The present document defines the Stage 2 service description for the Evolved 3GPP Packet Switched Domain - also known as the Evolved Packet System (EPS) in this document. The Evolved 3GPP Packet Switched Domain provides IP connectivity using the Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
The specification covers both roaming and non-roaming scenarios and covers all aspects, including mobility between E-UTRAN and pre-E-UTRAN 3GPP radio access technologies, policy control and charging, and authentication.
The Radio Access Network functionality is documented only to the extent necessary to describe the overall system. TS 36.300 contains the overall description of the Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
ITU-T Recommendation I.130  describes a three-stage method for characterisation of telecommunication services, and ITU-T Recommendation Q.65  defines Stage 2 of the method.
TS 23.402 is a companion specification to this specification.
An Evolved Packet System architecture optimised for the support of Cellular IoT (Internet of Things) applications is also defined in this document.
The Evolved Packet System also provides support for the E-UTRAN to control a Dual Connectivity radio connection that uses a combination of E-UTRA and another radio access technology (e.g. NR). TS 36.300 contains the overall description for Dual Connectivity.
Enhancements to support interworking of EPS with 5GS are captured in TS 23.501 and TS 23.502.
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
MME Pool Area:
An MME Pool Area is defined as an area within which a UE may be served without need to change the serving MME. An MME Pool Area is served by one or more MMEs ("pool of MMEs") in parallel. MME Pool Areas are a collection of complete Tracking Areas. MME Pool Areas may overlap each other.
Serving GW Service Area:
A Serving GW Service Area is defined as an area within which a UE may be served without need to change the Serving GW. A Serving GW Service Area is served by one or more Serving GWs in parallel. Serving GW Service Areas are a collection of complete Tracking Areas. Serving GW Service Areas may overlap each other.
The association between a PDN represented by an APN and a UE, represented by one IPv4 address and/or one IPv6 prefix (for IP PDN Type) or by the UE Identity (for Non-IP and Ethernet PDN Types).
The EPS bearer which is first established for a new PDN connection and remains established throughout the lifetime of the PDN connection.
A Default APN is defined as the APN which is marked as default in the subscription data and used during the Attach procedure and the UE requested PDN connectivity procedure when no APN is provided by the UE.
eCall Only Mode:
A UE configuration option that allows the UE to attach at EPS and register in IMS to perform only eCall Over IMS, and an IMS call to a non-emergency MSISDN or URI for test and/or terminal reconfiguration services. For a short period following either such call, an incoming call (e.g. callback from a PSAP or HPLMN operator) or other incoming session (e.g. for USIM reconfiguration) is possible. At other times when the UE is configured in this mode, the UE is required to refrain from any signalling to a network. Use of eCall Only Mode is configured in the USIM for the UE.
PDN Connection to the SCEF:
The association between a UE, represented by the UE Identity, and a PDN represented by an APN to external packet data network via SCEF to allow transfer of Non-IP data. It includes establishment and persistence of T6 connection between MME and SCEF (see TS 29.128).
Emergency attached UE:
A UE which only has bearer(s) related to emergency bearer service.
LIPA PDN connection:
a PDN Connection for local access (e.g. for IP or Ethernet access) for a UE connected to a HeNB.
a PDN connection for SIPTO at local network for a UE connected to a (H)eNB.
For a LIPA PDN connection, Correlation ID is a parameter that enables direct user plane path between the HeNB and L-GW.
SIPTO Correlation ID:
For a SIPTO at local network PDN connection, SIPTO Correlation ID is a parameter that enables direct user plane path between the (H)eNB and L-GW when they are collocated.
Local Home Network:
A set of (H)eNBs and L-GWs in the standalone GW architecture, where the (H)eNBs have IP connectivity for SIPTO at the Local Network via all the L-GWs.
Local Home Network ID:
An identifier that uniquely identifies a Local Home Network within a PLMN.
