From 802.11a to 802.11m and beyond: How much do you know about essential wireless LAN terminology? Our handy WLAN glossary provides concise definitions with links to more complete explanations and further information. Want to test your knowledge? Try our WLAN quiz .
802.11 : an evolving family of specifications for wireless LANs, developed by a working group of the Institute of Electrical and Electronics Engineers(IEEE). 802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.
802.11a : provides specifications for wireless ATM systems. 802.11a is also used in wireless hubs. Networks using 802.11a operate at radio frequencies between 5.725 GHz and 5.850 GHz. The specification uses a modulation scheme known as orthogonal frequency-division multiplexing (OFDM) that is especially well suited to use in office settings.
802.11b : WLAN standard often called Wi-Fi; backward compatible with 802.11. Instead of the phase-shift keying (PSK) modulation method historically used in 802.11 standards, 802.11b uses complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference.
802.11d : a wireless network communications specification for use in countries where systems using other standards in the 802.11 family are not allowed to operate. Configuration can be fine-tuned at the Media Access Control layer (MAC layer) level to comply with the rules of the country or district in which the network is to be used. Rules subject to variation include allowed frequencies, allowed power levels, and allowed signal bandwidth. 802.11d facilitates global roaming.
802.11e : a proposed adaptation to the 802.11a and 802.11b specifications that enhances the 802.11 Media Access Control layer (MAC layer) with a coordinated time division multiple access (TDMA) construct, and adds error-correcting mechanisms for delay-sensitive applications such as voice and video. The 802.11e specification provides seamless interoperability between business, home, and public environments such as airports and hotels and offers all subscribers high-speed Internet access with full-motion video, high-fidelity audio, and Voice over IP (VoIP).
802.11g : offers transmission over relatively short distances at up to 54 megabits per second (Mbps), compared with the 11 Mbps theoretical maximum of 802.11b. 802.11g employs orthogonal frequency division multiplexing (OFDM), the modulation scheme used in 802.11a, to obtain higher data speed. Computers or terminals set up for 802.11g can fall back to speeds of 11 Mbps, so that 802.11b and 802.11g devices can be compatible within a single network.
802.11h : intended to resolve interference issues introduced by the use of 802.11a in some locations, particularly with military radar systems and medical devices. Dynamic frequency selection (DFS) detects the presence of other devices on a channel and automatically switches the network to another channel if and when such signals are detected. Transmit power control (TPC) reduces the radio-frequency (RF) output power of each network transmitter to a level that minimizes the risk of interference.
802.11i : provides improved encryption for networks that use 802.11a, 802.11b, and 802.11g standards. Requires new encryption key protocols, known as Temporal Key Integrity Protocol (TKIP) and Advanced Encryption Standard (AES). Other features include key caching, which facilitates fast reconnection to the server for users who have temporarily gone offline, and pre-authentication, which allows fast roaming and is ideal for use with advanced applications such as Voice over Internet Protocol (VoIP).
802.11j : proposed addition to the 802.11 family of standards that incorporates Japanese regulatory extensions to 802.11a; the main intent is to add channels in the radio-frequency (RF) band of 4.9 GHz to 5.0 GHz. WLANs using 802.11j will provide for speeds of up to 54 Mbps, and will employ orthogonal frequency division multiplexing (OFDM). The specification will define how Japanese 802.11 family WLANs and other wireless systems, particularly HiperLAN2 networks, can operate in geographic proximity without mutual interference.
802.11k : proposed standard for how a WLAN should perform channel selection, roaming, and transmit power control (TPC) in order to optimize network performance. In a network conforming to 802.11k, if the access point (AP) having the strongest signal is loaded to capacity, a wireless device is connected to one of the underutilized APs. Even though the signal may be weaker, the overall throughput is greater because more efficient use is made of the network resources.
802.11m : an initiative to perform editorial maintenance, corrections, improvements, clarifications, and interpretations relevant to documentation for 802.11 family specifications. 802.11m also refers to the set of maintenance releases itself.
