ISO 22663:2015

INTERNATIONAL ISO
STANDARD 22663
Third edition
2015-08-15
Space data and information transfer
systems — Proximity-1 space link
protocol — Data link layer
Systèmes de transfert des informations et données spatiales —
Protocole pour liaisons spatiales de proximité 1 — Couche de liaisons
de données
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 22663 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 211.0-B-5, December 2013) and was adopted (without modifications except those stated in clause 2
of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.

This third edition of ISO 22663:2015 cancels and replaces the second edition (ISO 22663:2007), which
has been technically revised.
Recommendation for Space Data System Standards
PROXIMITY-1 SPACE
LINK PROTOCOL—
DATA LINK LAYER
RECOMMENDED STANDARD
CCSDS 211.0-B-5
BLUE BOOK
December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
AUTHORITY
Issue: Recommended Standard, Issue 5
Date: December 2013
Location: Washington, DC, USA
This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS documents is detailed in Organization and Processes for
the Consultative Committee for Space Data Systems (CCSDS A02.1-Y-3), and the record of
Agency participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This document is published and maintained by:

CCSDS Secretariat
Space Communications and Navigation Office, 7L70
Space Operations Mission Directorate
NASA Headquarters
Washington, DC 20546-0001, USA
CCSDS 211.0-B-5 Page i December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
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 Recommended Standards and are
not considered binding on any Agency.
This Recommended Standard is issued by, and represents the consensus of, the CCSDS
members. Endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:
o Whenever a member establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommended Standard. Establishing such a standard
does not preclude other provisions which a member may develop.
o Whenever a member establishes a CCSDS-related standard, that member will
provide other CCSDS members with the following information:
-- The standard itself.
-- The anticipated date of initial operational capability.
-- The anticipated duration of operational service.
o Specific service arrangements shall be made via memoranda of agreement. Neither
this Recommended Standard nor any ensuing standard is a substitute for a
memorandum of agreement.
No later than three years from its date of issuance, this Recommended Standard 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 Standard is issued, existing
CCSDS-related member standards and implementations are not negated or deemed to be
non-CCSDS compatible. It is the responsibility of each member to determine when such
standards or implementations are to be modified. Each member is, however, strongly
encouraged to direct planning for its new standards and implementations towards the later
version of the Recommended Standard.
CCSDS 211.0-B-5 Page ii December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
FOREWORD
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights. CCSDS shall not be held responsible for identifying any or all such
patent rights.
Through the process of normal evolution, it is expected that expansion, deletion, or
modification of this document may occur. This Recommended Standard is therefore subject
to CCSDS document management and change control procedures, which are defined in
Organization and Processes for the Consultative Committee for Space Data Systems
(CCSDS A02.1-Y-3). 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 211.0-B-5 Page iii December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
At time of publication, the active Member and Observer Agencies of the CCSDS were:
Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– China National Space Administration (CNSA)/People’s Republic of China.
– Deutsches Zentrum für Luft- und Raumfahrt (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.
– UK Space Agency/United Kingdom.
Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– China Satellite Launch and Tracking Control General, Beijing Institute of Tracking
and Telecommunications Technology (CLTC/BITTT)/China.
– 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.
– Departamento de Ciência e Tecnologia Aeroespacial (DCTA)/Brazil.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Geo-Informatics and Space Technology Development Agency (GISTDA)/Thailand.
– 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.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Agency of the Republic of Kazakhstan (NSARK)/Kazakhstan.
– National Space Organization (NSPO)/Chinese Taipei.
– Naval Center for Space Technology (NCST)/USA.
– Scientific and Technological Research Council of Turkey (TUBITAK)/Turkey.
– South African National Space Agency (SANSA)/Republic of South Africa.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– Swiss Space Office (SSO)/Switzerland.
– United States Geological Survey (USGS)/USA.
CCSDS 211.0-B-5 Page iv December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
DOCUMENT CONTROL
Document Title Date Status
CCSDS Proximity-1 Space Link Protocol October Original issue,
211.0-B-1 2002 superseded
CCSDS Proximity-1 Space Link Protocol— April 2003 Superseded
211.0-B-2 Data Link Layer
CCSDS Proximity-1 Space Link Protocol— May 2004 Superseded
211.0-B-3 Data Link Layer
CCSDS Proximity-1 Space Link Protocol— July 2006 Superseded
211.0-B-4 Data Link Layer, Recommended
Standard, Issue 4
CCSDS Proximity-1 Space Link Protocol— December Current issue:
211.0-B-5 Data Link Layer, Recommended 2013
This update includes
Standard, Issue 5
several improvements and
clarifications—
accomplishing better
alignment and
consistency with the other
Proximity-1 Blue
Books—and the addition
of an option for Low-
Density Parity-Check
(LDPC) codes.
NOTE – Changes from the previous issue are too numerous to permit markup.

