The TSG Core Network and Terminals WG3 (CT WG3) specifies the bearer capabilities for circuit and packet switched data services, and the necessary interworking functions towards both, the user equipment in the UMTS PLMN and the terminal equipment in the external network. In addition CT is responsible of end to end QoS for the UMTS core network in Release 5 and beyond.

Terms of reference

The latest terms of reference were approved at CP#72 in document CP-160283.zip

1. General

CT3 is responsible for:

1. Interworking between a 3GPP PLMN and external nodes or networks, interworking between PLMNs as well as interworking between PLMN domains.
2. Policy and charging control, end-to-end QoS mechanisms.

2. Areas of responsibility

• CS domain
  • Transport protocols from the core network towards the UE, incl. rate adaptation and RLP.
  • Data call signalling parameters from the core network towards the UE.
  • Control plane and user plane interworking towards the fixed network.
  • User plane protocols between MGWs (Nb interface).
• PS domain and WLAN
  • Interworking between GPRS/EPS and external IP networks including enterprise networks. Stage 2 and stage 3 responsibility for bearer level and AAA and DHCP functionality.
  • Interworking between WLAN and external IP networks, incl. bearer level and AAA functionality.
  • Providing presence information to the Presence Network Gateway from access network (e.g. GPRS and WLAN) gateways.
  • Interworking between packet data network gateways (e.g. GGSN, P-GW and MBMS GW) and service networks/nodes such as the BM-SC.
  • R reference point (TE – MT) related to the PDP context de/activation (scope of TS 27.060), including general requirements for AT commands.
  • Interworking between the MTC Interworking Function (MTC-IWF) and Service Capability Server (SCS).
  • Interworking between the Proximity-services (ProSe) function to the ProSe application server.
  • Interworking between the Group Communication Service Application Server (GCS AS) and the Broadcast-Multicast Service Centre (BM-SC).
    
    
• IM CN subsystem (IMS) of the PS domain
  • Interworking with CS networks
  • Interworking with external IP networks
  • Bearer related network entities, e.g. IM-MGW, TrGW. Incl. stage 2 specification of H.248 interfaces for interworking cases.
  • NGN related interworking impacts
  • Inter-IMS protocol profiles and procedures
    
    
• Services
  • Circuit switched data services, incl. multimedia, facsimile and text telephony
  • Service Change and UDI Fallback (SCUDIF), stage 2
  • Service interworking
    
    
• Policy and Charging Control, QoS
  • Policy and Charging Control within a PLMN and between PLMNs
  • Policy and Charging Control with external Application Functions
  • QoS mapping between service layer and access network bearer layer
  • End-to-end QoS mapping and negotiation
  • Usage of QoS protocols (such as DiffServ, RSVP and NSIS)
  • Provisioning of QoS rules and QoS policy at access network gateways
  • User layer application detection and related control functionality
  • Interworking between the Policy and Charging Rules Function (PCRF) and  the online charging system (OCS)
  • Interactions with external policy control (e.g. Support for BroadBand Forum Accesses Interworking) and Policy and Charging Control for supporting traffic from fixed terminals and NSWO traffic from 3GPP UE in fixed broadband access networks
  • Policy Control on User Plane Congestion
  • Interworking between Service Capability Exposure Function (SCEF) and Policy and Charging Rules Function (PCRF)
  • Interworking between the Service Capability Exposure Function (SCEF) and RAN Congestion Awareness Function (RCAF)
  • Interworking between the Policy and Charging Rules Function (PCRF) and Traffic Steering Support Function (TSSF)

3. Dependencies with other groups

CT3 has important dependencies with the following work performed in other 3GPP groups:

• CT1: The radio interface layer 3 procedures and protocols, IMS signalling
• CT4: Diameter coordination, stage 2 for the split CS architecture  and TrFO, Mc and Mn and Ix interfaces, GTP, PMIP, DSMIP
• RAN3: Iu-cs interface
• SA1: Service requirements
• SA2: Overall architecture
• SA3: Security Aspects
• SA4: PS services e.g. MBMS user services, conversational services used in IMS
• SA5: Gy/Gyn interfaces for Flow Based Charging and Application Based Charging
• SA6: Mission Critical Push To Talk (MCPTT) over LTE protocol aspects

Furthermore, CT3 has important dependencies with work performed in the following external entities: ITU-T, IETF, ETSI TISPAN and Broadband Forum.

4. Specifications

CT3 is responsible for the technical specifications and reports listed under the following link: http://www.3gpp.org/ftp/Specs/html-info/TSG-WG--C3.htm

Useful links and information