TAU procedure in LTE | Tracking Area Update procedure in LTE

This page describes TAU procedure used in LTE system. TAU stands for Tracking Area Update in LTE system. It mentions TAU procedure without S-GW change and with S-GW change.

A standalone TAU (tracking area update) without or with S-GW change happens when GPRS-attached UE or E-UTRAN-attached UE will go thorough certain conditions as mentioned in the 3GPP TS 23.401 document section 5.3.3.0.

TAU procedure without S-GW Change

The figure-1 depicts message flow between E-UTRAN entities during TAU procedure without S-GW (Serving Gateway) Change.

TAU procedure with S-GW Change

The figure-2 depicts message flow between E-UTRAN entities during TAU procedure with S-GW (Serving Gateway) Change.

REFERENCE:
3GPP TS 23.401 version 11.3.0 Release 11
3GPP TS 24.301 V8.1.0

What is difference between

RF and Wireless Terminologies