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NR-UL Handover Preparation Transfer Complete

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In 5G New Radio (NR) networks, the "NR-UL Handover Preparation Transfer Complete" procedure is a technical process that signifies the successful completion of the handover preparation for uplink (UL) data transfer when a User Equipment (UE) moves from one cell to another within the NR network. This procedure ensures that the UE can seamlessly transition to the new cell while maintaining its UL data communication. Here's a detailed technical explanation of the NR-UL Handover Preparation Transfer Complete procedure:

Background: Handover in NR Networks:

  • Handovers are crucial in mobile networks to maintain continuous connectivity as a UE moves between different cells.
  • In NR networks, handovers can involve both the downlink (DL) and uplink (UL) directions.

Handover Trigger:

  1. The NR-UL Handover Preparation Transfer Complete procedure is initiated as a result of a handover trigger, which could be due to factors like:
  • UE mobility: The UE is moving out of the coverage area of the current serving cell.
  • Load balancing: The network decides to move the UE to a different cell for resource optimization.
  • Radio quality: The network determines that the UE will have better radio conditions in another cell.

Handover Command:

  1. When the network decides to initiate a handover for the UE, it sends a handover command to the UE.
  2. The handover command specifies the target cell, indicating where the UE should move, and provides instructions for the handover.

UL Data Transfer Continuation:

  1. During the handover preparation phase, the UE continues to transmit UL data to the current serving cell. It also monitors the target cell's radio conditions and resources.
  2. The UE prepares to switch to the target cell for UL data transfer while maintaining ongoing communication.

Resource Configuration:

  1. The UE configures its UL resources for communication with the target cell. This involves setting up physical channels, allocating radio bearers, and configuring Quality of Service (QoS) parameters.

Confirmation and Handover Request:

  1. Once the UE has completed the necessary preparations, it sends a confirmation message to the network to indicate that it is ready for the UL handover.

Network Confirmation:

  1. The network receives the UE's confirmation and ensures that the necessary resources are allocated in the target cell for the UL data transfer.

Handover Preparation Transfer Complete Message:

  1. After confirming that both the UE and the target cell are ready for the UL handover, the network generates an "NR-UL Handover Preparation Transfer Complete" message.
  2. This message serves as confirmation that the handover preparation for UL data transfer is complete.

Message Transmission to UE:

  1. The network transmits the "NR-UL Handover Preparation Transfer Complete" message to the UE, signaling that it can proceed with the UL handover.

UE Handover Confirmation:

  1. The UE receives the handover completion message and acknowledges it, confirming that it has successfully transitioned to the target cell for UL data transfer.

UL Data Transfer in the Target Cell:

  1. After handover confirmation, the UE begins transmitting UL data in the target cell. The data transfer continues as usual, ensuring seamless communication.

The NR-UL Handover Preparation Transfer Complete procedure ensures that the UE can smoothly transition from the current serving cell to the target cell while maintaining ongoing UL data transfer. This is essential for providing uninterrupted services and a seamless user experience as UEs move within the network. The procedure's precise steps and parameters may vary depending on network configurations and mobility management strategies.