CCSDS 211.0-B-5 Page v December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
CONTENTS
Section Page
1 INTRODUCTION . 1-1

1.1 PURPOSE . 1-1
1.2 SCOPE . 1-1
1.3 APPLICABILITY . 1-1
1.4 RATIONALE . 1-2
1.5 CONVENTIONS AND DEFINITIONS. 1-2
1.6 REFERENCES . 1-7

2 OVERVIEW . 2-1

2.1 CONCEPT OF PROXIMITY-1 . 2-1
2.2 OVERVIEW OF SERVICES . 2-6

3 PROTOCOL DATA UNITS . 3-1

3.1 OVERVIEW—CONTEXT OF THE VERSION-3 TRANSFER FRAME . 3-1
3.2 VERSION-3 TRANSFER FRAME . 3-1

4 DATA LINK LAYER . 4-1

4.1 FRAME SUBLAYER . 4-1
4.2 MEDIUM ACCESS CONTROL SUBLAYER . 4-2
4.3 DATA SERVICES SUBLAYER . 4-5
4.4 INPUT/OUTPUT SUBLAYER . 4-7

5 PROXIMITY-1 TIMING SERVICES . 5-1

5.1 OVERVIEW . 5-1
5.2 TIME TAG RECORDING . 5-1
5.3 TIME CORRELATION PROCESS . 5-2
5.4 TRANSFERRING TIME TO A REMOTE ASSET . 5-3

6 DATA SERVICES OPERATIONS . 6-1

6.1 OVERVIEW . 6-1
6.2 PROXIMITY-1 STATE TABLES . 6-1
6.3 ELEMENTS AND EVENTS THAT AFFECT STATE STATUS . 6-14
6.4 STATE TRANSITION TABLES AND DIAGRAMS . 6-19
6.5 INTERFACES WITH THE PHYSICAL LAYER (VIA CODING AND
SYNCHRONIZATION SUBLAYER) . 6-31
CCSDS 211.0-B-5 Page vi December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
CONTENTS (continued)
Section Page
6.6 SENDING OPERATIONS . 6-32
6.7 RECEIVING OPERATIONS . 6-34

