Product Description
Platform Requirements
Licenses
Network Deployment and Interfaces
MME in the E-UTRAN/EPC Network
Supported Logical Network Interfaces (Reference Points)
S1-MME Interface
S3 Interface
S6a Interface
S10 Interface
S11 Interface
S13 Interface
SGs Interface
Sv Interface
Gn Interface
Features and Functionality - Base Software
IMPORTANT:
3GPP R8 Identity Support
ANSI T1.276 Compliance
APN Restriction Support
Authentication and Key Agreement (AKA)
Bulk Statistics Support
Congestion Control
IMPORTANT:
EPS Bearer Context Support
EPS GTPv2 Support on S11 Interface
IMPORTANT:
HSS Support Over S6a Interface
Inter-MME Handover Support
Interworking Support
Interworking with SGSNs
Handover Support for S4-SGSNs
IPv6 Support
Load Balancing
Load Re-balancing
Management System Overview
IMPORTANT:
MME Pooling
MME Selection
Mobile Equipment Identity Check
Mobility Restriction
Multiple PDN Support
NAS Protocol Support
EPS Mobility Management (EMM)
NAS Signalling Security
Operator Policy Support
Overload Management in MME
CAUTION:
Packet Data Network Gateway (P-GW) Selection
Radio Resource Management Functions
Reachability Management
SCTP Multi-homing Support
Serving Gateway Pooling Support
Serving Gateway Selection
Session and Quality of Service Management
Subscriber Level Session Trace
Threshold Crossing Alerts (TCA) Support
IMPORTANT:
Tracking Area List Management
Features and Functionality - External Application Support
Web Element Management System
IMPORTANT:
Features and Functionality - Licensed Enhanced Feature Software
Circuit Switched Fall Back (CSFB) and SMS over SGs Interface
IMPORTANT:
IP Security (IPSec)
IMPORTANT:
IMPORTANT:
Lawful Intercept
Location Services
Optimized Paging Support
Session Recovery Support
IMPORTANT:
User Location Information Reporting
IMPORTANT:
How the MME Works
EPS Bearer Context Processing
Subscriber-initiated Initial Attach Procedure
Step | Description |
---|---|
1 | The UE initiates the Attach procedure by the transmission of an Attach Request (IMSI or old GUTI, last visited TAI (if available), UE Network Capability, PDN Address Allocation, Protocol Configuration Options, Attach Type) message together with an indication of the Selected Network to the eNodeB. IMSI is included if the UE does not have a valid GUTI available. If the UE has a valid GUTI, it is included. |
2 | The eNodeB derives the MME from the GUTI and from the indicated Selected Network. If that MME is not associated with the eNodeB, the eNodeB selects an MME using an “MME selection function”. The eNodeB forwards the Attach Request message to the new MME contained in a S1-MME control message (Initial UE message) together with the Selected Network and an indication of the E-UTRAN Area identity, a globally unique E-UTRAN ID of the cell from where it received the message to the new MME. |
3 | If the UE is unknown in the MME, the MME sends an Identity Request to the UE to request the IMSI. |
4 | The UE responds with Identity Response (IMSI). |
5 | If no UE context for the UE exists anywhere in the network, authentication is mandatory. Otherwise this step is optional. However, at least integrity checking is started and the ME Identity is retrieved from the UE at Initial Attach. The authentication functions, if performed this step, involves AKA authentication and establishment of a NAS level security association with the UE in order to protect further NAS protocol messages. |
6 | The MME sends an Update Location Request (MME Identity, IMSI, ME Identity) to the HSS. |
7 | The HSS acknowledges the Update Location message by sending an Update Location Ack to the MME. This message also contains the Insert Subscriber Data (IMSI, Subscription Data) Request. The Subscription Data contains the list of all APNs that the UE is permitted to access, an indication about which of those APNs is the Default APN, and the 'EPS subscribed QoS profile' for each permitted APN. If the Update Location is rejected by the HSS, the MME rejects the Attach Request from the UE with an appropriate cause. |
