Assume that there is a call going on between two parties over a voice channel.
When the mobile unit moves out of coverage area of a particular cell site the reception becomes weak.
Then the cell site will request a hand off.
The system will switch the call to a new cell site without interrupting the call or changing the user. This procedure is called as the hand off procedure or handover procedure.
Following are various types of handoffs. Supported by a Mobile Station (MS):
1. Hard Hand Off
2. Soft Hand off
3. Queued hand off
4. Delayed hand off
5. Forced hand off
1. Hard hand off:
A hard handoff is a handoff technique used with cellular networks that requires the user's connection to be entirely broken with an existing base station before being switched to another base station.
2. Soft hand off:
The hand off is known as soft handoff if the MS starts communication with a new base station without stopping the communication with the older base station.
3. Delayed Hand off:
In many situations, instead of one level, a two level handoff procedure is used, in order to provide a high opportunity for a successful handoff. A hand off can be delayed if on available cell take the call.
4. Forced handoff:
A forced handoff is defined as the off which would normally occur but prevented from happening or a handoff that should not occur but is forced to happen.
5. Queued handoff:
In the queued handoff process, the MTSO arranges the handoff requests in a queue instead of rejecting them, if the new cell sites are busy.