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). When the TC Space Data Link Protocol is used, the TC Synchronization and Channel
Coding Recommended Standard must be used for the Synchronization and Channel Coding
Sublayer. Likewise, when the TM or AOS Space Data Link Protocol is used, the TM
Synchronization and Channel Coding Recommended Standard must be used for the
Synchronization and Channel Coding Sublayer.
Ground System or
Spacecraft Spacecraft Network Layer and
Protocols Data Link
Sublayer Space Data
Link Protocol Space Data
Link Protocol Sync & Channel
Sublayer Sync & Channel
Coding Sync & Channel
Coding RF &
Modulation RF &
Modulation Data Link
Layer Physical Layer Space Link Figure 2-3: Layer Architecture
Below the Synchronization and Channel Coding Recommended Standards, Physical Layer
protocols (for example, the CCSDS RF and Modulation Systems defined in reference )
are used to transmit delimited and coded Transfer Frames over space links. 1 A third CCSDS-developed standard for the Synchronization and Channel Coding Sublayer of the Proximity-1
Space Link Protocol is outside the scope of this Report (cf. 2.1). CCSDS 130.2-G-1 Page 2-4 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS Above the Space Data Link Protocols, higher-layer protocols belonging to the Network
Layer and above use the services provided by the Space Data Link Protocols. Most of these
higher-layer protocols are end-to-end protocols and are responsible for transferring data from
end to end across the entire network, which contains the space link.
How the Space Data Link Protocols should be used in the entire space data system is
explained in reference . CCSDS 130.2-G-1 Page 2-5 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS 3
3.1 WHAT DO THE SPACE DATA LINK PROTOCOLS PROVIDE? FROM USERS’ PERSPECTIVE
SERVICES The Space Data Link Protocols provide protocols of the Network and higher layers with
services to transfer data over a space link. The entities (i.e., the elements that implement
communications protocols) of the Space Data Link Protocols are called service providers and
the entities that use services are called service users.
A service provided by a service provider (an entity of a Space Data Link Protocol) transfers
data supplied by a service user (sending user) to another service user (receiving user) over a
space link (see figure 3-1). In doing this, the Space Data Link Protocol uses the capabilities of
the Synchronization and Channel Coding Sublayer and the Physical Layer as explained in 2.3.
However, the physical characteristics of the space link are invisible to the service users.
The point at which a service is provided by a service provider for a service user is called a
Service Access Point (SAP). Each SAP has a SAP address, and the service user that uses the
service through the SAP is also identified by the SAP address. In figure 3-1, there are two
SAPs: one for the sending user and the other for the receiv...
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This document was uploaded on 03/06/2014.
- Spring '14