Mobile Communications

Concepts and Terms

IMSI

IMSI International Mobile Subscriber Identity is an unique number, usually fifteen digits, associated with Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UTMS) network mobile phone users, identifying a GSM subscriber. The number has two parts: first six digits (North American standard) identify the network operator in a specific country with whom the subscriber holds an account. The second part is allocated by the network operator to uniquely identify a subscriber.

LTE Architecture

UE

User Equipment.

LTE Long Term Evolution.

SAE

System Architecture Evolution (SAE) is the core network architecture of 3GPP LTE wireless communication standard.

EPC

Evolved packet core is the main component of the SAE.

MME

Mobility Management Entity is the main signaling node in the EPC, responsible for initiating paging and authentication of the mobile device. MME retains location information at the tracking area level for each user and then selects the appropriate gateway during the initial registration process. MME connects to the evolved node b (eNB) through the S1-MME interface and connects to S-GW through S11 interface. Multiple MMEs can be grouped together in a pool to meet increasing signaling load in the network. MME is also the main control node in the LTE access network. It has the following functions:

• 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: provide seamless inter-working.
• Roaming Management.
• UE Reachability. MME manages communication with the UE and HSS to provide UE reachability and activity-related information.
• Tracking Area Management: