What Are the LTE RRC States?
Let me explain you clearly how RRC states work in LTE, because this is something you really need to understand if you’re trying to get how your device interacts with the network. RRC stands for Radio Resource Control, and these states define how your mobile device behaves in terms of connectivity and resource usage. Your phone doesn’t stay constantly connected in full communication mode — instead, it switches between modes to save battery and optimize network resources.
There are mainly two RRC states your device moves between: RRC_IDLE and RRC_CONNECTED. I’ll break both down for you.
1. RRC_IDLE
In this state, your device is not actively connected for data transfer. That doesn’t mean it’s disconnected — it’s just in a passive state. Here’s what your device does in RRC_IDLE:
- It listens for paging messages from the network — for example, if there’s an incoming call or message.
- It performs cell reselection, meaning it looks for a better signal if one is available.
- If you try to browse, call, or use data, it will request to move to RRC_CONNECTED state.
This state helps conserve battery when your phone isn’t being used for active communication.
2. RRC_CONNECTED
This is the active state where your phone is fully communicating with the network. Once you start a voice call, open an app that needs internet, or send a message — your device transitions here.
Here’s what your device handles in RRC_CONNECTED:
- It exchanges both user data and signaling with the eNodeB (the base station).
- It performs handovers when you’re moving between cells, ensuring uninterrupted service.
- It measures signal strength and reports back to the network for mobility decisions.
This state uses more power but is essential for real-time communication.
So in simple terms — when you’re not using your phone actively, it stays in RRC_IDLE to save power. The moment you do something that needs network access, it jumps to RRC_CONNECTED. And when you stop, it may return to idle after a short delay. This switching helps keep your device efficient while staying responsive to your needs.