LTE RRCConnectionReestablishment procedure

The purpose of RRCConnectionReestablishment procedure is to re-establish the RRC connection, which involves the resumption of SRB1 operation, the re-activation of security and the configuration of only the PCell.

E-UTRAN applies the procedure as follows:
1. To reconfigure SRB1 and to resume data transfer only for this RB
2. To re-activate AS security without changing algorithm.

The UE only initiate the procedure when AS security has been activated. Following conditions has to be met
1. Detect radio link failure. Upon receiving N310 consecutive "out-of-sync" indications for the PCell from lower layers while neither T300, T301, T304 nor T311 is running. (UE shall start timer T310)
2. Detect radio link failure. Upon receiving N313 consecutive "out-of-sync" indications for the PCell from lower layers while T307 is not running. (UE shall start timer T313)
3. Upon handover failure. 36.331 5.3.5.6
4. Upon mobility from E-UTRA failure. 36.331 5.4.3.5
5. Upon integrity check failure indication from lower layers
6. Upon an RRC connection reconfiguration failure. 36.331 5.3.5.5

Upon initiation of the procedure, the UE shall:
1. Stop timer T310, if running
2. Stop timer T312, if running
3. Stop timer T313, if running
4. Stop timer T307, if running
5. Start timer T311
6. Suspend all RBs except SRB0
7. Reset MAC
8. Release the MCG SCell(s), if configured. 36.331 5.3.10.3a
9. Apply the default physical channel configuration as specified in 36.331 9.2.4
10. For the MCG, apply the default semi-persistent scheduling configuration as specified in 9.2.3
11. For the MCG, apply the default MAC main configuration as specified in 9.2.2
12. Release powerPrefIndicationConfig, if configured and stop timer T340, if running
13. Release reportProximityConfig and clear any associated proximity status reporting timer.
14. Release obtainLocationConfig, if configured
15. Release idc-Config, if configured.
16. Release measSubframePatternPCell, if configured
17. Release the entire SCG configuration, if configured, except for the DRB configuration (as configrued by drb-ToAddModListSCG)
18. Release naics-Info for the PCell, if configured
19. Release the RN subframe, if connected as RN and configured with an RN subframe configuration.
20. Perform cell selection process as specified in 36.304

Upon receiving the RRCConnectionReestablishmentReject message, the UE shall perform the action upon leaving RRC_CONNECTED as specified in 5.3.12 with release cause 'RRC connection failure'.