How to identify and finding root cause for Optimization solution on GSM and UMTS Network?
Drop call rate is Main KPI that very important in KPI,Based on my experience the root cause of Drop Call Rate can be listed as follow:
This problem is very critical related to all KPI including Drop Call rate. If the problem is coming from hardware, percentage of drop call rate would be very high(usually more than 1 %) and you have to replace bad module with good module. For example in GSM Network you have to check and make sure TRX module such as GRFU/CU or Combiner/Duamco working properly. To make sure the problem was coming from hardware or bad module, you can identify by trying Swap module first. For example: if the problem high drop call rate is occurred in sector-1, you can swap TRX Module sector-1 to sector-2 and Combiner from sector-1 to sector-3. If the problem move to other sector then indicate the problem is coming from that module.
Frequency interference is include in problem that can impact to high drop call rate because the Noise(Interference Signal) is very high and affecting to Carrier( primary Signal) and also affect to bad vice quality. To overcome the problem in GSM network you have to re-tune/ change Frequency that suspected Interference especially on BCCH Frequency for RF Hoping cells.
Overshooting cell can be the one that causing high drop call rate in the network. To overcome this issue you have to change tilt configuration of Antenna, for example change Mechanical Tilt from 0 to 2. Overshoot is common problem for both GSM and UMTS that causing drop call due to bad
Missing neighbor also will causing High drop call rate in your network. You have to check and make sure relation of the cells is complete and no missing neighbor. The solution is same for both GSM and UMTS, you have to make sure no missing neighbor to avoid high drop call rate.
Wrong Parameter Configuration
Wrong parameter configuration will causing high drop call rate in your network. Make sure to check all parameter and configure accordingly. In GSM there is parameter related drop call rate KPI such as : RLT(Radio Link Timeout), You can set by increase RLT to reduce drop call but will affect to Customer Experiences because release call is too long even when radio environment is poor and conditionally should be released.
Power or Transmission Problem
Power problem can make high drop call rate in the network. You have to make sure no power problem by check the alarm and Cell Availability.If the problem occurred you need to follow up the problem to Field Maintenance Team to fix it.
Transmission problem also can make drop call rate very high and affecting to your KPI.