From Wikipedia, the free encyclopedia.
A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier: the last link with the users is wireless, to give a network connection to all users in a building or campus. The backbone network usually uses cables.
WLAN is expected to continue to be an important form of connection in many business areas. The market is expected to grow as the benefits of WLAN are recognized. Frost and Sullivan estimate the WLAN market to have been 0.3 billion US dollars in 1998 and 1.6 billion dollars in 2005. So far WLANs have been installed primarily in warehouses and resellers, but are recently being installed in various kinds of schools. Large future markets are estimated to be in health care, educational institutes and corporate offices. In the business environment, meeting places, public areas and side offices would be ideal for WLAN (although in the UK the exhorbatant cost of using such connections has so far limited use to Airport's Business Class lounges etc.)
Origionally WLAN hardware was so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Such places could be old protected buildings or classrooms, althgough the restricted range of the 802.11b (typically 30ft.) limits it's use to smaller buildings. WLAN components are now cheap enough to be used in the home, with many being set-up so that one PC (eg parents) can be sued to share an Internet connection with the whole familiy (whilst retaining access control at the parents PC).
Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, primarily the various versions of IEEE 802.11 (Wi-Fi) (see separate articles) and HomeRF (2 Mbit/s, intended for home use, unknown in the UK). An alternative ATM-like 5 GHz standardized technology, HIPERLAN, has so far not succeeded in the market and with the release of the faster 54Mbs 802.11a standard, almost certainly never will.
The lack of default security of Wireless connections is fast becoming an issue, especially in the UK, where many Broadband (ADSL) connections are now offered together with a Wireless Basestation/ADSL Modem/Firewall/Router access point. Further, many Laptop PC's now have Wireless Networking built in (cf. Intel 'Centrino' campaign) thus eliminating the need for an additional plug-in (PCMCIA) card. This might even be enabled, by default, without the owner ever realising it, thus 'broadcsting' the Laptop's accessability to any Computer nearby.
The use of Windows XP as the 'standard' in home PC's makes it very easy to setup a PC as a Wireless LAN 'basestation' and (using XP built in Internet Connection Sharing mode) allows all the PC's in the home to acess the Internet via the 'base' PC. However lack of expertise in setting up such systems often means that your nextdoor neighbour also shares your Internet connection, sometimes without you (or they) ever realising it.
In the UK, the frequencies over which 802.11b is permitted to operate are restricted, which leads to more cross-interference. Many users find that choosing US mode (or leaving the settings as default) gives a more realiable connection.
There are two possible types of infrastructure: Peer-to-peer or ad-hoc mode and the so called infrastructure mode.
Peer-to-peer: This mode is a method for wireless devices to directly communicate with each other. Operating in ad-hoc mode allows wireless devices within range of each other to discover and communicate in peer-to-peer fashion without involving central access points. Typically used by 2 PC's to connect to one another, so that one can share the others Internet connection for example.
Infrastructure mode: This mode of wireless networking bridges a wireless network to a wired Ethernet network. Infrastructure mode wireless also supports central connection points for WLAN clients. A wireless access point is required for infrastructure mode wireless networking, which serves as the central WLAN communication station. Typically used by a stand-alone base-station (such as a Broadband/ADSL connection box).
Classification of Computer network
Local area network (LAN)
Wide area network (WAN)
Ethernet - History and Basics
Router - History, Functionality and Manufacturers