ISO 22670:2006

INTERNATIONAL ISO
STANDARD 22670
First edition
2006-04-15
Space data and information transfer
systems — Space link extension (SLE) —
Return-channel-frames service
Systèmes de transfert des informations et données spatiales —
Extension de liaisons spatiales (SLE) — Service de réseau pour liaison
retour
Reference number
©
ISO 2006
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ii © ISO 2006 – 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 22670 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 911.2-B-1, November 2004) 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.

INTERNATIONAL STANDARD ISO 22670:2006(E)

Space data and information transfer systems — Space link
extension (SLE) — Return-channel-frames service
1 Scope
This International Standard specifies a return-channel-frames (RCF) service for a space link extension (SLE).
The RCF service is an SLE transfer service that delivers to a mission user all telemetry frames from one
master channel or one virtual channel.
It defines, in an abstract manner, the RCF service in terms of:
a) the operations necessary to provide the service;
b) the parameter data associated with each operation;
c) the behaviours that result from the invocation of each operation; and
d) the relationship between, and the valid sequence of, the operations and resulting behaviours.
The scope and field of application are furthermore detailed in subclauses 1.2 and 1.3 of the enclosed CCSDS
publication.
2 Requirements
Requirements are the technical recommendations made in the following publication (reproduced on the
following pages), which is adopted as an International Standard:
CCSDS 911.2-B-1, November 2004, Space link extension — Return channel frames service specification.
For the purposes of international standardization, the modifications outlined below shall apply to the specific
clauses and paragraphs of publication CCSDS 911.2-B-1.
Pages i to v
This part is information which is relevant to the CCSDS publication only.
Page 1-14
Add the following information to the reference indicated:
[1] Document CCSDS 910.4-B-1, May 1996, is equivalent to ISO 15396:1998.
[2] Document CCSDS 131.0-B-1, September 2003, is equivalent to ISO 22641:2005.
[3] Document CCSDS 132.0-B-1, September 2003, is equivalent to ISO 22645:2005.
[4] Document CCSDS 732.0-B-1, September 2003, is equivalent to ISO 22666:2005
[5] Document CCSDS 301.0-B-3, January 2002, is equivalent to ISO 11104:2003
[7] ISO/IEC 8824:1998 (all parts) has been cancelled and replaced by ISO/IEC 8824:2002 (all parts),
Information technology — Abstract Syntax Notation One (ASN.1)
3 Revision of publication CCSDS 911.2-B-1
It has been agreed with the Consultative Committee for Space Data Systems that Subcommittee
ISO/TC 20/SC 13 will be consulted in the event of any revision or amendment of publication
CCSDS 911.2-B-1. To this end, NASA will act as a liaison body between CCSDS and ISO.

2 © ISO 2006 – All rights reserved

RECOMMENDATION FOR SPACE
DATA SYSTEM STANDARDS
SPACE LINK EXTENSION—
RETURN CHANNEL
FRAMES SERVICE
SPECIFICATION
CCSDS 911.2-B-1
Blue BOOK
November 2004
(Blank page)
4 © ISO 2006 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
AUTHORITY
Issue: Blue Book, Issue 1
Date: November 2004
Location: Toulouse, France
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 Recommendations is detailed in the Procedures Manual
for the Consultative Committee for Space Data Systems, and the record of Agency
participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This Recommendation is published and maintained by:

CCSDS Secretariat
Office of Space Communication (Code M-3)
National Aeronautics and Space Administration
Washington, DC 20546, USA
CCSDS 911.2-B-1 Page i November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
STATEMENT OF INTENT
(WHEN THIS RECOMMENDATION IS FINALIZED, IT WILL CONTAIN THE
FOLLOWING STATEMENT OF AUTHORITY:)

The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of member space Agencies. 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 considered binding on any Agency.
This Recommendation is issued by, and represents the consensus of, the CCSDS Plenary
body. Agency endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:

o Whenever an Agency establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommendation. Establishing such a standard does not
preclude other provisions which an Agency may develop.

