| 2G |
Second-generation wireless network.
2G systems are Digital cellular telephone networks such as GSM. |
| 2.5G |
Commonly used to describe
enhancements to 2G networks, such as GPRS, which offer data services
in addition to the existing voice services |
| 3G |
Short for third-generation wireless,
3G refers to next-generation networks for personal and business
wireless connectivity, especially mobile communications. |
| ANSI |
American National Standards Institute
|
| Availability |
Link availability is the percentage
of time a link is useable when considering real-world causes for
outage, such as weather conditions in in local climates, outages due
to equipment failure and other system problems. 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 8.76 hours per year.
Four-nines (4-9's) availability translates into only 52.6 minutes per
year of down-time and five-nines averages just 5.26 minutes of
downtime per year. |
| Backbone |
The part of the communications
network that connects main nodes, central offices or LANs. When
speaking of the Internet, the backbone refers to the set of paths that
local or regional networks connect to for long-distance
interconnection. |
| Backhaul |
In wireless cellular/PCS networks,
transmission links between cell sites and the system operator's
switching centre. In general, transmitting data from remote locations
to a point from which it can be distributed over a network. |
| Bandwidth |
In analogue communications, bandwidth
referred to the width of the frequency range allocated for
transmission. In the digital world, it is more common to talk about
bandwidth in terms of the number of bits transmitted per second (bps).
|
| BER |
Bit Error Rate.
A way to measure data transmission integrity. The bit error rate (BER)
is a ratio of bad bits to total bits. Typically expressed in
exponential form, nx10-x . |
| Bit |
Binary Digit.
Basic unit of digital data, represented as a one or zero. Memory or
data transferred per unit of time is measured in bits. Bits are
lowercase (b) when used in abbreviations. |
| BLEC |
Building Local Exchange Carrier.
BLECs have contracts with building owners to provide services to
tenants. See Carrier |
| Broadband |
Originally, the term broadband meant
to incorporate more than one channel into a communications
transmission. T1 is a broadband communications protocol because it
carries 24 conversations over four wires; its European counterpart,
E1, carries 32 channels. Cable TV is also broadband because it carries
many TV channels over one coax. Currently, broadband refers to
communications technologies capable of transmitting more than
'narrowband' telephone connections. ADSL, at 256kbps, is described as
broadband. |
| Byte |
Eight bits. Memory storage is
measured in bytes. Bytes are uppercase (B) when used in abbreviations.
|
| Carrier |
A telephone or networking company
that sells or rents telecommunication transmission services or
capacity. A local exchange carrier (LEC) is a local phone company and
an inter-exchange carrier (IEC or IXC) carries long-distance calls.
|
| CDMA |
Code Division Multiple Access. A
modulation method used in Wireless LAN some cellular telephone
networks to enable multiple users access to a single section of radio
spectrum. See Spread Spectrum. |
| CLEC |
Competitive Local Exchange Carrier. |
| Cost/bit |
The cost to transmit one bit. |
| Dark Fiber |
Dark fiber refers to unlit and
therefore unused fiber-optic cable. Often, companies lay more fiber
lines than are needed at the time, and defer the cost of the
associated fiber-optic components until increased network traffic
justifies the extra investment. |
| DWDM |
Dense Wavelength Division
Multiplexing
An optical technology used to increase bandwidth over existing fiber.
DWDM combines and transmits multiple signals simultaneously at
different wavelengths on the same fiber. |
| EMI |
Electromagnetic Interference
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. |
| 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"). |
| FDDI |
Fiber-Distributed Data Interface
A set of ANSI protocols for sending digital data over fiber optic
cable. Typically used as a LAN backbone protocol. |
| Fixed Wireless |
The operation of wireless devices or
systems in fixed locations such as homes and offices. |
| FSO |
Free Space Optics (FSO), also called
Free Space Photonics (FSP) or Optical Wireless, refers to the
transmission of modulated visible or infrared (IR) beams through the
atmosphere to obtain broadband communications. FSO systems can
function over distances of several kilometers. As long as there is a
clear line of sight between the source and the destination,
communication is theoretically possible, given enough power. |
| Full Duplex |
A system which allows simultaneous
transmission between two nodes on a network. |
| Giga (G) |
Engineering notation for one billion.
|
| Gigabit |
One billion bits.
In data communications, a gigabit is one billion bits. Commonly used
for measuring the amount of data that is transferred in a second
between two telecommunication points. |
| Gigabit Ethernet |
A transmission technology based on
the Ethernet frame format and protocol used in local area networks
(LANs), provides a data rate of 1 billion bits per second (one
Gigabit). Gigabit Ethernet is carried primarily on optical fiber (with
very short distances possible on copper media). |
| Gigabyte |
One billion bytes |
| GPS |
Global Positioning System.
