build as high a quality network as possible. On the other hand, there must be cost-efficiency - how much money the operator can spend for the investments SO that the business is financially profitable. The two factors - network quality and investments - are connected to profit. The link is not straighforward but, is one factor, if the network end user quality perception is good it has an impact on the profits. This explains the complexity of network planning; sufficient cellular network coverage and capacity needs to be created with as low an investment as possible. The coverage targets include the geographical coverage, coverage thresholds for different areas and coverage probability. Examples of coverage thresholds are presented in Table 2.1. The range for a typical coverage probability is 90-95 %. The geographical coverage is case-specific and can be defined in steps according to network roll-out phases. The quality targets are those agreed in association with the customer and network planning. The main quality parameters are call success or drop call rate, handover success, congestion or call attempt success and customer observed downlink (DL) quality. The DL quality is measured according to BER as defined in GSM specifications and mapped to RXQUAL values. Normally downlink RXQUAL classes 0 to 5 are considered as a sufficient call quality for the end user. The classes 6 and 7 represent poor performance Radio Network Planning and Optimisation Table 2.2 Typical network quality targets Quality parameter Target value Drop call rate Handover success rate > 95% Call attempt success rate > 98% DL quality > :RXQUAL 5 and thus need to be avoided. The target value for RXQUAL can be, for example, 95 % or the time equal or better than 5. Example values for network quality targets are shown in Table 2.2. The coverage and quality targets need to be considered in connection with the network evolution strategy. The subscriber forecast predicts the need and pace of network enlargement. Due to this obvious connection it is imp