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Handover Request

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A Handover Request is a technical procedure in mobile communication networks, such as LTE (Long-Term Evolution) and 5G, that is used to request the transfer of an ongoing call or data session from the current serving cell or base station to a new target cell or base station. Handover requests are crucial for ensuring seamless communication while a user moves through the network and maintains a consistent quality of service. Below is a detailed technical explanation of the Handover Request procedure:

1. Triggering Event:

  • A Handover Request is triggered by various events, including:
  • UE Mobility: When the User Equipment (UE) moves out of the coverage area of the current serving cell and into the coverage area of a neighboring cell, a handover may be necessary to maintain the connection.
  • Load Balancing: The network may initiate a handover to balance the load among cells or to optimize resource utilization.
  • Quality of Service (QoS) Improvement: If the current cell's signal quality or capacity deteriorates, a handover to a cell with better conditions may be initiated.

2. Measurement and Evaluation:

  • Before initiating a handover request, the UE continuously measures the signal quality and other parameters of neighboring cells. These measurements are reported to the network through dedicated measurement reports.
  • The network evaluates the measurement reports to determine if a handover is necessary.

3. Handover Decision:

  • Based on the evaluation of measurements and network policies, the network makes a decision to initiate a handover.
  • The network selects the target cell (new serving cell) to which the UE will be handed over.

4. Handover Request Message Generation:

  • The network generates a Handover Request message, which includes critical information needed for the handover process. This message is typically generated by the Mobility Management Entity (MME) in LTE or the Access and Mobility Management Function (AMF) in 5G.
  • The Handover Request message includes information such as:
  • The UE's identity and current cell identity.
  • The identity and parameters of the target cell.
  • Handover type (e.g., Intra-LTE, Inter-RAT).
  • Security information to protect the message.

5. Transmission to the UE:

  • The Handover Request message is transmitted to the UE over the current serving cell's air interface. It informs the UE of the upcoming handover and provides details about the target cell.

6. UE Acknowledgment:

  • Upon receiving the Handover Request, the UE acknowledges the message to confirm its readiness for the handover.

7. Network Coordination:

  • The network coordinates with both the current serving cell and the target cell to prepare for the handover.
  • Radio resources are allocated in the target cell, and the necessary signaling is set up.

8. UE Handover Preparation:

  • The UE also prepares for the handover by tuning its receiver to the frequency and parameters of the target cell.
  • It may also perform handover measurements to ensure a smooth transition.

9. Handover Execution:

  • At the appropriate time, the network issues a command to execute the handover.
  • The UE switches its connection to the target cell, and data traffic and signaling are rerouted accordingly.

10. Handover Completion: - The Handover Request procedure is considered complete when the UE is successfully handed over to the target cell, and the connection continues without interruption.

Handover requests are essential for providing uninterrupted mobile services, especially in scenarios where users are moving within the network's coverage area or when the network needs to optimize its resource utilization. Proper handover management ensures a seamless and reliable user experience.