wireless networking

Definition of wireless networking in The Network Encyclopedia.

What is Wireless Networking?

Networking that uses electromagnetic waves traveling through free space to connect stations on a network. Wireless transmission is said to use unguided media, as opposed to the guided media of copper cabling and fiber-optic cabling used in traditional wired networks. Wireless networking is typically used for:

  • Communication with mobile stations, which precludes the use of fixed cabling, or for mobile users who roam over large distances, such as sales reps with laptops that have cellular modems.
  • Work areas in which it is impractical or expensive to run cabling, such as older buildings that are costly to renovate. In this case, two solutions are possible:
    • Create a wireless LAN (WLAN) that uses no cabling between stations.
    • Create a combination of traditional wired local area networks (LANs) and as many wireless stations as needed.
  • Networking buildings on a campus using a wireless bridge or router. You can typically use wireless bridges or routers over distances up to 25 miles. They might support point-to-point or multipoint connections and often support Internet Protocol (IP) or Internetwork Packet Exchange (IPX) routing using static routing or the Routing Information Protocol (RIP).

Wireless networking suffers somewhat from lower data transmission rates (the maximum is currently about 10 Mbps), greater susceptibility to electromagnetic interference (EMI), and greater risk of eavesdropping than transmission over guided media. You can largely solve the security issue by using secure network protocols, but you should be sure to isolate wireless stations from sources of EMI in the operating frequency range of the network. A microwave oven, for example, can degrade wireless communication that is based on the microwave portion of the electromagnetic spectrum.

How wireless networking Works

In the broadest sense, wireless networking is composed of all forms of network communication that use electromagnetic waves of any wavelength or frequency, which includes the following portions of the electromagnetic spectrum:

  • Infrared (IR):
    Ranges from frequencies of about 300 GHz to 200 THz and is used primarily in confined areas where line-of-sight communication is possible. IR cannot penetrate buildings or structures, but it can reflect off light-colored surfaces.

     

  • Microwave:
    Ranges from 2 GHz to 40 GHz and is used for both point-to-point terrestrial communication and satellite communication. Microwave suffers from signal degradation when weather conditions are poor (for example, in fog or rain).

     

  • Broadcast radio:
    Ranges from 30 MHz to 1 GHz, is less affected by poor atmospheric conditions than microwave, and can travel through most buildings and structures, but suffers from multipath interference over long distances.

     

To connect wireless stations to a traditional wired LAN, you need only two components:

  • One or more access points, which are transceivers connected to the wired LAN. They broadcast signals to and receive signals from the wireless stations on the LAN, forwarding signals between the wired network and the wireless stations as needed. The effective reception range from an access point defines a circular area called a cell, or more properly, a Basic Service Set. When more than one access point exists on a network and their cells overlap, the access point devices must also hand off communication as roaming stations move from one cell to another. The number of wireless stations that an access point can effectively handle is inversely proportional to the average traffic generated by each station. A typical wireless access point device might provide up to 3000 square meters of coverage in open areas (or less when obstacles are present) and support data transmission rates of 1 to 10 Mbps.
  • A WLAN adapter, which can be an external device called a station adapter that plugs into the RJ-45 port of a 10BaseT Ethernet card, an external device that connects to an RS-232 serial port, or a special PCMCIA card. Whatever configuration you use, the wireless adapter turns the computer in which it is installed into a wireless station on the network. A fixed or detachable antenna is generally included and gives the station better transmission and reception. For a small-scale WLAN, the typical power output for an adapter might be 100 mW, resulting in a coverage range of about 305 meters in open areas (or less when obstacles are present).

    Graphic W-14. Wireless networking.

The existing standard for wireless networking is IEEE 802.11 of Project 802, which specifies the physical layer (PHY) and media access control (MAC) protocols and characteristics for wireless communication between networked stations. In particular, 802.11 covers low-power wireless microwave communication in the Industrial, Scientific, and Medial (ISM) communication band centering on 2.4 GHz that was set aside by the Federal Communications Commission (FCC) in the early 1980s for unlicensed wireless communication. 802.11 covers both common spread spectrum communication methods (direct sequencing and frequency hopping), includes an exportable encryption algorithm called wired equivalent privacy (WEP) to prevent eavesdropping, and specifies a maximum data transmission speed of either 1 or 2 Mbps. 802.11 also specifies standards for wireless communication using infrared light. 802.11 is currently being revised to support transmission speeds of up to 20 Mbps.

NOTE

Both direct sequencing spread spectrum (DSSS) and frequency hopping spread spectrum (FHSS) wireless technologies can operate in the unlicensed 2.4-GHz ISM band. DSSS equipment is also available for operation in a portion of the 900-MHz frequency band - the same part of the electromagnetic spectrum used by Cellular Digital Packet Data (CDPD) cellular telephone and Personal Communications Services (PCS) paging technologies - and is better able to penetrate buildings and structures than 2.4-GHz equipment. When you use a wireless bridge, 900 MHz is preferred for longer distances; 2.4 GHz works better over shorter distances and provides greater network throughput.

Most wireless systems use the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) media access method, in contrast to the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) method used in wired Ethernet networks. The primary reason for this is that it is difficult to detect collisions between unguided electromagnetic waves.

TIP

Use an omnidirectional antenna if your wireless bridge or router is being used for point-to-point communication.

Expand your wireless network range: NETGEAR AC750 WiFi Range Extender (EX3700-100NAS) (Amazon store).