Glossary of Terms

A| B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Select the first letter of the word from the list above to jump to appropriate section of the glossary. link.

- A -

Asymmetric connection

A connection with different "upstream" and "downstream" speeds.

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- B -

Baud

The carrier signal is characterized by the number of signal intervals, or pulses, that are transmitted per second. Each pulse is called a baud.

Bps

stands for bits per second. Bps is a measure of how many bits can be transmitted during one pulse (one baud). So, bps = baud * number of bits per baud. The general technique for "packing" bits into a baud is called quadrature amplitude modulation (qam).

 

Binder

Cable pairs are typically arranged under the cable sheath in binder groups. The binder is a spirally wound colored thread or plastic ribbon used to separate and identify cable pairs by means of color coding.

          Bridged Tap

           Any portion of a loop that is not in the direct talking path between the central office and the consumer's
           terminating equipment.  see the "line impairment factors" section for detail
           

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- C -

CAP

Carrier-less Amplitude/Phase modulation, and describes a version of QAM in which incoming data modulates a single carrier that is then transmitted down a telephone line. see xDSL modulation for details.

Carrier Set

A set of one or more frequencies associated with the PSD mask of a particular xDSL Recommendation.

Central Office (CO)

A circuit switch that terminates all the local access lines in a particular geographic serving area; a physical building where the local switching equipment is found. xDSL lines running from a subscriber’s home connect at their serving central office.

          Coding gain
          The increase in efficiency that a coded signal provides over an uncoded signal. Expressed in decibels, the
          coding gain indicates a level of power reduction that can be achieved.

Crosstalk

Interference from an adjacent channel

         CPE

         Costumer Premise Equipment represent any equipment sits at the home, which can connect to a network
        (terminals, printers, telephones, etc.)

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- D -

DMT

Discrete Multi-Tone - a version of multicarrier modulation in which incoming data is collected and then distributed over a large number of small individual carriers, each of which uses a form of QAM modulation. see xDSL modulation for details.

 

          DS0

In T-carrier systems(any digitally multiplexed telecommunications carrier system) Digital Signal 0 is a  basic digital signaling rate of 64kbps corresponding to the one voice-frequency-equivalent channel.

DWMT

Discrete Wavelet Multi-Tone - describes a version of multicarrier modulation in which each carrier is created by Wavelet transform rather than Fourier Transform.

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- E -

Echo cancellation

Echo is the sound of a voice reverberating in the telephone receiver while talking. When timed properly, echo is not a problem in the conversation; however, if the echo interval exceeds approximately 25 ms, it can be distracting to the speaker. In the traditional telephony network, echo is generally caused by an impedance mismatch when the four-wire network is converted to the two-wire local loop.
In a digital packet network over public switched telephone network (PSTN), an echo canceller is needed to reduce the level of echoes that leak from paths within the gateway between the two networks.

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- F -

FFT

Fast Fourier Transform, a fast algorithm used for converting a signal from the frequency-domain to the time-domain

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- G -

GALF

An octet with value 81(hexa), which is the ones complement an HDLC flag.

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- H -

HSTU-C/R

Hand S hake Transceiver Unit - Central/Remote

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- I -

IFFT

Inverse Fast Fourier Transform, a fast algorithm used for converting a signal from the time-domain to the frequency-domain

Interoperability

the ability of two or more systems or components to exchange information and to use the information that has been exchanged

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- J -

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- K -

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- L -

Loop

A generic term for the connection between the customer’s premises (home, office, etc.) and the provider’s serving central office. Also sometimes referred to as "the last mile" (even though the actual distance can vary).

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- M -

MIB

Management Information Base - a database of object that can be monitored by a network management system.

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- N -

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- O -

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- P -

PDN

Premise Distribution Network,  a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public.