o Whenever an Agency establishes a CCSDS-related standard, the Agency will provide
other CCSDS member Agencies 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
Recommendation nor any ensuing standard is a substitute for a memorandum of
agreement.
No later than five years from its date of issuance, this Recommendation 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 Recommendation is issued, existing CCSDS-
related Agency standards and implementations are not negated or deemed to be non-CCSDS
compatible. It is the responsibility of each Agency to determine when such standards or
implementations are to be modified. Each Agency is, however, strongly encouraged to direct
planning for its new standards and implementations towards the later version of the
Recommendation.
CCSDS 911.2-B-1 Page ii November 2004
6 © ISO 2006 – All rights reserved

CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
FOREWORD
(WHEN THIS RECOMMENDATION IS FINALIZED, IT WILL CONTAIN THE
FOLLOWING STATEMENT OF AUTHORITY:)

This document is a technical Recommendation for use in developing ground systems for
space missions and has been prepared by the Consultative Committee for Space Data
Systems (CCSDS). The Space Link Extension Return Channel Frames Service described
herein is intended for missions that are cross-supported between Agencies of the CCSDS.
This Recommendation specifies a data service that extends certain of the space-to-ground
communications services previously defined by CCSDS (references [2], [3], and [4]) within
the framework established by the CCSDS Space Link Extension Reference Model (reference
[1]). It allows implementing organizations within each Agency to proceed with the
development of compatible, derived Standards for the ground systems that are within their
cognizance. Derived Agency Standards may implement only a subset of the optional
features allowed by the Recommendation and may incorporate features not addressed by the
Recommendation.
Through the process of normal evolution, it is expected that expansion, deletion or
modification to this document may occur. This Recommendation is therefore subject to
CCSDS document management and change control procedures, as 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 911.2-B-1 Page iii November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
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.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
– Russian Federal Space Agency (FSA)/Russian Federation.

Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– Centro Tecnico Aeroespacial (CTA)/Brazil.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Communications Research Laboratory (CRL)/Japan.
– Danish Space Research Institute (DSRI)/Denmark.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Federal Service of Scientific, Technical & Cultural Affairs (FSST&CA)/Belgium.
– 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.
– MIKOMTEK: CSIR (CSIR)/Republic of South Africa.
– Korea Aerospace Research Institute (KARI)/Korea.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic & Atmospheric Administration (NOAA)/USA.
– National Space Program Office (NSPO)/Taipei.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– United States Geological Survey (USGS)/USA.

CCSDS 911.2-B-1 Page iv November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
DOCUMENT CONTROL
Document Title Date Status
CCSDS Space Link Extension— November 2004 Blue Book
911.2-B-1 Return Channel Frames Service
Specification
CCSDS 911.2-B-1 Page v November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
CONTENTS
Section Page
1 INTRODUCTION. 1-1

1.1 PURPOSE OF THIS RECOMMENDATION. 1-1
1.2 SCOPE.1-1
1.3 APPLICABILITY.1-2
1.4 RATIONALE.1-2
1.5 DOCUMENT STRUCTURE.1-2
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS . 1-5
1.7 REFERENCES.1-13

2 DESCRIPTION OF THE RETURN CHANNEL FRAMES SERVICE . 2-15

2.1 OVERVIEW.2-15
2.2 SPACE LINK EXTENSION REFERENCE MODEL. 2-16
2.3 SERVICE MANAGEMENT.2-17
2.4 ARCHITECTURE MODEL—FUNCTIONAL VIEW. 2-18
2.5 ARCHITECTURE MODEL—CROSS SUPPORT VIEW . 2-21
2.6 FUNCTIONAL DESCRIPTION.2-22
2.7 OPERATIONAL SCENARIO.2-31
2.8 SECURITY ASPECTS OF THE SLE RCF TRANSFER SERVICE . 2-33

