All cellular telephone systems exhibit several fundamental characteristics, as summarized in the following:
- The geographic area served by a cellular system is broken up into smaller geographic areas/cells. Uniform hexagons most frequently are employed to represent these cells on maps and diagrams; in practice, though, radio waves do not confine themselves to hexagonal areas, so the actual cells have irregular shapes.
- All communication with a mobile or portable instrument within a given cell is made to a base station that serves the cell.
- Because of the low transmitting power of battery-operated portable instruments, specific sending and receiving frequencies assigned to a cell may be reused in other cells within the larger geographic area.
- Thus, the spectral efficiency of a cellular system (that is, the uses to which it can put its portion of the radio spectrum) is increased by a factor equal to the number of times a frequency may be reused within its service area.