8.5.22 Actions when entering another RAT from connected mode

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

NOTE: This section does not apply when entering GERAN Iu mode from UTRAN connected mode.

When entering another RAT from connected mode (due to Inter-RAT handover from UTRAN, Inter-RAT cell change order from UTRAN or Inter-RAT cell reselection from UTRAN), after successful completion of the procedure causing the transition to the other RAT, the UE shall:

1> if the USIM is present, for each CN domain:

2> if a new security key set was received for this CN domain but was not used either for integrity protection or ciphering during this RRC connection:

3> set the START value for this domain to zero and;

3> store this START value for this domain in the volatile memory of the ME;

2> else:

3> store the current START value for every CN domain in the volatile memory of the ME.

NOTE: Prior to storing the START value, the UE should calculate this START value according to subclause 8.5.9.

1> if the SIM is present, for each CN domain:

2> if a new security key was received for this CN domain but was not used either for integrity protection or ciphering during this RRC connection:

3> set the START value for this domain to zero and;

3> store this START value for this domain in the volatile memory of the ME.

2> else:

3> store the current START value for this CN domain in the volatile memory of the ME.

NOTE: Prior to storing the START value, the UE should calculate this START value according to subclause 8.5.9.