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NR-Handover From E-UTRA Preparation Failure

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In 5G (New Radio or NR), NR-Handover From E-UTRA Preparation Failure is a scenario where the preparation phase of a handover from the LTE (E-UTRA) network to the 5G NR network encounters issues or failures. This failure could be due to various reasons, and it's crucial to handle such scenarios efficiently to ensure seamless and reliable handover. Let's explore the technical aspects of this preparation failure scenario:

  1. Handover Decision and Configuration:The network (E-UTRAN) decides to initiate a handover to the 5G NR network based on network conditions and UE capabilities. The target 5G NR cell is configured for the handover, including radio parameters and resource allocations.
  2. UE Context Preparation:The network begins preparing the UE context, gathering essential information about the UE and the ongoing session. This context is vital for a successful handover.
  3. Handover Parameters:The network determines the appropriate handover parameters, including radio resource allocation, security context transfer, and other aspects relevant to the handover.
  4. Sending the Handover Command:The network sends the NR-Handover From E-UTRA Command to the UE, instructing it to initiate the handover process.
  5. UE Reception and Processing:The UE receives the handover command, processes the information, and prepares for the handover based on the provided parameters.
  6. Measurement Configuration:The UE may be instructed to perform specific measurements on the target 5G NR cell. These measurements are essential for evaluating the target cell's suitability for handover.
  7. Handover Preparation Failure:During the preparation phase, various issues may arise that prevent successful handover preparation. These could include insufficient radio resources, congestion, incorrect configurations, incompatible UE capabilities, or interference.
  8. Error Detection and Indication:The UE detects the preparation failure and generates an error indication or failure message, specifying the reason for the failure.
  9. Failure Handling and Recovery:Upon receiving the failure indication, the network initiates recovery procedures. This may involve reconfiguring the handover parameters, reallocating resources, or selecting an alternative target 5G NR cell.
  10. Handover Retrial:The network may initiate a retrial of the handover preparation, attempting to overcome the previous failure by adjusting configurations or resource allocations.
  11. Failure Reporting:The UE reports the failure and relevant details to the network, allowing for troubleshooting and further analysis to prevent similar failures in the future.
  12. Fallback Procedures:In some cases, if the handover preparation failure persists or cannot be resolved, fallback procedures may be initiated to maintain UE connectivity or to attempt an alternative handover to a different cell.

In summary, NR-Handover From E-UTRA Preparation Failure is a scenario where issues arise during the preparation phase of a handover from LTE to 5G NR. Effective handling of these failures and appropriate recovery procedures are essential to maintain a robust and reliable handover process in 5G.