 data traffic. Pre-planning and nominal planning steps, such as site survey and site selection, remain the same as with GSM, as explained in Chapter 2. Detailed planning of the GPRS network takes account of the data traffic and the new equipment added to the network for this. The detailed planning again focuses on coverage, capacity, frequency and parameter planning. GPRS: NETWORK PLANNING AND OPTIMISATION Coverage Planning Coverage in a GPRS network depends are the S/N (signal-to-noise ratio) and data transmis- sion rates. Interference can be a limiting factor for the maximum data rate in the network. Each of the coding schemes (CS-1, CS-2, etc.) works for a certain range of C/I (channel to interference ratio) for a given value of block error rate (BLER). The coverage plans are made with the objective of providing a balanced link budget for both the uplink and downlink directions. The link budget is similar to that of a GSM radio network. However, the threshold requirements change in GPRS networks, thereby giving a different coverag area by a cell. The two main parameters that are required for link budget calculation are the transmitted power (from mobile station and base station) and the receiver sensitivity. As the coding schemes in a GPRS radio network have different S/N requirements, the areas covered will be different. Coding scheme CS-1 covers a large area compared to scheme CS-4. One important change that is seen in the link budget calculations is the removal of a body loss value for CS-2, thereby giving GPRS services a 3 dB advantage compared with GSM services. The S/N requirements for CS-3 and CS-4 are quite high, thereby reducing the area covered by them. CS-1 and CS-2 are usually used for GPRS radio network coverage planning, while CS-3 and CS-4 are used for the call centre. As coverage in a GPRS network is limited by interference (rather than by noise), the C/I ratio distribution becomes a detrimental factor in coverage area predictions. Capacity Planning Capacity planning of a GPRS network may be su