0+

3G – is the third generation of telecommunication hardware standards and general technology for mobile networking. 3G networks enable network operators to offer users a wider range of more advanced mobile services, such as wireless voice telephone, video calls, and broadband wireless data, while achieving greater network capacity. Unlike Wi–Fi or WLAN networks, 3G networks are wide–area cellular telephone networks that evolved to incorporate high–speed Internet access and video telephony.

4G – is a term used to describe the next complete evolution in wireless communications. 4G will be a complete replacement for current networks and be able to provide a comprehensive and secure IP solution to provide voice, data, and streamed multimedia on an "Anytime, Anywhere" basis, and at much higher data rates than previous generations.

A

American National Standards Institute (ANSI) – An official body within the United States delegated with the responsibility of defining standards.

American Standard Code for Information Interchange (ASCII) – Assigns specific letters, numbers, and control codes to the 256 different combinations of 0s and 1s in a byte. analog – A continuously varying signal or wave. As with all waves, analog waves are susceptible to interference which can change the character of the wave.

asymmetric digital subscriber line (ADSL) – A group of DSL technologies that reserve more bandwidth in one direction than the other, which is advantageous for users that do not need equal bandwidth in both directions. See DSL.

asynchronous – Occurring at different times. For example, electronic mail is asynchronous communication because it does not require the sender and receiver to be connected at the same time.

asynchronous transfer mode (ATM) – A method of data transportation whereby fixed length packets are sent over a switched network. The ability to ensure reliable delivery of packets at a high rate makes it suitable for carrying voice, video, and data.

availability – (also referred to as reliability) Link availability is the percentage of uptime a communications link is available in a given year. Reduced availability reflects unplanned downtime, such as that caused by specific weather encountered in various climates, assuming no outages due to equipment failure or other system problem. Availability is typically quoted in nines. For example, 99.9%, or three–nines (3–9's) availability, means, on average, the link is expected to be not available 0.1% of the time, or an average of 43 minutes per month. Four–nines (4–9's) availability translates into only four minutes per month of down–time and five–nines averages just 30 seconds of downtime per month.

The following table shows the downtime allowed for a particular percentage of availability, presuming that the system is required to operate continuously.

B

backbone – The part of a communications network that connects the main points of presence (POP) and handles the major traffic using the highest–speed, and often longest, paths in the network.

backhaul – In cellular/PCS systems, refers to the transmission links between cell sites and the system operator's switching center. In general terms, refers to transmitting data from remote locations to a point from which it can be distributed over a network. Backhaul is applicable to millimeter–wave, point–to–point, wi–fi, nanocell and hybrid networks.

bandwidth – standard capacity measure for communications media. Greater bandwidth allows communication of more information in a given period of time (bits transmitted per second for digital; Hertz (Hz) per second for analog).

basic rate ISDN (BRI–ISDN) – The basic rate ISDN interface provides two 64 Kb/s channels (called B channels) to carry voice or data and one 16 Kb/s signaling channel (the D channel) for call information.

beam wander – arises when turbulent wind current (eddies) larger than the diameter of the transmitted optical beam cause a slow, but significant, displacement of the transmitted beam. Beam wander may also be the result of seismic activity that causes a relative displacement between the position of the transmitting laser and the receiving antenna.

bit – A single unit of data, either a one or a zero, used in digital data communications. When discussing digital data a small "b" refers to bits, and a capital "B" refers to bytes. Binary digit.

bit error rate (BER) – a way to measure data transmission integrity. The bit error rate is a ratio of bad to total bits.

bridge – A device that connects two local–area networks (LANs), or two segments of the same LAN. The two LANs being connected can be alike or dissimilar. For example, a bridge can connect an Ethernet with a Token–Ring network. Unlike routers, bridges are protocol–independent. They simply forward packets without analyzing and re–routing messages. Consequently, they're faster than routers but also less versatile.

broadband – An adjective used to describe large–capacity networks that are able to carry several services at the same time, such as data, voice, and video. Generally refers to communications technologies capable of transmitting over 45 Mbps over any type of media.

broadband integrated services digital network (BISDN) – A second–generation ISDN technology that uses fiber optics for a network that can transmit data at speeds of 155 megabits per second and higher.

byte – A compilation of bits, seven bits in accordance with ASCII standards and eight bits in accordance with EBCDIC standards.

