Broadband Glossary

Broadband Glossary:

ANI û Automatic Number Identification. The capability of a voice network switch to provide the called party with the calling partyÆs telephone number. Used extensively in call centers and in computer telephony integration (CTI) applications.

ACD û Automatic Call Distributor: A device that directs incoming calls to a specific agent (telephone) in appropriate sequential or priority order and provides management support to a supervisor over the call queue and agents supported by the ACD. An ACD may be integrated in a PBX or be a stand-alone system.

ATM û Asynchronous Transfer Mode. A broadband switching and multiplexing, connection-oriented, high-performance integrated technology for supporting B-ISDN services(e.g..multimedia) under specified QoS guarantees. Since capacity is allocated on demand with no clocking control between users, it is called asynchronous. Information is transmitted at very high rates in fixed-length packets called cells. Traffic streams can be distinguished according to different QoS Classes. The ATM Reference Model describes the various functions, services, protocols and standards encompassed by the ATM technology.

BANDWITDTH û Originally defining the frequency range supported by an analog circuit, this term is now commonly used to define the transmission capacity of any communications medium, for analog circuits it is measured in Hertz (Hz or cycles per second); for digital circuits, it is measured in bps. (Bits Per Second).

BAUD û A measure of the change in the signaling speed, it is defined as the number of changes of the signal voltage per second. The link transmission rate in (in bps), is a multiple of (though usually equal to) the lineÆs baud rate.

B-CHANNEL û Bearer Services Channel. A component of an ISDN physical interface that operates at 64 kbps (DS-0 rate). It is used for supporting user traffic (such as digital data, audio, video and voice. (See also ISDN, D-Channel, H-channel).

BIT û Binary Digit. One binary integer (0 or 1); a pulse of data.

BLOCKING û Refers to situations where a packet or message or a circuit (i.e. a call in telephony) is blocked (denied access to the network) due to the unavailability of sufficient network resources (bandwidth, buffer capacity).

CDMA û Code Division Multiple Access. A channel-based multiple access technique used in wireless (spread-spectrum) communication. While in FDMA a channel is subdivided into frequency bands, in CDMA a transmission can utilize the entire bandwidth based on coding techniques (each bit is coded into a sequence of bits).

CELL SITE û The location of a carrierÆs cellular antenna within a cell.

CHANNEL û The smallest subdivision of a circuit that provides a type of communications service.

CIRCUIT û A communications path or network between two devices.

CLEC û Competitive Local Exchange Carrier. Emerging companies in competition with the traditional local exchange carriers (e.g. Pacbell, ICG, Global Crossing).

COM û Continuation of Message. A field in a message header that identifies the middle segments of a multi-segment data frame.

CONNECTION û A path established between two devices that runs across a network for the purpose of transferring information.

CSU û Channel Service Unit. Equipment at the user end that provides an interface between the user and the communications network (i.e. T-1 lines). The CSU can be combined with the DSU in the same device.
CSU/DSU û Channel Service Unit/Data Service Unit. The combination of a CSU and a DSU, it is used as an interface between a digital line and a communication device.

CTI û Computer Telephone Integration. Term for the procedures that support the coordination of a LAN-based data system and a PBX-based voice system so that related voice and data functions occur at an ACD agentÆs desktop for an incoming call.

D-CHANNEL û Data Channel. A component of an ISDN interface, it is a channel that is used to carry network management NM) and control signaling messages over the ISDN interface. It may also carry user packet data. There are tow standards: BRI (at 16 kbps) and PRI (at 64 kbps).

DIGITAL SIGNAL û A way of representing information as a set of discreet values (i.e., electrical voltage pulses or light pulses), within a certain range. Binary signals are the digital signals that assume the values of 0 and 1.

