Wireless Technologies
Overview

WLANs are only one usage of the radio frequency (RF) spectrum. Figure illustrates the distance versus data rate relationships that exist in different wireless technologies. Figure lists the different radio frequency bands, along with the name of the transmitted waves in each band and typical usages. A multitude of different and complex technologies crowd the frequency spectrum and cannot be fully covered in this course.

The U.S. General Services Administration definition of radio is as follows:

  1. Telecommunication by modulation and radiation of electromagnetic waves
  2. A transmitter, receiver, or transceiver used for communication via electromagnetic waves
  3. A general term applied to the use of radio waves

Wireless technologies are comprised of many variable parameters, as listed in Figure . Some technologies provide one-way communications while others provide two-way simultaneous communications. Some operate at low power levels, whereas others operate at high power levels. Some are digital and some are analog. Some operate at short distances of 30.5 m (100 ft.) or less, and others operate over larger spans, even across continents. The cost of various wireless technologies can vary from several U.S. dollars to billions of U.S. dollars.

Wireless technologies, some of which are shown in Figure , have been around for many years. Television, AM/FM radio, satellite TV, cellular phones, remote control devices, radar, alarm systems, weather radios, CBs, and cordless phones are integrated into everyday life. Beneficial technologies that depend on wireless include weather radar systems, x-rays, Magnetic Resonant Imaging (MRIs), microwave ovens, and Global Positioning Satellites (GPSs). Wireless technology surrounds humanity on a daily basis, in business and in personal life.


Interactive Media Activity

Interactive Activity: From LAN to WLAN

This activity shows a regular wired LAN.