Cisco ASR 5000 Series, Обзор продукта

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Mobility Management Entity Overview
▀ Features and Functionality - Base Software
▄ Cisco ASR 5000 Series Product Overview
OL-22938-02
The GUTI is used to support subscriber identity confidentiality, and, in the shortened S-TMSI form, to enable more
efficient radio signaling procedures (e.g. paging and Service Request).
Tracking Area Identity (TAI) : Provides the function to assign the TAI list to the mobile access device to limit
the frequency of Tracking Area Updates in the network. The TAI is the identity used to identify the tracking
area or group of cells in which the idle mode access terminal will be paged when a remote host attempts to
reach that user. The TAI consists of the Mobile Country Code (MCC), Mobile Network Code (MNC) and
Tracking Area Code (TAC).
MME S1-AP UE Identity (MME S1-AP UE ID) : This is the temporary identity used to identify a UE on the
S1-MME reference point within the MME. It is unique within the MME per S1-MME reference point instance.
Tracking Area List Management
Provides the functions to allocate and reallocate a Tracking Area Identity (TAI) list to the UE to minimize the Tracking
Area updates.
The MME assigns the TAI list to a UE so as to minimize the TA updates that would be sent by the UE. The TAI list
should not be very long as this would mean that the paging load would be high. There is a trade-off between paging load
and Tracking Area Update procedures number.
To avoid ping-pong effect, the MME includes the last visited TAI (provided that the TA is handled by the MME) in the
TAI list assigned to the UE.
The tracking area list assigned to different UEs moving in from the same tracking area should be different so as to avoid
Tracking Area Update message overflow.
Reachability Management
It provides a mechanism to track a UE which is in idle state for EPS connection management.
To reach a UE in idle state the MME initiates paging to all eNodeBs in all tracking areas in the TA list assigned to the
UE. The EPS session manager have knowledge about all the eNodeB associations to the MME and generates a list of
eNodeBs that needs to be paged to reach a particular UE.
The location of a UE in ECM-IDLE state is known by the network on a Tracking Area List granularity. A UE in ECM-
IDLE state is paged in all cells of the Tracking Areas in which it is currently registered. The UE may be registered in
multiple Tracking Areas. A UE performs periodic Tracking Area Updates to ensure its reachability from the network.
Network Operation Management Functions
This section describes following features:
Overload Management in MME
Radio Resource Management Functions
Mobile Equipment Identity Check