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RRC CONNECTED INACTIVE Transition

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RRC (Radio Resource Control) stands for Radio Resource Control. In wireless communication systems like LTE (Long-Term Evolution) and 5G, the RRC protocol manages the connection between the user equipment (UE) and the network.

RRC state transition involves different states that a UE goes through during its communication with the network. RRC Connected Inactive transition specifically refers to the state where the UE is registered with the network but is not actively exchanging data. In this state, the UE is reachable by the network, but it has temporarily stopped data transmission to conserve power or due to the absence of active communication needs.

Here is a more detailed technical explanation of the RRC Connected Inactive transition:

  1. Initial Connection Establishment: When a UE initially attaches to the network or re-establishes a connection after being in a dormant state, it goes through a series of steps called RRC Connection Establishment. During this process, the UE negotiates connection parameters with the network and eventually enters the RRC Connected state.
  2. RRC Connected State: In the RRC Connected state, the UE is actively exchanging data with the network. It can transmit and receive data packets, establish radio bearers, and perform various communication tasks.
  3. Transition to RRC Connected Inactive: When the UE is in the RRC Connected state but remains idle without any data to send or receive for a certain period, it can transition to the RRC Connected Inactive state. This transition helps in conserving battery life and reducing unnecessary resource usage both on the UE side and within the network.
  4. Inactive State Characteristics:
    • UE Context Retention: The network retains UE context information, allowing it to quickly re-establish active communication when needed without the need for a full reconnection process.
    • Reduced Resource Utilization: The UE may be allocated fewer resources by the network, such as reduced radio resource allocation, to conserve power and network capacity.
    • Quick Activation: When there's data to be transmitted or received, the UE can quickly transition back to the RRC Connected state without undergoing a full reconnection process, using the retained context.
  5. Trigger for State Transition: The transition to RRC Connected Inactive state may be triggered by several factors such as inactivity timers, network configurations, or specific signaling between the UE and the network.
  6. Exit from RRC Connected Inactive: The UE can exit the RRC Connected Inactive state when it needs to transmit or receive data. This can be initiated either by the UE itself, when it has data to send or needs to receive data, or by network commands triggering the UE to become active again.

Overall, the RRC Connected Inactive state helps optimize resource usage, extend battery life, and efficiently manage communication in wireless networks by allowing UEs to temporarily suspend active data exchange when not needed.