Wi-Fi, popularly known as an acronym for wireless fidelity, was originally a brand licensed by the Wi-Fi Alliance to describe the embedded technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. Use of the term has now broadened to generically describe the wireless interface of mobile computing devices, such as laptops in LANs. Wi-Fi is now increasingly used for more services, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions, DVD players, and digital cameras. More standards are in development that will allow Wi-Fi to be used by cars on highways in support of an Intelligent Transportation System to increase safety, gather statistics, and enable mobile commerce (see IEEE 802.11p). Wi-Fi and the Wi-Fi CERTIFIED logo are registered trademarks of the Wi-Fi Alliance - the trade organization that tests and certifies equipment compliance with the 802.11x standards.

Uses

A person with a Wi-Fi enabled device such as a pc, cell phone or PDA can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot. Hotspots can range from a single room to many square miles of overlapping hotspots. Wi-Fi can also be used to create a mesh network. Both architectures are used in community networks.[citation needed]

Wi-Fi also allows connectivity in peer-to-peer (wireless ad-hoc network) mode, which enables devices to connect directly with each other. This connectivity mode is useful in consumer electronics and gaming applications.

When the technology was first commercialized there were many problems because consumers could not be sure that products from different vendors would work together. The Wi-Fi Alliance began as a community to solve this issue so as to address the needs of the end user and allow the technology to mature. The Alliance created the branding Wi-Fi CERTIFIED to show consumers that products are interoperable with other products displaying the same branding.

Wi-Fi at home

Home Wi-Fi clients come in many shapes and sizes, from stationary PCs to digital cameras. The trend today is to incorporate wireless into every electronic device where mobility is desired.

Wi-Fi devices in home or consumer-type environments connect in the following ways:

• Via a broadband Internet connection into a single router which can serve both wired and wireless clients
• Ad-hoc mode for client to client connections
• Built into non-computer devices to enable wireless connectivity to other devices or the Internet

Wi-Fi in Gaming

Gaming consoles and handhelds make use of Wi-Fi technology to enhance the gaming experience. Examples include:

• The Nintendo DS handheld is Wi-Fi compatible, and is compatible with WEP encryption.
• The Wii is Wi-Fi compatible, and is compatible with WEP and WPA encryption.
• The PlayStation 3 Premium model features built-in Wi-Fi, while the Basic model can be upgraded with a separate wireless adapter.
• The PlayStation Portable is Wi-Fi compatible, and is compatible with WEP and WPA encryption.
• The Xbox 360 can be made Wi-Fi compatible if the user purchases a separate wireless adapter.

Wi-Fi in Business

Business and industrial Wi-Fi has taken off, with the trends in implementation varying greatly over the years. Current technology trends in the corporate wireless world are:

• Dramatically increasing the number of Wi-Fi Access Points in an environment, in order to provide redundancy,support fast roaming and increasing overall network capacity by using more channels and/or creating smaller cells
• Designing for wireless voice applications (VoWLAN or WVOIP)
• Moving toward ‘thin’ Access Points, with more of the network intelligence housed in a centralized network appliance; relegating individual Access Points to be simply ‘dumb’ radios
• Outdoor applications utilizing true mesh topologies
• A proactive, self-managed network that functions as a security gateway, firewall, DHCP server, intrusion detection system, and a myriad of other features not previously considered relevant to a wireless network.

Technical information

Wi-Fi: How it Works
Wi-Fi networks use radio technologies called IEEE 802.11 to provide secure, reliable, fast wireless connectivity. A typical Wi-Fi setup contains one or more Access Points (APs) and one or more clients. An AP broadcasts its SSID (Service Set Identifier, “Network name”) via packets that are called beacons, which are usually broadcast every 100 ms. The beacons are transmitted at 1 Mbit/s, and are of relatively short duration and therefore do not have a significant effect on performance. Since 1 Mbit/s is the lowest rate of Wi-Fi it assures that the client that receives the beacon can communicate at at least 1 Mbit/s. Based on the settings (e.g. the SSID), the client may decide whether to connect to an AP. If two APs of the same SSID are in range of the client, the client firmware might use signal strength to decide with which of the two APs to make a connection.

The Wi-Fi standard leaves connection criteria and roaming totally open to the client. This is a strength of Wi-Fi, but also means that one wireless adapter may perform substantially better than another. Since Wi-Fi transmits in the air, it has the same properties as a non-switched wired Ethernet network, and therefore collisions can occur. Unlike a wired Ethernet, and like most packet radios, Wi-Fi cannot do collision detection, and instead uses an acknowledgment packet for every data packet sent. If no acknowledgement is received within a certain time a retransmission occurs. Also, a medium reservation protocol can be used when excessive collisions are experienced or expected (RequestToSend/ClearToSend used for Collision Avoidance or CA) in an attempt to try to avoid collisions.

A Wi-Fi network can be used to connect computers to each other to the internet and to wired networks (which use IEEE 802.3 or Ethernet). Wi-Fi networks operate in the unlicensed 2.4 (802.11b/g) and 5 GHz (802.11a/h) radio bands, with an 11 Mbps (802.11b) or 54 Mbps (802.11a or g) data rate or with products that contain both bands (dual band). They can provide real world performance similar to the basic 10BaseT wired Ethernet networks.