. On receiving a change notification, the UE acquires the new system information immediately from the start of the next modification period. The UE applies the previously acquired system information until the UE acquires the new system information. The paging message is used to inform UEs in RRC_IDLE and in RRC_CONNECTED about a system information change. If the UE receives a paging message indicating a system information modification, the UE by default expects that the system information will change at the next modifi- cation period boundary. Although the UE may be informed about changes in system information, no further details are provided, e.g., regarding which system information will change. The System Information Block Type 1 includes a value tag that indicates if a change has occurred in the SI messages. The UEs may use the tag on return from out-of-coverage to verify whether the previously stored SI messages are still valid. Furthermore, the UE considers stored system information to be invalid after three hours from the moment it was successfully confirmed as valid, unless otherwise specified. E-UTRAN may not update the tags on change of some system information, such as ETWS information or regularly changing parameters like cdma2000 system time. Similarly, E-UTRAN may BCCH Modification Period (k) BCCH Modification Period (k+1) Change Notification Updated Information FIGURE 4-28 Change of system information in time [18] CHAPTER 4 IEEE 802. 16m System Operation and State Diagrams not include the system information modification within the paging message on change of some system information. The UE verifies that stored system information remains valid by either checking the tags in System Information Block Type 1 after the modification period boundary, or by attempting to find the system information modification indication during the modification period in case no paging is received. If no paging message is received by the UE during a modification period, the UE may assume that no change of system information