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.
4G Short for Forth Generation Wireless, 4G refers to LTE – Long Term Evolution for wireless networks 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.
LTE Long Term Evolution, refers to a standard for wireless networks especially mobile communications. Often referred to as 4G.
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
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