8 | The MME selects an S-GW using “Serving GW selection function” and allocates an EPS Bearer Identity for the Default Bearer associated with the UE. If the PDN subscription context contains no P-GW address the MME selects a P-GW as described in clause “PDN GW selection function”. Then it sends a Create Default Bearer Request (IMSI, MME Context ID, APN, RAT type, Default Bearer QoS, PDN Address Allocation, AMBR, EPS Bearer Identity, Protocol Configuration Options, ME Identity, User Location Information) message to the selected S-GW. |
9 | The S-GW creates a new entry in its EPS Bearer table and sends a Create Default Bearer Request (IMSI, APN, S-GW Address for the user plane, S-GW TEID of the user plane, S-GW TEID of the control plane, RAT type, Default Bearer QoS, PDN Address Allocation, AMBR, EPS Bearer Identity, Protocol Configuration Options, ME Identity, User Location Information) message to the P-GW. |
10 | If dynamic PCC is deployed, the P-GW interacts with the PCRF to get the default PCC rules for the UE. The IMSI, UE IP address, User Location Information, RAT type, AMBR are provided to the PCRF by the P-GW if received by the previous message. |
11 | The P-GW returns a Create Default Bearer Response (P-GW Address for the user plane, P-GW TEID of the user plane, P-GW TEID of the control plane, PDN Address Information, EPS Bearer Identity, Protocol Configuration Options) message to the S-GW. PDN Address Information is included if the P-GW allocated a PDN address Based on PDN Address Allocation received in the Create Default Bearer Request. PDN Address Information contains an IPv4 address for IPv4 and/or an IPv6 prefix and an Interface Identifier for IPv6. The P-GW takes into account the UE IP version capability indicated in the PDN Address Allocation and the policies of operator when the P-GW allocates the PDN Address Information. Whether the IP address is negotiated by the UE after completion of the Attach procedure, this is indicated in the Create Default Bearer Response. |
12 | The Downlink (DL) Data can start flowing towards S-GW. The S-GW buffers the data. |
13 | The S-GW returns a Create Default Bearer Response (PDN Address Information, S-GW address for User Plane, S-GW TEID for User Plane, S-GW Context ID, EPS Bearer Identity, Protocol Configuration Options) message to the new MME. PDN Address Information is included if it was provided by the P-GW. |
14 | The new MME sends an Attach Accept (APN, GUTI, PDN Address Information, TAI List, EPS Bearer Identity, Session Management Configuration IE, Protocol Configuration Options) message to the eNodeB. |
15 | The eNodeB sends Radio Bearer Establishment Request including the EPS Radio Bearer Identity to the UE. The Attach Accept message is also sent along to the UE. |
16 | The UE sends the Radio Bearer Establishment Response to the eNodeB. In this message, the Attach Complete message (EPS Bearer Identity) is included. |
17 | The eNodeB forwards the Attach Complete (EPS Bearer Identity) message to the MME. |
18 | The Attach is complete and UE sends data over the default bearer. At this time the UE can send uplink packets towards the eNodeB which are then tunnelled to the S-GW and P-GW. |
19 | The MME sends an Update Bearer Request (eNodeB address, eNodeB TEID) message to the S-GW. |
20 | The S-GW acknowledges by sending Update Bearer Response (EPS Bearer Identity) message to the MME. |
21 | The S-GW sends its buffered downlink packets. |
22 | After the MME receives Update Bearer Response (EPS Bearer Identity) message, if an EPS bearer was established and the subscription data indicates that the user is allowed to perform handover to non-3GPP accesses, and if the MME selected a P-GW that is different from the P-GW address which was indicated by the HSS in the PDN subscription context, the MME sends an Update Location Request including the APN and P-GW address to the HSS for mobility with non-3GPP accesses. |
23 | The HSS stores the APN and P-GW address pair and sends an Update Location Response to the MME. |
24 | Bidirectional data is passed between the UE and PDN. |
Subscriber-initiated Detach Procedure
Step | Description |
