How does 4G handle handovers between different cells in a network?

In a 4G network, handovers between different cells occur when a mobile device moves from the coverage area of one cell (base station) to another while maintaining an ongoing communication session. This handover process is crucial for maintaining a seamless connection and quality of service for users.

Here's a technical breakdown of how 4G handles handovers between different cells:

1. Initial Cell Selection and Connection Establishment: When a mobile device is powered on or moves into an area with wireless coverage, it scans available cells and selects the most suitable one based on signal strength, quality, and other factors. The device then establishes a connection with the selected cell.
2. Measurement and Signal Strength Monitoring: As the device stays connected to the serving cell, it continuously monitors the signal strength and quality of neighboring cells. This is done by periodically measuring the signal from adjacent cells while still maintaining the connection with the current serving cell.
3. Trigger for Handover: If the signal strength of the current serving cell weakens beyond a certain threshold or if the quality deteriorates due to interference or other reasons, the mobile device may decide to initiate a handover to a more suitable neighboring cell.
4. Handover Decision: The decision for a handover is typically made by the network's mobility management system, which takes into account measurements from the mobile device and network parameters. It determines the most appropriate target cell for the handover based on criteria like signal strength, interference levels, and available resources in neighboring cells.
5. Handover Preparation: Before initiating the handover, the mobile device and the target cell exchange necessary information. This includes signaling messages between the device and the network to prepare for the transition.
6. Execution of Handover: Once the preparations are complete, the actual handover process takes place. The serving cell instructs the mobile device to switch to the target cell, ensuring a smooth transition of the ongoing communication session.
7. Handover Completion: The mobile device switches its connection to the new cell and verifies the quality of the connection. The network updates its routing tables and configurations to ensure that data packets are now routed through the new serving cell.
8. Post-Handover Optimization: After the handover, the network continues to monitor the connection and may perform additional adjustments to optimize the quality and performance of the communication session in the new cell.