The performance of GSM network is measured in terms of KPIs (Key Performance
Indicators) based on statistics generated from the network. The most important of these
performance indicators from the operators’ perspective are BER (bit error rate), the FER
(frame error rate) and the DCR (dropped call rate).
The Dropped Call Rate (DCR) is a measure of the calls dropped in a network as it gives a
quick overview of network quality and revenues lost. This makes it one of the most
important parameters in network optimization. At the frame level in the NMS (Network
Management System), the DCR is measured against the Slow Associated Control Channel
(SACCH) frame. If the SACCH frame is not received, then it is considered to be dropped
calls.
For this work data was acquired form the Network Management System of various GSM
operators in Nigeria (e.g. MTN, Celtel, Globacom etc.). The acquired data was analyzed
to statistically illustrate the extent of revenue that is lost as a result of dropped calls and
the consequent impact on the customers/subscribers