7 COMMUNICATION OPERATIONS PROCEDURE FOR
PROXIMITY LINKS . 7-1

7.1 OVERVIEW . 7-1
7.2 SENDING PROCEDURES (FOP-P) . 7-1
7.3 RECEIVING PROCEDURES (FARM-P) . 7-7

8 INPUT/OUTPUT SUBLAYER OPERATIONS . 8-1

8.1 OVERVIEW . 8-1
8.2 SENDING OPERATIONS . 8-1
8.3 RECEIVING OPERATIONS . 8-2

ANNEX A PROTOCOL IMPLEMENTATION CONFORMANCE
STATEMENT (PICS) PROFORMA (NORMATIVE) . A-1
ANNEX B VARIABLE-LENGTH SUPERVISORY PROTOCOL DATA
FIELD FORMATS (NORMATIVE) .B-1
ANNEX C MANAGEMENT INFORMATION BASE PARAMETERS
(NORMATIVE) . C-1
ANNEX D NOTIFICATIONS TO VEHICLE CONTROLLER (NORMATIVE) . D-1
ANNEX E SECURITY, SANA, AND PATENT CONSIDERATIONS
(INFORMATIVE) .E-1
ANNEX F NASA MARS SURVEYOR PROJECT 2001 ODYSSEY ORBITER
PROXIMITY SPACE LINK CAPABILITIES (INFORMATIVE) . F-1
ANNEX G NASA MARS RECONNAISSANCE ORBITER 2005 PROXIMITY
SPACE LINK CAPABILITIES (INFORMATIVE) . G-1
ANNEX H INFORMATIVE REFERENCES (INFORMATIVE) . H-1
ANNEX I ABBREVIATIONS AND ACRONYMS (INFORMATIVE) . I-1
ANNEX J PROXIMITY-1 DATA FORMAT HIERARCHY (INFORMATIVE) . J-1
Figure
1-1 Bit Numbering Convention . 1-6
1-2 Proximity-1 Rate Terminology . 1-7
2-1 Proximity-1 Layered Protocol Model . 2-2
3-1 Proximity-1 Protocol Data Unit Context Diagram . 3-1
3-2 Version-3 Transfer Frame . 3-2
CCSDS 211.0-B-5 Page vii December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
CONTENTS (continued)
Figure Page
3-3 Transfer Frame Header . 3-3
3-4 Proximity-1 Transfer Frame Data Field Contents of a U-Frame . 3-9
3-5 Proximity Link Control Word Fields . 3-13
4-1 COP-P Process . 4-6
5-1 Proximity Time Tag Recording . 5-2
5-2 Transferring Time to a Remote Asset . 5-5
6-1 Full Duplex State Transition Diagram . 6-20
6-2 Half Duplex State Transition Diagram . 6-25
6-3 Simplex Operations . 6-31
B-1 Type 1 SPDU Data Field Contents .B-2
B-2 SET TRANSMITTER PARAMETERS Directive .B-3
B-3 SET CONTROL PARAMETERS Directive .B-6
B-4 SET RECEIVER PARAMETERS Directive .B-9
B-5 SET V(R) Directive .B-12
B-6 Report Request .B-13
B-7 SET PL EXTENSIONS .B-15
B-8 Report Source Spacecraft ID .B-19
B-9 Type 2 SPDU Data Field Contents .B-21
F-1 NASA Mars Surveyor Project 2001 Odyssey
SET TRANSMITTER PARAMETERS Directive . F-2
F-2 NASA Mars Surveyor Project 2001 Odyssey
SET RECEIVER PARAMETERS Directive . F-4
F-3 Proximity Link Control Word Fields . F-7

Table
3-1 U-Frame Data Field Construction Rules . 3-4
3-2 Setting the SCID Field and Source-or-Destination Identifier
When the Frame Is Created . 3-6
3-3 SCID Field and Source-or-Destination Identifier When the
Frame Is Received . 3-7
3-4 Segment Header Sequence Flags . 3-10
3-5 Fixed-Length Supervisory Protocol Data Unit . 3-12
3-6 Variable-Length Supervisory Protocol Data Unit . 3-15
6-1 Proximity-1 Data Services Operations Roadmap . 6-1
6-2 States Independent of the DUPLEX Variable . 6-2
6-3 States When DUPLEX = Full . 6-3
6-4 States When DUPLEX = Half . 6-4
6-5 States When DUPLEX = Simplex (Receive or Transmit) . 6-6
6-6 Proximity-1 Control Variable Initialization Table . 6-16
CCSDS 211.0-B-5 Page viii December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
CONTENTS (continued)
Table Page
6-7 Full Duplex Session Establishment/Data Services State Transition Table . 6-21
6-8 Full Duplex Communication Change State Table . 6-23
6-9 Full Duplex Session Termination State Table . 6-24
6-10 Half Duplex Session Establishment and Data Services . 6-26
6-11 Half Duplex Communication Change State Table . 6-29
6-12 Half Duplex Session Termination State Table . 6-29
6-13 Simplex State Transition Table . 6-31
6-14 Data Source Selection for Output Coded Symbol Stream with
TRANSMIT = on and MODULATION = on . 6-33