3 RCF SERVICE OPERATIONS . 3-1

3.1 GENERAL CONSIDERATIONS . 3-1
3.2 RCF-BIND.3-14
3.3 RCF-UNBIND.3-20
3.4 RCF-START.3-24
3.5 RCF-STOP.3-30
3.6 RCF-TRANSFER-DATA.3-32
3.7 RCF-SYNC-NOTIFY.3-35
3.8 RCF-SCHEDULE-STATUS-REPORT.3-39
3.9 RCF-STATUS-REPORT.3-43
3.10 RCF-GET-PARAMETER.3-46
3.11 RCF-PEER-ABORT.3-50

4 RCF PROTOCOL . 4-1

4.1 GENERIC PROTOCOL CHARACTERISTICS. 4-1
4.2 RCF SERVICE PROVIDER BEHAVIOR. 4-4
CCSDS 911.2-B-1 Page vi November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
CONTENTS (continued)
Section Page
ANNEX A Data Type Definitions. A-1
ANNEX B Index to Definitions.B-1
ANNEX C Acronyms. C-1
ANNEX D Conformance Matrix . D-1
ANNEX E Informative References.E-1

Figure
1-1 SLE Services Documentation. 1-4
2-1 Return Frame Processing SLE-FG . 2-18
2-2 RCF Service Production and Provision. 2-21
2-3 Example of the Management and Provision of RCF Service. 2-22
2-4 Simplified RCF Service Provider State Transition Diagram . 2-25
2-5 Communications Realization of RCF Service. 2-27
2-6 Buffers and Delivery Modes . 2-31

Table
2-1 RCF Operations . 2-23
3-1 Setting of RCF Service Configuration Parameters. 3-5
3-2 RCF-BIND Parameters. 3-15
3-3 RCF-UNBIND Parameters. 3-21
3-4 RCF-START Parameters. 3-25
3-5 RCF-STOP Parameters. 3-30
3-6 RCF-TRANSFER-DATA Parameters. 3-32
3-7 RCF-SYNC-NOTIFY Parameters. 3-35
3-8 RCF-SCHEDULE-STATUS-REPORT Parameters. 3-40
3-9 RCF-STATUS-REPORT Parameters. 3-43
3-10 RCF-GET-PARAMETER Parameters . 3-46
3-11 RCF Parameters. 3-48
3-12 RCF-PEER-ABORT Parameters. 3-50
4-1  Provider Behavior. 4-6
4-2 Event Description References . 4-12
4-3 Predicate Descriptions. 4-12
4-4 Boolean Flags . 4-13
4-5 Compound Action Definitions. 4-13
D-1 Conformance Matrix for RCF Service (Operations) . D-1
D-2 Conformance Matrix for RCF Service (Other Requirements) . D-2

