Forword
This document is drafted in accordance with GB/T 1.1-2020 Guidelines for Standardization - Part 1: Structure and Drafting Rules of Standardization Documents.
Please note that some of the contents of this document may involve patents. The issuing agency of this document does not assume the responsibility of identifying the patent. This document is proposed by and under the jurisdiction of National Aerospace Technology and Its Application Standardization Technical Committee (SAC/TC 425).
1 Scope
This document specifies the unified spatial data link protocol (USLP) services of the spatial data and information transmission system, data unit format, protocol flow, management parameters and supporting spatial data link security protocols.
This document is applicable to the data link layer data transmission service of spacecraft to ground, ground to spacecraft and spacecraft communication using the unified spatial data link protocol.
2 Normative References
The contents in the following documents, through normative references, constitute indispensable provisions of this document. Where, for dated references, only the version corresponding to that date applies to this document; For undated references, the latest version (including all amendments) is applicable to this document.
GB/T2900.54 Electrotechnical terminology -- Radio communication transmitter, receiver, network and operation
GB/T 39344-2020 Operating Procedures for Jiuxin Spatial Data and Information Transmission System
GB/T 39348-2020 Telemetry Synchronization and Channel Coding for Space Data and Information Transmission Systems
GB/T 39349-2020 Remote Control Synchronization and Channel Coding of Spatial Data and Information Transmission System
GB/T 39,353-2020 Spatial Data and Communication System Back Transmission System Proximity Spatial Link Protocol Synchronization and Coding Sublayer
GB/T 42041 Space Terminology Space Data Navigation and Information Transmission
3 Terms and definitions
The terms and definitions defined in GB/T 2900.54, GB/T 42041 and the following are applicable to this document.
three point one
Delimited
Data has known and finite length characteristics.
three point two
Mission phase
A period of time for a space mission, during which the mission process has specific objectives.
Note: The conversion of two consecutive task phases may cause the interruption of communication services.
three point three
Space link
Communication link between spacecraft and corresponding ground system or between two spacecraft.
Note: A spatial link contains one or more unidirectional or bidirectional physical channels.
4 Abbreviations
The following abbreviations are applicable to this document.
5 Protocol Overview
5.1 Related concepts
5.1.1 Protocol architecture
USLP protocol is a data link layer protocol, which is designed to meet the efficient transmission requirements of various types and characteristics of space application data on space links in space missions.
The hierarchical relationship between the USLP protocol and the OSI reference model is shown in Figure 1. Referring to CCSDS spatial link protocol, two sublayers of the data link layer are defined. The USLP protocol is located in the data link protocol sublayer and provides the function of transmitting various data using variable length or fixed length protocol data units (i.e. USLP transmission frames). The data link protocol sublayer also provides optional spatial data link layer security protocols. The synchronization and channel coding sublayer provides other functions required for transmission of transmission frames on the spatial link, including delimitation/synchronization of transmission frames, error correction coding/decoding (optional), and bit conversion generation/removal (optional).
6 Business
6.1 Business Data Unit
6.1.1 General
7 Data cell format
7.1 Bit number convention
This document uses the following bit number convention to identify each bit in the N-bit data field.
8 Protocol Process
8.1 Sender protocol process
8.1.1 General
See 5.3.2 for the protocol flow of the sending end, as shown in Figure 5.
8.1.2 Multiple access point packet processing function
8.1.2.1 Multi access point packet processing of fixed length transmission frame data domain
The MAPP processing function of fixed length TFDZ is used to transmit variable length packets in the fixed length TFDZ of TFDF. Each MAP channel has a MAPP processing function instance. MAPP processing function splices packages together until the maximum length of TFDZ is exceeded. Packets that exceed the maximum length of the TFDZ need to be split. Fill the TFDZ completely, and then start a new TFDZ with the rest on the same MAP channel.
If you want to transmit multiple versions of packets on a MAP channel, these packets of different versions should be multiplexed into a continuous packet string before building a TFDZ. FHP is used to identify the position of the first byte of the first packet in TFDZ. If the user is unable to provide sufficient packets at the time of transmission frame transmission, the MAPP processing function will generate a package free packet of appropriate length to complete TFDZ.
The abstract model of MAPP processing function of fixed length TFDF is shown in Figure 13.
9 Management parameters
9.1 General
This chapter lists the management parameters used by USLP for each channel and packet transmission. These parameters are abstract definitions and do not represent any specific implementation of the management system. Management parameters generally remain unchanged for a long period of time, and their changes usually indicate that the agreement entities related to specific tasks need to be reconfigured. By using the management system, the management parameters pass the required information to the protocol entities.
Note: This chapter specifies the management parameters of the USLP that does not support the SDLS protocol. Other USLP management parameters that support the SDLS protocol are specified in Chapter 10.
9.2 Physical Channel Management Parameters
See Table 5 for physical channel management parameters and their descriptions.
10 Spatial Data Link Security Protocol
10.1 General requirements
This chapter specifies the USLP protocol PDU and protocol processing flow supporting SDLS protocol. If the USLP protocol entity supports SDLS, each virtual channel contains parameters determined by the task to identify whether SDLS is used in this channel (see 10.4). Chapter? And Chapter 8 are protocol provisions that do not support SDLS.
Whether SDLS protocol is selected is determined by the task.
The USLP protocol provides eight types of services, and the SDLS protocol can provide the following security protection for the business data units transmitted by some services:
a) Encryption: encrypt the data content
b) Authentication: Confirm the data source and data integrity.
See Table 1 for the services provided by the USLP protocol. Only MAPP services, MAPA services and MAP byte stream services can be protected by the SDLS protocol.
10.2 Format of spatial data link security protocol
10.2.1 General
10.2.1.1 In order to support the application of SDLS features, a security head and a security tail are defined in the transmission frame.
Appendix A (normative) Truncated transmission frame protocol data unit
Appendix B (Informative) Randomized Implementation Method of Only Idle Data Transmission Frame
Appendix C (Normative) CRC-16 Frame Error Control Region Coding Process
Forword
1 Scope
2 Normative References
3 Terms and definitions
4 Abbreviations
5 Protocol Overview
6 Business
7 Data cell format
8 Protocol Process
9 Management parameters
10 Spatial Data Link Security Protocol
Appendix A (normative) Truncated transmission frame protocol data unit
Appendix B (Informative) Randomized Implementation Method of Only Idle Data Transmission Frame
Appendix C (Normative) CRC-16 Frame Error Control Region Coding Process
