24.3793GPPMission Critical Push To Talk (MCPTT) call controlProtocol specificationRelease 18TS
This clause contains the information required for the IANA registration of info package g.3gpp.mcptt-floor-request in accordance with IETF RFC 6086 .
J.1.2 g.3gpp.mcptt-floor-request info package
J.1.2.1 Overall description
When a temporary group call includes constituent MCPTT groups in partner systems where a MCPTT call is ongoing and if the floor is occupied by a participant with a permission to speak, the non-controlling MCPTT function of a MCPTT group needs to transfer information of the current speaker(s) to the controlling MCPTT function hosting the temporary group. The information is transferred in the form of a floor request.The controlling MCPTT function will then determine if the participant will be permitted to continue to speak or if the permission to speak is revoked.
This package is used to transport a floor request from the non-controlling MCPTT function of an MCPTT group to the controlling MCPTT function hosting the temporary group.
J.1.2.3 Appropriateness of INFO Package Usage
A number of solutions were discussed for the transportation of the floor request to the controlling MCPTT function hosting the temporary MCPTT group. The solutions were:
1) Use of the session related methods (e.g. SIP 200 (OK) response to the SIP INVITE request).
2) Use of the SIP MESSAGE method.
3) Use of the SIP INFO method as described in IETF RFC 6086, by defining a new info package.
The result of the evaluation of the above solutions were:
1) To include such a large amount of data in a SIP 200 (OK) response to an SIP INVITE request could cause problems with the size of the SIP 200 (OK) response resulting in packet fragmentation.
2) The use of the SIP MESSAGE request would result in that the recommended value of size of the information transferred by the SIP MESSAGE request would be exceeded.
3) The use of SIP INFO request was found as the most appropriate solution since the SIP INFO request could be sent in the existing SIP session.
J.1.2.4 Info package name
J.1.2.5 Info package parameters
J.1.2.6 SIP options tags
J.1.2.7 INFO message body parts
The MIME type of the message body carrying participant identities is application/vnd.3gpp.floor-request+xml. The application/vnd.3gpp.floor-request+xml MIME type is defined in 3GPP TS 24.379.
When associated with the g.3gpp.mcptt-floor-request info package, the Content-Disposition value of the message body carrying the floor request is "info-package".
J.1.2.8 Info package usage restrictions
J.1.2.9 Rate of INFO Requests
Single INFO request generated after session set up.
J.1.2.10 Info package security considerations
The security is based on the generic security mechanism provided for the underlying SIP signalling. No additional security mechanism is defined.
J.1.2.11 Implementation details and examples
UAC generation of INFO requests: See 3GPP TS 24.379: "Mission Critical Push To Talk (MCPTT) call control; Protocol specification".
UAS processing of INFO requests: See 3GPP TS 24.379: ""Mission Critical Push To Talk (MCPTT) call control; Protocol specification"
EXAMPLE: A controlling MCPTT function hosting a temporary MCPTT group inviting a constituent MCPTT group hosted by a non-controlling MCPTT function of a MCPTT group in a partner system where an MCPTT call is ongoing with one or two of the participants granted to speak. Then the non-controlling MCPTT function of the an MCPTT group sends a SIP INFO request carrying a floor request in an application/vnd.3gpp.mcptt-floor-request+xml MIME body using the g.3gpp.mcptt-floor-request info package.