EN 16603-50:2022

SLOVENSKI STANDARD
01-september-2022
Nadomešča:
SIST EN 16603-50:2014
Vesoljska tehnika - Komunikacije
Space engineering - Communications
Raumfahrttechnik - Kommunikation
Ingénierie spatiale - Communications
Ta slovenski standard je istoveten z: EN 16603-50:2022
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 16603-50

NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2022
ICS 49.140
Supersedes EN 16603-50:2014
English version
Space engineering - Communications
Ingénierie spatiale - Communications Raumfahrttechnik - Kommunikation
This European Standard was approved by CEN on 13 March 2022.

CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical
references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to
any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2022 CEN/CENELEC All rights of exploitation in any form and by any means
Ref. No. EN 16603-50:2022 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 6
Introduction . 7
1 Scope . 8
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 10
3.1 Terms defined in other standards . 10
3.2 Terms specific to the present standard . 10
3.3 Abbreviated terms. 13
4 Space communications engineering principles . 15
4.1 Context . 15
4.2 Overall space communication . 16
4.3 Space communication domains . 21
4.3.1 Overview . 21
4.3.2 Space network . 21
4.3.3 Space link . 22
4.3.4 Ground network . 23
4.4 Communications engineering process . 24
4.4.1 Introduction . 24
4.4.2 Communication engineering activities . 24
4.4.3 Process milestones . 26
4.5 Relationship with other standards . 26
4.6 <> . 27
4.7 Spacecraft control considerations . 27
5 Requirements . 28
5.1 Introduction . 28
5.2 Space communication system engineering process . 28
5.2.1 Requirements engineering . 28
5.2.2 Analysis . 29
5.2.3 Design and configuration. 30
5.2.4 Implementation . 31
5.2.5 Verification . 32
5.2.6 Operations . 33
5.3 Space communication system . 33
5.3.1 Bandwidth allocation . 33
5.3.2 Congestion . 34
5.3.3 Cessation of emission . 34
5.4 Telecommanding . 34
5.4.1 Commandability at all attitudes and rates . 34
5.4.2 Telecommand delivery service . 34
5.4.3 Erroneous telecommand rejection . 34
5.4.4 Essential telecommand distribution . 34
5.4.5 Command authentication . 35
5.4.6 Command encryption . 35
5.4.7 Commanding-in-the-blind . 35
5.4.8 Telecommand acknowledgement . 35
5.4.9 Hot redundancy of on-board telecommand chains . 35
5.4.10 Telecommand destination identification . 36
5.5 Telemetry . 36
5.5.1 Telemetry at all attitudes and rates . 36
5.5.2 Essential telemetry acquisition . 36
5.5.3 Telemetry source identification . 37
5.5.4 Telemetry-in-the-blind . 37
5.5.5 Telemetry data time stamping . 37
5.5.6 Simultaneous support of differing source rates . 37
5.5.7 Telemetry authentication and encryption . 37
5.6 Space link . 38
5.6.1 Introduction . 38
5.6.2 Directionality . 38
5.6.3 Short contact periods . 38
5.6.4 Interoperability . 39
5.6.5 Orbits . 39
5.6.6 Noise sources . 39
5.6.7 Mission phases . 39
5.6.8 Link setup times . 39
5.6.9 Mixed isochronous and asynchronous traffic . 39
5.6.10 Mixed housekeeping and payload data . 40
5.6.11 Space link performance . 40
5.6.12 Space link frequency . 41
5.6.13 Space link protocol . 42
5.6.14 Space link service . 43
5.7 Space network . 45
5.7.1 On-board network . 45
5.7.2 On-board network services . 46
5.7.3 Inter-spacecraft network . 47
5.7.4 Inter-spacecraft network services . 48
5.8 Ground network . 48
5.8.1 Overview . 48
5.8.2 Data labelling . 49
5.8.3 Security . 49
5.8.4 Error rates . 49
5.8.5 Hot redundant operation of ground network nodes . 49
5.8.6 Ground network availability . 49
Annex A (normative) Communication system requirements document
(CSRD) - DRD . 50
Annex B (normative) Communication system baseline definition (CSBD) -
DRD . 54
Annex C (normative) Communication system analysis document (CSAD) -
DRD . 59
Annex D (normative) Communication system verification plan (CSVP) -
DRD . 62
Annex E (normative) Communication system architectural design
document (CSADD) - DRD . 65
Annex F (normative) Communication system detailed design document
(CSDDD) - DRD . 68
Annex G (normative) Communication system profile document (CSPD) -
DRD . 70
Annex H (normative) Communication system operations manual (CSOM) -
DRD . 72
Annex I (informative) Documentation summary . 75
Bibliography . 78

Figures
Figure 4-1: Example configuration of a space communication system . 16
Figure 4-2: CCSDS and Internet space link protocols . 20

Tables
Table I-1 : ECSS-E-ST-50 DRD list . 76

European Foreword
This document (EN 16603-50:2022) has been prepared by Technical Committee CEN-CENELEC/TC 5
“Space”, the secretariat of which is held by DIN.
