Wireless Fidelity (Wi-Fi) - page 2

WiFi is the marketing name for IEEE802.11, an international standard from the Institute of Electrical and Electronics Engineers (IEEE) for WLAN that operates at up to 54 megabits per second and has a range up to 300 metres outdoors. IEEE802.11b, which provides 11Mbps, has become the most popular worldwide standard for setting up WLANs in offices, colleges, homes and is becoming widely available in public spaces. Competing technologies such as HomeRF have been abandoned and equipment suppliers are focussing on supply of WiFi. Multi-millions of pounds in R&D and manufacturing capacity is now delivering dual 802.11b/g products where 11g runs at up to 54Mbps. Laptop computers and pocket PCs from major PC manufacturers have 802.11b/g built-in. New appliances such as portable phones and MP3 players will soon be 802.11b/g compatible.

Competition has already driven down the costs of deploying WiFi networks which can now be deployed by businesses to give their employees mobility within the business. Home users can buy WiFi kit to extend their DSL or cable broadband Internet access wirelessly to the entire house. In universities and schools a wireless network can allow computers to be integrated more effectively into teaching as classes no longer need to be held in the ICT room.

802.11b/g operate in the 2.4 GHz unlicensed frequency band and are the most popular WiFi standards. 802.11a has also been standardised by the IEEE and provides up to 54Mbps in the 5GHz unlicensed frequency band. 11a is more popular in the US than in the rest of the world.

The main measure of 802.11b/g equipment interoperability is the Wireless Fidelity (WiFi ®) certification program. Administered by the industry group, Wireless Ethernet Compatibility Alliance (WECA), the Wi-Fi logo (shown above is a registered trade mark of WECA) on a product certifies its interoperability with other products containing the logo. An independent lab, the Agilent/Silicon Valley Networking Lab performs the actual testing.

802.11e or Wireless Multi Media (WMM) provides Quality of Service (QoS) over 802.11a/b/g. Large file downloads use most of the bandwidth on a wireless link, which might cause a VoIP call to "break up" or a video stream to "block up". WMM allows users to use real time services such as video streaming and VoIP while web browsing and downloading files. In order for WMM to function correctly, both a compatible Access Point and Client are required. Proxim equipment supplied by Daconi supports WMM.

802.11n is a forthcoming standard that will provide higher speeds than existing wireless systems. It utilises Multiple Input Multiple Output (MIMO) antenna technology to achieve data rates of 100Mbps+, this is achieved by using more of the available wireless spectrum. The standard is expected to be finalised in 2008. There are a number of "pre-N" products currently on the market using MIMO technology, but these are not guaranteed to be compatible with 802.11n when it is standardised. It will operate on both 2.4Ghz and 5Ghz bands. Note that a .11n client is required to take advantage of increased data rates.