GB/T 39350-2020 in English

1. Core architecture and technical features of the protocol

This standard corresponds to the data link layer of the OSI model and adopts a variable-length PDU transmission mechanism. The key features include:

• Service data unit segment assembly: Supports large data segment transmission and small data aggregation
• Virtual channel (VC) multiplexing: 6-bit VCID enables multiple services to share the physical channel
• Security protocol support: Optional SDLS provides encryption and authentication (the security header and tail are up to 1017 bytes)

2. Service classification and data transmission

Note: MAPP service supports multiple versions of packets and distinguishes user data by PVN (packet version number)

III. Detailed explanation of protocol data unit

7.2 Remote control transmission frame structure

Key field definition:

• Leading header (5 bytes): including TFVN(00), SCID(10bit), VCID(6bit)
• Data field (1019 bytes): supports segment header (optional) to implement MAP segmentation
• FECF (2 bytes): CRC-16 checksum, polynomial X¹⁶+X¹²+X⁵+1

IV. Technology Evolution and Implementation Recommendations

9.1 Management Parameter Configuration

Key Parameter Examples:

• Physical channel: maximum frame length 1024 bytes, SCID set dynamic configuration
• Virtual channel: frame sequence number 8bit cycle, CLCW report rate ≥1Hz
• MAP channel: segmentation permission flag, MAP_ID range 0-63

10.5 SDLS Enhanced Security

Security implementation requires synchronous configuration:

• Virtual channel level: security header/tail length independent setting
• Class D frames are exclusively protected, and Class C frames are distinguished by control flags (1bit)