Throughout this Specification, such an
8-bit word is called an ‘octet’. The numbering for octets within a data structure starts with
‘0’.
1.6
REFERENCES
The following document contains provisions which, through reference in this text, constitute provisions of this document. At the time of publication, the edition indicated was valid. All documents are subject to revision, and users of this document are encouraged to investigate the possibility of applying the most recent edition of the document indicated below. The
CCSDS Secretariat maintains a register of currently valid CCSDS documents.
[1] CCSDS 131.0-B-2, “TM Synchronization and Channel Coding,” Blue Book. Issue 2.
August 2011.
[2] CCSDS 131.2-B-1, “Flexible Advanced Coding and Modulation Scheme for High Rate
Telemetry Applications,” Blue Book. Issue 1. March 2012
[3] CCSDS 131.3-B-1, “CCSDS Space Link Protocols over ETSI DVB-S2 Standard,” Blue
Book. Issue 1. March 2013.
[4] ETSI EN 302 307 V1.2.1 (2009-08), “Digital Video Broadcasting (DVB); Second
Generation Framing Structure, Channel Coding and Modulation Systems for
Broadcasting, Interactive Services, News Gathering and other Broadband Satellite
Applications.” Sophia-Antipolis: ETSI, 2009.
[5] CCSDS 401.0-B-23, “Radio Frequency and Modulation Systems--Part 1: Earth Stations and Spacecraft,” Blue Book. Issue 23. December 2013.
[6] CCSDS 132.0-B-1, “TM Space Data Link Protocol. Recommendation for Space Data
System Standards,” Blue Book. Issue 1. September 2003.
[7] CCSDS 732.0-B-2, “AOS Space Data Link Protocol. Recommendation for Space Data
System Standards,” Blue Book. Issue 2. July 2006.
CCSDS 131.1-R-0.1 Page 1-3 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
2.1
ARCHITECTURE
Figure 2-1: Relationship with OSI layersFigure 2-1 illustrates the relationship of this
Recommended Practice to the Open Systems Interconnection reference model (reference
[A2]). Two sublayers of the Data Link Layer are defined for CCSDS space link protocols.
The TM and AOS Space Data Link Protocols specified in Ref.s [6] and [7], respectively, correspond to the Data Link Protocol Sublayer, and provide functions for transferring data using the protocol data unit called the Transfer Frame. The Synchronization and Channel
Coding Sublayer provides methods of synchronization and channel coding for transferring
Transfer Frames over a space link while the Physical Layer provides the RF and modulation methods for transferring a stream of bits over a space link in a single direction.
This Recommended Standard covers the functions of both the Synchronization and Channel
Coding Sublayer and the Physical Layer.
OSI layers CCSDS layers CCSDS protocols
Network and upper layers
Network and upper layers
Data link protocol sublayer
TM or AOS space data link protocol
Data link layer
Synchronization and channel coding sublayer
CADU stream generation
VCM PROTOCOL
Physical layer Physical layer
Recommendation content
Figure 2-1: Relationship with OSI layers
2.2
SLICER AND PLFRAME STRUCTURE
The VCM protocol operates, consistent with Ref.s [2] and [3], by taking CCSDS Transfer
Frames as input, adding an attached sync marker to form Channel Access Data Units
(CADUs), slicing the CADUs asynchronously into encoder-input-sized blocks, encoding them with a channel code, producing modulation symbols corresponding to the encoded block, prepending a physical layer frame (PLFRAME) header, and optionally inserting pilot
CCSDS 131.1-R-0.1 Page 2-1 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES symbols within the modulations symbols of the non-header part of the PLFRAME. This
structure is shown in Figure 2-2.
CCSDS
M bits M bits M bits
...
Transfer Frames
Stream of
M bits M bits M bits
Attached Sync Markers
(ASM) ...
CADUs slicer
Information blocks
(chanel encoder input)
...
K bits K bits K bits
...
Encoded blocks N bits N bits N bits
Modulation Symbols for each codeword
Physical layer frame
(PLFRAME)
CW syms CW syms CW syms
...
PL header
CW 1 symbols
CW 2 symbols
...
symbols
PLFRAME with pilot symbols inserted
CW syms
P
CW syms
S
CW syms pilot symbols
Figure 2-2: Structure of the PLFRAME of the VCM protocol
CCSDS 131.1-R-0.1 Page 2-2 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.1
PHYSICAL LAYER FRAME STRUCTURE
The VCM protocol specified here is compatible with, and a generalization of, the VCM protocols incorporated into Ref.s [2], [3], and [4]. The transmission shall consist of a sequence of physical layer frames (PLFRAMEs), transmitted contiguously without gaps.
Each PLFRAME shall comprise:

A Frame Marker (FM), transmitted using 𝜋/2 BPSK, to enable the synchronization of PLFRAMES

An optional Frame Descriptor (FD), transmitted using 𝜋/2 BPSK, to enable the determination of the VCM mode (code and modulation) used

Modulation symbols from either 1 codeword or 16 codewords, using a VCM mode from the VCM mode table

The optional insertion of pilot symbols
For each PLFRAME, a single VCM mode shall be used, i.e., the same code and modulation shall be used for all codewords and modulation symbols of the PLFRAME. This PLFRAME
structure is shown in Figure 3-1, when 16 codewords are used in a PLFRAME.
Figure 3-1: PLFRAME structure
3.2
FRAME MARKER (FM)
The Frame Marker (FM), also called the Start Of Frame (SOF), shall be either a sequence of length 256, or a sequence of length 26.
3.2.1
FM OF LENGTH 256 BITS
3.2.2
WHEN THE FM HAS LENGTH 256 BITS, IT SHALL BE THE LENGTH-256
SEQUENCE SHOWN IN FM OF LENGTH 26 BITS
When the FM has length 26 bits, it shall be the length-26 sequence shown in Table 3-1. This is the SOF defined in Ref. [4]. Care should be taken to note that the first hexadecimal numeral, “1,” represents only two bits, “01,” not four bits.
Table 3-1. This is the FM defined in Ref. [2]. It is a Gold sequence which can be generated
using the following polynomials for the feedback loop: 𝑔
1
(𝑥) = 𝑥 8 + 𝑥 6 + 𝑥 5 + 𝑥 4 + 1
CCSDS 131.1-R-0.1 Page 3-1 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES 𝑔
2
(𝑥) = 𝑥 8 + 𝑥 6 + 𝑥 5 + 𝑥 4 + 𝑥 3 + 𝑥 + 1
NOTE – Figure 3-2 shows the logical block diagram of the sequence generator using shift
registers and exclusive-OR operators.
Figure 3-2: Frame Marker Sequence Generator
3.2.3
FM OF LENGTH 26 BITS
When the FM has length 26 bits, it shall be the length-26 sequence shown in Table 3-1. This
is the SOF defined in Ref. [4]. Care should be taken to note that the first hexadecimal numeral, “1,” represents only two bits, “01,” not four bits.
Table 3-1: FM sequences
FM Length
256
26
FM Sequence
FB44 1F1D BDD7 76F2
16
= 1111 1011…0010
2
18D 2E82
16
= 01 1000…0100
2
3.3
FRAME DESCRIPTOR (FD)
When present, the FD, also called the physical layer signaling (PLS) code in Ref. [4], is constructed by taking as input a sequence of seven bits, 𝑏
1 𝑏
2
… 𝑏
7
as defined in Table 3-2.
The first five bits specify which VCM mode is used in the remainder of the PLFRAME. The meaning of these bits is given in Section 3.4. The sixth bit selects whether the pilot is used.
CCSDS 131.1-R-0.1 Page 3-2 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
The seventh bit selects between long and short frame length options, if applicable, and shall otherwise be set to zero. When compatibility is needed with the DVB-S2 protocol in Ref.
[4], the sixth and seventh bits may swapped.
Table 3-2: FD input bits content
Bit Number
1
Content 𝑏
1 𝑏
2 𝑏
3 𝑏
4 𝑏
5
VCM mode index (0 to 31), with 𝑏
1
being the most significant bit 𝑏
6+𝐼
𝐷𝑉𝐵
Distributed pilot on (=1) / off (=0) 𝑏
7−𝐼
𝐷𝑉𝐵
Frame-length option long (=1) or short (=0)
The FD of length 64 bits shall be constructed from 𝑏
1
[ 𝑏
1 𝑏
2
… 𝑏
6
] is encoded to 𝑌 = [𝑦
1 𝑦
2
… 𝑦
32 𝑏
2
… 𝑏
7
as follows. First,
] = 𝒃𝐺, where 𝐺 is given by: 𝒃 =
This is a bi-orthogonal (32,6) code with minimum distance 32, equivalent to a first-order
Reed-Muller code. Next, each symbol of 𝑌 shall be repeated and the repeated symbol shall be XORed with 𝑏
7
and placed in the order shown in Figure 3-3.
Figure 3-3: FD code structure
1 When the DVB-S2 system [3] is used, we set 𝐼
𝐷𝑉𝐵
Otherwise, we set 𝐼
𝐷𝑉𝐵
= 0.
= 1 , so that the roles of the bits 𝑏
6
and 𝑏
7
are interchanged.
CCSDS 131.1-R-0.1 Page 3-3 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
Finally, the coded bits are scrambled by exclusive-ORing them with the binary sequence
0111000110011101100000111100100101010011010000100010110111111010
The result sequence of 64 bits is the FD.