This standard (EN 16603-50:2022) originates from ECSS-E-ST-50C Rev.1 DIR1.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2023, and conflicting national standards shall
be withdrawn at the latest by January 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such
patent rights.
This document supersedes EN 16603-50:2014.
The main changes with respect to EN 16603-50:2014 are:
• Implementation of Change Requests
• Update w.r.t. of replacment of EN 16603-50-01:2014, EN 16603-50-03:2014 and EN 16603-50-04:2014
by EN 16603-50-21 to EN 16603-50-26
• Update of Terms, definitions and abbreviated terms in clause 3
• Term “space network” replaced by “on-board network”
• Update of Purpose and objective of Annex F “Communication system details design document
(CSDDD) – DRD”
• Update of Purpose and objective of Annex F “Communication system profile document (CSPD) –
DRD”
• Update of Annex I “Documentation summary”
This document has been prepared under a standardization request given to CEN by the European
Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has therefore precedence
over any EN covering the same scope but with a wider domain of applicability (e.g. : aerospace).
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of
Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia,
Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Introduction
This standard specifies requirements for the development of the end-to-end
data communication system for spacecraft. Implementation aspects are defined
in ECSS-E-ST-50 Level 3 standards, ECSS Adoption Notices, and CCSDS
standards.
The complete set of standards to define a complete communication link is
project dependent and cannot be specified here. ECSS-E-HB-50 provides some
guidance on this aspect, and gives some practical examples.

Scope
This Standard specifies the requirements for the development of the end-to-end
data communications system for spacecraft.
Specifically, this standard specifies:
• The terminology to be used for space communication systems
engineering.
• The activities to be performed as part of the space communication system
engineering process, in accordance with the ECSS-E-ST-10 standard.
• Specific requirements on space communication systems in respect of
functionality and performance.
The communications links covered by this Standard are the space-ground (i.e.
space-to-ground and ground-to-space) and space-to-space links used during
spacecraft operations, and the communications links to the spacecraft used
during the assembly, integration and test, and operational phases.
Spacecraft end-to-end communication systems comprise components in three
distinct domains, namely the ground network, the space link, and the space
network. This Standard covers the components of the space link and space
network in detail. However, this Standard only covers those aspects of the
ground network that are necessary for the provision of the end-to-end
communication services.
NOTE Other aspects of the ground network are covered
in ECSS-E-ST-70.
This Standard may be tailored for the specific characteristics and constraints of
a space project in conformance with ECSS-S-ST-00.
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revisions of any of these
publications, do not apply. However, parties to agreements based on this ECSS
Standard are encouraged to investigate the possibility of applying the most
recent editions of the normative documents indicated below. For undated
references the latest edition of the publication referred to applies.

EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system — Glossary of terms
Terms, definitions and abbreviated terms
3.1 Terms defined in other standards
a. For the purpose of this Standard, the terms and definitions from
ECSS-S-ST-00-01 apply, in particular for the following terms:
1. function
2. interface
b. For the purpose of this Standard, the terms and definitions from
ECSS-E-ST-20 apply, in particular for the following term:
1. essential function
NOTE Synonym to the term “vital function” from
ECSS-E-ST-70-11
c. For the purpose of this Standard, the terms and definitions from
ECSS-E-ST-70-11 apply, in particular for the following terms:
1. commandable vital function
2. high priority command
3. high priority telemetry
4. vital function
NOTE Synonym to the term “essential function” from
ECSS-E-ST-20.
