Inter-cell handover in 5G, also known as handover between cells or cell handover, is a critical process that enables seamless and continuous communication for User Equipment (UE) as it moves across different cells within the 5G network. This process is crucial for maintaining high-quality connectivity, optimizing resource usage, and ensuring a smooth transition for users. Here’s a detailed explanation of the inter-cell handover process in 5G:
- Handover Triggering:
- Inter-cell handover is triggered by various events, such as changes in the radio signal quality, signal strength, or interference in the current serving cell. The decision to perform a handover is typically made by the gNodeB (gNB) based on measurements and evaluations of the radio environment.
- Measurement and Evaluation:
- The UE continuously measures the radio signal quality from neighboring cells. These measurements include parameters like signal strength, signal quality, and interference levels. The UE reports these measurements to the serving gNB.
- Event Reporting:
- The UE reports the measurement results to the serving gNB. The gNB evaluates the information and decides whether a handover is necessary based on predefined thresholds or policies.
- Neighboring Cell Selection:
- If the decision is made to initiate a handover, the serving gNB selects a suitable neighboring cell as the target for handover. The selection is based on factors such as signal quality, available resources, and network load.
- Handover Preparation:
- The serving gNB and the target gNB exchange relevant information to prepare for the handover. This information includes details about the UE, radio resources, and other parameters needed for a smooth transition.
- Path Switching:
- The serving gNB instructs the UE to start communicating with the target gNB. This involves configuring the UE to use the radio resources allocated by the target gNB and initiating the path switch from the current serving cell to the target cell.
- Data Forwarding:
- During the handover process, data continuity is maintained by forwarding the user’s data from the serving gNB to the target gNB. This ensures that ongoing communication sessions are not interrupted during the handover.
- Handover Execution:
- The UE executes the handover by connecting to the target gNB and establishing communication with the new cell. The handover process involves adjusting the radio parameters and ensuring a seamless transition in the connection.
- Radio Bearer Reconfiguration:
- The gNBs may reconfigure the radio bearers to optimize resource usage and adapt to the new network conditions. This may involve adjusting modulation and coding schemes, configuring beamforming, or changing other radio parameters.
- Handover Confirmation:
- Once the handover is successfully completed, the target gNB sends a handover completion message to the serving gNB. The serving gNB acknowledges the completion, and the handover process concludes.
- Release of Resources:
- After successful handover, the serving gNB releases the radio resources allocated to the UE in the previous cell. This ensures efficient resource utilization within the network.
- Minimization of Service Disruption:
- The goal of inter-cell handover is to minimize service disruption for the UE. The handover process is designed to be fast and efficient, allowing users to maintain their connections as they move across different cells in the 5G network.
In summary, inter-cell handover in 5G is a dynamic and coordinated process that ensures continuous and uninterrupted connectivity for UEs as they transition between different cells within the network. It involves measurement, evaluation, neighboring cell selection, handover preparation, path switching, data forwarding, handover execution, radio bearer reconfiguration, handover confirmation, release of resources, and the minimization of service disruption.