Handover (or handoff) is a process in mobile networks where a device’s ongoing call or data session is transferred from one cell to another. There are mainly two basic handover types:
- Hard Handover: In hard handover, also known as a “break-before-make” handover, the connection with the old cell is cut-off 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 cut-off. This ensures a seamless transition between cells without any service interruptions. 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 diagrams below:
