what is mme tau (3g to 4g)

Question

Hi what are the customer facing KPI for 3G and LTE ? Means how to check the customer experience for 3G and 4G users ?

What ever customer is experiencing during browsing, may be latency, loading etc. What could be the calculation method for the same ?

Answer 1

When an UE primarily attaches to LTE network with the "combined attach type" , UE can move to 3G network while keeping context at MME. As part of combined attach, MME establishes a session with the relevant SGGN based on the mapping of LTE tracking area <-> UMTS routing area. In that case if UE is moving to a geographical location where only 3G coverage is there, then UE handed over to SGSN. When UE again moves to an LTE area, it perform tracking area update.

Answer 2

TAU means "Tracking Area Update" which is used in LTE which is known as RAU i.e. Routing Area Update in GERAN/UTRAN/3G. These procedures are initiated by UE when it detects a new tracking area or routing area.

Whenever UE moves from 3g to 4G-LTE then TAU procedure is initiated, but could not understand your query fully so dont know what to answer. Please check 23.401 or provide input so that it can be answered.