Recommendation for
Space Data System Practices
VARIABLE CODED
MODULATION PROTOCOL
DRAFT RECOMMENDED PRACTICE
CCSDS 131.5-M-1
DRAFT MAGENTA BOOK
March 2015
EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
AUTHORITY
Issue:
Draft Magenta Book, Issue 1.2
Date:
March 2015
Location:
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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
STATEMENT OF INTENT
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 nonCCSDS 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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
FOREWORD
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
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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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
DOCUMENT CONTROL
Document
Title
Date
Status
CCSDS
Variable Coded Modulation
131.5-M-1.1 Protocol, Recommended Practice,
Issue 1, Draft 1
March 2014 Superseded
CCSDS
Variable Coded Modulation
131.5-M-1.2 Protocol, Recommended Practice,
Issue 1, Draft 2
March 2015 Current draft
- References VCM
protocols [2], [4]
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
CONTENTS
Section
1
2
3
4
Page
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
OVERVIEW ................................................................................................................... 2-1
2.1 ARCHITECTURE .................................................................................................. 2-1
2.2 SLICER ................................................................................................................... 2-1
VARIABLE CODED MODULATION PROTOCOL................................................ 3-1
3.1 PHYSICAL LAYER FRAME STRUCTURE ....................................................... 3-1
3.2 FRAME MARKER (FM) ..................... ERROR! BOOKMARK NOT DEFINED.
3.2.1 FM OF LENGTH 256 BITS ..... ERROR! BOOKMARK NOT DEFINED.
3.2.2 FM OF LENGTH 26 BITS ....... ERROR! BOOKMARK NOT DEFINED.
3.3 FRAME DESCRIPTOR (FD) .............. ERROR! BOOKMARK NOT DEFINED.
3.4 VCM MODE TABLES ........................ ERROR! BOOKMARK NOT DEFINED.
3.4.1 VCM MODE TABLE FOR CCSDS TURBO AND LDPC CODES......... 3-1
3.4.2 VCM MODE TABLE FOR CCSDS SCCC ............................................... 3-3
3.4.3 VCM MODE TABLE FOR CCSDS DVB-S2 CODES ............................. 3-4
3.4.4 USER-SPECIFIED VCM MODE TABLE ................................................ 3-5
3.5 PILOT INSERTION ............................. ERROR! BOOKMARK NOT DEFINED.
3.5.1 PILOT BLOCKS OF LENGTH P = 36 SYMBOLS ...................... ERROR!
BOOKMARK NOT DEFINED.
3.5.2 DVB-S2 .................................... ERROR! BOOKMARK NOT DEFINED.
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
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Table
No table of contents entries found.
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
1
1.1
INTRODUCTION
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 specify various combinations of coding and
modulations in Ref.s [1], [2], [4], and [5], that can operate under the VCM protocol defined in
[2] and [4]. This enables, for example, CCSDS recommended channel codes [1] and
modulations [5] to be used with the CCSDS VCM protocol. The main applications are for
space missions needing high data rate telemetry or operation in dynamic environments.
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;
c) the word ‘may’ implies an optional specification;
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
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
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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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
2
2.1
OVERVIEW
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
Network and
upper layers
Network and
upper layers
Data link
protocol
sublayer
Data link layer
Synchronization and
channel coding
sublayer
CCSDS protocols
TM or AOS space
data link protocol
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 symbols within the
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
modulations symbols of the non-header part of the PLFRAME. This structure is shown in
Figure 2-2.
CCSDS
Transfer Frames
M bits
Stream of
CADUs
M bits
M bits
...
M bits
Attached Sync Markers
(ASM)
M bits
...
M bits
slicer
Information blocks
(chanel encoder input)
K bits
Encoded blocks
N bits
Modulation Symbols
for each codeword
Physical layer frame
(PLFRAME)
PLFRAME with
pilot symbols inserted
K bits
...
K bits
N bits
N bits
CW syms CW syms CW syms
PL header
CW 1
CW 2
symbols
symbols
CW syms
CW syms
...
...
...
symbols
CW syms
P
S
pilot
symbols
Figure 2-2: Structure of the PLFRAME of the VCM protocol
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3
VARIABLE CODED MODULATION PROTOCOL
3.1
PHYSICAL LAYER FRAME STRUCTURE
This Recommended Practice is compatible with existing CCSDS-approved VCM protocols, as
specified in [2] and [3]. In particular, 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 a VCM mode table in Section 3.2 – 3.5.

