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What is the role of MME in LTE technology?

+6 votes

I am new for LTE technology.
Please help me to get understand the role of MME in LTE technology?

posted Nov 24, 2013 by Harshita

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3 Answers

+1 vote

As I replied you for your earlier question about the interfaces supported in LTE network. There are so many nodes in the network which do their specific jobs.
MME stands for "Mobility Management Entity". LTE network comprises of two parts of the network.
1. LTE AS network and 2. LTE Core network.
MME belongs to core network. It is the main controlling entity of NAS (Non Access stratum) Signalling.
It does multiple jobs like
1. Authentication of UE, NAS Security Activation , bearer establishment/modification and release.
2. S1-AP handover with MME relocation and with out MME relocation as well.
3. Idle mode mobility when UE context has been deleted at eNodeB and maintained at MME.
There are so many things which I can't cover here.
Please check 3GPP 24.301 and 23.401.

answer Nov 24, 2013 by Vimal Kumar Mishra
+1 vote

MME: The MME is the control node which processes the signalling between the UE
and the CN. The protocols running between the UE and the CN are known as the
Non-Access Stratum (NAS) protocols.
The main functions supported by the MME are classified as:
Functions related to bearer management. This includes the establishment, maintenance
and release of the bearers, and is handled by the session management layer in
the NAS protocol.
Functions related to connection management. This includes the establishment of the
connection and security between the network and UE, and is handled by the connection
or mobility management layer in the NAS protocol layer.

• E-SMLC. The E-SMLC manages the overall coordination and scheduling of resources
required to find the location of a UE that is attached to E-UTRAN. It also calculates
the final location based on the estimates it receives, and it estimates the UE speed and
the achieved accuracy.

answer Nov 24, 2013 by Giri Prasad
0 votes

MME can be assumed as the main control node of the LTE network and It has the following functionality.

Network Access Control: MME manages authentication and authorization for the UE. It also facilitates UE access to the network to gain IP connectivity.
Radio Resource Management: MME works with the HSS and the RAN to decide the appropriate radio resource management strategy (RRM) that can be UE-specific.
Mobility Management: One of the most complex functions MME performs. Providing seamless inter-working has multiple use cases such as Inter-eNB and Inter-RAT, among others. The use cases become more complex depending on a change in MME, S-GW, P-GW or inter-working across other wireless networks.
Roaming Management: MME supports outbound and inbound roaming subscribers from other LTE/EPC systems and legacy networks.
UE Reach-ability: MME manages communication with the UE and HSS to provide UE reach-ability and activity-related information.
Tracking Area Management: Allocates and reallocates a tracking area identity list to the UE.
Lawful Intercept: Since MME manages the control plane of the network, MME can provide the whereabouts of a UE to a law enforcement monitoring facility.
Load Balancing Between S-GWs: Directs UEs entering an S-GW pool area to an appropriate S-GW. This achieves load balancing between S-GWs.

Following image should help...

answer Nov 24, 2013 by Salil Agrawal
Similar Questions
+1 vote

Generally MME serves a group of tracking areas and belongs to at least one PLMN.
Lets assume, MME receives S1-setup request from eNodeB with the list of supported TAs.
Now, there are three possibilities as captured below.
1. All supported TAIs match at MME
2. Not even a single TAI match at MME
3. Few TAIs match at MME

I want to know, what MME will do for case 2 and case 3 ? How it will respond to eNodeB ?
If MME responds with S1-setup failure then what would be the cause value ? I did not find any reference in 36.413 for these scenarios.

0 votes

As per LTE core network architecture, MME shares S11 interface with SGW and SGW has S5/S8 interface with PGW.
I went through Create Session Response message sent by SGW to MME and found PGW-C and PGW-U tunnel ids.
I want to know what MME does with these PGW-C and PGW-U tunnel Ids ?

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