Timing Advance Measurements in LTE and 5G: Frequency, Triggers, and Use Cases

RAN
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1

Hello all,

In LTE and 5G, how often is a Timing Advance measurement being taken by the BTS and UE? Is it only occuring during a registration or RACH? TELCOMs are documenting some of this information in their historical records. I am curious to see how complete the document is.

What prompts a timing advance measurement to be taken? The network, the UE, both? Are these measurements being taken during a connected session?

Thank you for your time and assistance.

2

Absolute TA was measured by the network during RACH and sent to UE.
Afterwards, the network periodically measures TA and sends to the UE a relative TA adjustment with respect to previous TA.

If a connected UE does not get TA information with a certain time, UE will be considered out-of-sync and has to use RACH to restore UL synchronization

3

I understand. Thank you!