handover call flow in 5g

5G networks, a handover, also known as a handoff, is a process that enables a mobile device to seamlessly switch its connection from one base station (NodeB/gNB) to another while maintaining an ongoing communication session. This is crucial for providing continuous connectivity and improving the overall quality of service. The handover process involves multiple steps and signaling procedures. Below is a technical explanation of the handover call flow in 5G:

1. Event Triggering:
   • The handover process in 5G is initiated when certain events occur, such as a deteriorating signal quality, high interference, or mobility of the user equipment (UE) from one cell to another.
2. Measurement and Decision:
   • The UE continuously measures the signal quality of neighboring cells and reports these measurements to the serving cell (source cell). The network evaluates these measurements and makes a decision on whether a handover is necessary.
3. Handover Decision:
   • If the network determines that a handover is needed, it decides on the target cell (destination cell) to which the UE will be handed over. This decision is based on factors like signal strength, load balancing, and network optimization.
4. Handover Request:
   • The source cell sends a Handover Request message to the target cell, informing it of the upcoming handover and providing necessary information about the UE, such as its identity, capabilities, and the reason for the handover.
5. Handover Preparation:
   • The target cell prepares for the handover by allocating resources and configuring the necessary parameters for the UE to be seamlessly transferred to the new cell.
6. Handover Command:
   • The target cell sends a Handover Command message to the UE, instructing it to switch to the target cell. This message includes information about the target cell and the timing of the handover.
7. Handover Execution:
   • The UE follows the instructions in the Handover Command and starts transmitting and receiving data through the target cell. The handover execution must be done within a specified time to minimize service disruption.
8. Handover Completion:
   • Both the source and target cells exchange Handover Complete messages to finalize the handover procedure. The UE is now fully connected to the target cell, and the source cell releases the resources allocated for the UE.
9. Path Switch Confirmation:
   • The UE sends a confirmation message to the target cell, confirming that the handover has been successfully completed. This ensures that both the network and the UE are aware of the successful handover.

It's important to note that the 5G handover process is designed to be fast and efficient, providing a seamless transition for users and maintaining high-quality service even during mobility. The exact procedures may vary depending on the specific scenario and the network architecture in use.