---|---|
1 | The UE sends NAS message Detach Request (GUTI, Switch Off) to the MME. Switch Off indicates whether detach is due to a switch off situation or not. |
2 | The active EPS Bearers in the S-GW regarding this particular UE are deactivated by the MME sending a Delete Bearer Request (TEID) message to the S-GW. |
3 | The S-GW sends a Delete Bearer Request (TEID) message to the P-GW. |
4 | The P-GW acknowledges with a Delete Bearer Response (TEID) message. |
5 | The P-GW may interact with the PCRF to indicate to the PCRF that EPS Bearer is released if PCRF is applied in the network. |
6 | The S-GW acknowledges with a Delete Bearer Response (TEID) message. |
7 | If Switch Off indicates that the detach is not due to a switch off situation, the MME sends a Detach Accept message to the UE. |
8 | The MME releases the S1-MME signalling connection for the UE by sending an S1 Release command to the eNodeB with Cause = Detach. |
Service Request Procedures
UE-initiated Service Request Procedure
Step | Description |
---|---|
1 | (NAS) The UE sends a Network Access Signaling (NAS) message Service Request (S-TMSI) towards the MME encapsulated in an RRC message to the eNodeB. |
2 | The eNodeB forwards NAS message to the MME. The NAS message is encapsulated in an S1-AP: Initial UE message (NAS message, TAI+ECGI of the serving cell). |
3 | NAS authentication procedures may be performed. |
4 | The MME sends an S1-AP Initial Context Setup Request (S-GW address, S1-TEID(s) (UL), EPS Bearer QoS(s), Security Context, MME Signalling Connection Id, Handover Restriction List) message to the eNodeB. This step activates the radio and S1 bearers for all the active EPS Bearers. The eNodeB stores the Security Context, MME Signalling Connection Id, EPS Bearer QoS(s) and S1-TEID(s) in the UE RAN context. |
5 | The eNodeB performs the radio bearer establishment procedure. |
6 | The uplink data from the UE can now be forwarded by eNodeB to the S-GW. The eNodeB sends the uplink data to the S-GW address and TEID provided in step 4. |
7 | The eNodeB sends an S1-AP message Initial Context Setup Complete message (eNodeB address, List of accepted EPS bearers, List of rejected EPS bearers, S1 TEID(s) (DL)) to the MME. |
8 | The MME sends a Modify Bearer Request message (eNodeB address, S1 TEID(s) (DL) for the accepted EPS bearers, RAT Type) to the S-GW. The S-GW is now able to transmit downlink data towards the UE. |
9 | The S-GW sends a Modify Bearer Response message to the MME. |
Network-initiated Service Request Procedure
Step | Description |
---|---|
1 | A downlink data packet is received on the S-GW from PDN for the targeted UE. The S-GW checks to see if the UE is user-plane connected (the S-GW context data indicates that there is no downlink user plane (TEID)). The downlink data is buffered and the S-GW identifies which MME is serving the intended UE. |
2 | The S-GW sends a Downlink Data Notification message to the MME for the targeted UE. |
3 | The MME responds with a Downlink Data Notification Acknowledgement message to the S-GW. |
4 | The MME send a Paging Request to the eNodeB for the targeted UE. The Paging Request contains the NAS ID for paging, TAI(s), the UE identity based DRX index, and the Paging DRX length. The Paging Request is sent to each eNodeB belonging to the tracking area(s) where the UE is registered. |
5 | The
eNodeB broadcasts the Paging Request in its coverage area for the
UE.
|
6 |
Upon receipt of the
Paging indication in the E-UTRAN access network, the UE initiates
the UE-triggered Service Request procedure and the eNodeB starts
messaging through the UE Paging Response.
The MME supervises the
paging procedure with a timer. If the MME receives no Paging Response
from the UE, it retransmits the Paging Request. If the MME receives
no response from the UE after the retransmission, it uses the Downlink
Data Notification Reject message to notify the S-GW about the paging
failure.
|
7 | The S-GW sends a Stop Paging message to MME. |
8 | The buffered downlink data is sent to the identified UE. |
Supported Standards
IETF References