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NR-Handover Cancel

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In 5G (fifth-generation) wireless communication systems, NR-Handover Cancel is a signaling procedure used to abort an ongoing handover process initiated by the network (gNodeB) for a user equipment (UE). Handover cancellation may occur due to various reasons, such as a change in network conditions, improved handover options, or other operational considerations. Let's explore the technical details of NR-Handover Cancel:

Purpose of Handover Cancellation:

  • NR-Handover Cancel is initiated to terminate an ongoing handover procedure.
  • The cancellation may be necessary due to network optimizations, changes in UE status, or handover errors.

Reasons for Handover Cancellation:

  • Better Handover Option: A more suitable handover target is identified during the ongoing handover, prompting the cancellation to switch to a better target cell or gNodeB.
  • UE Change of Status: The UE's status or capabilities change during the handover, making the ongoing handover unnecessary or inefficient.
  • Handover Failure: If the ongoing handover encounters errors or fails to complete successfully, a cancellation may be necessary to avoid service disruption.

Handover Cancel Request:

  • The NR-Handover Cancel procedure is initiated by the gNodeB by sending a handover cancellation request to the UE.
  • The request includes information about the reason for the cancellation and any necessary parameters related to the handover being canceled.

Parameters in Handover Cancel Request:

  • UE Identifier: Identifies the UE for which the handover is being canceled.
  • Handover Cause: Specifies the reason for the handover cancellation, such as a better handover option or UE change of status.

Signaling Mechanism:

  • The NR-Handover Cancel request is sent using dedicated RRC (Radio Resource Control) signaling channels and protocols.

UE Handling of Handover Cancel Request:

  • Upon receiving the handover cancel request, the UE processes the information provided and takes appropriate actions based on the handover cause.
  • The UE may stop any ongoing handover procedures and maintain the existing connection or follow instructions for an alternative handover.

Error Handling and Recovery:

  • If an error occurs during the handover cancellation procedure, predefined error handling mechanisms ensure proper recovery and handling to maintain network stability and continuity.

Effect on Handover Procedure:

  • The handover cancellation effectively halts the ongoing handover process and prevents the UE from switching to the target cell or gNodeB intended for the handover.

Synchronization and Rollback:

  • Depending on the point in the handover process at which the cancellation occurs, synchronization and rollback procedures may be necessary to revert to the pre-handover state.

In summary, NR-Handover Cancel is a signaling procedure used in 5G networks to abort an ongoing handover process for a UE. This is done to address various reasons, such as identifying a better handover option or dealing with changes in UE status, ensuring that the most appropriate handover decisions are made to maintain network performance and service quality.