8.5.2 Actions when entering idle mode from connected mode

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

When entering idle mode from connected mode, the UE shall:

1> clear or set variables upon leaving UTRA RRC connected mode as specified in subclause 13.4;

1> stop timer T323 if it is running;

1> clear the variable SYSTEM_INFORMATION_CONTAINER;

1> if the RRC CONNECTION RELEASE message was received and the IE "Redirection info" was present therein:

2> if the IE "Frequency info" is present, attempt to camp on a suitable cell on the indicated UTRA carrier included in the RRC CONNECTION RELEASE message;

2> if the IE "GSM target cell info" is present, attempt to camp on a suitable cell of the list of cells for the indicated RAT included in the RRC CONNECTION RELEASE message. If no cells were indicated for that RAT or no suitable cell of the indicated cells for that RAT is found within 10s, attempt to camp on any suitable cell of that RAT; or

2> if the IE "E-UTRA target info" is present, attempt to camp on any of the frequencies for the indicated RAT included in the RRC CONNECTION RELEASE message, excluding any cell indicated in the list of not allowed cells for that RAT (i.e. the "exclude-listed cells per freq list" for E-UTRA), if present. If no suitable cell on the indicated frequencies for that RAT is found in less than N seconds (where N is the number of E-UTRA frequencies listed in IE "E-UTRA target info"), attempt to camp on any suitable cell on any frequencies of that RAT in less than 4 seconds;

2> if no suitable cell is found on the indicated UTRA carrier or RAT camp on any suitable cell.

1> For UTRA TDD, if the RRC CONNECTION RELEASE message was received and the IE "Redirection info" was not present:

2> if the to be released RRC connection was established due to CSFB call initiated in E-UTRA:

3> attempt to camp on a suitable cell on an E-UTRA frequency. If no suitable cell is found on any of E-UTRA frequencies in less than 2 seconds, attempt to camp on any suitable cell.

1> attempt to select a suitable cell to camp on.

When leaving connected mode according to [4], the UE shall:

1> perform cell selection.

While camping on a cell, the UE shall:

1> acquire system information according to the system information procedure in subclause 8.1;

1> perform measurements according to the measurement control procedure specified in subclause 8.4; and

1> if the UE is registered:

2> be prepared to receive paging messages according to the paging procedure in subclause 8.2.

If the UE is operating in "GSM-MAP mode", the UE shall:

1> delete any NAS system information received in connected mode;

1> acquire the NAS system information in system information block type 1; and

1> proceed according to subclause 8.6.1.2.

When entering idle mode, 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> if the current "START" value, according to subclause 8.5.9 for a CN domain, is greater than or equal to the value "THRESHOLD" of the variable START_THRESHOLD:

4> delete the ciphering and integrity keys that are stored in the USIM for that CN domain;

4> set the "START" values for this CN domain to zero and store it in the volatile memory of the ME;

4> inform the deletion of these keys to upper layers.

3> else:

4> 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.

1> else:

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

3> 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:

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

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

3> else:

4> if the current "START" value, according to subclause 8.5.9 for this CN domain, is greater than or equal to the value "THRESHOLD" of the variable START_THRESHOLD:

5> delete the Kc key for this CN domain;

5> delete the ciphering and integrity keys that are stored in the UE for that CN domain;

5> set the "START" values for this CN domain to zero and store it the volatile memory of the ME;

5> inform the deletion of the key to upper layers.

4> else:

5> 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.

1> if the UE supports RAN-assisted WLAN interworking:

2> if timer T330 is not configured:

3> clear the variable WLAN_OFFLOAD_INFO;

3> use the information stored in the variable SYSTEM_INFO_WLAN_OFFLOAD_INFO as specified in [4], and forward it to upper layers.

2> else:

3> if timer T330 is not running:

4> start the timer T330;

4> use the information stored in the variable WLAN_OFFLOAD_INFO as specified in [4], and forward it to upper layers.