wireless communications

   A method of connecting a node or a group of nodes into the main network using a technology other than conventional cabling.

   The following methods are in use:

   • Infrared line of sight

   High-frequency light waves are used to transmit data between nodes up to 24.4 meters (80 feet) apart using an unobstructed path; infrared beams cannot pass through masonry walls. Data rates are relatively high, in the tens of megabits per second range.

   • High-frequency radio

   High-frequency radio signals transmit data to nodes from 12.2 to 39.6 meters (40 to 130 feet) apart, depending on the nature of obstructions separating them; the signal can penetrate thin walls but not supporting masonry. Data rates are usually less than 1Mbps.

   • Spread-spectrum radio

   A small set of frequencies are available for wireless LANs without FCC approval. The 902 to 928Mhz band is known as the Industrial, Scientific,

   Medical (ISM) band and is not regulated. The 2.4 to 2.483Ghz band is regulated and requires an FCC license for use. Spreadspectrum nodes can be up to 243.8 meters (800 feet) apart in an open environment, and these radio waves can pass through masonry walls. However, in an environment with fully enclosed offices, distances are limited to 33.5 meters (110 feet). Data rates are usually less than 1Mbps.

   Wireless LANs are not always completely wireless and may be used to replace the cabling on certain network segments or to connect groups of networks that use conventional cabling.

   See also mobile computing.