Presence Reporting Area:
An area defined within 3GPP Packet Domain for the purposes of reporting of UE presence within that area due to policy control and/or charging reasons. In the case of E-UTRAN, a Presence Reporting Area may consist in a set of neighbor or non-neighbor Tracking Areas, or eNodeBs and/or cells. There are two types of Presence Reporting Areas: "UE-dedicated Presence Reporting Areas" and "Core Network pre-configured Presence Reporting Areas" that apply to an MME pool.
RAN user plane congestion:
RAN user plane congestion occurs when the demand for RAN resources exceeds the available RAN capacity to deliver the user data for a prolonged period of time.
an eNodeB that has the capability of IOPS mode operation, which provides local connectivity (e.g. for IP or Ethernet) and public safety services to IOPS-enabled UEs via a Local EPC when the eNodeB has lost backhaul to the Macro EPC or it has no backhaul to the Macro EPC.
an IOPS network consists of one or more eNodeBs operating in IOPS mode and connected to a Local EPC.
a Local EPC is an entity which provides functionality that eNodeBs in IOPS mode of operation use, instead of the Macro EPC, in order to support public safety services.
Macro EPC: the EPC which serves an eNodeB when it is not in IOPS mode of operation.
a deployable system which has the capability to provide radio access (via deployable IOPS-capable eNodeB(s)), local connectivity (e.g. for IP or Ethernet) and public safety services to IOPS-enabled UEs in the absence of normal EPS
a UE with multiple USIMs, capable of maintaining a separate registration state with a PLMN for each USIM at least over 3GPP Access and supporting one or more of the enhancements described in clause 4.3.33.
is an UE that is configured to use networks operating in IOPS mode.
Cellular network supporting low complexity and low throughput devices for a network of Things. Cellular IoT supports IP, Ethernet and Non-IP traffic.
a 3GPP Radio Access Technology that forms part of Cellular IoT. It allows access to network services via E-UTRA with a channel bandwidth limited to 180 kHz (corresponding to one PRB). Unless otherwise indicated in a clause, Narrowband-IoT is a subset of E-UTRAN.
a 3GPP RAT type Identifier used in the Core Network only, which is a sub-type E-UTRAN RAT type, and defined to identify in the Core Network the E-UTRAN when used by a UE indicating Category M in its UE radio capability.
in the RAN, WB-E-UTRAN is the part of E-UTRAN that excludes NB-IoT. In the Core Network, the WB-E-UTRAN also excludes LTE-M.
DCN identity identifies a specific dedicated core network (DCN).
For the purposes of the present document, the following terms and definitions given in TS 23.167 apply:
eCall Over IMS:
A UE is attached only for accessing Restricted Local Operator Services (see TS 23.221).
For the purposes of this specification, this is a NR Secondary RAN node is further described in TS 37.340 that supports Integrated access and backhaul (IAB) feature and provides connection to the core network to IAB-nodes. It supports the CU function of the CU/DU architecture for IAB defined in TS 38.401.
A relay node that supports wireless in-band and out-of-band relaying of NR access traffic via NR Uu backhaul links. It supports the UE function and the DU function of the CU/DU architecture for IAB defined in TS 38.401.
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
Allocation and Retention Priority
Aggregate Maximum Bit Rate
Cell Broadcast Centre
Cell Broadcast Entity
Closed Subscriber Group
Closed Subscriber Group Identity
CIoT Serving Gateway Node
CSG Subscriber Server
Dual Active Protocol Stacks
Dedicated Core Network
Donor eNode B
DownLink Traffic Flow Template
E-UTRAN Cell Global Identifier
EPS Connection Management
Explicit Congestion Notification
EPS Mobility Management
evolved Node B
Evolved Packet Core
Evolved Packet System
E-UTRAN Radio Access Bearer
Evolved Universal Terrestrial Radio Access Network
Guaranteed Bit Rate
Globally Unique MME Identifier
Globally Unique Temporary Identity
Home eNode B
Home eNode B Gateway
Hyper Frame Number
Integrated Access and Backhaul
IMEI Type Allocation Code
Isolated E-UTRAN Operation for Public Safety
Internet of Things
Idle mode Signalling Reduction
Licensed Assisted Access
Linked EPS Bearer Id
Local IP Access
LTE/WLAN Radio Level Integration with IPsec Tunnel