A wireless LAN (WLAN) is a

wireless computer network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking allows homes, telecommunications networks, and business installations to avoid the costly process of introducing cables int ...

that links two or more devices using

wireless communication Wireless communication (or just wireless, when the context allows) is the transfer of information (''telecommunication'') between two or more points without the use of an electrical conductor, optical fiber or other continuous guided med ...

to form a

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...

(LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

. Wireless LANs based on the

IEEE 802.11 IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) technical standards, and specifies the set of medium access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer com ...

standards are the most widely used computer networks in the world. These are commonly called

Wi-Fi Wi-Fi () is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital devices to exchange data by ...

, which is a trademark belonging to the

Wi-Fi Alliance The Wi-Fi Alliance is a non-profit organization that owns the Wi-Fi trademark. Manufacturers may use the trademark to brand products certified for Wi-Fi interoperability. It is based in Austin, Texas. History Early IEEE 802.11, 802.11 product ...

. They are used for home and small office networks that link together

laptop computer A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer scree ...

s, printers,

smartphone A smartphone is a mobile phone with advanced computing capabilities. It typically has a touchscreen interface, allowing users to access a wide range of applications and services, such as web browsing, email, and social media, as well as multi ...

s, Web TVs and gaming devices through a wireless network router, which in turn may link them to the Internet.

Hotspots Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Tr ...

provided by routers at restaurants, coffee shops, hotels, libraries, and airports allow consumers to access the internet with portable wireless devices.

History

Norman Abramson Norman Manuel Abramson (April 1, 1932biography
from

, a professor at the

University of Hawaii A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

, developed the world's first wireless computer communication network,

ALOHAnet ALOHAnet, also known as the ALOHA System, or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaii. ALOHAnet became operational in June 1971, providing the first public demonstration of a wireless pack ...

. The system became operational in 1971 and included seven computers deployed over four islands to communicate with the central computer on the

Oahu Oahu (, , sometimes written Oahu) is the third-largest and most populated island of the Hawaiian Islands and of the U.S. state of Hawaii. The state capital, Honolulu, is on Oahu's southeast coast. The island of Oahu and the uninhabited Northwe ...

island without using phone lines. WLAN PCI Card cleaned

Wireless LAN hardware initially cost so much that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by

technical standard A technical standard is an established Social norm, norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and producti ...

s, primarily the various versions of IEEE 802.11 (in products using the

brand name). Beginning in 1991, a European alternative known as HiperLAN/1 was pursued by the

European Telecommunications Standards Institute The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of information and communications. ETSI supports the development and testing of global technical ...

(ETSI) with a first version approved in 1996. This was followed by a HiperLAN/2 functional specification with ATM influences accomplished February 2000. Neither European standard achieved the commercial success of 802.11, although much of the work on HiperLAN/2 has survived in the physical specification ( PHY) for IEEE 802.11a, which is nearly identical to the PHY of HiperLAN/2. In 2009, 802.11n was added to 802.11. It operates in both the 2.4 GHz and 5 GHz bands at a maximum data transfer rate of 600 Mbit/s. Most newer routers are ''dual-band'' and able to utilize both wireless bands. This allows data communications to avoid the crowded 2.4 GHz band, which is also shared with

Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is li ...

devices and

microwave oven A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...

s. The 5 GHz band also has more channels than the 2.4 GHz band, permitting a greater number of devices to share the space. Not all WLAN channels are available in all regions. A HomeRF group formed in 1997 to promote a technology aimed at residential use, but it disbanded in January 2003.

Architecture

Stations

All components that can connect into a wireless medium in a network are referred to as stations. All stations are equipped with

wireless network interface controller Wireless communication (or just wireless, when the context allows) is the transfer of information (''telecommunication'') between two or more points without the use of an electrical conductor, optical fiber or other continuous guided med ...

s. Wireless stations fall into two categories:

wireless access point In Computer networking device, computer networking, a wireless access point (WAP) (also just access point (AP)) is a networking hardware device that allows other Wi-Fi devices to connect to a wired network or wireless network. As a standalone ...

s (WAPs) and clients. WAPs are base stations for the wireless network. They transmit and receive radio frequencies for wireless-enabled devices to communicate with. Wireless clients can be mobile devices such as laptops,

personal digital assistant A personal digital assistant (PDA) is a multi-purpose mobile device which functions as a personal information manager. Following a boom in the 1990s and 2000s, PDAs were mostly displaced by the widespread adoption of more highly capable smar ...

