WiFi

wireless local area networks (WLAN) based on the IEEE 802.11 specifications.

Wi-Fi was intended to be used for wireless devices and LANs, but is now often used for Internet access. It enables a person with a wireless-enabled computer or personal digital assistant to connect to the Internet when in proximity of an access point called a hotspot.

Certified products can use the official Wi-Fi logo, which indicates that the product is interoperable with any other product also showing the logo.

Wi-Fi vs. cellular

Some argue that Wi-Fi and related consumer technologies hold the key to replacing cellular telephone networks such as GSM. Some obstacles to this happening in the near future are missing roaming and authentication features (see 802.1x, SIM cards and RADIUS), the narrowness of the available spectrum and the limited range of Wi-Fi. Despite such problems, companies like Zyxel, SocketIP and Symbol Technologies are offering telephony platforms (Central Office replacements and terminals (phones)) that use Wi-Fi transport.

Many operators are now selling mobile internet products that link cellular wireless and Wi-Fi radio system in a more or less transparent way to take advantage of the benefits of both systems. Future wireless systems are expected to routinely switch between a variety of radio systems.

The term 4G is occasionally used for Wi-Fi, the implication being that the bandwidth and capabilities offered are already greater than those promised by the 3G cellular telephone standards.

The main difference between cellular and Wi-Fi is that cellular system use licensed spectrum, and Wi-Fi is implemented in unlicensed bands. The economic basis for their implementation is therefore completely different. the success of Wi-Fi has made many people look to unlicensed spectrum as the future of wireless access, rather than spectrum licensed and controlled by large corporations.

Commercial Wi-Fi

Commercial Wi-Fi services are available in places such as Internet cafes, coffee houses and airports around the world, although coverage is patchy in comparison with cellular:

• T-Mobile provides hotspots in many Starbucks in the U.S;
• Pacific Century Cyber Works provides hotspots in Pacific Coffee shops in Hong Kong;
• a Columbia Rural Electric Association subsidiary offers 2.4 GHz Wi-Fi service across a 3,700 mi² (9,500 km²) region within Walla Walla and Columbia counties in Washington and Umatilla County, Oregon;
• Other large hotspot providers in the U.S. include Boingo, Wayport and iPass;
• Sify, India's largest Internet service provider, has set up 120 wireless access points in Bangalore,India in hotels, malls and government offices.

Free Wi-fi

While commercial services attempt to move existing business models to Wi-Fi many groups and communities have set up free use Wi-Fi networks. Many have adopted a in order that each network can openly share with each other.

Many municipalities have joined with the local community groups to help grow the free Wi-Fi network, many have not. Some community groups have built thier Wi-Fi networks on volunteer efforts and donations.

A few of the free Wi-fi networks you can find around the globe are...

Advantages of Wi-Fi

• Uses an unlicensed bit of the brodcast spectrum, this means less regulatory controls in many countries.
• Frees network devices from cables, allows for a more dynamic network to be grown.
• Many reliable and bug-free Wi-Fi products on the market.
• Competition amongst vendors has lowered prices considerably since their inception.
• While connected on a Wi-Fi network, it is possible to move about without breaking the network connection.

Disadvantages of Wi-Fi

• The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum, which is crowded with other devices such as Bluetooth, microwave ovens, cordless phones (900 MHz or 5.8 GHz are, therefore, alternative phone frequencies one can use if one has a Wi-Fi network), or video sender devices, among many others. This may cause a degradation in performance. Other devices which use microwave frequencies such as certain types of cell phones can also cause degradation in performance.
• Power consumption is fairly high compared to other standards, making battery life and heat a concern.
• It is not always configured properly by users. In addition, Wi-Fi commonly uses WEP (Wired Equivalent Privacy) protocol for protection, which has been shown to be easily breakable even when properly configured. Newer wireless solutions are slowly providing support for the superior WPA (Wi-Fi Protected Access) protocol (a preliminary implementation of the 802.11i protocol), though many systems still employ WEP. The adoption of the 802.11i (aka WPA2) protocol in June 2004 makes available a rather better security scheme for future use — when properly configured.
• Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g might have a range of 150 ft (46 m) indoors and 300 ft (92 m) outdoors. But about 10 US$ and an hour of building will get you an antenna that can go much further.

Wi-Fi and free software

As of version 2.6, little Wi-Fi hardware is supported by the Linux kernel. However, see the Adapters section below for pointers.

Trademark

Wi-Fi is a trademark of the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance), the trade organization that tests and certifies equipment compliance with the 802.11x standards.

Unintended use by outsiders

Many business and residential users do not bother to protect their network, which can therefore also be used by people just outside the building, see warchalking and wardriving. Configuration is not hard, but requires both knowledge and effort.

See also

• OSGi Alliance
• WiMAX