C

carrier – A telephone or other company that sells or rents telecommunication transmission service. Also refers to an electromagnetic wave or alternating current that is modulated to carry signals in radio, telephonic, or telegraphic transmission.

code division multiple access (CDMA) – a channel access method utilized by various radio communication technologies. central processing unit (CPU) – The "brains" of a computer, which uses a stored program to manipulate information.

circuit switched network – A type of network in which a continuous link is established between a source and a receiver. Circuit switching is used for voice and video to ensure that individual parts of a signal are received in the correct order by the destination site.

common carrier – A business, including telephone and railroads, which is required by law to provide service to any paying customer on a first–come, first–serve basis.

competitive local exchange carrier (CLEC) – An American term for a telephone company that was created after the Telecommunications Act of 1996 made it legal for companies to compete with the ILECs. Contrast with ILEC.

compression – The process of reducing the amount of information necessary to transmit a specific audio, video, or data signal. core network – The combination of telephone switching offices and transmission plant connecting switching offices together. In the U.S. local exchange network, core networks are linked by several competing Inter–exchange networks; in the rest of the world the core network extends to national boundaries.

D

dark fiber – Unused fiber–optic cable. Companies typically lay more fiber lines than initially needed to support current network traffic. Companies must then ‘light’ the lines to truly monetize their investment.

dedicated connection – A communication link that operates constantly.

dense wavelength division multiplexing (DWDM) – An optical technology used to increase bandwidth over existing fiber. DWDM combines and transmits multiple signals simultaneously at different wavelengths on the same fiber. DWDM–based networks can transmit data in IP, ATM, SONET/SDH, and Ethernet, and handle bit–rates between 100 Mb/s and 2.5 Gbps.


digital signal – A signal that takes on only two values, off or on, typically represented by "0" or "1." Digital signals require less power but (typically) more bandwidth than analog, and copies of digital signals can be made exactly like the original.

digital subscriber line (DSL) – A data communications technology that transmits information over the copper wires that make up the local loop of the public switched telephone network (See local loop).) It bypasses the circuit–switched lines that make up that network and yields much faster data transmission rates than analog modem technologies.

digital subscriber line access multiplexer (DSLAM) – A device found in telephone company central offices that takes a number of DSL subscriber lines and concentrates these onto a single ATM line.

direct broadcast satellite (DBS) – A broadcast technology that uses satellites orbiting the Earth to broadcast television or data signals to an 18" dish antenna.

domain name system (DNS) – The protocol used for assigning text addresses for specific computers and computer accounts on the Internet.

DS–3 – A dedicated digital communication link that offers 44.74 megabits per second of bandwidth.

E

E–1 – A dedicated digital communication link provided by a European telephone company that offers 2.048 megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

echo cancellation – The elimination of reflected signals ("echoes") in a two–way transmission created by some types of telephone equipment, used in data transmission to improve the bandwidth of the line.

electro–magnetic interference (EMI) – Interference caused by a radio signal or other electromagnetic field. Any device or system that generates an electromagnetic field in the radio frequency spectrum has the potential to disrupt the operation of electronic components, devices and systems in its vicinity. 


ethernet – One of the oldest communication protocols for networking personal computers, and the most widely–used local area network (LAN) technology. Generally refers now to 10BASE–T systems, operating at 10 Mbps.

F

fast ethernet – Fast Ethernet is a local area network (LAN) transmission standard that provides a data rate of 100 megabits per second (referred to as "100BASE–T").

fiber distributed data interface (FDDI) – A set of ANSI protocols for sending digital data over fiber optic cable. FDDI networks are typically used as backbones for wide–area networks.

fiber–to–the–curb (FTTC) – The deployment of fiber optic cable from a central office to a platform serving numerous homes. The home is linked to this platform with coaxial cable or twisted pair (copper wire). Each fiber carries signals for more than one residence, lowering the cost of installing the network versus fiber to the home.

fiber–to–the–home (FTTH) – The deployment of fiber optic cable from a central office to an individual home. This is the most expensive broadband network design, with every home needing a separate fiber optic cable to link it with the central office.

fog – Fog is vapor composed of water droplets, which are only a few hundred microns in diameter but can modify light characteristics or completely hinder the passage of light through a combination of absorption, scattering, and reflection. This can lead to a decrease in the power density of the transmitted beam, decreasing the effective distance of a free space optical (FSO) link.

frame relay – A high–speed packet switching protocol used in wide area networks (WANs), often to connect local area networks (LANs) to each other, with a maximum bandwidth of 44.725 megabits per second.