CCSDS 911.2-B-1 Page vii November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
1 INTRODUCTION
1.1 PURPOSE OF THIS RECOMMENDATION
The purpose of this Recommendation is to define the Space Link Extension (SLE) Return
Channel Frames (RCF) service in conformance with the SLE Reference Model (reference
[1]). The RCF service is an SLE transfer service that delivers to a mission user all telemetry
frames from one master channel or one virtual channel.
NOTE – The first issue of reference [1] defines the Return Master Channel Frames (Rtn
MC Frames) service and the Return Virtual Channel Frames (Rtn VC Frames)
service as two distinct services. Subsequent study has indicated that it is
preferable to define one service that provides the functionality of both. The RCF
service defined here does just that. It is anticipated that the next issue of
reference [1] will take the same approach, deleting the Rtn MC Frames and R VC
Frames services and replacing them with the RCF service.
1.2 SCOPE
This Recommendation defines, in an abstract manner, the RCF service in terms of:
a) the operations necessary to provide the service;
b) the parameter data associated with each operation;
c) the behaviors that result from the invocation of each operation; and
d) the relationship between, and the valid sequence of, the operations and resulting
behaviors.
It does not specify:
a) individual implementations or products;
b) the implementation of entities or interfaces within real systems;
c) the methods or technologies required to acquire telemetry frames from signals
received from a spacecraft;
d) the methods or technologies required to provide a suienvironment for
communications; or
e) the management activities required to schedule, configure, and control the RCF service.
CCSDS 911.2-B-1 Page 1-1 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
1.3 APPLICABILITY
1.3.1 APPLICABILITY OF THIS RECOMMENDATION
This Recommendation provides a basis for the development of real systems that implement
the RCF service. Implementation of the RCF service in a real system additionally requires
the availability of a communications service to convey invocations and returns of RCF
service operations between RCF service users and providers. This Recommendation requires
that such a communications service must ensure that invocations and returns of operations
are transferred:
a) in sequence;
b) completely and with integrity;
c) without duplication;
d) with flow control that notifies the application layer in the event of congestion; and
e) with notification to the application layer in the event that communications between
the RCF service user and the RCF service provider are disrupted, possibly resulting in
a loss of data.
It is the specific intent of this Recommendation to define the RCF service in a manner that is
independent of any particular communications services, protocols, or technologies.
1.3.2 LIMITS OF APPLICABILITY
This Recommendation specifies the RCF service that may be provided by an SLE Complex
for inter-Agency cross support. It is neither a specification of, nor a design for, real systems
that may be implemented for the control and monitoring of existing or future missions.
1.4 RATIONALE
The goal of this Recommendation is to create a standard for interoperability between the
tracking stations or ground data handling systems of various Agencies and the consumers of
spacecraft telemetry.
1.5 DOCUMENT STRUCTURE
1.5.1 ORGANIZATION
This document is organized as follows:
a) section 1 presents the purpose, scope, applicability and rationale of this
Recommendation and lists the definitions, conventions, and references used
throughout the Recommendation;
CCSDS 911.2-B-1 Page 1-2 November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
b) section 2 provides an overview of the RCF service including a functional description,
the service management context, and protocol considerations;
c) section 3 specifies the operations of the RCF service;
d) section 4 specifies the dynamic behavior of the RCF service in terms of the state
transitions of the RCF service provider;
e) annex A provides a formal specification of RCF service data types using Abstract
Syntax Notation One (ASN.1);
f) annex B lists all terms used in this Recommendation and identifies where they are
defined;
g) annex C lists all acronyms used within this document;
h) annex D provides a conformance matrix that defines what capabilities must be
provided for an implementation to be considered compliant with this
Recommendation;
i) annex E provides a list of informative references.
1.5.2 SLE SERVICES DOCUMENTATION TREE
This Recommendation is based on the cross support model defined in the SLE Reference
Model (reference [1]). It expands upon the concept of an SLE transfer service as an
interaction between an SLE Mission User Entity (MUE) and an SLE transfer service
provider for the purpose of providing the RCF transfer service.
This Recommendation is part of a suite of documents specifying the SLE services. The SLE
services constitute one of the three types of Cross Support Services:
a) Part 1: SLE Services;
b) Part 2: Ground Domain Services;
c) Part 3: Ground Communications Services.
The basic organization of the SLE services documentation is shown in figure 1-1. The
various documents are described in the following subsections.
CCSDS 911.2-B-1 Page 1-3 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
SpaceSpace Link E Link Exxtensiotensionn
CCrroosss Ss Suupppporortt
CCrroossss S Suuppppoorrt Ct Conconceptept SLSLE EE Exxeeccuuttivive e
RRefeefererence Monce Modeldel
SSuummammaryry
PPaarrtt 11:: S SLLE SeE Serrvviciceess
PaParrtt 11:: S SLLEE Se Serrvviicceess
SLE Transfer Services
SLE TransfSLE Transfeerr Se Servicrviceess
FFFooorrrwwwarararddd S S SLLLE SeE SeE Serrrvvviciciceee  ReReRetttuuurrrnnn S S SLLLE SeE SeE Serrrvvviciciceee  SSSLLLE APE APE APIII f f fooorrr  SLSLSLE SeE SeE Serrrvvviiiccceee
SpeciSpeciSpecifffiiicccatiatiatiooonsnsns  TTTrrrananansfsfsfer Ser Ser Seeervirvirviccceseses
SSSpecipecipecifffiiicccatiatiatiooonsnsns MMMaaanananagegegememementntnt S S Suuuiiittteee
Legend:
Recommendation Report (Green) Report (Yellow)