VoIP phone A VoIP phone or IP phone uses voice over IP technologies for placing and transmitting telephone calls over an IP network, such as the Internet. This is in contrast to a standard phone which uses the traditional public switched telephone network ...

s and other

s, or non-portable devices such as

desktop computer A desktop computer, often abbreviated as desktop, is a personal computer designed for regular use at a stationary location on or near a desk (as opposed to a portable computer) due to its size and power requirements. The most common configuratio ...

s, printers, and

workstation A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...

s that are equipped with a wireless network interface.

Service set

The basic service set (BSS) is a set of all stations that can communicate with each other at PHY layer. Every BSS has an identification (ID) called the BSSID, which is the

MAC address A MAC address (short for medium access control address or media access control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use i ...

of the access point servicing the BSS. There are two types of BSS: Independent BSS (also referred to as IBSS), and infrastructure BSS. An independent BSS (IBSS) is an ad hoc network that contains no access points, which means they cannot connect to any other basic service set. In an IBSS the STAs are configured in ad hoc (peer-to-peer) mode. An extended service set (ESS) is a set of connected BSSs. Access points in an ESS are connected by a distribution system. Each ESS has an ID called the SSID which is a 32-byte (maximum) character string. A distribution system (DS) connects access points in an extended service set. The concept of a DS can be used to increase network coverage through roaming between cells. DS can be wired or wireless. Current wireless distribution systems are mostly based on WDS or Mesh protocols, though other systems are in use.

Types of wireless LANs

The

has two basic modes of operation: ''infrastructure'' and ''ad hoc'' mode. In ad hoc mode, mobile units communicate directly peer-to-peer. In infrastructure mode, mobile units communicate through a

(WAP) that also serves as a bridge to other networks such as a

or the Internet. Since wireless communication uses a more open medium for communication in comparison to wired LANs, the 802.11 designers also included encryption mechanisms:

Wired Equivalent Privacy Wired Equivalent Privacy (WEP) is an obsolete, and insecure security algorithm for 802.11 wireless networks. It was introduced as part of the original IEEE 802.11 standard ratified in 1997. The intention was to provide a level of security and pr ...

(WEP), no longer considered secure,

Wi-Fi Protected Access Wi-Fi Protected Access (WPA) (Wireless Protected Access), Wi-Fi Protected Access 2 (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security certification programs developed after 2000 by the Wi-Fi Alliance to secure wireless computer n ...

(WPA, WPA2, WPA3), to secure wireless computer networks. Many access points will also offer

Wi-Fi Protected Setup Wi-Fi Protected Setup (WPS), referred to as Wi-Fi Simple Configuration in the specification, and branded as WPS, is a standard designed to ease the setup of Wi-Fi networks in home and small office environments. Created by Wi-Fi Alliance, the p ...

, a quick, but no longer considered secure, method of joining a new device to an encrypted network.

Infrastructure

Most Wi-Fi networks are deployed in ''infrastructure mode''. In infrastructure mode, wireless clients, such as laptops and smartphones, connect to the WAP to join the network. The WAP usually has a wired network connection and may have permanent wireless connections to other WAPs. WAPs are usually fixed and provide service to their client nodes within range. Some networks will have multiple WAPs using the same SSID and security arrangement. In that case, connecting to any WAP on that network joins the client to the network, and the client software will try to choose the WAP that gives the best service, such as the WAP with the strongest signal.

Peer-to-peer

An ad hoc network is a network where stations communicate only

peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...

(P2P). There is no base and no one gives permission to talk. This is accomplished using the Independent Basic Service Set (IBSS). A

Wi-Fi Direct Wi-Fi Direct is a Wi-Fi standard for wireless connections that allows two devices to establish a direct Wi-Fi connection without an intermediary wireless access point, Router (computing), router, or Internet connection. Wi-Fi Direct is single-hop ...

network is a different type of wireless network where stations communicate peer-to-peer. In a peer-to-peer network wireless devices within range of each other can discover and communicate directly without involving central access points. In a Wi-Fi P2P group, the group owner operates as an access point and all other devices are clients. There are two main methods to establish a group owner in the Wi-Fi Direct group. In one approach, the user sets up a P2P group owner manually. This method is also known as ''autonomous group owner'' (''autonomous GO''). In the second method, called ''negotiation-based group creation'', two devices compete based on the group owner intent value. The device with higher intent value becomes a group owner and the second device becomes a client. Group owner intent value can depend on whether the wireless device performs a cross-connection between an infrastructure WLAN service and a P2P group, available power in the wireless device, whether the wireless device is already a group owner in another group or a received signal strength of the first wireless device. Wifi hidden station problem

defines the PHY and

medium access control In IEEE 802 LAN/MAN standards, the medium access control (MAC), also called media access control, is the layer that controls the hardware responsible for interaction with the wired (electrical or optical) or wireless transmission medium. The ...