The optional insertion of pilot symbols
The reader is directed to [2] and [3] for details on these VCM signals. Annex A contains a
summary of their similarities and differences.
3.2
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.
3.2.1 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:
VCM
Mode
0
1
2
3
4
5
6
7
8
Modulation
Code
DUMMY PLFRAME
BPSK
Turbo
BPSK
Turbo
BPSK
Turbo
BPSK
AR4JA LDPC
BPSK
AR4JA LDPC
BPSK
AR4JA LDPC
BPSK
C2
QPSK
AR4JA LDPC
CCSDS 131.1-R-0.1
Code rate
Input length
(short)
Input length
(long)
1/6
1/4
1/3
1/2
2/3
4/5
223/255
1/2
1784
1784
1784
1024
1024
1024
7136
1024
8920
8920
8920
16384
16384
16384
7136
8920
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
QPSK
QPSK
QPSK
8-PSK
8-PSK
8-PSK
8-PSK
16-APSK
16-APSK
16-APSK
16-APSK
32-APSK
32-APSK
32-APSK
32-APSK
64-APSK
64-APSK
64-APSK
64-APSK
Reserved
Reserved
Reserved
Reserved
CCSDS 131.1-R-0.1
AR4JA LDPC
AR4JA LDPC
C2
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
C2
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
C2
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
C2
AR4JA LDPC
AR4JA LDPC
AR4JA LDPC
C2
2/3
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
1/2
2/3
4/5
223/255
Page 3-2
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
1024
1024
1024
7136
16384
16384
7136
16384
16384
16384
7136
16384
16384
16384
7136
16384
16384
16384
7136
16384
16384
16384
7136
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.2.2 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:
VCM Mode
Modulation
Code
Code rate
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
QPSK
QPSK
QPSK
QPSK
QPSK
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
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
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
SCCC
0.36
0.43
0.52
0.61
0.7
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
0.7
0.76
0.82
0.89
0.69
0.74
0.80
0.84
0.9
CCSDS 131.1-R-0.1
Page 3-3
Input length
(short)
5758
6958
8398
9838
11278
13198
11278
13198
14878
17038
19198
21358
19198
21358
23518
25918
28318
25918
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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.2.3 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
Modulation
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
CCSDS 131.1-R-0.1
Code
Code rate
Input length
(short)
Input length
(long)
1/4
1/3
2/5
1/2
3/5
2/3
3/4
4/5
5/6
8/9
9/10
3/5
2/3
3/4
5/6
8/9
9/10
2/3
3/4
4/5
5/6
8/9
9/10
3/4
4/5
5/6
8/9
9/10
3 072
5 232
6 312
7 032
9 552
10 632
11 712
12 432
13 152
14 232
n/a
9 552
10 632
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
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
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
DUMMY PLFRAME
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
QPSK
BCH+LDPC
8-PSK
BCH+LDPC
8-PSK
BCH+LDPC
8-PSK
BCH+LDPC
8-PSK
BCH+LDPC
8-PSK
BCH+LDPC
8-PSK
BCH+LDPC
16-APSK
BCH+LDPC
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
32-APSK
BCH+LDPC
32-APSK
BCH+LDPC
Reserved
Reserved
Reserved
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
3.2.4 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.
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
4
MANAGED PARAMETERS
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 3.2.

VCM protocol. The VCM protocol shall conform to either [2] or [3].

Transmission of Frame Descriptor. (Transmitted / not transmitted).
CCSDS 131.1-R-0.1
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
ANNEX A
INFORMATIVE REFERENCES
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
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EXPERIMENTAL SPECIFICATION FOR SHORT BLOCKLENGTH LDPC CODES
ANNEX B
INFORMATIVE SUMMARY OF VCM PROTOCOLS IN [2] AND [3]
The VCM protocols in [2] and [3] are similar in many respects, and contain a few
differences. The table below summarizes these similarities. Differences are highlighted in
bold type.
Basic VCM protocol
structure
Input to Protocol
Transfer Frame Sync
method
Transfer Frame Slicer?
FM length
FD length
FD structure
FD protection
FM+FD TX modulation
Pilot symbols
Codes
Modulations
CCSDS 131.1-R-0.1
131.1-B-2 (DVB-S2) [3]
FM, FD, codeblock, optional
pilot
CCSDS Transfer Frames
CCSDS ASM
131.2-B-2 (SCCC) [2]
FM, FD, codeblock, optional
pilot
CCSDS Transfer Frames
CCSDS ASM
Yes (asynchronous)
26 bits
7 bits
5 bits to specify VCM mode;
pilot flag; long/short frame flag
Yes (asynchronous)
256 bits
7 bits
5 bits to specify VCM mode;
pilot flag; long/short frame
flag
(64,7) linear code
𝜋/2 BPSK
16 pilot syms, every 540
syms
SCCC
QPSK, 8-PSK,
16/32/64-APSK
(64,7) linear code
𝜋/2 BPSK
36 pilot syms, every 1440
syms
DVB-S2
QPSK, 8-PSK,
16/32-APSK
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