NOTE – Transmission of the FD is optional. When the VCM mode table is such that each
VCM mode gives rise to a unique PLFRAME length, the VCM mode can be directly deduced from the length of separation between FMs, without the explicit use of a Frame
Descriptor (FD). When the FD is not transmitted, the FM shall be followed immediately by the modulation symbols of the codeword(s), without gap.
3.4
VCM MODE TABLES
This Recommended Practice allows various VCM mode tables. The particular VCM mode table being used shall be a managed parameter which is external to the VCM protocol. See
Section 4.
CCSDS 131.1-R-0.1 Page 3-4 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.4.1
VCM MODE TABLE FOR CCSDS TURBO AND LDPC CODES
The VCM protocol of this Recommended Practice is compatible with codes recommended in
Ref. [1], and modulations in Ref.s [2] and [5]. The set of coded modulation modes using these codes and modulations shall be:
18
19
20
21
22
14
15
16
17
27
28
29
30
31
23
24
25
26
VCM
Mode
0
1
2
7
8
9
10
3
4
5
6
11
12
13
Modulation Code
DUMMY PLFRAME
BPSK Turbo
BPSK Turbo
BPSK
BPSK
BPSK
BPSK
Turbo
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
BPSK
QPSK
QPSK
QPSK
QPSK
8-PSK
8-PSK
C2
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
C2
AR4JA LDPC
AR4JA LDPC
8-PSK
8-PSK
AR4JA LDPC
C2
16-APSK AR4JA LDPC
16-APSK AR4JA LDPC
16-APSK AR4JA LDPC
16-APSK C2
32-APSK AR4JA LDPC
32-APSK AR4JA LDPC
32-APSK AR4JA LDPC
32-APSK C2
64-APSK AR4JA LDPC
64-APSK AR4JA LDPC
64-APSK AR4JA LDPC
64-APSK
Reserved
Reserved
Reserved
Reserved
C2
4/5
223/255
1/2
2/3
4/5
223/255
1/2
2/3
4/5
223/255
1/2
2/3
4/5
223/255
Code rate Input length
(short)
1/6
1/4
1784
1784
1/3
1/2
2/3
4/5
223/255
1/2
2/3
4/5
223/255
1/2
2/3
1784
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
16384
7136
16384
16384
16384
7136
16384
16384
16384
7136
16384
16384
16384
7136
Input length
(long)
8920
8920
8920
16384
16384
16384
7136
8920
16384
16384
7136
16384
16384
CCSDS 131.1-R-0.1 Page 3-5 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.4.2
VCM MODE TABLE FOR CCSDS SCCC
This Recommended Practice is compatible with the specification given in Ref. [2]. The set of coded modulation modes shall be:
23
24
25
26
27
28
29
30
31
19
20
21
22
VCM Mode Modulation Code Code rate Input length
(short)
1 QPSK SCCC 0.36 5758
2
3
4
5
QPSK
QPSK
QPSK
QPSK
SCCC
SCCC
SCCC
SCCC
0.43
0.52
0.61
0.7
6958
8398
9838
11278
10
11
12
13
14
6
7
8
9
15
16
17
18
QPSK
8-PSK
8-PSK
8-PSK
8-PSK
8-PSK
8-PSK
16-APSK
16-APSK
16-APSK
16-APSK
16-APSK
32-APSK
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
0.81
0.46
0.54
0.61
0.7
0.79
0.88
0.59
0.66
0.73
0.8
0.87
0.64
13198
11278
13198
14878
17038
19198
21358
19198
21358
23518
25918
28318
25918
32-APSK
32-APSK
32-APSK
32-APSK
64-APSK
64-APSK
64-APSK
64-APSK
64-APSK
Reserved
Reserved
Reserved
Reserved
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
0.7
0.76
0.82
0.89
0.69
0.74
0.80
0.84
0.9
28318
30958
33358
35998
33358
35998
38638
41038
43678
Input length
(long) n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a
CCSDS 131.1-R-0.1 Page 3-6 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.4.3
VCM MODE TABLE FOR CCSDS DVB-S2 CODES
This Recommended Practice is compatible with the specification given in Ref.s [3] and [4].
The set of coded modulation modes shall be:
VCM Mode
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Modulation
QPSK
QPSK
QPSK
QPSK
QPSK
8-PSK
8-PSK
Code
DUMMY PLFRAME
QPSK BCH+LDPC
QPSK
QPSK
QPSK
QPSK
QPSK
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
BCH+LDPC
Code rate Input length
(short)
1/4
1/3
3 072
5 232
2/5
1/2
3/5
2/3
3/4
4/5
5/6
8/9
BCH+LDPC 9/10
BCH+LDPC 3/5
BCH+LDPC 2/3
6 312
7 032
9 552
10 632
11 712
12 432
13 152
14 232 n/a
9 552
10 632
18
19
20
21
22
14
15
16
17
27
28
29
30
31
23
24
25
26
8-PSK
8-PSK
8-PSK
8-PSK
32-APSK BCH+LDPC 8/9
