phical areas are each optimised to ensure QoS in that area. Geographical areas can be selected based of different methods, but the sites should be in geographical proximity and interference coming in to the cluster from neighbouring areas should be minimised. The quality targets are defined for each cluster in terms of, for example, overall RSCP and Ec/No, pilot pollution areas, drop call rate and call setup success rate. Cluster Preparation The cluster preparation phase consists of activities that can be done without drive test data. They should also take place to ensure that the drive test can take place and that it reveals planning related performance problems: Defining clusters Planning the drive route Radio parameter audit Radio Network Planning and Optimisation Site configuration check Neighbour list verification Fault management check Cell availability check Prior to any drive tests a cluster should have the majority of its sites integrated and these sites should also be operational and available. Defining Clusters Clusters should be geographically contiguous areas comprising typically between 15 and 20 sites. The clusters are defined primarily based on geography: site locations, major roads, RNC borders, other geographical aspects, e.g. rivers. The secondary method for cluster definition is interference analysis, used to minimise the amount of external interference to a cluster from neighbouring clusters. Planning the Drive Route The drive route for a cluster includes all sites predicted for that cluster as well as sites not on air at the time of the drive but planned to be integrated before the network is launched. The drive route should cover a good percentage of main roads and motorways and also all areas of special interest, e.g. airport routes, corporate routes. Before the drive test can be performed parameter and configuration checks are made to ensure correct settings for the sites within the cluster. Also the alarms indicating potential hardware or software problems are checked to ensure that no p