free space optics (FSO) – an optical communication technology that uses light propagating in free space (i.e. no FCC spectrum license requirements) to transmit data between two points where line of sight visibility exists. The technology is particularly useful where the physical connection by the means of fiber optic cables is impractical, due to high costs or other considerations OR in dense urban areas where microwave are impractical from an interference standpoint. Also referred to as wireless light communication (WLC).

frequency – The number of oscillations in an alternating current that occur within one second, measured in Hertz (Hz).

frequency division multiplexing (FDM) – The transmission of multiple signals simultaneously over a single transmission path by dividing the available bandwidth into multiple channels that each cover a different range of frequencies.

fresnel zone – one of a (theoretically infinite) number of concentric ellipsoids of revolution which define volumes in the radiation pattern of a (usually) circular aperture. To maximize receiver strength, one needs to minimize the effect of the out of phase signals by removing obstacles from the radio frequency line of sight (RF LoS). The strongest signals are on the direct line between transmitter and receiver and always lie in the 1st Fresnel Zone. Unlike radio technologies, FSO is not affected by operational limitations resulting from fresnel zones.

FSO link – in free space optics networking, refers to a pair of FSO telescopes, each aiming a laser beam at the other. At least one telescope has duplex capability to act as a laser transmitter as well as a receiver. Typically, these telescopes are installed on the top of the building.

full–motion video – The projection of 20 or more frames (or still images) per second to give the eye the perception of movement. Broadcast video in the United States uses 30 frames per second, and most film technologies use 24 frames per second.

G

gigabit – One billion bits

gigabit ethernet (GigE) – Traditionally carried on optical fiber, a transmission technology based on the Ethernet protocol providing a transmission rate of 1 billion bits per second (one gigabit).

global positioning system (GPS) – A system of low Earth orbiting satellites used to measure location on the ground or in the air. A GPS receiver contains a computer that "triangulates" its own position by measuring its distance from at least three of the 24 GPS satellites. The result is the longitude and latitude of the receiver, accurate to within about 10 meters for most receivers.

graphical user interface (GUI) – A computer operating system that is based upon icons and visual relationships rather than text. Windows and the Macintosh computer use GUIs because they are more user friendly.

H

hybrid fiber/coax (HFC) – A type of network that includes coaxial cables to distribute signals to a group of individual locations, and a fiber optic backbone to connect these groups. Next generation networks may also include free space optics (FSO) technology to connect to fiber backbone.

I

incumbent local exchange carrier (ILEC) – A large telephone company that has been providing local telephone service in the United States since the divestiture of the AT&T telephone monopoly in 1982.

Institute of Electrical and Electronics Engineers (IEEE) – A membership organization comprised of engineers, scientists and students that sets standards for computers and communications.

integrated services digital network (ISDN) – A circuit–switched communication network, closely associated with the public switched telephone network, that allows dial–up digital communication at speeds up to 128 kilobits per second.

inter exchange carrier (IXC) – A long–distance telephone carrier.

International Organization of Standardization (ISO) – Develops, coordinates, and promulgates international standards that facilitate world trade.

International Telecommunication Union (ITU) – A United Nations organization that coordinates use of the electromagnetic spectrum and creation of technical standards for telecommunication and radio communication equipment.

International Telecommunication Union/Telecommunication Standardization Sector (ITU–T) – The branch of the ITU that is responsible for telecommunication standardization.

internet engineering task force (IETF) – The standards organization that standardizes most Internet communication protocols, including Internet protocol (IP) and hypertext transfer protocol (HTTP).

internet protocol (IP) – The standard signaling method used for all communication over the Internet. Most networks combine IP with a higher–level protocol called Transport Control Protocol (TCP), which establishes a virtual connection between a destination and a source.

internet service provider (ISP) – An organization offering and providing Internet access to the public using computer servers connected directly to the Internet.

integrated services digital network (ISDN) – An international communications standard for sending voice, video, and data over digital telephone lines or normal telephone wires.. ISDN supports data transfer rates of 64 Kbps (64,000 bits per second).