Figure 1-1: SLE Services Documentation
a) Cross Support Concept—Part 1: Space Link Extension Services (reference [E2]): a
Report introducing the concepts of cross support and the SLE services;
b) Cross Support Reference Model—Part 1: Space Link Extension Services (reference
[1]): a Recommendation that defines the framework and terminology for the
specification of SLE services;
c) SLE Return Service Specifications: a set of Recommendations that will provide
specification of all return link SLE services (this Recommendation is one of the
specifications in that set);
d) SLE Forward Service Specifications: a set of Recommendations that will provide
specification of all forward link SLE services;
e) SLE Service Management Specifications: a set of Recommendations that establish
the basis of SLE service management.

CCSDS 911.2-B-1 Page 1-4 November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
1.6 DEFINITIONS, NOMENCLATURE, AND CONVENTIONS
1.6.1 DEFINITIONS
1.6.1.1 Definitions from Open Systems Interconnection (OSI) Basic Reference Model
This Recommendation makes use of a number of terms defined in reference [6]. The use of
those terms in this Recommendation shall be understood in a generic sense; i.e., in the sense
that those terms are generally applicable to technologies that provide for the exchange of
information between real systems. Those terms are:
a) abstract syntax;
b) application entity;
c) application layer;
d) application process;
e) flow control;
f) Open Systems Interconnection (OSI);
g) real system;
h) Service Access Point (SAP).
1.6.1.2 Definitions from Abstract Syntax Notation One
This Recommendation makes use of the following terms defined in reference [7]:
a) Abstract Syntax Notation One (ASN.1);
b) object identifier;
c) (data) type;
d) (data) value.
NOTE – In annex A of this Recommendation, ASN.1 is used for specifying the abstract
syntax of RCF service operation invocations and returns. The use of ASN.1 as a
descriptive language is intended to support the specification of the abstract RCF
service; it is not intended to constrain implementations. In particular, there is no
requirement for implementations to employ ASN.1 encoding rules. ASN.1 is
simply a convenient tool for formally describing the abstract syntax of RCF
service operation invocations and returns.
1.6.1.3 Definitions from TM Synchronization and Channel Coding
This Recommendation makes use of the following terms defined in reference [2]:
CCSDS 911.2-B-1 Page 1-5 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
a) Attached Sync Marker;
b) Reed-Solomon check symbols;
c) Reed-Solomon code.
1.6.1.4 Definitions from TM Space Data Link Protocol
This Recommendation makes use of the following term defined in reference [3]:
a) Frame Error Control Field (FECF);
b) TM Transfer Frame.
1.6.1.5 Definitions from AOS Space Data Link Protocol
This Recommendation makes use of the following terms defined in reference [4]:
a) AOS Transfer Frame;
b) Frame Error Control Field (FECF);
1.6.1.6 Definitions from SLE Reference Model
This Recommendation makes use of the following terms defined in reference [1]:
a) abstract binding;
b) abstract object;
c) abstract port;
d) abstract service;
e) invoker;
f) Mission Data Operation System (MDOS);
g) Mission User Entity (MUE);
h) offline delivery mode;
i) online delivery mode;
j) operation;
k) performer;
l) physical channel;
m) return data;
CCSDS 911.2-B-1 Page 1-6 November 2004
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
n) Return All Frames channel (RAF channel);
o) Return All Frames service (RAF service);
p) Return Master Channel Frame Service (MC service)
q) Return Virtual Channel Frame Service (VC Frame service)
r) service agreement;
s) service provider (provider);
t) service user (user);
u) SLE Complex;
v) SLE Complex Management;
w) SLE data channel;
x) SLE Functional Group (SLE-FG);
y) SLE Protocol Data Unit (SLE-PDU);
z) SLE Service Data Unit (SLE-SDU);
aa) SLE service package;
bb) SLE System;
cc) SLE transfer service instance;
dd) SLE transfer service production;
ee) SLE transfer service provision;
ff) SLE Utilization Management;
gg) space link;
hh) space link data channel;
ii) Space Link Data Unit (SL-DU);
jj) space link session.
1.6.1.7 Additional Definitions
1.6.1.7.1 Association
An association is a cooperative relationship between an SLE service-providing application
entity and an SLE service-using application entity. An association is formed by the
CCSDS 911.2-B-1 Page 1-7 November 2004
CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
