Handover/handoff, is a process in mobile networks that allows for the seamless transfer of a device's ongoing call or data session from one cell to another. This article introduces two basic handover types: hard handover and soft handover.
Hard Handover
In hard handover, also known as a "break-before-make" handover, the connection with the old cell is severed before the connection with the new cell is established. During this brief transition, the mobile device may experience a short service interruption. A hard handover can be triggered when the signal strength of the current cell falls below a predefined threshold, and the signal strength of the neighboring cell exceeds it.
Soft Handover
In a soft handover, also known as a "make-before-break" handover, the connection with the new cell is established before the connection with the old cell is terminated. This ensures a seamless transition between cells without any service interruption. A soft handover is typically used in CDMA-based networks like UMTS and is designed to provide improved call quality and coverage, especially in areas with weak or fluctuating signal strength.
The handover process in LTE is represented by the diagram below.