5. vital telecommand
3.2 Terms specific to the present standard
3.2.1 channel
combination of protocol and medium that provides a physical layer service
from end-to-end
NOTE This is the transfer of the unstructured bitstream
from point-to-point.
3.2.2 communication service
service that provides the capability of moving data between users.
NOTE At least two users are involved when a
communication service is used, one sending data
and the other(s) receiving data.
3.2.3 cross support
use by one party of part of another party’s data system resources to
complement its own system
3.2.4 downlink
see “telemetry link”
3.2.5 duplex service
point-to-point system composed of two or more connected parties or devices
that can communicate with one another in both directions
3.2.6 entity
active element within a system
3.2.7 essential telecommand
telecommand that controls essential or vital functions
NOTE This corresponds to “high priority telecommand”
in ECSS-E-ST-70-11).
3.2.8 essential telemetry
telemetry that enables a reliable determination of the current status of vital
on-board equipment available under all circumstances
NOTE This correspond to “high priority telemetry” in
ECSS-E-ST-70-11.
3.2.9 frame
service data unit passed, at the sending end, from the protocol sublayer to the
coding and synchronization sublayer
NOTE For definition of layers see Figure 4-2.
3.2.10 isochronous service
service providing for the transfer of data with a defined maximum deviation
from a nominal delay from end to end
3.2.11 protocol
set of rules and formats (semantic and syntactic) that determine the
communication behaviour of layer entities in the performance of
communication functions
3.2.12 service
capability of a layer, and the layers beneath it (a service-provider), that is
provided to service-users at the boundary between the service-provider and the
service-users
NOTE The service defines the external behaviour of the
service-provider, independent of the mechanisms
used to provide that behaviour. Layers, layer
entities, and application-service-elements are
examples of components of a service-provider.
3.2.13 service data unit
amount of information whose identity is preserved when transferred between
peer (N+1) entities and which is not interpreted by the supporting (N) entities
NOTE Also knowsnas: (N) service data unit.
3.2.14 service-provider
abstract representation of the totality of those entities which provide a service to
service-users
NOTE A service provider includes entities in the layer at
which the service is provided, and in the layers
beneath it.
3.2.15 service-user
entity in a single system that makes use of a service
NOTE The service-user makes use of the service through
a collection of service primitives defined for the
service.
3.2.16 simplex
communicating in one direction from data source to data sink
3.2.17 source
entity that sends service-data-units, using a service provider
3.2.18 sink
entity that receives service-data-units from a service provider
3.2.19 telecommand
command data transmitted to a spacecraft through a telecommand link
3.2.20 telecommand link
communication link from ground to space by which a spacecraft is commanded
NOTE The term “uplink” is synonymous.
3.2.21 telemetry
housekeeping data and payload data generated on-board the spacecraft and
transmitted through a telemetry link
3.2.22 telemetry link
communication link from spacecraft to ground over which data generated on
the spacecraft is provided to ground
NOTE The term “downlink” is synonymous.
3.2.23 uplink
see “telecommand link”
3.2.24 user
service-user
3.2.25 user application
application that makes use of data handling system services
NOTE An application can be a software entity or a
non-software entity which is controlling an
onboard system.
