ADSL - Asymmetric Digital Subscriber Line. A high-speed
transmission technology using existing twisted pair lines that permits
simultaneous POTS and high-speed data communication. A much higher data
rate is employed downstream than upstream.
AMI - Alternate Mark Inversion. A line coding technique
used to accommodate the ones density requirements of E1 or T1 lines.
ANSI - American National Standards Institute. Accredits
and implements standards. Member of ISO.
ATM - Asynchronous Transfer Mode. A high-bandwidth,
low-delay, connection-oriented switching and multiplexing technique using
Attenuation - The dissipation of the power of a
transmitted signal as it travels over a wire.
ATU-R - ATU - Remote. Equipment placed at the customer
premises in support of DSL-based services.
AWG - American Wire Gauge. An indication of wire
size. The heavier the gauge, the lower the AWG number and the lower the
Backbone - Equipment that provides connectivity
for users of distributed network and includes the network infrastructure.
Bandwidth - The difference between the highest and
lowest frequencies of a band that can be passed by a transmission medium
without undue distortion.
BPS - Bits per second. Indicates the speed at which
bits are transmitted across a data connection.
BRI - Basic Rate Interface. An ISDN service rate
of 144 kbps, provided as two B-channels of 64 kbps for data transfer and
one D-channel of 16 kbps for control and signalling. Bridged tap Any part
of the local loop that is not in the direct transmission path between
the CO and the service user.
Cable Binder - A cable binder is used to bundle
multiple insulated copper pairs together in the telephone network.
CAP - Carrierless Amplitude & Phase Modulation.
A transmission technology for implementing a DSL connection. Transmit
and receive signals are modulated into two wide-frequency bands using
passband modulation techniques.
CO - Central Office/Central Site. In North America,
a CO houses one or more switches to serve local telephone subscribers.
Known as a public exchange elsewhere.
Crosstalk - Line distortion caused by wire pairs
in the same bundle being used for separate signal transmission.
CSA - Carrier Serving Area.
DMT - Discrete MultiTone. DSL technology using
digital signal processors to divide the signal into 256 subchannels.
Downstream - Refers to the transmission direction
from the CO to the customer premises.
DSL - Digital Subscriber Line. The non-loaded, local-loop
copper connection between the NSP and the customer premises. DSL can provide
simultaneous high-speed digital data access and POTS service over the
same twisted-pair wiring.
DSLAM - Digital Subscriber Line Access Multiplexer.
A platform for DSL modems that provides high-speed data transmission and
optional POTS service simultaneously over traditional twisted-pair wiring.
E1 - A wideband digital interface operating at 2.048
Mbps, as defined by the ITU recommendations G.703 and G.704. Generally
available outside North America.
ETSI - European Telecommunications Standardisation Institute.
An organization that produces technical standards in the area of telecommunications.
FDM - Frequency Division Multiplexing.
Frame Relay - A high-speed connection-oriented packet
switching WAN protocol using variable-length frames.
HDSL - High-bit-rate Digital Subscriber Line. A
technique for high bandwidth, bi-directional transmission over copper
wire for T1 and E1 services.
Hertz - Frequency measurement. 1 Hertz = 1 cycle
IP - Internet Protocol. An open networking protocol
used for Internet packet delivery.
ISDN - Integrated Services Digital Network. Telecommunication
service that uses digital transmission and switching technology to provide
voice and data communications on a bearer channel while sending signalling
on a data channel.
kbps - Kilobits per second. One kilobit is usually
taken to be 1,024 bits.
Local loop - The distance between the CO and the
Mbps - Megabits per second. One megabit is 1,048,576
MDF - Main Distribution Frame. The point where all
local loops are terminated at a CO.
NEXT - Near End Crosstalk. Crosstalk in which the
interfering signal is travelling in the opposite direction as the desired
NSP - Network Service Provider. A vendor, such as
an ISP, local telephone company, CLEC or corporate LAN, that provides
network services to subscribers.
POTS - Plain Old Telephone Service. Standard telephone
service over the PSTN, with an analog bandwidth of less than 4 KHz.
PSTN - Public Switched Telephone Network. A network
shared among many users who can use telephones to establish connections
between two points. Also known as the dial network.
QAM - Quadrature Amplitude Modulation. Modulation
technique using variations in signal amplitude.
RADSL - Rate Adaptive Digital Subscriber Line. Transmission
technology that supports both asymmetric and symmetric applications on
a single twisted pair telephone line. Allows adaptive data rates up to
SDSL - Symmetric Digital Subscriber Line. Provides
high bandwidth, bi-directional transmission over one copper wire pair
for T1 or E1 services.
T1 - A term for a digital carrier facility used
to transmit a DS1 formatted digital signal at 1.544 Mbps. It is primarily
used in the United States.
2B1Q - Two Binary, one Quaternary. A line coding
technique that compresses two binary bits of data into one time state
as a four-level code.
VDSL - Very-high-bit rate DSL. Generally refers
to a data transmission speed from
DSL - Refers to all DSL-based services.