Call failure caused by too narrow MS search window

Call failure caused by too narrow MS search window
Typical case:
In call procedure, MS Rx power is normal, Tx power is normal also;
In call procedure, pilot Ec/Io is too low and can not maintain the requirement for demodulation, finally call is failed;
Use PN Scanner to test pilot, the pilot Ec/Io of PN in active set is normal.

Analyzing:
MS Rx power and Tx power are all normal, use PN Scanner to test pilot: the pilot Ec/Io of the PN in active set is normal, but MS received Ec/Io is too low. This indicates MS can not distinguish some useful multipath signal. Usually it is caused by too narrow search window of MS.
If MS search window is too low, MS can not find strong multipath signal. This will lead the useful signal dropping outside the search window;the Ec/Io will be too low; the unuseful signal dropping outside the search window will become strong interference. If MS can not demodulate forward signal, the call will be failed finally.

Note:
The above case is about MS search window problem. Also, for reverse signal BTS has search window: they are access channel search window and traffic channel search window, if they are too low, the reverse multipath signal will drop outside and call will be failed.

Optimization method:
Check OMC wireless parameters and adjust the search windows.