802.1X : standard designed to enhance 802.11 WLAN security. 802.1X provides an authentication framework, allowing a user to be authenticated by a central authority. The actual algorithm that is used to determine whether a user is authentic is left open and multiple algorithms are possible.
access point (AP): a station that transmits and receives data (sometimes referred to as a transceiver). An access point connects users to other users within the network and also can serve as the point of interconnection between the WLAN and a fixed wire network. The number of access points a WLAN needs is determined by the number of users and the size of the network.
access point mapping (also called war driving): the act of locating and possibly exploiting connections to WLANs while driving around a city or elsewhere. To do war driving, you need a vehicle, a computer (which can be a laptop), a wireless Ethernet card set to work in promiscuous mode, and some kind of an antenna which can be mounted on top of or positioned inside the car. Because a WLAN may have a range that extends beyond an office building, an outside user may be able to intrude into the network, obtain a free Internet connection, and possibly gain access to company records and other resources.
ad-hoc network : a LAN or other small network, especially one with wireless or temporary plug-in connections, in which some of the network devices are part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network.
antenna : a specialized transducer that converts radio-frequency (RF) fields into alternating current (AC) or vice-versa. There are two basic types: the receiving antenna, which intercepts RF energy and delivers AC to electronic equipment, and the transmitting antenna, which is fed with AC from electronic equipment and generates an RF field.
digital pulse wireless : (see also: ultra wideband or UWB) is a wireless technology for transmitting large amounts of digital data over a wide spectrum of frequency bands with very low power for a short distance. Ultra wideband radio can carry a huge amount of data over a distance up to 230 feet at very low power (less than 0.5 milliwatts), and has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power.
evil twin : a home-made wireless access point that masquerades as a legitimate one to gather personal or corporate information without the end-user's knowledge. It's fairly easy for an attacker to create an evil twin by simply using a laptop, a wireless card and some readily-available software. The attacker positions himself in the vicinity of a legitimate Wi-Fi access point and lets his computer discover what name and radio frequency the legitimate access point uses. He then sends out his own radio signal, using the same name.
Extensible Authentication Protocol (EAP): authentication protocol for wireless networks that expands on methods used by the Point-to-Point Protocol (PPP), a protocol often used when connecting a computer to the Internet. EAP can support multiple authentication mechanisms, such as token cards, smart cards, certificates, one-time passwords, and public key encryption authentication.
fixed wireless : wireless devices or systems in fixed locations such as homes and offices. Fixed wireless devices usually derive their electrical power from the utility mains, unlike mobile wireless or portable wireless which tend to be battery-powered. Although mobile and portable systems can be used in fixed locations, efficiency and bandwidth are compromised compared with fixed systems.
HiperLAN : WLAN communication standards primarily used in European countries. There are two specifications: HiperLAN/1 and HiperLAN/2. Both have been adopted by the European Telecommunications Standards Institute (ETSI). The HiperLAN standards provide features and capabilities similar to 802.11. HiperLAN/1 provides communications at up to 20 Mbps in the 5-GHz range of the radio frequency (RF) spectrum.
hot spot : (see also access point) a WLAN node that provides Internet connection and virtual private network (VPN) access from a given location. A business traveller, for example, with a laptop equipped for Wi-Fi can look up a local hot spot, contact it, and get connected through its network to reach the Internet and their own company remotely with a secure connection. Increasingly, public places, such as airports, hotels, and coffee shops are providing free wireless access for customers.
hot zone : a wireless access area created by multiple hot spots located in close proximity to each other. Hot zones usually combine public safety access points with public hot spots. Each hot spot typically provides network access for distances between 100 and 300 feet; various technologies, such as mesh network topologies and fiber optic backbones, are used in conjunction with the hot spots to create areas of coverage.
