Page 495 - 5G Basics - Core Network Aspects

Core network aspects 1

Table 27 – Network selection key transfer indication (TLM-FE → NID-FE)

Information element Explanation

Mobility service subscriber identifier The user/UE identifier authenticated for mobility services. This will be
the same as the transport subscriber identifier in the integrated scenario.
Keying material The material used for security association between the UE and NID-FE.

7 Procedures

This clause describes the information flows required to achieve initial attachment, network discovery and
handover for a mobile UE. In each stage, the procedures vary depending on UE capabilities and network
arrangements, and the scenarios in this Recommendation, therefore, can be referred to only as examples.

7.1 Overview of mobility procedures
Figure 4 shows the key procedures involved in the whole mobility process and their general sequence. It
should be noted that depending on different deployment requirements, the handover preparation can vary
slightly.

Initial Network
attachment discovery

Pre-authentication
and
pre-authorization
Power
on
Pre-configuration

Handover
execution
Location update
and new data path
establishment

Proactive
resource
reservation
Handover preparation
Y.2018(09)_F04

Figure 4 – Overview of the handover process

1) Initial attachment
When a UE is powered on it will perform the initial attachment process defined in [ITU-T Y.2014]. For mobile
UE, mobility authentication will be performed along with network access authentication. Also mobility
location registration and binding will be done at the end of the phase.
After the initial attachment procedure, IP connectivity exists between the UE and the network.

2) Network discovery
Network discovery is performed by the mobile UE. Once a mobile UE is powered on, it may periodically scan
for potential attachment points. The handover threshold can be triggered by multiple reasons such as link
deterioration, etc. When this happens, the UE sends its current list of candidate attachment points to the
HDC-FE to initiate the handover decision process. This process results in the selection of the target access
point.

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