Drop call due to excessive TA happens when the TA value at drop call connection is higher than the cell parameter TALIM (TADROP > TALIM) and from this counter TFDISTA is incremented.
Probable Reason |
Location |
High sites or sites next to water pick up traffic from far away |
Parameter setting |
Very low TALIM setting, which would indicate a ‘false’ excessive timing advance |
How to analyze:
- Check cell parameter MAXTA and TALIM. If it covers far coverage, it is possible to setting of the cell parameters MAXTA and TALIM to a higher value (for e.g. MAXTA=63, TALIM=62)
- If the cell is really covering far away from the site, other options are reducing the coverage by down tilting the antennas, reducing antenna height, changing antenna or reducing output power
- If it is a rural area and need to cover a larger area, Extended Range feature might be useful to be considered.
Drop due other reason equal to total number of drops subtracts all drops with reason. If any of the above drop reason didn’t meet the criteria, the reason for drop will be in the ‘Other Reason’.
Probable Reason |
H/W fault |
Hardware Problem (Managed Object in BTS) |
Disturbance |
Link/ Transmission disturbance problem |
Parameter Setting |
Wrongly defined setting (for e.g. LAC – Location Area Code) |
Mobile Station |
MS problem |
Interference |
Interference problem (Uplink) |
How to analyze:
- Check the BTS error log for hardware faults. (run commands: RXELP & RXMFP to look the hardware faults log)
- Check if ICM is indicating uplink interference in the cell.
- Check with O&M regarding transmission problems, HW problems and service affecting maintenance work during the time period. The average cell downtime and TCH availability should also be check. It might be intermittent link connection.
- Check object type MOTS, which is based on drop on Timeslot (TS) in order to find faulty devices.