Glossary of Wi-Fi terms
10BASE-T:
IEEE 802.3 standard for a twisted-pair Ethernet network. 10 Mbps transmission rate over baseband using unshielded, twisted-pair cable. In English: this is the cable you see in most offices, that connects computers to networks and the internet. It's much faster than phone modems etc.
3G:
an ITU (International Telecommunication Union) specification for the third generation (analog cellular was the first generation, digital the second) of mobile communications technology. 3G promises increased bandwidth, up to 384Kbps when a device is stationary or moving at pedestrian speed, 128 Kbps in a car, and 2Mbps in fixed applications.
802.11:
refers to a family of specifications developed by the IEEE for W-LAN technology. 802.11 specify an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997.
802.11a:
an extension to 802.11 that applies to wireless LANs and provies up to 54 Mbps in the 5GHz band. While hardware is for sale in the market, it is as of yet currently not widely adopted. 802.11a is seen as the next step in the WLAN market.
802.11b:
also referred to as Wi-Fi. An extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission in the 2.4 Ghz spectrum. 802.11b is the 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.
802.11g:
an improvement of the 802.11b standard providing 20+ Mbps in the 2.4an improvement of the 802.11b standard providing 20+ Mbps in the 2.4 Ghz band. Hardware not yet on the market in larger numbers.
A
Access Point:
Also known as AP. A hardware device that provides a bridge between Ethernet wired LANs and the wireless network. Access points are the connectivity point between Ethernet wired networks and devices (laptops, hand-held computers, point-of-sale terminals) equipped with a wireless LAN adapter card.
Analogue phone:
Comes from the word "analogous," which means similar to. In telephone transmission, the signal being transmitted from the phone - voice, video or image - is analogous to the original signal.
Antenna-Directional:
Transmits and receives radio waves off the front of the antenna. The power behind and to the sides of the antenna is reduced. The coverage area is oval with the antenna at one of the narrow ends. Typical directional antenna beam width angles are from 90 degrees (somewhat directional) to as little as 20 degrees (very directional). A directional antenna directs power to concentrate the coverage pattern in a particular direction. The antenna direction is specified by the angle of the coverage pattern called the beam width.
Antenna-Omni-directional:
Transmits and receives radio waves in all directions. The coverage area is circular with the antenna at the centre. Omni-directional antennas are also referred to as whip or low-profile antennas.
Asynchronous Transfer Mode. A type of high-speed wide area network.
B
Backbone:
A network that interconnects other networks, employing high-speed transmission paths and often spanning a large geographic area.
Bandwidth:
The range of frequencies, expressed in hertz (Hz), that can pass over a given transmission channel. The bandwidth determines the rate at which information can be transmitted through the circuit.
C
Circuit switching:
The process of setting up and keeping a circuit open between two or more users so that users have exclusive and full use of the circuit until the connection is released.
Client:
A computer that accesses the resources of a server.
Client/Server:
A network system design in which a processor or computer designated as a server (such as a file server or database server) provides services to other client processors or computers.
D
Digital Phone System:
Proprietary phone system provided by a vendor, such as AT&T, Mitel, Northern Telecom, and so on. The signal being transmitted in a digital phone system is the same as the signal being transmitted in an analogue phone system. The system can consist of a proprietary PBX system that converts voice signals from their analogue form to digital signals, and then converts those digital signals back to analogue. Alternatively, the conversion from analogue-to-digital can occur in a digital phone.
Direct-Sequence (DS) Spread Spectrum:
Direct sequence transmits data by generating a redundant bit pattern for each bit of information sent. Commonly referred to as a "chip" or "chipping code," this bit pattern numbers 10 chips to one per bit of information. Compared with frequency hopping, direct sequence has higher throughput, wider range and is upgradeable in the 2.4GHz band.
E
Enabler:
An enabler is a company that provides authenication, billing and other necessary services (sometimes called AAA, for Authentication, Authorisation, and Accounting) for providing public WLAN.
Encryption:
Entails scrambling and coding information, typically with mathematical formulas called algorithms, before the information is transmitted over a network.
Ethernet:
A local area network used for connecting computers, printers, workstations, terminals, servers, and so on, within the same building or campus. Ethernet operates over twisted wire and over coaxial cable at speeds up to 100 Mbps, with 1 Gbps speeds coming soon.
F
Frequency Hopping (FH) Spread Spectrum:
frequency hopping transmits using a narrowband carrier that changes frequency in a given pattern. There are 79 channels in a 2.4GHz ISM band, each channel occupying 1MHz of bandwidth. A minimum hop rate of 2.5 hops per channel per second is required in the United States.Ê Frequency hopping technology is recognized as superior to direct sequence in terms of echo resistance, interference immunity, cost and ease-of-installation. To date, there has also been a greater selection of WLAN products from which to chose.
