 to be verified carefully and in the case of measurement errors the incorrect parts need to be filtered. As an output the tool gives correction factors for each measured clutter type. Example correction factors for some clutter types using the Okumura-Hata model are presented in Table 2.8. A small value in the correction factor means easy propagation conditions. 2.5 Coverage Planning 2.5.1 Coverage Planning in GSM Networks The target for coverage planning is to find optimal locations for base stations to build continuous coverage according to the planning requirements. Especially in the case of a coverage limited network the BTS location is critical. With a capacity limited network the capacity requirements also need to be considered. Coverage planning is performed with a planning tool including a digital map with topography and morthography information. The propagation model is selected and customised with model tuning mea- surements before the coverage planning phase has been started. The model selection is done according to the planning parameters, e.g. frequency, macro/micro cell environment, BTS antenna height. The COV- erage prediction is based on the map and the model and therefore the accuracy is dependent on those as well. As the link budget calculations are created for all the network configurations, which means different combinations of the planning parameters, the cell size determination can be started. The number of different combinations is targeted to be kept as small as possible, but some different BTS profiles are normally needed. Sometimes there can be restrictions in the antenna usage, e.g. only small ones can be used in the city area, and this creates different link budgets for urban and rural areas. The link budget defines the maximum allowed path loss with certain configurations. Firstly, the theoretical maximum for the cell size is calculated using the selected basic propagation model. Coverage Planning Figure 2.14 Lower tail of normal distribution for the location probability calculation A