L

laser – From the acronym for "Light Amplification by Stimulated Emission of Radiation." A laser usually consists of a light–amplifying medium placed between two mirrors. Light not perfectly aligned with the mirrors escapes out the sides, but light perfectly aligned will be amplified. One mirror is made partially transparent. The result is an amplified beam of light that emerges through the partially transparent mirror.

laser class – To control the risk of injury from lasers, various specifications define "classes" of laser depending on their power and wavelength, and the sale and usage of lasers is typically subject to government regulations. Even relatively small amounts of laser light can lead to permanent eye injuries as they can burn the retina of the eye, or even the skin. These regulations also prescribe required safety measures, such as labeling lasers with specific warnings, and wearing laser safety goggles when operating lasers.

last mile – a term typically used by telecommunications and cable television industries referencing the final leg of delivering connectivity from a communications provider to a home or business customer. The actual distance of this leg may be considerably more than a mile, especially in rural areas. Last-mile technology represents a major challenge to broad adoption of high-bandwidth applications such as on-demand television, fast Internet access, and multi-media rich Web content. It is typically seen as an expensive challenge because architecting and installing wires and cables is a considerable physical undertaking.

laser to the home (LTTH) – a revolutionary SKYFIBER™ approach that deploys a wireless version of a
Fiber-to-the-Home (FTTH) network at a franction of the cost and deployment time of fiber.

local access transport area (LATA) – The geographical areas defining local telephone ser–vice. Any call within a LATA is handled by the local telephone company, but calls between LATAs must be handled by long–distance companies, even if the same local telephone company provides service in both LATAs.

local area network (LAN) – A network connecting a number of computers to each other or to a central server so that the computers can share programs and files.

license free operation – International regulations and national laws regulate the use of radio receivers and transmitters. Some communication technologies, such as free space optics (FSO), operating at frequencies considered ‘free space’ and thus do not require FCC spectrum licensing.

local exchange carrier (LEC) – A local telephone company. LECs provide telephone service for phone calls originating and terminating within a single LATA.

long term evolution (LTE) – the next generation broadband network beyond 3G. Designed to move data rather than voice, LTE is an IP network based on OFDM technology and boasts very high speed transmission rates. Many believe this will be the standard adopted by major carriers but will take time to roll out, with deployments reaching mass adoption by 2012.

M

media access control (MAC) – a data communication protocol sub–layer of the Data Link Layer specified in the seven–layer OSI model (layer 2). It provides addressing and channel access control mechanisms that make it possible for several terminals or network nodes to communicate within a multipoint network, typically a local area network (LAN) or metropolitan area network (MAN).

metropolitan area network (MAN) – large computer networks ranging from several blocks of buildings to entire cities. They typically use wireless infrastructure or Optical fiber connections to link their sites. MANs can also depend on communications channels of moderate–to–high data rates. A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. MANs might also be owned and operated as public utilities. They will often provide means for internetworking of local networks.

mb/s – Megabits per second.

megabit – One million bits.

megabyte – 1,000,000 bytes, or 1,000 kilobytes (see Byte).

millions of instructions per second (MIPS) – This is a common measure of the speed of a computer processor.

mesh network – is a way to route data, voice and instructions between communication links. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from link to link until the destination is reached. Mesh networks are self–healing: the network can still operate even when a link breaks down or a connection goes bad. As a result, this network is very reliable. This concept is applicable to wireless networks, wired networks, and software interaction. Wireless mesh networks are the most topical of mesh architectures, with links providing specific functions – such as client access, backhaul service or scanning radios for high speed handover in mobility applications.

modem (MOdulator–DEModulator) – A device that converts digital data into analog signals and vice–versa for transmission over a telephone line.

multicast – The transmission of information over the Internet to two or more users at the same time.

multiple laser multiple detector (MLMD) – in free space optics (FSO), use of a MLMD architecture is believed to resolve or significantly reduce the effect of adverse environmental conditions on FSO networks. Additionally, the power requirements for an MLMD system are significantly lower than those of commercial Single Laser Single Detector (SLSD) systems and, thus, significantly higher data rates can be supported using equivalent transmit powers.

multiplexing – Transmitting multiple signals over a single communications line or computer channel. The two common multiplexing techniques are frequency division multiplexing, which separates signals by modulating the data onto different carrier frequencies, and time division multiplexing, which separates signals by interleaving bits one after the other.

N

narrowband – A designation of bandwidth less than 56 kilobits per second.

narrowband ISDN (N–ISDN) – same as ISDN.

network access provider (NAP) – Another name for a provider of networked telephone and associated services, usually in the U.S.

network service provider (NSP) – A high–level Internet provider that offers high–speed backbone services.

network termination equipment (NTE) – The equipment at the ends of the communication path.

