oken down for different services, e.g. a call setup success rate for voice, a call setup success rate for video, a call setup success rate for PS background services, etc. Low Level Performance Indicators After identifying a problem in high level performance indicators in order to find out what is causing the problem, low level performance indicators need to be analysed. There are large numbers of performance indicators; thus the analysis of low level indicators is based on analysing large numbers of statistical counters. There are different approaches to start with. One approach is to calculate high level KPIs (drop call rate, call setup success rate) for individual cells and find out which cells should have a closer analysis. Another approach is to identify a problem type or a counter indicating a problem type, and only after that is the next step to identify which cells have this problem (shown in Figure 2.98). Radio Network Optimisation Expand All Collapse All Latest sample 14:51 Latest sample 14:51 RRC and RAB Failure Evaluation IJB transmission failures based or IJB WSP fail.res based on RAB Cells with decreased voice traffic elAval/CSFR.DCR per RNC (CEL elAvallCSFR.DCR per ZONE(CEI Hourly check of netact tables Daiy check of netact tables Daily check of NDW tables Alorm based FlexiHopper quality TEST: Cells with high Droc Call Rat Latest sample 15:21 Latest sample 14:51 On-line celavail overview On-line list of blocked cells Cel Working States Cells with SIB-problems Cells with low availability Cells with RAB but no RRC Cells with RRC Setup Failures Cells with RRC Access Failures Cells with low setup success rate Cells with many restarts Cells with high drop call rate Figure 2.97 Example of cell availability monitoring Analysing the geographical proximity of cells having problems might indicate something wrong with a whole cluster of cells, e.g. the HW/SW problem related to the transmission network, etc. When network elements having problems have been identified then the symptoms of the problem need to be 