- 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 non-collocated 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.
manages and stores UE context (for idle state: UE/user identities, UE mobility state, user security parameters). It generates temporary identities and allocates them to UEs. It checks the authorization whether the UE may camp on the TA or on the PLMN. It also authenticates the user.
The SGW routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic between 2G/3G systems and PDN GW).
The PDN GW provides connectivity to the UE to external packet data networks by being the point of exit and entry of traffic for the UE. A UE may have simultaneous connectivity with more than one PDN GW for accessing multiple PDNs. The PDN GW performs policy enforcement, packet filtering for each user, charging support, lawful Interception
and packet screening.
- Air Interface Physical Layer
- GPRS Tunnelling Protocol User Plane (GTP-U)
- GTP-U Transport
- Medium Access Control (MAC)
- Non-Access-Stratum (NAS) Protocol
- Packet Data Convergence Protocol (PDCP)
- Radio Link Control (RLC)
- Radio Resource Control (RRC)
- S1 Application Protocol (S1AP)
- S1 layer 1
- S1 Signalling Transport
- X2 Application Protocol (X2AP)
- X2 layer 1
- X2 Signalling Transport
- The keys used for NAS and AS protection shall be dependent on the algorithm with which they are used.
- The eNB keys are cryptographically separated from the EPC keys used for NAS protection (making it impossible to use the eNB key to figure out an EPC key).
- The AS (RRC and UP) and NAS keys are derived in the EPC/UE from key material that was generated by a NAS (EPC/UE) level AKA procedure (KASME) and identified with a key identifier (KSIASME).
- The eNB key (KeNB) is sent from the EPC to the eNB when the UE is entering ECM-CONNECTED state (i.e. during RRC connection or S1 context setup).
- Intra-frequency E-UTRAN measurements
- Inter-frequency E-UTRAN measurements
- Inter-RAT measurements for UTRAN and GERAN
- Inter-RAT measurements of CDMA2000 HRPD or 1xRTT frequencies
charging will help operators monetize their LTE investment by providing customers with a variety of QoS and charging options when choosing a service.
- PCRF (policy and charging rules function) provides policy control and flow based charging control decisions.
- PCEF (policy and charging enforcement function) implemented in the serving gateway, this enforces gating and QoS for individual IP flows on the behalf of
- the PCRF. It also provides usage measurement to support charging
- OCS (online charging system) provides credit management and grants credit to the PCEF based on time, traffic volume or chargeable events.
- OFCS (off-line charging system) receives events from the PCEF and generates charging data records (CDRs) for the billing system.
Policy control and charging for LTE networks
Quality of Service (QoS) and Policy Management in Mobile Data Networks
- SLg between the GMLC and the MME
- SLs between the E-SMLC and the MME
- Diameter-based SLh between the HSS and the HGMLC