* @field version: contains the version number of this PDU definition. For this version of this data type it shall be equal to `1`.
*
* @field segmentationTime: contains information on when the message or file was segmented into 1 or several pieces.
* So the segmentationTime of all the segments for this message or file shall be the same.
*
* - not included in the present version @field segmentationLocation: is the location at which the message or file was segmented
* @field distributedAid: the ITS-AID of the file. The Psid/ Its-AID is a variable length INTEGER number.
*
* @field fileId: the id of the file to be distributed. It shall be set to the output of the SHA-256 hash function calculated on the transmitted CTL or file content.
*
* @field fileDescription: the file description or metadata of the segmented file.
* For instance, metadata could contain parameters required when coding scheme using a FEC encoding is used (cf. IETF RFC 6726)
* In the current version of this standard, the fileDescription shall be of 0 byte length.
*
* @field segmentContent : contains the segmented data of the message or file.
*/
SegmentPDU ::= SEQUENCE {
version Uint8,
segmentationTime Time64,
segmentContent SegmentedData {Psid}
SegmentPDU {Psid} ::= SEQUENCE {
version Uint8,
segmentationTime Time32,
distributedAid Psid,
fileId HashedId8,
fileDescription OCTET STRING (SIZE(0..63)),
segmentContent SegmentedData
}
/**
* This component represents the payload of a segment/fragment of the file data.
*/
SegmentedData ::= CHOICE {
seqChunks SequentialChunksSegmentedData,
...
}
/**
* This component represents the payload of a segment/fragment of the file data when the sequential
* segmentation method is used. This method is applied in case the fileDescription is set to value 'FF'.
* It is composed of the following fields:
* @field distributedAid: the ITS-AID of the file. The Psid/ Its-AID is a variable length INTEGER number.
* In the present version, the length of Its-AID will be less than or equal to 2 bytes.
*
* @field fileId: the id of the file to be distributed. It shall be set to the output of the SHA-256 hash function calculated on the transmitted CTL file content.
*
* @field fileDescription: optionally, the file description or metadata of the segmented file.
* For instance, metadata could contain parameters required when coding scheme using a FEC encoding is used (cf. IETF RFC 6726)
*
* @field messageSegmentTotalNumber: the total number of segments/fragments constituting the complete file.
*
* @field thisMessageSegmentNumber: the number that indicates the rank or position of this segment in the ordered sequence of segments constituting the complete CTL.
*
* The fields messageSegmentTotalNumber and thisMessageSegmentNumber may be present or absent depending on the use of a network/transport
* coding technique. If network/transport coding is used, these fields are unused and shall be absent.
* Note that coding technique is not specified in the current version of the standard.
...
...
@@ -56,26 +73,24 @@ SegmentPDU ::= SEQUENCE {
* MAX value is equal to the maximum size of the payload contained in the Segment PDU, i.e. the MTU-GN - control fields size. MTU value depends
* on the network access technology and on the network layer. For instance, if ITS-G5 access layer
* and GeoNetworking SHB protocol is used, MTU-GN - GN-Header - BTP-Header = 1428 bytes and MAX value is calculated as:
* 1428 - control fields size (30 bytes restricting the ITS-AID size to a maximum of 2 bytes).
* 1428 - control fields size.
*
* All segments of the original full CTL, except the last one, shall have the same size equal to MAX value.
* All the segments, but the last one, of the original file (e.g. the full CTL) shall have the same size equal to MAX value.
* The Segmented CTL Responsemessage (SCRM) is a specific Segment PDU: it uses the parametrized data type SegmentedData where the psid parameter value is set to
* the ITS-AID value of the CTL service as specified in ETSI TS 102 965 (i.e. value 624)
* The Segmented CTL Responsemessage (SCRM) is a specific Segment PDU: it uses the parametrized data type
* SegmentedData where the psid parameter value is set to the ITS-AID value of the CTL service as specified in
* ETSI TS 102 965 (i.e. value 624). For the SCRM message, the size of the control information (“header” fields) is 23 bytes.