3.3 Abbreviated terms
For the purpose of this Standard, the abbreviated terms from ECSS-ST-00-01
and the following apply:
Abbreviation Meaning
AIT assembly, integration, and test
AR acceptance review
ARQ automatic repeat request
BER bit error rate
CCITT Consultative Committee for International Telegraph and
Telephone
CCSDS Consultative Committee for Space Data Systems
CDMU central data management unit
CDR critical design review
CSAD communication system analysis document
CSADD communication system architectural design document
CSBD communication system baseline definition
CSDDD communication system detailed design document
CSOM communication system operations manual
CSPD communication system profile document
CSRD communication system requirements document
CSVP communication system verification plan
DRD document requirements definitions
EIRP equivalent isotropically radiated power
EMC electromagnetic compatibility
ISO International Organization for Standardization
ITU International Telecommunication Union
ITU/RR ITU / Radio Regulations
LEOP launch and early operations phase
MEC mission experiment centre
OSI open system interconnection
OCC operational control centre
PDR preliminary design review
PFD power flux density
QR qualification review
RF radio frequency
SDLS space data link security
SDU service data unit
SRR system requirements review
TT&C telemetry, tracking and command
Space communications engineering
principles
4.1 Context
Space communications engineering is concerned with the provision of
end-to-end communication services to and from spacecraft. Communication
links are generally between the spacecraft and ground. However, this Standard
also addresses spacecraft-to-spacecraft links, e.g. in spacecraft constellations,
and can be applied to links between spacecraft and landed elements such as
orbiter-lander or orbiter-lander-rover configurations.
End-to-end communication is used both to control the operation of the
spacecraft, and to transfer data, such as payload data. However, the
requirements on the communications system for controlling the spacecraft
differ from those for payload data transfer. For control operations, the
communication system objective is to provide guaranteed delivery of
commands in the order of transmission. Commands can be repeated, but not
lost. By contrast, the requirement for payload data transfers is to transfer as
much data as possible. Some loss of data may be acceptable, and delivery order
is generally unimportant, provided the data can be reconstituted.
In addition to the end-to-end transfer of commands and data, some additional
services are provided across space communication links, such as time
correlation and orbit determination (via e.g. ranging and/or Doppler
measurements). Time correlation is used to accurately relate the local time
maintained at each end of the communication link in order to determine the
absolute time relationship between events. Ranging and/or Doppler
measurements are used to determine the distance and/or the velocity between a
ground station antenna and the spacecraft for orbit determination.
The goals of standardization for space communication systems are:
• to ensure efficient use of the RF spectrum allocated to the space
infrastructure in a non-interfering manner;
• to ensure that the RF links to and from the spacecraft can be used for
orbit determination (via e.g. ranging and/or Doppler measurements);
• to ensure reliable and error free end-to-end communication between
ground stations and the spacecraft or between a spacecraft and a landed
element;
• to enable the use of the same ground segment infrastructure by different
spacecraft;
• to ensure that standard communication interfaces are provided to the
spacecraft payloads and experiments in order to simplify the spacecraft
development process;
• to enable cross support between agencies.
Cross support can be beneficial for many reasons, including:
• Technical: to attain additional network coverage or to conduct some
programmatic endeavour, such as very long baseline interferometry
measurements.
• Economic: to avoid the expense of duplicate implementation, especially
to meet some short term requirement.
• Emergency: to increase mission support over that normally planned.
• Research: to avoid the cost and time delay of repeating investigations or
re-flying an experiment and to obtain unique data acquired in the past
and held by another agency.
These arguments were apparent as long ago as the early 1970s. For this reason,
the Consultative Committee for Space Data Systems (CCSDS) was established
to standardize space link protocols. Where appropriate, this ECSS Standard
calls up CCSDS recommendations directly.
4.2 Overall space communication
Figure 4-1 shows an example of a configuration for a space communication
system.
NOTE This configuration includes a space-to-space link
between two flight elements.
Mission
Spacecraft 2 Operation
Spacecraft 1 Ground Experiment
(e.g. Probe, Control
(e.g. Orbiter) station Centre
Lander) Centre (OCC)
Terrestrial Terrestrial
Space link Space link (MEC)
link link
(space-to- (space-to-
space) ground)
Figure 4-1: Example configuration of a space communication system
The overall data communication requirement is to transfer data to and from any
element of the space system in accordance with the mission requirements.
The elements of a space communication system are described in the following
paragraphs. In a real space communication system, the number and type of
elements actually present can vary. For example, in complex missions, there can
be several spacecraft, and multiple ground stations. In other missions, a single
spacecraft can be controlled from a single operation control centre, without a
mission experiment centre.
