An infinitely extendable number of channels. Mobile communications are usually allocated bands in the 50MHz to 1GHz band. At these frequencies the effects of scattering and shadowing are significant. Lower frequencies would improve this performance, but HF bandwidth is not available for this purpose. The extensive investigation of propagation characteristics required prior to installation.
Mobile communication work by limiting transmitter powers.
This restricts the range of communication to a small region. Outside this region, other transmitters can operated independently. Each region is termed a cell . These cells are often represented in diagrams as hexagons. In practise the cell shape is determined by local propagation characteristics.