DS-1 û Digital Signal-Level 1. Electrical interface for digital transmission at the rate of 1.55 Mbps containing 24 64-kbps DS-0 circuits. They physical interface first defined to carry a DS-1 electrical signal is known as T1 and operates over a pair of unshielded twisted 9UTP) wires. DS-1 has subsequently been specified to operate over a wide variety of media such as microwave and fiber optics. The terms TS-1 and T1 are often (incorrectly) used interchangeably.

DSL û Digital Subscriber Line. General name for several specifications supporting digital customer local loops.

DTMF û Dual Tone Multi-Frequency. A technique for using two tones, transmitted simultaneously, to identify a specific digit being pressed on a numeric pad, such as a telephone.

DUAL MODE û Describes a wireless telephone handset that works in both digital and analog networks.

ECHO û Noise generated when the transmitted signal is reflected back to the transmitter. Noticeable when the length of the circuit is sufficient to cause the echo to be significantly separated from the transmission signal.

ESN û Electronic Serial Number û The unique identification number embedded in a wireless phone by the manufacturer.

FCC û Federal Communications Commission. An U.S. government body that deals with various communications issues regulates and oversees the operation of the broadcasting and telecommunication companies.

GHz û GigaHertz. One billion Hertz (Hz).

GUI û Graphic User Interface. Refers to any computer system that interacts with users by employing graphical symbols, icons and pictures.

HUB û A LAN device that interconnects several stations.

Hz û Hertz. Signal or channel frequency unit (1 fHz = 1 cycle per second).

ISDN û Integrated Services Digital Network. An ITU-T protocol reference model intended for providing a ubiquitous, end-to-end, interactive, digital service for data, audio and video. ISDN is available as BRI and PRI.

kbps û Kilobits per second. Transmission speed or rate of one thousand bits per second.

KHz û KiloHertz. One thousand Hertz (Hz).

LAN û Local Area Network. A network that interconnects PCÆs , terminals, workstations, servers, printers and other peripherals over short distances.

MHz û MegaHertz. One million Hertz (Hz).

MODEM - Modulator/Demodulator. A physical device that converts between an analog signal and a digital one. Analog-to-digital conversion is called A/D or modulation with digital-to-analog conversion is called D/A or demodulation. A modem is typically attached to a computer to allow access to the analog local subscriber loop of the public telephone network.

MULTIMEDIA û An integrated way of presenting to the user a combination of different kinds of information such as text, data, images, video, audio, and graphics.

PBX û Private Branch Exchange. A customer-owned circuit switch that creates connections for telephones, faxes, terminals (modems) or other voice-grade communications equipment and provides access to the public telephone system.

PROTOCOL û A set of rules that govern (establish, maintain and manage) end-to-end or node-to-node communication between two peer (at the same level) entities across a network.

PSTN û Public Switched Telephone Network. A generic name for the worldwide public telephone network.

REPEATER û A device the restores a degraded digital signal (amplitude and waveform) for continued transmission. Also called a regenerator.

SWITCH û Any device that is responsible for switching traffic based on real or virtual circuits. It is also common for a switch to perform traffic management and control functions such as admission control, congestion and control and signaling. There exist various switch architectures, which can be classified according to different characteristics.

T1 û A TDM digital channel carrier that operates at a rate of 1.554 Mbps over two twisted pair of wiring. Often confused with DS-1, the specifications for framing and transmitting a 1.544 Mbps bit stream consisting of twenty-four 64 kbps DS-0 channels. DS-1 was originally specified to be transmitted over T1 wiring but has subsequently been specified on other types of media as well. As a result, the terms T1 and DS-1 are often used interchangeably.

[color blue]T1 = 24 - Lines
T2 = 4 - T1Æs
T3 = 6 - T2Æs
T4 = 7 - T3Æs [/color]

VIDEOCONFERENCING û Real-time audio and video-based communication between two or more parities, at a transmission rate ranging from 1.5 Mbps up to 45 Mbps. B-ISDN services are designed to fully support videoconferencing.

VoIP û Voice Over IP. General terms for several techniques for the transmission of voice over an IP-based router network.