exchange of SLE protocol data units through the use of an underlying communications
service.
1.6.1.7.2 Communications Service
A communications service is a capability that enables an SLE service-providing application
entity and an SLE service-using application entity to exchange information.
NOTE – If an SLE service user and an SLE service provider are implemented using
different communications services, then interoperability between them is possible
only by means of a suigateway. Adherence to this Recommendation ensures, at
least in principle, that it is possible to construct such a gateway.
1.6.1.7.3 Confirmed Operation
A confirmed operation is an operation that requires the performer to return a report of its
outcome to the invoker.
1.6.1.7.4 Delivery Criteria
Delivery criteria are rules that determine whether a data unit acquired from the space link by
an SLE service provider shall be delivered to a user.
NOTE – For RCF service, the delivery criteria are:
a) the Earth Receive Time (ERT) of the frame is within the period defined by the
start and stop times specified in the RCF-START operation;
b) the spacecraft identifier (SCID) of the frame matches the SCID of the global
VCID specified in the RCF-START operation; and
c) the Virtual Channel Identifier (VCID) of the frame matches the VCID of the
global VCID specified in the RCF-START operation.
1.6.1.7.5 Frame Error Control Field
The Frame Error Control Field (FECF) of a frame is the FECF of a TM Transfer Frame
(reference [3]) or the FECF of an AOS Transfer Frame (reference [4]), as applicable.
1.6.1.7.6 Frame Version Number
The frame version number is either the transfer frame version number (reference [3]) or the
version number in the AOS transfer frame primary header (reference [4]).
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
NOTE – The definitions of frame version number given in references [3] and [4] are
equivalent. If a CCSDS-compatible telemetry frame is known to contain no
errors, the frame version number enables one to distinguish between a transfer
frame and an AOS transfer frame.
1.6.1.7.7 Initiator
The initiator is the object that issues the request to bind to another object (the responder).
1.6.1.7.8 Invocation
The invocation of an operation is the making of a request by an object (the invoker) to
another object (the performer) to carry out the operation.
1.6.1.7.9 Master Channel
The sequence of all telemetry frames with the same Transfer Frame Version Number
(TFVN) and the same SCID on the same physical channel constitutes a master channel.
NOTE – Depending on the TFVN, the definition of SCID is as given in either reference
[3] or reference [4].
1.6.1.7.10 Parameter
A parameter of an operation is data that may accompany the operation’s invocation or return.
NOTE – The term parameter is also used to refer to mission-dependent configuration
information used in the production or provision of the service.
1.6.1.7.11 Performance
The performance of an operation is the carrying out of the operation by an object (the
performer).
1.6.1.7.12 Port Identifier
A port identifier identifies a source or a destination in a communications system.
NOTE – See 2.6.4.5 for more information.
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1.6.1.7.13 Responder
The responder is the object that receives a request to bind and completes the binding (if
possible) with the initiator in order for a service association to exist between the two objects.
1.6.1.7.14 Return
The return of an operation is a report, from the performer to the invoker, of the outcome of
the performance of the operation.
1.6.1.7.15 Service Instance Provision Period
A service instance provision period is the time during which a service instance (i.e., the
capability to transfer one or more SLE data channels of a given type) is scheduled to be
provided.
NOTE – Reaching of the beginning of this period constitutes the event ‘start of service
instance provision period’ (see 4.2.2).
1.6.1.7.16 Spacecraft Identifier
The spacecraft identifier (SCID) of a telemetry frame is as defined in reference [3] if the
frame is a TM Transfer Frame or as defined in reference [4] if the frame is an AOS Transfer
Frame.
1.6.1.7.17 Telemetry Frame
A telemetry frame is a TM Transfer Frame (as defined in reference [3]) or an AOS Transfer
Frame (as defined in reference [4]). In case a distinction of the frame versions is necessary,
the full term as per references [3] or [4] is used.
1.6.1.7.18 Transfer Frame Version Number
The Transfer Frame Version Number (TFVN) is either the TFVN as defined in reference [3]
or the TFVN as defined in reference [4].
