Wireless Communication

 

The transfer of electromagnetic signals from place to place without cables, usually using infrared light or radio waves.

Communication by infrared light is practical only over short distances in unobstructed places with a clear line of sight. For example, infrared light is used by TV remote controls and occasionally to link a keyboard or mouse to a computer. It does not pass through walls.

Radio waves travel freely in all directions and penetrate obstacles. Every transmitter fills a large area with its signal. Since only a finite range of frequencies is available, transmitters often interfere with each other. Unlicensed transmitters are limited to very low power and short range; more powerful transmitters require regulation and licensing. Spread-spectrum technology provides an especially efficient way to share frequencies