WAN (Wide Area Network)

A WAN is generally an extension of an internal network into the wide area using private circuits such as T1 lines or virtual circuits in cell and packet switched networks such as ATM and frame relay. WANs links geographically dispersed offices in other cities or around the globe. Because WANs have been built with private leased lines, bandwidth has traditionally been low and costs have been high, which required careful monitoring and filtering of traffic between sites. WANs can also be constructed across the Internet by implementing VPN (virtual private network) technology. With VPNs private circuits are emulated in the form of encrypted tunnels from one site to another. 

WAP (Wireless Application Protocol)  

WAP is a worldwide standard for providing Internet communications and advanced telephony services on digital mobile phones, pagers, personal digital assistants and other “smart” wireless terminals. The WAP Forum developed the protocol as a means of transferring information to mobile wireless devices using a standard interface and display format. 

WDM (Wavelength Division Multiplexing)

WDM is an FDM (frequency division multiplexing) technique for fiber-optic cable in which multiple optical signal channels are carried across a single strand of fiber at different   wavelengths of light. These channels are also called lambda circuits. Think of each wavelength as a different color of light in the infrared range that can carry data. A fiber-optic cable guides light from end to end. A signal is injected in one end by an LED          

 (light-emitting diode) or by semiconductor lasers. Lasers for silica-based fiber-optic cables produce light in a range called a “window.” These windows occupy the near infrared range at wavelengths of 850 nm (nanometer or billionths of a meter), 1,320 nm, 1,400 nm, 1,550 nm, and            

 1,620 nm.

Wireless IP

Wireless IP obviously refers to using the Internet Protocol over a wireless connection. At one time, the term “wireless IP” referred to CDPD (Cellular Digital Packet Data), a method for transmitting data packets across wireless cellular networks.

Wireless LANs   

Wireless LANs or “WLANs” are the equivalent of wired LANs (usually Ethernet) without the  wires. They are meant for office environments and even home use. Other wireless technologies are outlined under “Wireless Communications.” Mobile wireless (cellular telephones) is  discussed under “Wireless Mobile Communications.” Wireless access service (broadband Internet connections) is covered under “Wireless Broadband Access Technologies.”  A related wireless technology is the wireless PAN (personal area network), which is a   limited-range network for interconnecting mobile devices connecting with peripheral devices. Note that WLANs and PANs are very similar, except that the range of PANs is intentionally limited so that groups of people in the same area (conference room, restaurants, airport terminal) can spontaneously connect. By limiting the range, a typical office can have many  different PANs operating at the same time. See “Bluetooth” and “Wireless PANs (Personal Area Networks).      

Wireless Mobile Communications

There are a variety of wireless communication systems for transmitting voice, video, and data in local or wide areas. There are point-to-point wireless bridges, wireless local area networks, multidirectional wireless cellular systems, and satellite communication systems. This topic discusses “mobile” wireless technologies that provide voice and data               

Communication services to mobile users who use cell phones ,PDAs, Internet terminals ,And related computing devices.The number of wireless mobile devices is increasing globally. Users equipped with portable computers, PDAs (personal digital assistants), and a variety of small wireless communication devices increasingly need to connect to corporate networks, perform database queries, exchange messages, transfer files, and even participate in collaborative computing. At the same   time, wireless systems are achieving higher data rates to support Internet and other data-related applications. The newest mobile communication systems are targeting data rates as high as 2 Mbits/sec.                                                                                     

Wireless PANs (Personal Area Networks)

 A WPAN (Wireless PAN) is a short-distance wireless network specifically designed to support Portable and mobile computing devices such as PCs, PDAs, wireless sprinters and storage devices,cell phones, pagers, set-top boxes, and a variety of consumer electronics equipment. Bluetooth  is an example of a wireless PAN that allows devices within close proximity to join together in ad hoc wireless networks in order to exchange information. Many cell phones have two radio interfaces—one for the cellular network and one for PAN connections.