5 Architectural requirements

23.1803GPPMission critical services support in the Isolated Operation for Public Safety (IOPS) mode of operationRelease 17TS

5.1 General requirements

5.1.1 Description

This clause specifies the general requirements for the support of MC services in the IOPS mode of operation.

5.1.2 Requirements

[AR-5.1.2-a] For the case of a backhaul failure between the radio access network and the macro EPC, the IOPS MC system shall provide support for MC services in the IOPS mode of operation until the failure is recovered.

[AR-5.1.2-b] MC service UEs within the coverage of the IOPS EPS shall be able to provide MC services over the IOPS MC system.

[AR-5.1.2-c] The IOPS MC system shall provide mechanisms to verify the availability of MC service UEs within the IOPS MC system.

5.2 MC service requirements

5.2.1 Description

This clause specifies the MC service requirements in the IOPS mode of operation.

5.2.2 Requirements

[AR-5.2.2-a] The following MCPTT service features shall be supported in the IOPS mode of operation

– MCPTT group call

– MCPTT emergency group call

– MCPTT private call

– MCPTT emergency private call

[AR-5.2.2-b] The following MCData service features shall be supported in the IOPS mode of operation

– MCData short data service

5.3 Network bearer requirements

5.3.1 Description

This clause specifies the network bearer requirements in the IOPS mode of operation.

5.3.2 Requirements

[AR-5.3.2-a] The IOPS MC system shall provide support for unicast bearer establishment and modification to support MC services via unicast transmissions in the IOPS mode of operation.

[AR-5.3.2-b] The IOPS MC system shall provide support for multicast bearer establishment and modification to support MC services via multicast transmissions in the IOPS mode of operation.

[AR-5.3.2-c] The IOPS MC system shall support announcement of multicast bearers to the MC service UEs.

5.4 IP connectivity functionality

5.4.1 Description

The support of MC services in the IOPS mode of operation can be based on the support of the IP connectivity functionality. The IP connectivity functionality enables that MC services are provided by the MC service clients via the IOPS MC connectivity function.

An IOPS MC connectivity function supporting the IP connectivity functionality does not provide MC services. Instead, the IOPS MC connectivity function enables discovering MC service users and provides IP connectivity for the communication among the discovered MC service users, i.e. it distributes the related IP traffic to the MC service UEs over IP unicast and/or multicast transmissions. A MC service UE supporting the IP connectivity functionality in the IOPS mode of operation enables transmitting the IP packets related to a MC service communication over the IOPS MC connectivity function.

This clause specifies requirements for the support of the IP connectivity functionality in the IOPS mode of operation.

5.4.2 General requirements

[AR-5.4.2-a] The IOPS MC connectivity function supporting the IP connectivity functionality shall support discovering MC service users within the coverage of the IOPS EPS.

[AR-5.4.2-b] The IOPS MC connectivity function supporting the IP connectivity functionality shall support announcement, subscription and notification mechanisms for discovered MC service users supporting the IP connectivity functionality.

[AR-5.4.2-c] The IOPS MC connectivity function supporting the IP connectivity functionality shall provide IP connectivity for communication among MC service users requesting the support of the IP connectivity functionality.

[AR-5.4.2-d] The MC service UEs supporting the IP connectivity functionality in the IOPS mode of operation shall enable transmitting the IP packets related to a MC service communication over the IOPS MC connectivity function.

5.4.3 Bearer management requirements

[AR-5.4.3-a] The MC service UEs shall use specific APNs for the support of the IP connectivity functionality, as follows:

– An APN for the IOPS related application signalling related to the IP connectivity functionality support, e.g. for IOPS discovery, subscription and notification.

– An MC service APN for the communication with another MC user or group via the IOPS MC connectivity function based on the IP connectivity functionality, e.g. for the signalling and media.

[AR-5.4.3-b] The APNs for the IP connectivity functionality support shall be made available to the MC service UEs either via UE (pre)configuration or via initial UE configuration, as described in 3GPP TS 23.280 [3].