When the tc space data link protocol is used the tc

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: reference [10]). 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 above Higher-layer Protocols Higher-layer Protocols Data Link Protocol Sublayer Space Data Link Protocol Space Data Link Protocol Sync & Channel Coding 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 [11]) 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 [12]. 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...
View Full Document

This document was uploaded on 03/06/2014.

Ask a homework question - tutors are online