Messages in NR like TAU update in LTE

Specs & Protocol Testing
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1

Hi NR Experts.

For Idle mode procedure:

  1. What messages seen like we have TAU update in LTE if UE move from cell 1 to cell 2 having different TAC.
  2. Is there any message like mobility registration update?
2

Do you mean Layer 3 messages?

3

Yes, L3 messages.

4

Registration Request with cause mobility update in 5G SA in that scenario.

There is no TAU update in 5G SA as far as I know in terms of signallng (NAS).

5

Thanks.

Do you mean UE need to indicate support of mobility registration update?

If UE move in 5G SA in idle mode between 2 cells having different TAC then what will happen?

6

Registration areas consist of different TACs, so for the scenario you mention above, yes UE needs to send registration request with mobility update to perform a registration success on new TAC.

For more info, check out TS 24.501 and 5G Standalone Access Registration Signaling Messages.

7

Ok, so it means mobility update is not OTA message seen in L3 it’s part of registration request.

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