O

orthogonal frequency–division multiplexing (OFDM) — essentially identical to Coded OFDM (COFDM) and Discrete multi–tone modulation (DMT) — is a frequency–division multiplexing (FDM) sheme utilized as a digital multi–carrier modulation method.

optical carrier 3 (OC–3) – A fiber optic line carrying 155 megabits per second; a U.S. designation generally recognized throughout the telecommunications community worldwide.

optical carrier 12 (OC–12) – A fiber optic line carrying 622.08 megabits per second of bandwidth.

optical carrier 48 (OC–48) –A fiber optic line carrying 2.49 gigabits per second of bandwidth.

optical network unit (ONU) – A form of access node that converts optical signals transmitted via fiber to electrical signals that can be transmitted via coaxial cable or twisted pair copper wiring to individual subscribers. (See hybrid fiber/coax.)

P

packet–switched network – A network that allows a message to be broken into small "packets" of data that are sent separately by a source to the destination. The packets may travel different paths and arrive at different times, with the destination sites reassembling them into the original message. Packet switching is used in most computer networks because it allows a very large amount of information to be transmitted through a limited bandwidth.

passive optical network (PON) – a point–to–multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises. A PON configuration reduces the amount of fiber and central office equipment required compared with point to point architectures.

peripheral – An external device that increases the capabilities of a communication system.

plain old telephone service (POTS) – An acronym identifying the traditional function of a telephone network to allow voice communication between two people across a distance. In most contexts, POTS is synonymous with the public switched telephone network (PSTN).

point of presence (POP) – The physical point of connection between a data network and a telephone network.

point to point network – type of communications network in which a message is sent from one designated link to another. A point–to–point network consists of many connections between individual pairs of links. As a general rule, large networks such as Wide Area Networks (WAN) are organized in this fashion. This type of network is the opposite of a broadcast network.

point to multipoint network – refers to communication which is accomplished via a specific and distinct type of multipoint connection, providing multiple paths from a single location to multiple locations. Point–to–multipoint is most typically used in wireless networking and provides both single and bi–directional communications. Point–to–multipoint is often abbreviated as P2MP, PtMP, or PMP.

postal, telegraph and telephone (PTT) – public switched telephone network (PSTN) – The worldwide communications network that carries phone calls and data.

private area network (PAN) – is a communications network typically used to provide broadband connectivity within a privately–owned enterprise or organization. The reach of a PAN is typically within close geographic proximity. PANs can be used for connecting to a higher level network and the internet.

primary–rate ISDN (PRI–ISDN) – The primary rate ISDN interface provides 23 64 Kb/s channels (called B channels) to carry voice or data and one 16 Kb/s signaling channel (the D channel) for call information.

R

radio frequency (RF) – Electromagnetic carrier waves upon which audio, video, or data signals can be superimposed for transmission. RF is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz.

rate–adaptive digital subscriber line (RADSL) – A variation of DSL that uses carrier–less amplitude phase modulation, divides the available frequencies into discrete sub–channels and also maximizes performance by adjusting the transmission to the quality of the phone line while in use.

Regional Bell Operating Company (RBOC) – One of the seven local telephone companies formed upon the divestiture of AT&T in 1984. The seven are: NYNEX, Bell Atlantic, BellSouth, Southwestern Bell, U S WEST, Ameritech, and Pacific Telesis.

router – The central switching device in a packet–switched computer network that directs and controls the flow of data through the network.

S

scintillation – in free space optics (FSO) communication, laser beam deformation can be caused by changes in the refraction index of the air. Scintillation affects the laser beam propagation and causes fluctuation at the receiver end signal. It occurs because of atmospheric turbulence (such as wind) that produces many temporary areas called pockets or Fresnel zones. These air pockets act like lenses with time–varying properties and can lead to sharp increases in the bit–error–rates of free space optical communication systems, particularly in the presence of direct sunlight. This phenomenon is similar to heat waves rising from pavement. This leads to fluctuation in signal amplitude, which leads to fluctuation at the FSO receiver.

software defined radio (SDR) – a radio communication system where components that have typically been implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors. etc.) are instead implemented using software on a personal computer or other embedded computing devices. Significant amounts of signal processing are handed over to a general–purpose processor, rather than done using special–purpose hardware. Such a design produces a radio that can receive and transmit a different form of radio protocol (sometimes referred to as a waveform) just by running different software.

spatial diversity – the use of multiple radio antennas to improve signal integrity, or the use of multiple beams within a free space optics (FSO) device.

symmetric digital subscriber line (SDSL) – This technology provides the same bandwidth in both directions, upstream and downstream. That means whether you're uploading or downloading information, you have the same high–quality performance. SDSL provides transmission speeds within a T1/E1 range, of up to 1.5 Mbps at a maximum range of 12,000 – 18,000 feet from a central office, over a single–pair copper wire. This option is ideal for small and medium sized businesses that have an equal need to download and upload data over the Internet.

synchronized ethernet (SyncE) – SyncE uses the physical layer interface to pass timing from node to node in the same way timing is passed in SONET/SDH or T1/E1. This is believed to make SyncE networks both cost–effective and as highly reliable as SONET/SDH and T1/E1 based networks.

