If you've been in an airport, coffee shop, library or hotel in the last few years, chances are you've been in the middle of a wireless data networking, where you can see people on their laptops checking their emails and browsing the Internet. Many people also use wireless networking, ( WiFi or 802.11 networking) to connect their computers at home, and an increasing number of cities use the technology to provide free or low-cost Internet access to residents (WiMax). With the advent of 3G mobile phone network, wireless networking has become so widespread that you can access the Internet just about anywhere at any time, without using wires.

WiFi

Wi-Fi , is a wireless-technology brand name owned by the Wi-Fi Alliance (a consortium of hardware manufactureres), whose aim is to improve the interoperability of wireless local area network products based on the IEEE 802.11 standards. It has coined the term 'Wi-Fi' to signify compliance. Compliance is achieved by ensuring all equipment meets defined interoperability requirements during testing in an independent laboratory before manufacturers may use the Wi-Fi logo.

A Wi-Fi-enabled device such as a PC, printer, cell phone, or PDA can connect to the Internet when within range of a WiFi network connected to the Internet. The coverage of one or more interconnected access points, called a hotspot can comprise an area as small as a single room with wireless-opaque walls or as large as many square miles covered by overlapping access points.

WiFi communication across a wireless network is a lot like two-way radio communication. The radios used are very similar to the radios used for walkie-talkies, cell phones and other devices and can transmit and receive radio waves in both directions at frequencies of 2.4 GHz(802.1b,g) or 5GHz (802.1a). 802.11b equipment shares the same spectrum as equipment such as household microwave ovens, cordless phones, barcode readers, biomedical telemetry, movement detectors, radio location devices, video surveillance, and many others.

The equipment is authorised by a radio communications class licence, which means you do not have to apply for a radio licence and no licence fees are payable. A class licence operates in a similar manner to a 'public park' where everyone operates in the same band and are subject to the same limits. Operation within the same frequency band is 'uncoordinated', but interference is generally avoided by the design of the equipment and by restricting the radio power they can use.

A wireless network is a group of computers, each equipped with one wireless adapter. Computers in a wireless network must be configured to share the same radio channel.

Ad-Hoc Network: Several PCs equipped with wireless cards or adapters can communicate with one another to form an ad-hoc network.

Infrastructure Network: The wireless adapters also provide users access to a wired network when using an access point or wireless router. An integrated wireless and wired network is called an infrastructure network. Each wireless PC in an infrastructure network can talk to any computer in a wired network infrastructure via the access point or wireless router.

An infrastructure configuration extends the accessibility of a wireless PC to a wired network, and may double the effective wireless transmission range for two wireless PCs inad-hoc mode. Since an access point is able to forward data within a network, the effective transmission range in an infrastructure network may be doubled.

Infrastructure mode also supports roaming capabilities for mobile users. Roaming means that you can move your wireless PC within your network and the access points will pick up the wireless PC's signal, providing that they both share the same channel and SSID.