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. |
| Half Duplex |
A system where only one device can
transmit data on a network at a time. Examples are the original
Ethernet on coaxial cable, and modern 802.11 radio wireless LANs |
| HFC |
Hybrid Fiber Coax
When the cable companies wanted to start providing services that
required more capacity and distance than their coaxial cable networks
could handle, they laid fiber in addition to coax. The resulting
networks are referred to as HFC. |
| ILEC |
Incumbent Local Exchange Carrier.
The original state-owned telephone company, post-deregulation, were
sometimes broken into regional operating companies, such as in the
USA. |
| Mbps |
Megabits per second
Mbps stands for millions of bits per second or megabits per second and
is a measure of bandwidth (the total information flow per unit time)
in a telecommunications medium. |
| MTBF |
Mean Time Before Failure. A measure
of reliability quoted by equipment manufacturers, expected lifetime
before failure of a critical component |
| MTTF |
Mean Time To Failure. A measure of
reliability quoted by equipment manufacturers, expected lifetime
before failure of a critical component |
| MTTR |
Mean Time To Repair. A measure of
reliability |
| OC-x |
Short for Optical Carrier; a prefix
for SONET carrier hierarchies, which is followed by a number.
See table below for specific speeds: |
| |
OC-1 51.84 Mbps |
| |
OC-3 155.52 Mbps |
| |
OC-12 622.08 Mbps |
| |
OC-24 1.244 Gbps |
| |
OC-48 2.488 Gbps |
| |
OC-192 9.95328 Gbps |
| |
OC-768 39.81312 Gbps |
| Optical Wireless |
Free Space Optics (FSO), also called
Fiberless Optics or Optical Wireless, refers to the transmission of
modulated visible or infrared (IR) beams through the atmosphere to
carry broadband communications. FSO systems can function over
distances of several kilometers. As long as there is a clear line of
sight between the source and the destination, communication is
theoretically possible, given enough power. |
| OSI |
Open Systems Interconnect
The OSI model for communications protocols is a global ISO standard
for communications that contains protocols in seven layers. Control is
passed from one layer to the next, starting at one end, proceeding
through the layers to the other and back again. The following chart
names the layers and their functions: |
| |
Layer 7 Application Layer Connects an
application or program to a communications protocol |
| |
Layer 6 Presentation Layer Encodes
and decodes the data to be transmitted |
| |
Layer 5 Session Layer Establishes and
maintains connection to the communications processes in the lower
layers |
| |
Layer 4 Transport Layer Responsible
for error correction and direction of flow (transmit/receive) |
| |
Layer 3 Network Layer Switching and
routing layer |
| |
Layer 2 Data-link Layer Receives and
transmits data over the physical layer |
| |
Layer 1 Physical Layer The
transmission medium itself (twisted pair, fiber optic, free-space
optics, etc.) |
| Protocol |
A set of processes and rules that
communications equipment use to transfer bits and bytes(data). |
| Reliability |
Refers to the expected failure rate
of the equipment. Typical parameters quoted are MTBF, MTTF and, MTTR. |
| Router |
On the Internet, a router is a device
or, in some cases, software in a computer, that determines the next
network point to which a packet should be forwarded toward its
destination. |
| SDH |
Synchronous Digital Hierarchy
Standardized by the ITU, SDH is a family of digital carrier rates. SDH
is the term used by the ITU to refer to SONET OC rates, as they are
called in the United States. The basic SDH building block is a rate of
155.52 Mbps, called STM-1. Multiples are at 622.08, 2488.32 and
9953.28Mbps |
| SNMP |
Simple Network Management Protocol
An IETF-defined standard for network management across network
management systems and network components. Another definition is:
Protocol that governs network management and monitoring of network
devices and their functions. |
| SONET |
Synchronous Optical Network
Proposed by Bellcore in the ‘80s, SONET has become an ANSI (American
National Standards Institute) standard as well as an ITU international
standard named SDH that defines interface standards at the physical
layer 1 level. It allows data streams of differing rates to be
multiplexed. It is generally implemented over fiber optic cable and is
often configured in a ring allowing it to reroute traffic with no
interruption of service, should a cable be cut. |
| Spread Spectrum |
A modulation technology which
'spreads' transmitted signals over a wide portion of the RF spectrum,
to provide immunity to same-channel, co-channel and multipath
interference, and enable spectral re-use. Widely used in Wireless
LANs |
| STM |
Synchronous Transfer Mode |
| STS |
Synchronous Transport Signals; the
electrical version of OC (Optical Carrier) |
| Telco |
An abbreviation for telephone company
|
| Transceiver |
A combination of transmitter/receiver
in a single device |
| UMTS |
Universal Mobile Telephone System.
Another name for 3G |
| WDM |
Wavelength Division Multiplexing
Technology developed for multiplexing several signals onto a single
optical fiber. WDM modulates each of several data streams onto a
different part of the light spectrum. |
| Wireless LAN |
Wireless Local Area Network. Most
commonly, using the unlicensed spectrum at 2.4GHz with Spread Spectrum
modulation. |
| WLAN |
Short for Wireless LAN |