(MAC) layers based on carrier-sense multiple access with collision avoidance (CSMA/CA). This is in contrast to Ethernet which uses carrier-sense multiple access with collision detection (CSMA/CD). The 802.11 specification includes provisions designed to minimize collisions because mobile units have to contend with the

hidden node problem In wireless networking, the hidden node problem or hidden terminal problem occurs when a Node (networking), node can communicate with a wireless access point (AP), but cannot directly communicate with other nodes that are communicating with that ...

where two mobile units may both be in range of a common access point, but out of range of each other.

Bridge

A bridge can be used to connect networks, typically of different types. A wireless

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

bridge allows the connection of devices on a wired Ethernet network to a wireless network. The bridge acts as the connection point to the wireless LAN.

Wireless distribution system

A wireless distribution system (WDS) enables the wireless interconnection of access points in an IEEE 802.11 network. It allows a wireless network to be expanded using multiple access points without the need for a wired backbone to link them, as is traditionally required. The notable advantage of a WDS over some other solutions is that it preserves the MAC addresses of client packets across links between access points. An access point can be either a main, relay, or remote base station. A main base station is typically connected to the wired Ethernet. A relay base station relays data between remote base stations, wireless clients or other relay stations to either a main or another relay base station. A remote base station accepts connections from wireless clients and passes them to relay or main stations. Because data is forwarded wirelessly, consuming wireless bandwidth, throughput in this method is halved for wireless clients not connected to a main base station. Connections between base stations are done at layer-2 and do not involve or require layer-3 IP addresses. WDS capability may also be referred to as repeater mode because it appears to bridge and accept wireless clients at the same time (unlike traditional bridging). All base stations in a WDS must be configured to use the same radio channel and share WEP keys or WPA keys if they are used. They can be configured to different service set identifiers. WDS also requires that every base station be configured to forward to others in the system as mentioned above.

Roaming

There are two definitions for wireless LAN roaming: # Internal roaming: The mobile station (MS) moves from one access point (AP) to another AP within a home network if the signal strength is too weak. An authentication server performs the re-authentication of MS via 802.1x (e.g. with PEAP). The billing of QoS is in the home network. A MS roaming from one access point to another often interrupts the flow of data between the MS and an application connected to the network. The MS, for instance, periodically monitors the presence of alternative APs (ones that will provide a better connection). At some point, based on proprietary mechanisms, the MS decides to re-associate with an AP having a stronger wireless signal. The MS, however, may lose a connection with an AP before associating with another access point. To provide reliable connections with applications, the MS must generally include software that provides session persistence. # External roaming: The MS (client) moves into a WLAN of another

wireless Internet service provider A wireless Internet service provider (WISP) is an Internet service provider with a network based on wireless networking. Technology may include commonplace Wi-Fi wireless mesh networking, or proprietary equipment designed to operate over open ...

(WISP) and takes their services. The user can use a foreign network independently from their home network, provided that the foreign network allows visiting users on their network. There must be special authentication and billing systems for mobile services in a foreign network.

Common issues

WLAN signals often extends beyond the boundaries of a building and can create coverage where it is unwanted, offering a channel through which non-residents or other unauthorized people could compromise a system and retrieve personal data. To prevent this it is usually sufficient to enforce the use of authentication, encryption, or

VPN Virtual private network (VPN) is a network architecture for virtually extending a private network (i.e. any computer network which is not the public Internet) across one or multiple other networks which are either untrusted (as they are not c ...

that requires a password for network connectivity.Wangerien, Brian. "The Challenges of Wi-Fi." Communications News. Encyclopædia Britannica. Web http://www.britannica.com/bps/additionalcontent/18/21597846/The-challenges-of-WiFi.

References

{{Authority control Wireless networking American inventions Local area networks