 messages can be analysed to find out more details. Measurement Equipment Failure The measurement equipment is one source of potential problems. The dropped calls can be caused by failures in the measurement equipment or the mistakes made using the equipment. The drive test is prone to have errors, some of which can cause dropped calls. Verification The cluster optimisation analysis should be performed in two parts. Network verification is used to accept the network performance based on drive tests along reference routes' encompassing multiple clusters. KPIs are measured only in areas where 'acceptable' coverage has been achieved. Typically network verification measurements consist of larger areas than cluster measurements and are less detailed. They are also repeated to benchmark the performance over the time when the network develops and traffic patterns evolve. Performance Monitoring Statistics High Level Performance Indicators Analysing statistics is a top-down process. The high level (network or RNC level) performance indicators are monitored to find out if there is a problem in the network. The impact on high level performance indicators in greater depending on the number of network elements involved. Also, a severe problem on only a few network elements would have an impact on the RNC level performance. The need for deeper analysis can also be triggered by constant variation of performance graphs or odd regularity of performance variation. The high level performance problems, anomalies and regular patterns of performance variation are triggers that indicate a need for further investigation. Radio Network Planning and Optimisation Analyzer analysis Network Image Workbock Tools Workspace OpenLogtle UMTS Top 10 Loaded Data Fles Replay SuperStream001 3bnpo060204brs002b SuperStream001 3brpc060204brs002b(1) Top 10 cations Layout Print Cel Sites Super Streams Stranges 2 -10.0 -93.0 avn0067a SuperStream001 avn0067b1 Protocol Stack Browser SuperStream001 Uu RRC Vendor Specific Uu_RRC Syrk Msgs shoe Gndines Find Nex