l is dependent upon the area covered by the signal. The distance travelled by the signal is dependent upon radio propagation characteristics in the given area. Radio propagation varies from region to region and should be studied carefully, before predictions for both coverage and capacity are made. The requirement from the radio planners is generally a network design that covers 100% of the area. Fulfilling this requirement is usually impossible, SO efforts are made design a network that covers all the regions that may generate traffic and to have 'holes' only in no-traffic zones. The whole land area is divided into three major classes - urban, suburban and rural - based on human-made structures and natural terrains. The cells (sites) that are constructed in these areas can be classified as outdoor and indoor cells. Outdoor cells can be further classified as macro-cellular, micro-cellular or pico-cellular (see Figure 2.6). Macro-cells When the base station antennas are placed above the average roof-top level, the cell is a known as a macro-cell. As the antenna height is above the average roof-top level, the area RADIO NETWORK PLANNING AND OPTIMISATION Micro-cell Pico-cell Macro-cell Figure 2.6 Macro-, micro- pico-cells that can be covered is wide. A macro-cell range may vary from a couple of kilometres to 35 km, the distance depending upon the type of terrain and the propagation conditions. Hence, this concept is generally used for suburban or rural environments. Micro-cells When the base station antennas are below the average roof-top level, then the cell is known as a micro-cell. The area that can be covered is small, SO this concept is applied in urban and suburban areas. The range of micro-cells is from a few hundred metres to a couple of kilometres. Pico-cells Pico-cells are defined as the same layer as micro-cells and are usually used for indoor coverage. 2.2.2 Wave Propagation Effects and Parameters The signal that is transmitted from the transmitting antenna (BTS/MS) and received by the receiving antenna 