Hand off:
" Its the processes of transfering a call from one base station to other base station".
Why the hand offs are needed :
To Understand this let us take an example of a standing speaker which is not in motion and suppose you are moving away from that speaker .As you move away from speaker the intensity or strength of sound we receive will decrease . In the same way as we are moving in one "cell" away from its center point the strength of signal will go on decreasing and when we are at boundary of the cell the signal will be very weak weak . So in order to keep the communication noise free and with good strength the control of the current call is given to the other base station which is next to the current base station.
So when user moves towards end of that cell then again the call is handed off and is to be continued .
Types of handoffs:
There are two types of handoffs
1) Improper Handoff
2) Proper Handoff
Improper Handoff:
As illustrated in below figure in this type of handoffs the handoff is not performed when the signal is in minimum acceptable level .Because when the signal falls below this level then call will be terminated.
There are chances of call drops in this condition.
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| "IMPROPER HANDOFF" |
Proper Handoff:
"In this type the call is handed off when the signal is within the minimum acceptable level . So there is no risk of "call drop" in this condition.
The proper handoff condition is shown in below figure.
When The Hand Offs Are Made:
In todays mobile systems the handoffs are mobile assisted (MAHO) .Every mobile will measure the strength of signal received from the current base station and shares the results with serving base station . A handoff is initiated when power received from the neighbouring base station begin to exceed the power of current base station by certain level or for certain time period..
Disadvantages Of Handoff:
1) The handoff should be made within the given time period , otherwise it will lead to call drop or call disconnection.
2) The call should be handed off when it is really needed .
e g: Due to poor weather conditions some times we receive weak signals at that time the call should not be handed off .
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 |
When The Hand Offs Are Made:
In todays mobile systems the handoffs are mobile assisted (MAHO) .Every mobile will measure the strength of signal received from the current base station and shares the results with serving base station . A handoff is initiated when power received from the neighbouring base station begin to exceed the power of current base station by certain level or for certain time period..
Disadvantages Of Handoff:
1) The handoff should be made within the given time period , otherwise it will lead to call drop or call disconnection.
2) The call should be handed off when it is really needed .
e g: Due to poor weather conditions some times we receive weak signals at that time the call should not be handed off .
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