llected from the network management system is usually used to assess the capacity of the network. As coverage and capacity are interrelated, data collected from drive tests is also used for capacity assessment. The two aspects of this assessment are dropped calls and congestion. Generally, capacity-related problems arise when the network optimisation is taking place after a long period of time. Radio network optimisation also includes provid- ing new capacity to new hot-spots, or enhancing indoor coverage. Once the regional/area coverage is planned and executed in the normal planning phase, optimisation should take into consideration the provision of as much coverage as possible to the places that would expect high traffic, such as inside office buildings, inside shopping malls, tunnels, etc. Quality The quality of the radio network is dependent on its coverage, capacity and frequency allocation. Most of the severe problems in a radio network can be attributed to signal RADIO NETWORK PLANNING AND OPTIMISATION interference. For uplink quality, BER statistics are used, and for downlink FER statistics are used. When interference exists in the network; the source needs to be found. The entire frequency plan is checked again to determine whether the source is internal or external. The problems may be caused by flaws in the frequency plan, in the configuration plans (e.g. antenna tilts), inaccurate correction factors used in propagation models, etc. Parameter Tuning The ending of the assessment process sees the beginning of the complex process of fine- tuning of parameters. The main parameters that are fine-tuned are signalling parameters, radio resource parameters, handover parameters and power control parameters. The concepts that are discussed in the radio planning process and the KPI values should be achieved after the process is complete. The major complexity of this process is the inhomogeneity of the radio network. Network planning will have used standard propagation models and correction factors based on some t