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Handover From E-UTRA Complete

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The "Handover From E-UTRA Complete" is a technical procedure in LTE (Long-Term Evolution) networks that occurs when a User Equipment (UE) successfully completes a handover from one E-UTRAN (Evolved Universal Terrestrial Radio Access Network) cell to another. This procedure is vital for ensuring seamless connectivity and maintaining the quality of the communication session as the UE moves within the network. Here's a detailed technical explanation of the "Handover From E-UTRA Complete" procedure:

1. Initial UE Connection:

  • Normal Operation: The UE is initially connected to an E-UTRAN cell and is actively communicating with the network.

2. Trigger for Handover:

  • UE Movement: The need for handover arises when the UE moves from the source cell to a target cell. This movement may be due to factors like signal strength, cell load balancing, or network optimization.

3. Handover Preparation:

  • Network Assessment: The network evaluates the UE's movement and selects a target cell that can provide better signal quality or network resources.
  • Resource Allocation: Resources, including radio bearers, are allocated in the target cell to accommodate the incoming UE.

4. Handover Request:

  • UE Initiates Handover: The UE realizes it needs to switch to a new cell and initiates a Handover Request message. This message is typically sent to the source cell's eNodeB (E-UTRAN Node B).

5. Source Cell Processing:

  • Message Handling: The source cell's eNodeB receives the Handover Request message from the UE and processes it.
  • Verification: The source cell verifies the request's validity and ensures that the UE is allowed to perform a handover.

6. Handover Request Forwarding:

  • Target Cell Selection: Based on network algorithms and assessment, the source cell selects a target cell (another eNodeB) to which the UE should be handed over.
  • Forwarding to Target Cell: The source cell forwards the Handover Request to the target cell, indicating that the UE wishes to move to the new cell.

7. Target Cell Processing:

  • Message Reception: The target cell's eNodeB receives the forwarded Handover Request from the source cell and processes it.
  • Resource Availability: The target cell verifies that it has sufficient resources and capacity to accommodate the UE.

8. Handover Decision:

  • Decision in Target Cell: Based on its own assessment and resource availability, the target cell decides whether to accept the handover request.
  • Handover Parameters: If accepted, the target cell configures the necessary handover parameters and prepares for the UE's arrival.

9. Handover Request Acknowledge Generation:

  • Positive Acknowledgment: If the target cell accepts the handover request, it generates a Handover Request Acknowledge message.
  • Message Contents: The acknowledgment typically includes information about the handover procedure, such as new radio parameters and handover preparation details.

10. Message Signaling:

  • Response to Source Cell: The Handover Request Acknowledge message is sent back to the source cell, which will relay it to the UE.

11. Source Cell Handling:

  • Message Relay: The source cell's eNodeB receives the Handover Request Acknowledge message from the target cell and relays it to the UE.

12. UE Handover:

  • UE Switch: The UE switches its connection from the source cell to the target cell, and communication continues seamlessly in the new cell.

13. Handover Completion:

  • Confirmation: The source cell confirms the handover completion to the core network.
  • Service Continuation: The UE can continue its communication session, and the network ensures that data and voice services are not interrupted.

The "Handover From E-UTRA Complete" procedure is crucial for maintaining a high-quality and uninterrupted communication experience as UEs move within the LTE network. It allows for efficient resource allocation and ensures that the UE remains connected to the best available cell as it transitions through different coverage areas.