Sign in Subscribe

Serving Cell Change

Last updated on 


A Serving Cell Change, often referred to as a handover or handoff, is a critical procedure in LTE (Long-Term Evolution) and 5G mobile communication networks. It involves transferring an ongoing communication session from the current serving cell to a new target serving cell, ensuring seamless connectivity as a user equipment (UE) moves through the network. Let's delve into the technical details of the Serving Cell Change procedure:

  1. Trigger for Serving Cell Change:Various factors can trigger a serving cell change, such as deteriorating signal quality, congestion, load balancing, network optimization, or user mobility.
  2. Target Cell Selection:Based on measured parameters, network policies, and algorithms, a suitable target cell is selected for the handover. This cell is expected to provide improved signal quality and maintain the ongoing communication session.
  3. Handover Preparation:The network prepares for the handover by allocating resources in the target cell, configuring the target cell's radio interface, and establishing necessary channels for the handover.
  4. Handover Type and Parameters:Depending on the scenario and network policies, the handover type (e.g., hard handover, soft handover) and associated parameters (e.g., handover priority, timing, thresholds) are determined.
  5. Handover Request Generation:The source cell (e.g., source eNodeB in LTE, source gNodeB in 5G) generates a Handover Request message, including essential information about the ongoing session and the target cell.
  6. Transmission to Target Cell:The Handover Request message is transmitted to the target cell (e.g., target eNodeB in LTE, target gNodeB in 5G) over the appropriate signaling channels.
  7. Target Cell Processing:The target cell processes the Handover Request, validates the information, and prepares for the impending handover.
  8. Confirmation and Handover Execution:The target cell confirms its readiness to receive the UE and execute the handover at the appropriate timing based on the configured parameters.
  9. UE Handover Preparation:The UE adjusts its parameters and communication settings based on the handover request, preparing for the handover.
  10. Handover Execution:At the designated timing, the handover is executed, and the UE's connection is transferred from the source to the target cell.
  11. Handover Completion and Confirmation:The handover completion is confirmed, and communication resumes via the new serving cell.

The Serving Cell Change procedure ensures a seamless transition from one cell to another, providing uninterrupted communication for the UE. It plays a crucial role in maintaining a consistent and reliable connection while the UE moves within the network in LTE and 5G mobile networks.