The space communication system elements are:
• a spacecraft linked to the ground via a space link (space-ground). This
spacecraft can also be linked to other spacecraft, landers, and probes via
space-to-space (proximity) links;
• other spacecraft, landers, and probes linked only with the main
spacecraft via proximity links;
• other spacecraft, landers, and probes linked together forming an inter-
spacecraft network (see clause 4.3.2.3) not shown in Figure 4-1;
• a ground station that forms the terrestrial end of the space-ground space
link, and is connected to the operational control centre via a terrestrial
link;
• an operational control centre (OCC), connected to the ground station via
a terrestrial link. The OCC is used to control the spacecraft;
• a dedicated mission experiment centre (MEC) connected to the
operations control centre. Mission payloads and experiments are
operated from the MEC.
Each element includes a data handling system, which provides three main
communication functions:
• managing data communication interfaces internal to the element (internal
links);
• managing data communication interfaces with external links (i.e. space
links and terrestrial links to other elements);
• performing data processing for the transfer between internal and external
links.
The processing for transferring data from a sending element to a receiving
element of the space communication system via an external link consists of:
• For the downlink data stream:
 At the sending element
o Acquisition of data from subsystems or next element (e.g.
probe or lander).
o Processing and formatting of the data stream.
o Transmission of the data stream to the ground via the
external (space) link as telemetry.
 At the receiving element
o Acquisition of the data stream from the sender via the
external link.
o De-formatting and processing for delivery to receiver
internal elements (e.g. space system user when ground
station and OCC are in the same system) and for transfer to
the next element via an external link (e.g. transfer from
ground station to OCC).
o Delivery of data to receiver internal elements .
o Transmission of data to the next element via external
(terrestrial) link.
• For the uplink data stream:
 At the sending element
o Acquisition of data from space system user.
o Processing and formatting of the data stream.
o Transmission of the data stream to the spacecraft via the
external (space) link as telecommand.
 At the receiving element
o Acquisition of the data stream from the sender via the
external link.
o De-formatting and processing for delivery to receiver
internal elements (e.g. commands to spacecraft subsystems
for a link between ground station and spacecraft) and for
transfer to the next element (e.g. probe or lander) via an
external link.
o Delivery of data to receiver internal elements.
o Transmission of data to the next element via external (space-
to-space) link.
In the case of space-to-space links, the processing for transferring data from a
sending element to a receiving element of the space communication system via
return and forward link is similar to the one described for downlink and
uplink.
The type of data to be transmitted can be telemetry, files, video, and digital
voice for the downlink, and telecommands, files, video, and digital voice for the
uplink. The same type of data can be transmitted for return and forward links
in space-to-space transmission.
For each type of data transmission, protocols defined by CCSDS or other
standardization bodies can be used. Figure 4-2 shows some of the CCSDS and
internet protocols that can be used over the space links (i.e. space-ground and
space-to-space). Connections among standards are marked with arrow
highlighting the most usual data flow direction as seen on-board (e.g. the TC
data flow enters the spacecraft from the bottom while the TM data flow exits
the spacecraft towards the bottom; i.e. RF standards). However, not all the
possible connections among boxes are shown to avoid making the picture too
complex; e.g. the fact that CFDP can run directly on top of either TCP or UDP is
not shown. This figure illustrates some relationship to the seven ISO reference
model layers defined in ISO 7498. Data Link Layer (including the two Protocol
and Coding & Synchronization sublayers) and Physical Layer are shown in
detail while the other layers are grouped as Upper Layers.