G
GHz:
International unit for measuring frequency is Hertz (Hz), which is equivalent to the older unit of cycles per second. One Gigahertz (GHz) is one billion Hertz. Microwave ovens typically operate at 2.45 GHz.
GSM:
The Global System for Mobile Communications standard for worldwide wireless communications on wide area networks (WANs). This is the standard used in Europe, for example, for the mobile phone industry.
I
Interactive Voice Response:
System used to access a database access application using a telephone. The voice processing acts as a front-end to appropriate databases that reside on general purpose computers. For instance, DTMF (touch tone) input of a Personal Identification Number can be required for access or more unusual and expensive techniques such as voice recognition and voice print matching.
Internet:
World's largest network, often referred to as the Information Superhighway. The Internet is a virtual network based on packet switching technology.
Internet Commerce:
Electronic business transactions that occur over the Internet. Samples of Internet commerce applications include electronic banking, airline reservation systems, and Internet malls.
Internet Phone:
Device used to transmit voice over the Internet, bypassing the traditional PSTN and saving money in the process. An Internet phone can be a small phone (such as the NetVision Phone) or a multimedia PC with a microphone, speaker, and modem.
Interoperability:
The ability of equipment or software to operate properly in a mixed environment of hardware and software, from different vendors. Enabled by the IEEE 802.11 open standard.
IP (Internet Protocol):
The Internet standard protocol that defines the Internet datagram as the unit of information passed across the Internet. Provides the basis of the Internet connection-less- best-effort packet delivery service. The Internet protocol suite is often referred to as TCP/IP because IP is one of the two fundamental protocols.
International Roaming:
Ability to use one adapter worldwide.
Intranet:
A private network that uses Internet software and Internet standards. In essence, an intranet is a private Internet reserved for use by people who have been given the authority and passwords necessary to use that network.
ISDN:
Integrated Services Digital Network. Emerging network technology offered by local phone companies that is designed for digital communications, computer telephony, and voice processing systems.
ISM Band:
ISM bands--instrumental (902-928MHz), science (2.4-2.4835GHz), and medical (5.725-5.850GHz)--are the radio frequency bands allocated by the FCC for unlicensed continuous operations for up to 1W. The most recent band approved by the FCC for WLANs was the medical band in January 1997.
L
Local Area Networks:
(LANs) cover only a short distance, usually 100 m or less. They are usually installed within homes or offices and are accessible only to the residents or employees. For this reason, they are referred to as private networks. The PAN (Personal Area Network) is a special case of a wireless LAN, with a particularly short range. It can cover a distance of only 10 m and is envisaged as a way to connect devices carried by a single individual.
M
Microcell:
A bounded physical space in which a number of wireless devices can communicate. Because it is possible to have overlapping cells as well as isolated cells, the boundaries of the cell are established by some rule or convention.
Modem:
Equipment that converts digital signals to analogue signals and vice versa. Modems are used to send digital data signals over the analogue PSTN.
Mobile Unit Mode:
In this mode, the WLAN adapter connects to an access point (AP) or another WLAN installed system, allowing the device to roam freely between AP cells in the network. Mobile units appear as network nodes to other devices.
N
Node:
A network junction such as a switch or a routing centre.
P
Packet Switching:
Refers to sending data in packets through a network to some remote location. In a packet switched network, no circuit is left open on a dedicated basis. Packet switching is a data switching technique only.
PCMCIA (Personal Computer Memory Card International Association) Card:
A credit card-size device used in laptop computers and available as removable network adapters.
Plug and Play:
A feature that allows a computer to recognize the PCI adapter and configure the hardware interrupt, memory, and device recognition addresses; requires less user interaction and minimizes hardware conflicts.
Pocket PC:
The term adopted by Microsoft and its supporters to describe handheld computers employing Microsoft's Pocket PC operating system.
R
Roaming:
Movement of a wireless node between two microcells. Roaming usually occurs in infrastructure networks built around multiple access points. Moreover, the possibility for an end-user of a WLAN device to use the services of an operator other than the one he or she has bought the services of. Roaming implicitly indicates a relationship between a visited WISP, a home WISP, and the end-user who is client of the latter.
Bilateral roaming agreement:
A roaming agreement signed between two WISPs directly.Multilateral Roaming Agreement: a roaming agreement signed between a WISP and a central legal entity representing a community of member-WISP. Such an agreement allows for flexible tariffs with certain roaming partners while the entire administration is centralized
Roaming Agent:
a legal entity operating as a representative of the WISP community with the aim of facilitating the roaming administration (both from a legal and commercial point of view) of a WISP. The agent does not become a party in the roaming agreement between the WISPs (like Roaming Brokers do) and retains a neutral position with regard to tariffs and service content offered by the WISP. An agent operates a multilateral roaming model and typically offers multilateral settlement services.
