4G/5G

Mobility

Mobility and Connection Management

Overview

Mobility covers everything that keeps a device connected and reachable as it moves: choosing and keeping a cell in idle or inactive mode, moving between cells while connected, recovering when the radio link fails, and telling the network where the device is through registration and tracking area updates.

The same building blocks exist in LTE and NR. NTN and IoT add timing, location and power-saving constraints on top of them.

Specifications:TS 38.300 TS 38.331 TS 38.304 TS 36.300 TS 36.331 TS 36.304

Procedures

RRC states and mobility

State	Who controls mobility	Typical mechanism
RRC_IDLE	UE	Cell selection and reselection, paging, tracking area updates
RRC_INACTIVE (NR)	UE, with RAN notification area	Reselection, RNA updates, resume instead of new setup
RRC_CONNECTED	Network	Measurement reports, handover, conditional handover, re-establishment

Specifications

TS 23.009

Handover procedures

Architecture

Overview

Procedures

RRC states and mobility

Specifications

Handover procedures

Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode

Network-Based IP Flow Mobility (NBIFOM); Stage 2

IP flow mobility and seamless Wireless Local Area Network (WLAN) offload; Stage 2

Study of further architecture enhancements for uncrewed aerial systems and urban air mobility

Network-Based IP Flow Mobility (NBIFOM); Stage 3

Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3

Mobility management based on Dual-Stack Mobile IPv6; Stage 3

Mobility management based on Mobile IPv4; User Equipment (UE) - foreign agent interface; Stage 3

Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3

Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification

Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) interfaces for interworking with packet data networks and applications

Evolved Packet System (EPS); Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) related interfaces based on Diameter protocol

Proxy Mobile IPv6 (PMIPv6) based Mobility and Tunnelling protocols; Stage 3

3GPP Evolved Packet System (EPS); Optimized handover procedures and protocols between E-UTRAN access and cdma2000 HRPD Access; Stage 3

Optimised handover procedures and protocol between EUTRAN access and non-3GPP accesses (S102); Stage 3

Mobile IPv4 (MIPv4) based mobility protocols; Stage 3

5G System; Access and Mobility Policy Control Service; Stage 3

5G System; Access and Mobility Management Services; Stage 3

5G System; Access and Mobility Policy Authorization Service; Stage 3

Interface between the UE radio Capability Management Function (UCMF) and the Mobility Management Entity (MME); Stage 3

Charging management; 5G connection and mobility domain charging; Stage 2

5G Security Assurance Specification (SCAS); Access and Mobility management Function (AMF)

Security for mobility over non-3GPP access to avoid full primary authentication

Study on the security of Access and Mobility Management Function (AMF) re-allocation

Study on security of phase 2 for Uncrewed Aerial System (UAS), Uncrewed Aerial Vehicle (UAV) and Urban Air Mobility (UAM)

Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management

Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) procedures in idle mode

Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification

Evolved Universal Terrestrial Radio Access Network (E-UTRAN); X2 Application Protocol (X2AP)

Evolved Universal Terrestrial Radio Access (E-UTRA) and NR; Multi-connectivity; Overall Description; Stage-2

NR; Requirements for support of radio resource management

NR; User Equipment (UE) procedures in Idle mode and in RRC Inactive state

NR; Radio Resource Control (RRC); Protocol specification

NG-RAN; Xn Application Protocol (XnAP)

Study on Artificial Intelligence (AI)/Machine Learning (ML) for mobility in NR