Sudden Loss

Sudden loss of connection is valid if none of the first three types of urgency state (excessive TA, low signal strength or bad quality) are indicated and also the locating procedure indicates missing measurement results from the MS.
The term Sudden Loss is used because if the network cannot establish a connection with the lost MS after a pre-defined period, the sudden loss counter is incremented if the last reported measurement from the MS does not fulfil any of the reasons mentioned above. Counter TFSUDLOS will step if the last measurement report missing in period of time.

Probable Reason
Environment	Very sudden and severe drop in signal strength, such as when subscriber enter into building, parking garages etc
Interference	Very sudden and severe occurrence of interference or bad quality
Battery or subscriber behavior	MS running out of battery during conversation or pulling out battery
BTS H/W or MS fault	BTS Hardware fault & MS fault
Transmission fault	Synchronization or ABIS link Fault

How to analyze:

• Check radio link time-out and if for a tunnel and if you find it possible to retain the call, set longer RLINKT & RLINKUP if it possible to handle longer delays before it dropped.
• Check synchronization and ABIS link faults. If possible, run command GSSTP, GSCVP (Group switch status & Group switch clock value).
• Check the location of the drop where there is tunnel or any obstacles. If it is related to human behavior, there is nothing you can do.
• Check the ratio of handover to drop calls. This is to check whether high drop call rate due to handover performance.