CCSDS 211.0-B-5 Page ix December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
1 INTRODUCTION
1.1 PURPOSE
The purpose of this Recommended Standard is to specify the Data Link Layer used with the
Proximity-1 Data Link Coding and Synchronization Sublayer (reference [5]) and Physical
Layer (reference [6]). Proximity space links are defined to be short-range, bi-directional,
fixed or mobile radio links, generally used to communicate among probes, landers, rovers,
orbiting constellations, and orbiting relays. These links are characterized by short time
delays, moderate (not weak) signals, and short, independent sessions.
1.2 SCOPE
This Recommended Standard defines the Data Link Layer (Framing, Medium Access Control,
Data Services, and Input/Output [I/O] Sublayers). The specifications for the protocol data
units, framing, media access control, expedited and sequenced-controlled data transfer,
timing service, I/O control, and the procedures for establishing and terminating a session
between a caller and responder are defined in this document. The Coding and
Synchronization Sublayer is defined in the separate CCSDS Recommended Standard entitled,
Proximity-1 Space Link Protocol—Coding and Synchronization Sublayer (reference [5]). The
Physical Layer is defined in the separate CCSDS Recommended Standard entitled, Proximity-1
Space Link Protocol—Physical Layer (reference [6]).
This Recommended Standard does not specify a) individual implementations or products, b)
implementation of service interfaces within real systems, c) the methods or technologies
required to perform the procedures, or d) the management activities required to configure and
control the protocol.
1.3 APPLICABILITY
This Recommended Standard applies to the creation of Agency standards and to future data
communications over space links between CCSDS Agencies in cross-support situations. It
applies also to internal Agency links where no cross support is required. It includes
specification of the services and protocols for inter-Agency cross support. It is neither a
specification of, nor a design for, systems that may be implemented for existing or future
missions.
The Recommended Standard specified in this document is to be invoked through the normal
standards programs of each CCSDS Agency and is applicable to those missions for which
cross support based on capabilities described in this Recommended Standard is anticipated.
Where mandatory capabilities are clearly indicated in sections of this Recommended
Standard, they must be implemented when this document is used as a basis for cross support.
Where options are allowed or implied, implementation of these options is subject to specific
bilateral cross-support agreements between the Agencies involved.
CCSDS 211.0-B-5 Page 1-1 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
1.4 RATIONALE
The CCSDS believes it is important to document the rationale underlying the
recommendations chosen, so that future evaluations of proposed changes or improvements
will not lose sight of previous decisions. Concepts and rationale behind the decisions that
formed the basis for Proximity-1 are documented in the CCSDS Proximity-1 Space Link
Green Book (reference [H9]).
1.5 CONVENTIONS AND DEFINITIONS
1.5.1 DEFINITIONS
1.5.1.1 Terms from the Open Systems Interconnection (OSI) Basic Reference Model
This Recommended Standard makes use of a number of terms defined in reference [1]. In
this Recommended Standard those terms are used 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 as follows:
a) connection;
b) Data Link Layer;
c) entity;
d) Physical Layer;
e) protocol control information;
f) protocol data unit;
g) real system;
h) segmenting;
i) service;
j) service data unit.
1.5.1.2 Terms Defined in This Recommended Standard
For the purposes of this Recommended Standard, the following definitions also apply. Many
other terms that pertain to specific items are defined in the appropriate sections.
asynchronous data link: A data link consisting of a sequence of variable-length Proximity
Link Transmission Units (PLTUs), which are not necessarily concatenated.
caller and responder: Initiator and receiver, respectively, in a Proximity space link session.
A caller transceiver is the initiator of the link establishment process and manager of
CCSDS 211.0-B-5 Page 1-2 December 2013
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negotiation (if required) of the session. A responder transceiver typically receives
link establishment parameters from the caller. The caller initiates communication
between itself and a responder on a prearranged communications channel with
predefined controlling parameters. As necessary, the caller and responder may
negotiate the controlling parameters for the session (at some level between fully
controlled and completely adaptive).
COP-P: Communication Operations Procedure for Proximity links (COP-P). The COP-P
includes both the FARM-P and FOP-P of the caller and responder unit.
enterprise: A project or undertaking, especially one of some scope, complexity, and risk.
FARM-P: Frame Acceptance and Reporting Mechanism for Proximity links, for Sequence
Controlled service carried out within the receiver in the Proximity-1 link.
FOP-P: Frame Operation Procedure for Proximity links, for ordering the output frames for
Sequence Controlled service carried out in the transmitter in the Proximity-1 link.
forward link: That portion of a Proximity space link in which the caller transmits and the
responder receives (typically a command link).
hailing: The persistent activity used to establish a Proximity link by a caller to a responder
in either full or half duplex. It does not apply to simplex operations.
