3GPP 24.501 v20.0.0 — the document's own text

9.11.4.39 Protocol description

Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).

The purpose of the Protocol description information element is to provide protocol description for UL PDU set based handling to the UE.

The Protocol description information element is a type 6 information element with a minimum length of 6 octets.

The Protocol description information element is coded as shown in figure 9.11.4.39.1, figure 9.11.4.39.2, figure 9.11.4.39.3, figure 9.11.4.39.4, and table 9.11.4.39.1.

8	7	6	5	4	3	2	1
Protocol description IEI	octet 1
Length of Protocol description contents	octet 2octet 3
Protocol description 1	octet 4octet u
Protocol description 2	octet (u+1)octet w
...
Protocol description n	octet (w+1)octet s

Figure 9.11.4.39.1: Protocol description information element

8	7	6	5	4	3
Length of protocol description	octet 4octet 5
QoS Rule Identifier (QRI)	octet 6
0	0	PILPI	HEIPI	Transport Protocol	octet 7*
Spare	Spare
RTP header extension type	octet 8*
RTP header extension id	octet 9*
RTP payload information list	octet 10octet u

Figure 9.11.4.39.2: Protocol description

8	7	6	5	4	3	2	1
Length of RTP payload information list	octet 10octet 11
RTP payload information 1	octet 12octet o
RTP payload information 2	octet (o+1)octet p
...
RTP payload information m	octet qoctet r

Figure 9.11.4.39.3: RTP payload information list

8	7	6	5	4	3	2	1
RTP payload format	octet 12
Number of RTP payload type	octet 13
RTP payload type 1	octet 14
RTP payload type 2	octet 15*
...
RTP payload type t	octet (13+t)*

Figure 9.11.4.39.4: RTP payload information

Table 9.11.4.39.1: Protocol description information element

Length of protocol description (octet 4 and octet 5) (see NOTE 1)
The length of protocol description field indicates the length of the protocol description entry.

QoS Rule Identifier (QRI) (octet 6)
The QoS Rule Identifier (QRI) field contains the QoS rule identifier as specified in clause 9.11.4.13. Each protocol description entry is associated with the QoS rule identified by the QRI field.

Transport Protocol (octet 7, bits 1 to 4)The Transport Protocol field indicates the transport protocol used by the media flow, e.g. RTP or SRTP as specified in 3GPP TS 26.522 [69].
Bits
4	3	2	1
0	0	0	1	RTP
0	0	1	0	SRTP
All other values are spare.

If Transport Protocol field indicates a spare value, the corresponding entry for the protocol description shall be ignored.

RTP header extension information presence indicator (HEIPI) (bit 5 of octet 7)
The HEIPI field indicates whether the RTP header extension information (RTP header extension type field and RTP header extension id field) is included in the IE or not.
Bit
5
0		RTP header extension information not included
1		RTP header extension information included

RTP payload information list presence indicator (PILPI) (bit 6 of octet 7)
The PILPI field indicates whether the RTP payload information list is included in the IE or not.
Bit
6
0		RTP payload information list not included
1		RTP payload information list included

RTP header extension type (octet 8)
The RTP header extension type field contains the RTP header extension type, i.e the RTP Header Extension for PDU Set Marking as specified in clause 4.2 of 3GPP TS 26.522 [69].
Bits
8	7	6	5	4	3	2	1
0	0	0	0	0	0	0	1	RTP Header Extension for PDU Set Marking
All other values are spare.

RTP header extension id (octet 9)
If RTP header extension type has a value other than spare values, the RTP header extension id field contains the RTP header extension id which is coded as binary representation of an integer between 1(inclusive) and 255(inclusive) as defined in IETF RFC 8285 [70].

RTP payload information list (octets 10 to u) (see NOTE 2)
The RTP payload information list contains the RTP payload information for the RTP stream, which can be used to derive the PDU set information.

RTP payload format (octet 12)

Bits
8	7	6	5	4	3	2	1
0	0	0	0	0	0	0	1	RTP payload format for H.264/AVC codec as specified in clause A.2.2 of 3GPP TS 26.522 [69]
0	0	0	0	0	0	1	0	RTP payload format for H.265/HEVC codec as specified in clause A.2.2 of 3GPP TS 26.522 [69]
All other values are spare.

If the RTP payload format indicates a spare value, the corresponding entry for the RTP payload information shall be ignored.

RTP payload type (octet 14)
The RTP payload type field indicates the RTP or SRTP payload type, it contains the binary representation of an integer between 0(inclusive) and 127(inclusive). The other values are spare. If spare value is used, the UE shall ignore the value.

NOTE 1: If the value of the length of protocol description field is set to 1, the corresponding entry for the protocol description shall be deleted for the associated QoS rule. If the value of the length of protocol description field is greater than 1, the corresponding entry for the protocol description shall be added or replaced for the associated QoS rule.NOTE 2: In this release of the specification, the RTP payload information list shall contain only one RTP payload information entry.