E-UTRAN access (3GPP TS 23.401 V9.0.0)

Architecture model and concepts

Local breakout of IP traffic via the visited PLMN is supported, when network policies and user subscription allow it.Local breakout may be combined with support for multiple simultaneous PDN connections.
Architecture reference model

Non-roaming architecture

Non-roaming architecture for 3GPP accesses

Non-roaming architecture for 3GPP accesses. Single gateway configuration option


Roaming architecture

Roaming architecture for 3GPP accesses. Home routed traffic(remote breakout)

The Roaming with local breakout case with Application Function (AF) in the
Home Network and in the Visited Network respectively. The concurrent use of AF's in the home network and AF's in the visited network is not excluded.

Roaming architecture for local breakout, with home operator's application functions only

Roaming architecture for local breakout, with visited operator's application functions only

Reference points(Interfaces)
S1-MME: Reference point for the control plane protocol between E-UTRAN and MME.

S1-U: Reference point between E-UTRAN and Serving GW for the per bearer user plane tunnelling and inter eNodeB path switching during handover.

S3: It enables user and bearer information exchange for inter 3GPP access network mobility in idle and/or active state.

S4: It provides related control and mobility support between GPRS Core and the 3GPP Anchor function of Serving GW. In addition, if Direct Tunnel is not established, it provides the user plane tunnelling.

S5: It provides user plane tunnelling and tunnel management between Serving GW and PDN GW. It is used for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a noncollocated PDN GW for the required PDN connectivity.

S6a: It enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system (AAA interface) between MME and HSS.

Gx: It provides transfer of (QoS) policy and charging rules from PCRF to Policy and Charging Enforcement Function (PCEF) in the PDN GW.

S8: Inter-PLMN reference point providing user and control plane between the Serving GW in the VPLMN and the PDN GW in the HPLMN. S8 is the inter PLMN variant of S5.

S9: It provides transfer of (QoS) policy and charging control information between the Home PCRF and the Visited PCRF in order to support local breakout function.

S10: Reference point between MMEs for MME relocation and MME to MME information transfer.

S11: Reference point between MME and Serving GW.

S12: Reference point between UTRAN and Serving GW for user plane tunnelling when Direct Tunnel is established. It is based on the Iu-u/Gn-u reference point using the GTP-U protocol as defined between

SGSN and UTRAN or respectively between SGSN and GGSN. Usage of S12 is an operator configuration option.

S13: It enables UE identity check procedure between MME and EIR.

SGi: It is the reference point between the PDN GW and the packet data network. Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IMS services. This reference point corresponds to Gi for 3GPP accesses.

Rx: The Rx reference point resides between the AF and the PCRF in the TS 23.203 

SBc: Reference point between CBC and MME for warning message delivery and control functions.When data forwarding is used as part of mobility procedures different user plane routes may be used based on the network configuration (e.g. direct or indirect data forwarding). These routes can be between eNodeB and RNC, eNodeB and SGSN, RNC and S-GW or between S-GW and SGSN. Explicit reference points are not defined for these routes.