hailing channel: The forward and return frequency pairs that a caller and responder use to
establish physical link communications.
mission phase: A mission period during which specified communications characteristics are
fixed. The transition between two consecutive mission phases may cause an
interruption of the communications services.
PCID: Physical Channel ID, carried in transfer frames and in PLCWs. The PCID is intended
primarily for a receiving system having two concurrently operating transceiver units
(primary and backup, for example), where the PCID can be used to select which
receiver processes the received frame. It may identify either of two redundant
receivers at the receiving end.
P-frame: A Version-3 Transfer Frame that contains only self-identified and self-delimited
supervisory protocol data units (compare U-frame).
physical channel: The Radio Frequency (RF) channel upon which the stream of symbols is
transferred over a space link in a single direction.
PLCW: Proximity Link Control Word, the protocol data unit for reporting Sequence
Controlled service status via the return link from the responder back to the caller.
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PLTU: Proximity Link Transmission Unit, the data unit composed of the Attached
Synchronization Marker (ASM), the Version-3 Transfer Frame, and the attached
Cyclic Redundancy Check (CRC)-32.
Port ID: Identifier of the logical or physical port that is the destination for a user’s service
data unit.
protocol object: Directives, PLCWs, or status reports contained within an SPDU.
Proximity link: A full-duplex, half-duplex, or simplex link for the transfer of data between
Proximity-1 nodes in a session.
pseudo packet ID: The temporary packet ID assigned by the protocol to a user’s packet
within the segmentation process.
reconnect: Process in which the caller attempts to rehail the responder (because of lack of
communication progress) during the data services phase within the ongoing session.
Upon entering this state, the FARM-P and FOP-P variables of the caller and
responder are not reset (in particular their frame sequence counters).
resynchronization (COP-P): Process in which a sequence count anomaly is detected by the
caller and the caller forces the responder to readjust its Sequence Controlled frame
numbers via the SET V(R) activity.
return link: That portion of a Proximity space link in which the responder transmits and the
caller receives (typically a telemetry link).
Routing ID: Unique identifier of a user’s packet through the segmentation and reassembly
process. It is an internal identifier used by the I/O Sublayer and it consists of a PCID,
Port ID, and pseudo packet ID.
Sent queue (Sent Frame queue): Temporarily stored Sequence Controlled frames that have
been sent but not yet acknowledged by the receiver.
session: A dialog between two or more communicating Proximity link transceivers. A
session consists of three distinct operational phases: session establishment, data
services (which may include resynchronization and/or reconnect subphases), and
session termination. Session termination may be coordinated (through the exchange
of no-more-data-to-send directives), or if communication is lost (inability to
resynchronize or reconnect), the transceivers should eventually independently
conclude the dialog is over.
space link: A communications link between transmitting and receiving entities, at least one
of which is in space.
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SPDU: Supervisory Protocol Data Unit, used by the local transceiver either to control or to
report status to the remote partnered transceiver. Consists of one or more directives,
reports, or PLCWs.
synchronous channel: A data channel where the symbol data are continuously modulated
onto the channel at a fixed data rate. When no PLTU is available for transmission,
Idle data is transmitted to maintain the continuous symbol stream.
U-frame: A Version-3 Transfer Frame that contains user data information (compare P-
frame).
vehicle controller: The entity (e.g., spacecraft control computer) which receives the
notifications defined in annex D and potentially acts upon them.
Version-3 Transfer Frame: A Proximity-1 transfer frame.
1.5.2 NOMENCLATURE
1.5.2.1 NORMATIVE TEXT
The following conventions apply for the normative specifications in this Recommended
Standard:
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;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in text that is clearly
informative in nature.
1.5.2.2 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.
CCSDS 211.0-B-5 Page 1-5 December 2013
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1.5.3 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) is the first transmitted bit of the field, i.e., ‘Bit 0’, as shown in figure 1-1.
BIT 0 BIT N-1
N-BIT DATA FIELD
FIRST BIT TRANSMITTED = MSB
Figure 1-1: Bit Numbering Convention
In accordance with standard data-communications practice, data fields are often grouped into
8-bit ‘words’ that conform to the above convention. Throughout this Recommended
Standard, such an 8-bit word is called an ‘octet’.
The numbering for octets within a data structure begins with zero. Octet zero is the first
octet to be transmitted.
By CCSDS convention, all ‘spare’ bits are permanently set to value ‘zero’.
Throughout this Recommended Standard, directive, parameter, variable, and signal names
are presented with all upper-case characters; data-field and Management Information Base
(MIB)-parameter names are presented with initial capitalization; values and state names are
presented with predominantly lower-case characters, and are italicized.