NOTE – The definitions of TFVN given in references [3] and [4] are equivalent. If a
CCSDS-compatible telemetry frame is known to contain no errors, the TFVN
enables one to distinguish between a TM Transfer Frame and an AOS Transfer
Frame.
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CCSDS RECOMMENDATION FOR SLE RETURN CHANNEL FRAMES SERVICE
1.6.1.7.19 Unconfirmed Operation
An unconfirmed operation is an operation that does not require a report of its outcome to be
returned to the invoker by the performer.
1.6.1.7.20 Virtual Channel
All telemetry frames with the same TFVN, the same SCID, and the same virtual channel
identifier (VCID) on the same physical channel constitute a virtual channel.
1.6.1.7.21 Virtual Channel Identifier
The virtual channel identifier (VCID) of a telemetry frame is as defined in reference [3] if the
telemetry frame is a TM Transfer Frame or as defined in reference [4] if the telemetry frame
is an AOS Transfer Frame.
1.6.2 NOMENCLATURE
The following conventions apply throughout this Recommendation:
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.
1.6.3 CONVENTIONS
1.6.3.1 Specification of Operations
1.6.3.1.1 General
Section 3 of this Recommendation specifies the operations that constitute the RCF service.
The specification of each operation is divided into subsections as described in 1.6.3.1.2
through 1.6.3.1.4.
1.6.3.1.2 Purpose Subsection
The Purpose subsection provides a brief description of the purpose of the operation.
Additionally, it indicates whether the operation may be invoked by the user, provider, or
both; whether the operation is confirmed or unconfirmed; and whether there are any
constraints on when the operation may be invoked.
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1.6.3.1.3 Invocation, Return, and Parameters Subsection
The Invocation, Return, and Parameters subsection describes the parameters associated with
each operation, including their semantics. A accompanying the description of each operation
lists all parameters associated with the operation and, for both the invocation and return,
whether the parameter is always present, always absent, or conditionally present.
For parameters that are conditionally present, the parameter description specifies the
conditions for the presence or absence of the parameter. The condition is generally based on
the value of another parameter in the same invocation or return; for example, in the return of
an operation, the diagnostic parameter is present if and only if the value of the result
parameter is ‘negative result’. For a conditional parameter in a return, the condition may be
based on the value of a parameter in the corresponding invocation.
In the table, the following convention is used to indicate whether a parameter is always
present, always absent, or conditionally present:
M Always present
C Conditionally present
Blank Always absent
NOTE – Even though a parameter may be characterized as always present, its description
may specify that its value is permitted to be ‘null’ or ‘unused’ or the like.
1.6.3.1.4 Effects Subsection
The Effects subsection describes the effects an operation has on the invoker, the performer,
the association between them, or any combination thereof. The details of how those effects
occur or the mechanisms used are outside the scope of this Recommendation.
1.6.3.2 Typographic Conventions
1.6.3.2.1 Operation Names
Names of RCF service operations appear in uppercase and begin with the characters ‘RCF-’
(e.g., RCF-TRANSFER-DATA).
1.6.3.2.2 Parameter Names
In the main text, names of parameters of RCF service operations generally appear in
lowercase and are typeset in a fixed-width font (e.g., responder-port-identifier).
In annex A, the corresponding name is formed by omitting any hyphens contained in the
name and using mixed-case (e.g., responderPortIdentifier).
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1.6.3.2.3 Value Names
The values of many parameters discussed in this Recommendation are represented by names.
In the main text, those names are shown in quotation marks (e.g., ‘no such service instance’).
The corresponding name in annex A is formed by omitting any hyphens or white space
contained in the name and using mixed-case (e.g., noSuchServiceInstance). The
actual value associated with the name is constrained by the type of the parameter taking on
that value. Parameter types are specified in annex A of this Recommendation.
NOTE – The name of a value does not imply anything about its type. For example, the
value ‘
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