How does LTE handle handovers between different cells?

LTE (Long-Term Evolution) is designed to efficiently handle handovers (or handoffs) between different cells to ensure continuous and seamless connectivity for mobile devices as they move within the coverage area. Handover is the process of transferring an ongoing communication session from one cell (base station) to another while maintaining a reliable and uninterrupted connection. LTE employs various techniques and protocols to manage handovers effectively. Here's a technical explanation of how LTE handles handovers:

1. Measurement and Event Triggers: LTE-enabled mobile devices continuously measure the signal strength and quality of neighboring cells. Based on these measurements and predefined thresholds, the device determines when a handover should be initiated. These thresholds trigger handover-related events.
2. Handover Decision Making: When the device detects that the signal strength or quality of a neighboring cell exceeds a certain threshold, it triggers a handover decision. The decision can be based on parameters such as Received Signal Strength Indicator (RSSI), Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), and Signal-to-Interference-plus-Noise Ratio (SINR).
3. Measurement Reporting and Serving Cell Evaluation: The device reports its measurements to the current serving cell. The serving cell evaluates the measurements and decides whether a handover is necessary based on the reported signal conditions and network policies.
4. Handover Preparation: If a handover is deemed necessary, the network prepares the target cell for the handover. This preparation involves configuring the target cell, allocating resources, and informing the target eNodeB (eNB) about the upcoming handover.
5. Handover Execution: The serving eNB coordinates with the target eNB to initiate the handover. The target eNB prepares the necessary resources and synchronization for the handover. The serving eNB then instructs the device to switch to the target cell.
6. Data Forwarding and Path Switching: During the handover, the data path is switched from the serving cell to the target cell. The serving cell forwards the ongoing communication sessions and data packets to the target cell. The target cell takes over the communication, ensuring continuity.
7. Handover Completion and Cleanup: Once the handover is completed, the target cell takes full responsibility for the communication, and the serving cell releases the resources allocated for the session. The serving cell may also update its neighbor lists and measurement configurations based on the successful handover.
8. Post-Handover Optimization: After the handover, the network may perform optimizations to enhance the user experience, such as adjusting transmission power levels and configuring radio parameters to maintain a stable connection.

LTE's efficient handover mechanisms and protocols ensure that mobile devices can smoothly transition between cells, maintaining a high-quality connection even while on the move within the LTE network.