In Proximity-1, data rate (R ), coded symbol rate (R ), and channel symbol rate (R ) are
d cs chs
used to denote respectively:
– the data rate of the bitstream composed by PLTUs and Idle data measured at the
encoder input;
– the coded symbol rate measured at the interface between the Coding and
Synchronization Sublayer and the Physical Layer; and
– the rate measured at the output of the transmitter.
The terms are used as shown in figure 1-2.
CCSDS 211.0-B-5 Page 1-6 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
BITSTREAM CODED CHANNEL
FOR ENCODING SYMBOLS
SYMBOLS
ENCODER RF POWER AMPLIFIER
Bi-Phase-L
(or Bypass) MODULATOR & RF CHAIN
CHANNEL
SYMBOL RATE
DATA RATE CODED SYMBOL RATE
REFERENCE
REFERENCE POINT REFERENCE POINT
POINT
(R ) (R )
d cs
(R )
chs
Figure 1-2: Proximity-1 Rate Terminology
1.6 REFERENCES
The following publications contain provisions which, through reference in this text,
constitute provisions of this document. At the time of publication, the editions indicated
were valid. All publications are subject to revision, and users of this document are
encouraged to investigate the possibility of applying the most recent editions of the
publications indicated below. The CCSDS Secretariat maintains a register of currently valid
CCSDS publications.
[1] Information Technology—Open Systems Interconnection—Basic Reference Model: The
Basic Model. International Standard, ISO/IEC 7498-1:1994. 2nd ed. Geneva: ISO,
1994.
[2] TM Synchronization and Channel Coding. Issue 2. Recommendation for Space Data
System Standards (Blue Book), CCSDS 131.0-B-2. Washington, D.C.: CCSDS, August
2011.
[3] CCSDS Global Spacecraft Identification Field Code Assignment Control Procedures.
Issue 6. Recommendation for Space Data System Standards (Blue Book), CCSDS
320.0-B-6. Washington, D.C.: CCSDS, October 2013.
[4] Time Code Formats. Issue 4. Recommendation for Space Data System Standards (Blue
Book), CCSDS 301.0-B-4. Washington, D.C.: CCSDS, November 2010.
[5] Proximity-1 Space Link Protocol—Coding and Synchronization Sublayer. Issue 2.
Recommendation for Space Data System Standards (Blue Book), CCSDS 211.2-B-2.
Washington, D.C.: CCSDS, December 2013.
[6] Proximity-1 Space Link Protocol—Physical Layer. Issue 4. Recommendation for Space
Data System Standards (Blue Book), CCSDS 211.1-B-4. Washington, D.C.: CCSDS,
December 2013.
CCSDS 211.0-B-5 Page 1-7 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
2 OVERVIEW
2.1 CONCEPT OF PROXIMITY-1
Proximity-1 is a bi-directional Space Link Layer protocol for use by space missions. It has
been designed to meet the requirements of space missions for efficient transfer of data over
various types and characteristics of Proximity space links.
2.1.1 LAYERED MODEL
The Proximity-1 model consists of a Physical Layer (reference [6]) and a Data Link Layer.
Proximity-1 activities are divided between a send side and a receive side. The send side is
concerned with the transmitted physical channel, and also with the acquisition of the received
physical channel in order to establish a Proximity-1 link. The receive side is concerned with
the reception of data on the received physical channel: the input bitstream and the protocol
data units it contains.
On the send side, the Data Link Layer is responsible for providing data to be transmitted by
the Physical Layer. The operation of the transmitter is state-driven.
On the receive side, the Data Link Layer accepts the serial data output from the receiver and
processes the protocol data units received. It accepts directives both from the local vehicle
controller and across the Proximity link to control its operations. Once the receiver is turned
on, its operation is modeless. It accepts and processes all valid local and remote directives
and delivers received service data units to the users.
The interactions of the Proximity-1 layers and associated data and control flows are shown in
figure 2-1.
2.1.2 PHYSICAL LAYER
On the send side, the Physical Layer:
– accepts control variables from the Data Link Layer for control of the transceiver;
– accepts a PLTU from the Coding and Synchronization Sublayer for modulation onto
the radiated carrier;
– performs the required (as specified by the control variables) channel coding.
On the receive side, the Physical Layer:
– provides status signals (CARRIER_ACQUIRED and SYMBOL_INLOCK_STATUS)
to the Data Link Layer;
– outputs the serial coded symbol stream from the receiver’s Physical Layer to the
Coding and Synchronization Sublayer.
CCSDS 211.0-B-5 Page 2-1 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
CCSDS 211.0-B-5 Page 2-2 December 2013
LOCAL S/C
CONTROLLER INPUT of USER DATA + Routing Info
USER DATA Delivery
QOS Port SDUs Type Other
Directives
SEND   RECEIVE
SDUs
Flow
SDU
I/O Ports
Control
Acknowledgement
Status
(8/ per VC)
Of Delivery
I/O Sublayer
Seq. Ctrl Expedited
Transmit
Frame Q Frame Q
Duplex
& Mode P/U-Frame
U-Frame
U-Frame
MAC
Expedited
New SC Expedited Q
Seq. Ctrl Q
Frame Q
Frame Q Available
Sublayer Available
NN(R)
Retransmit-R(S)
VV(S)
Sent
Send
Data Services
Data Frame Select
Frame Q
PLCW
(MIB)
VE(S)
or Status
Sublayer
Status
Frame Pending
V(R)
V(R)+NN(R)
P/U-Frame
U-Frame
Persistence
Accepted
NEED
Received
MAC Frame Pending Select for Output
U-Frames
MAC
PLCW
PLCW
Frame
MAC P-Frame
U-Frames
Queue
Accepted
Frame Sublayer
Supervisory Frames
Received SPDUs
P-Frames
Processing (extract PLCWs)
Frame Ready
Frame
Frame
Transmit
Frame to Send
TimeTag
Modulate
Coding & Synchronization Sublayer
Output Coded Symbol Stream
CARRIER_ACQUIRED
Received Coded Symbols Key:
Doppler
SYMBOL_IN_LOCK_STATUS Physical Layer
RF Out Control/Status
RF In
Measurements
Data
Figure 2-1: Proximity-1 Layered Protocol Model

CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE DATA LINK PROTOCOL
2.1.3 DATA LINK LAYER
2.1.3.1 Sublayers in the Data Link Layer
There are five component sublayers within the Data Link Layer:
– Coding and Synchronization (C&S) Sublayer;
– Frame Sublayer;
– Medium Access Control (MAC) Sublayer;
– Data Services Sublayer;
– I/O Sublayer.
2.1.3.2 Coding and Synchronization Sublayer
The C&S Sublayer is specified separately in reference [5]. On the send side, the actions of
the C&S Sublayer include:
– construction of PLTUs, where each PLTU contains a Version-3 Transfer Frame
received from the Frame Sublayer;
– provision of the coded symbol stream (including PLTU and Idle data) to the Physical
Layer for inclusion of Idle data, adding channel coding and modulation onto the
radiated carrier.
On the receive side, the C&S Sublayer actions include:
– delimiting each PLTU contained in the data output from the receiver in the Physical
Layer;
– validation of the PLTUs, including channel decoding;
– for each valid PLTU, delivering the delimited transfer frame to the Frame Sublayer.
On both the send and receive sides, the C&S Sublayer provides time-tagged data on request
to support the Proximity-1 timing services.
2.1.3.3 Frame Sublayer
Subsection 4.1 specifies the functions of the Frame Sublayer. On the send side, the Frame
Sublayer:
– creates Version-3 Transfer Frames, carrying user data or protocol d
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