32-APSK BCH+LDPC 9/10
Reserved
Reserved
Reserved
BCH+LDPC
BCH+LDPC
BCH+LDPC 8/9
BCH+LDPC 9/10
16-APSK BCH+LDPC
16-APSK BCH+LDPC
16-APSK BCH+LDPC
16-APSK BCH+LDPC
16-APSK BCH+LDPC
32-APSK BCH+LDPC
32-APSK BCH+LDPC
32-APSK BCH+LDPC
3/4
5/6
2/3
3/4
4/5
5/6
8/9
16-APSK BCH+LDPC 9/10
3/4
4/5
5/6
11 712
13 152
14 232 n/a
10 632
11 712
12 432
13 152
14 232 n/a
11 712
12 432
13 152
14 232 n/a
48 408
53 840
57 472
58 192
43 040
48 408
51 648
53 840
57 472
58 192
48 408
51 648
53 840
57 472
58 192
Input length
(long)
16 008
21 408
25728
32 208
38 688
43 040
48 408
51 648
53 840
57 472
58 192
38 688
43 040
CCSDS 131.1-R-0.1 Page 3-7 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.4.4
USER-SPECIFIED VCM MODE TABLE
The VCM protocol of this Recommended Practice permits a user-specified VCM mode table which is different from the ones in the preceding sections, to allow variations in the type, length, rate of supported codes, and the type of modulation used.
3.5
PILOT INSERTION
To aid receiver synchronization, pilot symbols may be inserted into each PLFRAME. Each pilot symbol is an un-modulated symbol, identified by the complex baseband signal point 𝐼 =
1/√2 , 𝑄 = 1/√2 . The pilot symbols are periodically inserted within the modulation symbols of the codewords. After the PL header and the first 𝑆 modulation symbols of one or more codewords, a pilot block of length 𝑃 is inserted. After each subsequent 𝑆 modulation symbols, a pilot block of length 𝑃
is inserted. See Figure 2-2.
To encompass the pilot symbol patterns of both Ref. [2] and Ref. [3], two values of (𝑃, 𝑆) are allowed. The allowable values of 𝑃 and 𝑆
are shown in Table 3-3. Pilot pattern 1 is used by
Ref. [2], and pilot pattern 2 is used by Ref. [3].
Table 3-3: Pilot length ( 𝑷 ) and period ( 𝑺 )
Pattern
1
𝑃
16
𝑆
540
2 36 1440
CCSDS 131.1-R-0.1 Page 3-8 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
4.1
OVERVIEW
In order to conserve bandwidth on the space link, some parameters associated with modulation, synchronization, and channel coding are handled by management rather than by inline communications protocol. The managed parameters are generally those which tend to be static for long periods of time, and whose change generally signifies a major reconfiguration of the modulation, synchronization, and channel coding systems associated with a particular mission, i.e., parameters that are fixed within a mission phase. However, as mentioned in annex A, the coding and modulation scheme defined in this book also supports parameters that can be changed from one time interval to the next, within a sequence of time intervals in a mission phase. These two types will be referenced in this section respectively as
Permanent Managed Parameters and Variable Managed Parameters.
Through the use of a management system, management conveys the required information to the modulation, synchronization, and channel coding systems.
In this section, the managed parameters used by systems applying this recommended standard are listed. These parameters are defined in an abstract sense and are not intended to imply any particular implementation of a management system.
Managed parameters:

VCM mode table. See Section 3.4.

I_DVB (=0 or 1). See Table 3-2.

Transmission of FD (used / not used).

Number of codewords per PLFRAME (SCCC: 16, DVB-S2: 1)

Pilot length, 𝑃

Pilot insertion period, 𝑆
CCSDS 131.1-R-0.1 Page 4-1 March 2014

EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
A1 INFORMATIVE REFERENCES
[A1] J. Hamkins, “Performance of low-density parity-check coded modulation,” Proceedings of the Aerospace Conference, Big Sky, MT, Mar. 2010.
[A2] Information Technology—Open Systems Interconnection—Basic Reference Model:
The Basic Model. International Standard, ISO/IEC 7498-1. 2nd ed. Geneva: ISO,
1994.
CCSDS 131.1-R-0.1 Page 4-2 March 2014