IMT-2000 direct spread official name for W-CDMA (Wideband Code-Division Multiple Access): ITU standard derived from Code-Division Multiple Access (CDMA). W-CDMA is a third-generation (3G) mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in today's market.
IrDA : (Infrared Data Association) an industry-sponsored organization set up in 1993 to create international standards for the hardware and software used in infrared communication links. In this special form of radio transmission, a focused ray of light in the infrared frequency spectrum, measured in terahertz, or trillions of hertz (cycles per second), is modulated with information and sent from a transmitter to a receiver over a relatively short distance.
IR wireless : the use of wireless technology in devices or systems that convey data through infrared (IR) radiation. Infrared is electromagnetic energy at a wavelength or wavelengths somewhat longer than those of red light. The shortest-wavelength IR borders visible red in the electromagnetic radiation spectrum; the longest-wavelength IR borders radio waves.
microwave : electromagnetic energy having a frequency higher than 1 gigahertz (billions of cycles per second), corresponding to wavelength shorter than 30 centimeters. Microwave signals propagate in straight lines and are affected very little by the troposphere. They are not refracted or reflected by ionized regions in the upper atmosphere. Microwave beams do not readily diffract around barriers such as hills, mountains, and large human-made structures.
MIMO (multiple input, multiple output): an antenna technology for wireless communications in which multiple antennas are used at both the source (transmitter) and the destination (receiver). The antennas at each end of the communications circuit are combined to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna technology, the others being MISO (multiple input, single output) and SIMO (single input, multiple output).
MISO (multiple input, single output): an antenna technology for wireless communications in which multiple antennas are used at the source (transmitter). The antennas are combined to minimize errors and optimize data speed. The destination (receiver) has only one antenna. MISO is one of several forms of smart antenna technology, the others being MIMO (multiple input, multiple output) and SIMO (single input, multiple output).
Near Field Communication (NFC): a short-range wireless connectivity standard (Ecma-340, ISO/IEC 18092) that uses magnetic field induction to enable communication between devices when they're touched together, or brought within a few centimeters of each other. The standard specifies a way for the devices to establish a peer-to-peer (P2P) network to exchange data.
optical wireless : the combined use of conventional radio-frequency (RF) wireless and optical fiber for telecommunication. Long-range links are provided by optical fiber and links from the long-range end-points to end users are accomplished by RF wireless or laser systems. RF wireless at ultra-high frequencies (UHF) and microwave frequencies can carry broadband signals to individual computers at substantial data speeds.
radio frequency (RF): alternating current (AC) having characteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications.
SWAN (Structured Wireless-Aware Network): a technology that incorporates a WLAN into a wired wide-area network (WAN). SWAN technology can enable an existing wired network to serve hundreds of users, organizations, corporations, or agencies over a large geographic area. A SWAN is said to be scalable, secure, and reliable.
transponder : a wireless communications, monitoring, or control device that picks up and automatically responds to an incoming signal. The term is a contraction of the words transmitter and responder. Transponders can be either passive or active.
ultra wideband (UWB): (see also: digital pulse wireless) is a wireless technology for transmitting large amounts of digital data over a wide spectrum of frequency bands with very low power for a short distance. Ultra wideband broadcasts very precisely timed digital pulses on a carrier signal across a very wide spectrum (number of frequency channels) at the same time. UWB can carry a huge amount of data over a distance up to 230 feet at very low power (less than 0.5 milliwatts), and has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power.
virtual private network (VPN): a network that uses a public telecommunication infrastructure, such as the Internet, to provide remote offices or individual users with secure access to their organization's network. A VPN ensures privacy through security procedures and tunneling protocols such as the Layer Two Tunneling Protocol ( L2TP ). Data is encrypted at the sending end and decrypted at the receiving end.
VoWLAN (Voice over WLAN, sometimes called wireless VoIP, Wi-Fi VoIP): a method of routing telephone calls for mobile users over the Internet using the technology specified in IEEE 802.11b. Routing mobile calls over the Internet makes them free, or at least much less expensive than they would be otherwise.