It is also important that some of the CCSDS Standards are formally adopted by
ECSS via Adoptions Notices, namely:
ECSS Adoption Based on CCSDS Superseded ECSS Part of ECSS Standard
Notice superseded
ECSS-E-AS-50-21 CCSDS 131.0-B-3 (Sept. 2017) ECSS-E-ST-50-01C Whole ECSS Standard
- TM Synchronization and
31 July 2008
Channel Coding
ECSS-E-AS-50-22 CCSDS 132.0-B-2 (Sept. 2015) ECSS-E-ST-50-03C Clause 5 “TM Transfer
- TM Space Data Link Frame”
31 July 2008
Protocol
ECSS-E-AS-50-23 CCSDS 732.0-B-3 (Aug. 2016) ECSS-E-ST-50-03 was
- AOS Space Data Link limited to the TM
Protocol Transfer Frame. It did not
include the AOS Transfer
Frame
ECSS-E-AS-50-24 CCSDS 231.0-B-3 (Sept. 2017) ECSS-E-ST-50-04C Clause 8
- TC Synchronization and (Synchronization and
31 July 2008
Channel Coding channel coding sublayer)
Clause 9 (Physical layer)
ECSS-E-AS-50-25 CCSDS 232.0-B-3 (Sept. 2015) Clause 5 (Segmentation
- TC Space Data Link sublayer)
Protocol
Clause 6 (Transfer
sublayer)
ECSS-E-AS-50-26 CCSDS 232.1-B-2 (Sept. 2010) Clause 7 (COP-1)
- Communications Operation
Procedure-1
Figure 4-2 references the Proximity-1 suite of standards, that is however just
one possible choice for communications over proximity links.

CCSDS File Delivery Protocol (CFDP)
Application Specific Protocols
CCSDS 727.0-B
Bundle Protocol (BP)
Lossless Data Compression
CCSDS 121.0-B
CCSDS 734.2-B (**)
Image Data Compression
CCSDS 122.0-B
CCSDS 122.1-B
Lossless Multi&Hyper spectral Image
TCP UDP
Compression
CCSDS 123.0-B RFC-793 RFC-768
Application Specific LTP IP version 4 IP Sec IP version 6
IP
Source/Sink (****) CCSDS 734.1-B RFC-791 RFC-4301 RFC-1883
IP over CCSDS
CCSDS 702.1-B
Encapsulation Service Encapsulation Packet
Space Packet Protocol
CCSDS 133.0-B CCSDS 133.1-B
CCSDS 133.1-B
USLP Proximity-1
TC Space Data Link Protocol TM Space Data Link Protocol AOS Data Link Protocol
CCSDS Data Link Layer
CCSDS 232.0-B (*) CCSDS 132.0-B (*) CCSDS 732.0-B (*)
732.1-B (*) CCSDS 211.0-B
Data
Link
Layer
TC Synch. And TM Synch. and Proximity-1 Channel Coding
Flexible
Channel Coding Channel Coding & Sync. Layer
advanced
CCSDS Space
CCSDS 131.0-B
CCSDS 231.0-B CCSDS 211.2-B
coding and
Data Link
modulation
Protocols over
scheme for high
ETSI DVB-S2
rate TM
standard
applications Proximity-1
CCSDS 131.3-B
ECSS-E-50-05 “Radio Frequency and
Physical
(SCCC)
Physical Layer
Modulation” (***) CCSDS 131.2-B
Layer CCSDS 211.1-B
NOTES:
• CCSDS standard formally adopted by ECSS CCSDS standard not formally adopted by ECSS
• Internet TCP/IP standard ECSS standard
• (*) including Space Data Link Security Protocol (optional) CCSDS 355.0-B
• (**) including the Bundle Security Protocol (BSP) CCSDS 734.5-B (under development).
• (***) CCSDS has its own Physical Layer standard (401.0-B) which includes additional options with respect to
ECSS-E-50-05 “Radio Frequency and Modulation”
• (****) An axample of «Application Specific Source/Sink» is the ECSS-E-ST-70-41C «Telemetry and telecommand
packet utilization»
• Future Optical Communication Standards: CCSDS 141.0-B «Optical Communications Physical Layer» and CCSDS
142.0-B «Optical Communications Coding and Synchronization» are not shown in figure
• Uni-directional arrows are applicable to the On-Board segment, they are reversed in the Ground segment

Figure 4-2: CCSDS and Internet space link protocols
LOWER LAYERS UPPER LAYERS
Synchronization
Protocol
and Coding Sub-layer
Sub-layer
Each layer provides services and protocols defined either in ECSS standards, or
by other explicitly referenced standards such as CCSDS recommended
standards. Depending on their profile, users access services provided by any of
the on-board or ground layers. Communications internal to the on-board and
ground segments are performed via the local transfer protocols and sub-
networks, which are not covered by this Standard. End-to-end communications
between space and ground segments are via the spacelink upper layers
protocols and Data Link and Physical layers (i.e. the lower layers), which do
form part of this Standard.