T

T1.413 – The American National Standards Institute (ANSI) standard for asymmetric digital subscriber line using discrete multi–tone modulation, which the G.dmt standard is based on.

T–1 – A dedicated digital communication link provided by a telephone company that offers 1.544 megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

T–3 – A dedicated digital communication link provided by a telephone company that offers 44.75 megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

telecommuting – The practice of using telecommunication technologies to facilitate work at a site away from the traditional office location and environment.

teleconference – Interactive, electronic communication among three or more people at two or more sites. Includes audio–only, audio and graphics, and video–conferencing.

terabyte – 1,000,000,000,000 bytes, or 1,000 gigabytes (see Byte).

terahertz spectrum (THz) – terahertz waves occupy the space between microwaves and the infrared optical band (from 30 microns to 1 mm). Using terahertz waves for communications would make an unused region of the electromagnetic spectrum available. The high frequency of the waves means they could also transfer wireless data very rapidly. However, the waves are normally beyond the influence of traditional optical and electronics devices. Additionally, while they can penetrate fog, clouds and soil the moisture present in all three currently limit the effective range.

time division multiplexing (TDM) – A digital data transmission method that takes signals from multiple sources, divides them into pieces which are then placed periodically into time slots, transmits them down a single path and reassembles the time slots back into multiple signals on the remote end of the transmission.

topologies – refers to the arrangement of the components of a network, especially the physical connections between the nodes/links. Any particular network topology is determined only by the graphical mapping of the configuration of physical and/or logical connections between nodes, resulting in a geometrical shape that determines the physical topology of the network. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ in two networks and yet their topologies may be identical. Common topologies include ring, line, star, bus and – particularly in telecommunications – point to point, point to multipoint, and mesh networks.

transmission control protocol/Internet protocol (TCP/IP) – A method of packet–switched data transmission used on the Internet. The protocol specifies the manner in which a signal is divided into parts, as well as the manner in which "address" information is added to each packet to ensure that it reaches its destination and can be reassembled into the original message.

U

uniform resource locator (URL) – A text–based address used to identify specific resources on the Internet, such as web pages. URLs are arranged in a hierarchical form that specifies the name of the server on which a resource is located (such as www.skyfiber.com) and the name of the file on that server.

Universal ADSL Working Group (UAWG) – An organization composed of leading personal computer industry, networking and telecommunications companies with the goal of creating an interoperable, consumer–friendly ADSL standard titled the G.992.2 standard, and commonly referred to as the G.lite standard.

universal serial bus (USB) – A computer interface with a maximum bandwidth of 1.5 Megabytes per second used for connecting computer peripherals such as printers, keyboards and scanners.

universal service provider (USP) – A company that sells access to phone, data, and entertainment services and networks.

V

variable bit rate (VBR) – A data transmission that can be represented by an irregular grouping of bits or cell payloads followed by unused bits or cell payloads.

very high bit–rate digital subscriber line (VDSL) – An asymmetric DSL that delivers from 13 to 52 megabits per second downstream bandwidth and 1.5 to 2.3 megabits per second upstream.

video on demand (VOD) – A pay–per–view television service in which a viewer can order a program from a menu and have it delivered instantly to the television set, typically with the ability to pause, rewind, etc.

videoconference – Interactive, audiovisual communication among three or more people at two or more sites.

virtual reality markup language (VRML) – A computer language that provides a three–dimensional environment for traditional Internet browsers, resulting in a simple form of virtual reality available over the Internet.

W

wavelength division multiplexing (WDM) – In fiber–optic communications, wavelength–division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different wavelengths (colors) of laser light to carry different signals. This allows for a multiplication in capacity, in addition to enabling bidirectional communications over one strand of fiber. This is a form of frequency division multiplexing (FDM) but is commonly called wavelength division multiplexing.

wide area network (WAN) – A network that interconnects geographically–distributed devices.

wireless local area network (WLAN) – a wireless network that uses spread–spectrum or OFDM modulation technology to link two or more computers or devices to enable communication between devices in a limited area. This gives users the mobility to move around within a broad coverage area and still be connected to the network.