WAP (Wireless Application Protocol): a specification for a set of communication protocols to standardize the way that wireless devices, such as cellular telephones and radio transceivers, can be used for Internet access, including e-mail, the World Wide Web, newsgroups, and instant messaging.
war driving (also called access point mapping):, the act of locating and possibly exploiting connections to WLANs while driving around a city or elsewhere. To do war driving, you need a vehicle, a computer (which can be a laptop), a wireless Ethernet card set to work in promiscuous mode, and some kind of an antenna which can be mounted on top of or positioned inside the car. Because a WLAN may have a range that extends beyond an office building, an outside user may be able to intrude into the network, obtain a free Internet connection, and possibly gain access to company records and other resources.
W-CDMA (Wideband Code-Division Multiple Access): officially known as IMT-2000 direct spread; ITU standard derived from Code-Division Multiple Access (CDMA). W-CDMA is a third-generation (3G) mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in today's market.
Wi-Fi (short for wireless fidelity): a term for certain types of WLANs. Wi-Fi can apply to products that use any 802.11 standard. Wi-Fi has gained acceptance in many businesses, agencies, schools, and homes as an alternative to a wired LAN. Many airports, hotels, and fast-food facilities offer public access to Wi-Fi networks.
WiMAX : a wireless industry coalition whose members organized to advance IEEE 802.16 standards for broadband wireless access (BWA) networks. WiMAX 802.16 technology is expected to enable multimedia applications with wireless connection and, with a range of up to 30 miles, enable networks to have a wireless last mile solution. According to the WiMAX forum, the group's aim is to promote and certify compatibility and interoperability of devices based on the 802.16 specification, and to develop such devices for the marketplace.
Wired Equivalent Privacy (WEP): a security protocol specified in 802.11b, designed to provide a WLAN with a level of security and privacy comparable to what is usually expected of a wired LAN. Data encryption protects the vulnerable wireless link between clients and access points; once this measure has been taken, other typical LAN security mechanisms such as password protection, end-to-end encryption, virtual private networks (VPNs), and authentication can be put in place to ensure privacy.
wireless : describes telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path.
Wireless Abstract XML (WAX): an abstract markup language and associated tools that facilitate wireless application development. The major features of WAX include: the WAX language itself; translation stylesheets, which are used to translate the WAX language into the most suitable language for the requesting device; the device registry, which includes an XML database of device particulars; dynamic image and text selection, which allows content to be written a single time for multiple transformations; and the application foundation, a WAX servlet that creates a foundation for WAX applications.
wireless application service provider (WASP): provides Web-based access to applications and services that would otherwise have to be stored locally and makes it possible for customers to access the service from a variety of wireless devices, such as a smartphone or personal digital assistant (PDA).
wireless ISP (WISP): an Internet service provider (ISP) that allows subscribers to connect to a server at designated hot spots (access points) using a wireless connection such as Wi-Fi. This type of ISP offers broadband service and allows subscriber computers, called stations, to access the Internet and the Web from anywhere within the zone of coverage provided by the server antenna, usually a region with a radius of several kilometers.
wireless local area network (WLAN): a local area network (LAN) that users access through a wireless connection. 802.11 standards specify WLAN technologies. WLANs are frequently some portion of a wired LAN.
wireless service provider : a company that offers transmission services to users of wireless devices through radio frequency (RF) signals rather than through end-to-end wire communication.
Wireless Transport Layer Security (WTLS): the security level for Wireless Application Protocol (WAP) applications, developed to address the problematic issues surrounding mobile network devices - such as limited processing power and memory capacity, and low bandwidth - and to provide adequate authentication, data integrity, and privacy protection mechanisms.
Yagi antenna (sometimes called a Yagi-Uda array or simply a Yagi): a unidirectional antenna commonly used in communications when a frequency is above 10 MHz.