LTE RRC layer state diagram
This LTE tutorial covers RRC layer state diagram used by LTE UE.
This page covers LTE RRC state diagram for UE compliant to LTE standard. It covers RRC states idle and connected. Following are some of the points about UE in these modes.
RRC Idle State
• RRC IDLE state, UE is known in EPC and has IP address but not known in E-UTRAN/eNB
• In this LTE UE can receive broadcast or multi-cast data, it will monitor a paging channel to detect incoming calls, it will perform neighbor cell measurements and does cell selection as well as reselection and acquires system information.
• In the LTE RRC IDLE state, a UE specific DRX (discontinuous reception) cycle may be configured by upper layers to enable UE power savings
RRC Connected State
In the LTE RRC CONNECTED state, UE is known to both Evolved Packet Core(EPC)
and E-UTRAN eNB (LTE base sttaion).
Here location of UE is known at the cell level. Mobility is UE assisted and is network controlled.
LTE UE monitors control channels associated with shared data channel to determine if the data is scheduled for it or not. The Channel quality feedback information is also provided by the UE after measurements. It also performs neighbor cell measurements of UTRAN,EUTRAN and GSM cells.
LTE RRC Functions
• Configuration management
• Connection Management
• Paging control
• Security management
• Measurement configuration
• Measurement Reporting
• Cell selection and re-selection
• Mobility Management