Roaming Brokers:
an entity providing a (global) WISP network by trading broadband access between member WISPs at a fixed or transactional price. Brokers typically provide centralized authentication services in order to compute and validate the broadband traffic. Brokers fix the WISP airtime prices they trade in.Ê
Repeater:
A device used to extend cabling distances by regenerating signals.
The main device in any modern network that routes data blocks from source to destination using routing tables and determining the best path dynamically. It functions as an addressable entity on the LAN and is the basic building block of the Internet.
S
Site Survey:
Physical environment survey to determine the placement of access points and antennas, as well as the number of devices necessary to provide optimal coverage, in a new or expanding installation.
Spread Spectrum:
A transmission technique developed by the U.S. military in World War II to provide secure voice communications, spread spectrum is the most commonly used WLAN technology today. It provides security by "spreading" the signal over a range of frequencies. The signal is manipulated in the transmitter so that the bandwidth becomes wider than the actual information bandwidth. De-spreading the signal is impossible for those not aware of the spreading parameters; to them, the signal sounds like background noise. Interference from narrowband signals is also minimized to background noise when it is de-spread by the receiver. Two types of spread spectrum exist: direct sequence and frequency hopping.
T
T1:
A type of dedicated digital leased-line available from a public telephone provider with a capacity of 1.544 Mbps. A T1 line can normally handle 24 voice conversations, each one digitised at 64 Kbps. With more advanced digital voice encoding techniques, it can handle more voice channels. T1 is the standard for digital transmission in the U.S. Canada, Hong Kong, and Japan.
TCP/IP:
Networking protocol that provides communication across interconnected networks, between computers with diverse hardware architectures, and various operating systems. TCP/IP is used in the industry to refer to the family of common Internet protocols.
TCP (Transport Communication Protocol):
Controls the transfer of data from one client to one host, providing the mechanism for connection maintenance, flow control, retries, and time-outs.
W
Wide Area Networks (WANs):
cover a long distance, from several kilometers to the entire world or beyond. They are usually run by telecom companies and carry voice or data for various customers. The Internet and the phone system are both comprised of many WANs. They are often called public networks, because they carry traffic for anyone who can pay. (In this case, public does not refer to ownership: Whether owned by a government, a traded corporation, or a private individual, a network that carries traffic for others is considered public.) WANs are sometimes divided into subgroups, of which, the most important is the MAN (Metropolitan Area Network), a type that covers a city or other region of only a few kilometers. Because radio waves have a limited range, most wireless WANs are MANs. The exceptions are satellite networks, which can cover intercontinental distances.
WECA:
short for Wireless Ethernet Compatibility Alliance, an organization made up of leading wireless equipment and software providers with the mission of guaranteeing interoperability of Wi-Fi products and to promote Wi-Fi as the global WLAN standard across all markets.
WEP:
short for Wired Equivalent Privacy, a security protocol 802.11b. WEP is designed to provide the same level of security as that of a wired LAN. WEP aims to provide security by encrypting data over radio waves so that is is protected as it is tranmitted from one end point to another. However, it has been found that WEP is not as secure as once believed, due to how it was implemented.
Wi-Fi:
A logo granted as the "seal of interoperability" by the Wireless Ethernet Compatibility Alliance (WECA).Ê Only select wireless networking products possess this characteristic of IEEE802.11b.Ê In English Ð any product you buy, with a Wi Fi logo on it, will easily communicate with any other Wi Fi product, regardless of manufacturer. Unlike, say, Apple computers and non-Apple computers in the bad old days.
Wireless Local Area Network (WLAN):
A wireless LAN is a data communications system providing wireless peer-to-peer (PC-to-PC, PC-to-hub, or printer-to-hub) and point-to-point (LAN-to-LAN) connectivity within a building or campus. In place of TP or coaxial wires or optical fibre as used in a conventional LAN, WLANs transmit and receive data over electromagnetic waves. WLANs perform traditional network communications functions such as file transfer, peripheral sharing, e-mail, and database access as well as augmenting wired LANs.Ê WLANs must include NICs (adapters) and access points (in-building bridges), and for campus communications building-to-building (LAN-LAN) bridges.
WISP:
short for Wireless ISP, a service provider of public WLAN. a.Home WISP: the provider whom the end-user has a client relationship with. b.Visited WISP: the provider that allows access to its network to clients of the home WISP. c.Virtual WISP: a WISP that has not deployed and does not operate a WLAN infrastructure but offers the same services to its client base.