| 3G |
 |
A short term for third-generation wireless, it refers to near-future
developments in personal and business wireless technology, especially
mobile communications.
|
| ANSI |
|
American National Standards Institute
|
| Availability |
|
Link availability is the fraction of time a link is useable
in 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.
|
| 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 cellular/PCS systems, the transmission links between cell sites
and the system operator's switching center. In general, transmitting
data from remote locations to a point from which it can be distributed
over a network.
|
| Bandwidth |
|
In analog 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.
|
| Bit |
|
Binary Digit.
A unit of data represented as a one or a zero. Memory or data transferred
per unit of time is measured in bits. Bits are lowercase (b) when
used in abbreviations.
|
| Broadband |
|
The original meaning for broadband was incorporating more than one
channel into a communications transmission. T1 is a broadband
communications protocol because it carries 24 conversations over four
wires. Cable TV is also broadband because it carries many TV channels
over one coax. Currently, broadband refers to communications technologies
capable of transmitting over 45 Mbps over any type of media. For
example, a 155 Mbps Free Space Optics link would be considered broadband
even though only one channel is being transmitted in either direction.
|
| Byte |
|
Eight bits. Memory storage is measured in bytes. Bytes
are uppercase (B) when used in abbreviations.
|
| Carrier |
|
A telephone or other company that sells or rents telecommunication
transmission services. A local exchange carrier (LEC) is a local phone
company and an inter-exchange carrier (IEC or IXC) carries long-distance
calls.
|
| 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.
|
| 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.
|
| HFC |
|
Hybrid Fiber Coax
When the cable companies wanted to start providing services that
required more bandwidth than their coaxial cable networks could handle,
they laid fiber and the resulting networks were referred to as HFC.
|
| 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.
|
| 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 |
bps |
| 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 |
|
| Optical Wireless |
|
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 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.
|
| 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.
|
| 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.
|
| STM |
|
Synchronous Transfer Mode
|
| STS |
|
Synchronous Transport Signals; the electrical version of OC
(Optical Carrier)
|
| Telco |
|
Abbreviation for telephone company
|
| Transceiver |
|
A combination transmitter/receiver in the same device
|
| WDM |
|
Wavelength Division Multiplexing
Multiplexing technology developed for use on optical fiber. WDM
modulates each of several data streams onto a different part of the
light spectrum.
|