The space link Data Link and Physical layers enable access to the space link
medium and provide basic services for the transmission of delimited or
undelimited data across the link. The space link upper and lower layers can be
resident in a single data system or can be partitioned between data systems in
space and on the ground. In general the space link layers reside within the on-
board TT&C and Data Handling subsystems. On the ground they can reside
completely in the ground station, or can be partitioned between ground station
and control centre or customer facility.
The ground and on-board upper layers provide common services between the
space and ground segment. They operate in a peer-to-peer interaction with their
equivalent layers in the space and ground segments. The on-board and ground
upper layers make use of the services provided by the space link upper and
lower layers to transfer data from data system to data system.
The ground and on-board layers (upper and lower) implement the services and
protocols used for the independent operation of the on-board and ground
systems.
4.3 Space communication domains
4.3.1 Overview
A space communication system comprises three distinct domains that each
have markedly different characteristics. The three domains are
• the space network,
• the space link, and
• the ground network.
4.3.2 Space network
4.3.2.1 Overview
The space network comprises all of the nodes in the flight segment of a
spacecraft mission. These nodes can all be on a single spacecraft, or can be
distributed among several spacecraft, for example in a constellation. The space
network therefore includes both intra-spacecraft and inter-spacecraft links.
4.3.2.2 On-board network
On-board network is limited to intra-spacecraft links within a given spacecraft.
The type of network medium and topologies of the on-board network are
highly varied, often being based on proprietary protocols. The emphasis of this
Standard in this case is on the definition of appropriate upper layers services
that maintain freedom of choice in the on-board Data Link and Physical layers,
while also moving towards harmonization and better definition of the on-board
Data Link and Physical layers.
Except in very rare circumstances, the on-board network cannot be maintained
or upgraded during a mission. Usually, the technology used to implement the
on-board network is conservative, and reflects the state-of-the-art years before
launch. This severely constrains the performance available when compared
with the ground network.
4.3.2.3 Inter-spacecraft network
An inter-spacecraft network is a set of spacecraft connected by inter-spacecraft
links. An increasing number of missions involve a space segment consisting of
multiple elements possibly from different organizations, e.g. constellations of
spacecraft, or planetary missions consisting of an orbiter and lander, or
orbiter-lander-rover. These type of missions impact the nature of the space
network by including spacecraft-to-spacecraft unreliable/intermittent wireless
links (e.g. spacecraft constellations, and links between spacecraft and landed
elements such as orbiter-lander or orbiter-lander-rover configurations) and
introducing the potential for a variable network topology.
NOTE CCSDS 734.2-B-1 provides a Bundle Protocol (BP)
which defines end-to-end protocol, block formats,
and abstract service descriptions for the exchange
of messages (bundles) that support Delay Tolerant
Networking (DTN). For DTN, CCSDS-734.1-B-1
also provides a Licklider Transmission Protocol
(LTP) that provides optional reliability
mechanisms on top of an underlying (usually data
link) communication service.
4.3.3 Space link
The space link is essentially a point-to-point wireless link between a ground
station and a spacecraft or between two spacecraft as shown in Figure 4-1. This
link is inherently unreliable, and the emphasis of this Standard here is on the
achievement of reliable data transfer services. Users concerned only with the
exchange of data, either on-board or on ground, do not generally use the space
link services directly, accessing these services instead through their local
ground or on-board sub-networks, which are not covered by this Standard.
However, users concerned with the operation and control of the spacecraft can
access space link services for a number of reasons, including routine operations
such as orbital position determination, and emergency operations such as low
level commanding.
Equipment at the terrestrial end of the space link is essentially unconstrained in
terms of power, mass, and volume requirements. By contrast, equipment at the
on-board end of the space link is severely constrained in these respects. This
limits the bandwidth that can
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