Glossary

A B C D E F G I L M N O P Q R S T U V W
WAN (Wide Area Network)

A wide network that connects together several small networks (LAN, MAN), for example from different countries, cities or locations, over large distances by means of cable, fiber optics or satellite.

WDM (Wavelength Division Multiplex)

A method of concentration (multiplex method) on electrical, optical or wireless-based connections in order to achieve better utilization of the available bandwidth of the transmission paths and minimize the transfer costs per individual signal. A distinction is made between the following methods:

  • SDM (Space Division Multiplex): Spatial separation of individual signals, for example on separate lines
  • FDM (Frequency Division Multiplex): Individual signals are modulated onto different frequencies
  • TDM (Time Division Multiplex): Individual, usually digital, signals are transferred chronologically after each other
  • CDM (Code Division Multiplex): Code words are assigned to the individual digital signals
  • DWDM (Dense Wavelength Division Multiplex): An optical Frequency Division Multiplex method with a very dense channel (signal) spacing
  • WDM (Coarse Wavelength Division Multiplex): An optical Frequency Division Multiplex method with a wide (coarse) channel (signal) spacing; a lower-cost alternative to DWDM
WLAN (wireless LAN)

A radio-based transmission method that is usually operated in the license-free microwave band. Wireless LANs consist of radio cells in which users can log on in order to access the networks behind them. Several standards are currently new on the market, for example 802.11b (max. 11 Mbit/s), 802.11a (54 Mbit/s) or Bluetooth. All users of a radio cell share the bandwidth.