Logical Link Control
Logical Link Identifier; an optical network assignable address given to passive optical network (xPON) optical network units (ONUs) by the optical line termination (OLT) during the discovery process. Discovery is the process whereby newly connected or off-line ONUs are provided access to the PON. The process is driven by the OLT, which periodically makes available Discovery Time Windows during which off-line ONUs are given the opportunity to make themselves known to the OLT. The periodicity of these windows is unspecified and left up to the implementer. The OLT signifies that a discovery period is occurring by broadcasting a discovery gate message, which includes the starting time and length of the discovery window. Off-line ONUs, upon receiving this message, wait for the period to begin and then transmit a Register_Req message to the OLT. Discovery windows are unique in that they are the only times where multiple ONUs can access the PON simultaneously, and transmission overlap can occur. In order to reduce transmission overlaps, a contention algorithm is used by all ONUs. Measures are taken to reduce the probability for overlaps by artificially simulating a random distribution of distances from the OLT. Each ONU shall wait a random amount of time before transmitting the Register_Req message that is shorter than the length of the discovery time window. It should be noted that multiple valid Register_Req messages can be received by the OLT during a single discovery time period. Included in the Register_Req message is the ONU’s MAC address and number of maximum pending grants. Upon receipt of a valid Register_Req message, the OLT registers the ONU, allocating and assigning new port identities (LLIDs), and bonding corresponding MACs to the LLIDs. [Fre11]
Local Multipoint Distribution System
Low Noise Amplifier
Low Noise Blockdown Converter; a device within a satellite dish which converts C-Band, X-Band, Ku-Band, or Ka-Band satellite communications downlink frequencies (IF) to lower L-Band intermediate frequencies [Fib111]
LNB Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/l
Local Number Portability
Local Access and Transport Area (LATA)
A geographical area used for regulatory, pricing, and network organization purposes to partition the public switched telephone network into distinct regions. Or a geographical area designated by the telephone company. Frequently, but not always, corresponds to an area code.
Local Access and Transport Area Switching Systems Generic Requirements (LSSGR)
A very large set of documents published by Telcordia (formerly Bellcore) that describes the local telephone network.
Local Area Network (LAN)
A LAN is a collection of computing equipment at a single location (e.g., an office building or campus) that communicate with each other to share resources and information, such as disk storage and files, printers, and e-mail. See also WAN. Or a non-public data network in which serial transmission is used for direct data communication among data stations located on the user's premises.
Local Area Network
A communications network that is restricted to a small geographical area, usually within a building or on a campus, and that has cabling normally installed and/or controlled by the organization that operates the network. [Arr11]
Local Distribution System (LDS)
A wide band microwave system or cable system which is capable of transporting a number of television signals simultaneously. Used to interconnect cable system headends.
An exchange where telephone subscriber lines connect.
Local Exchange Carrier (LEC)
Telephone company lingo for your local telephone company. See also RBOC.
This portion of the telecommunications network physically connects end users to the central office network facilities and generally is dedicated to that particular user. Twisted pairs of copper wire form the traditional medium of the telephone network local loop, although other connections now are used in some cases.
Local Multipoint Distribution System (LMDS)
A fixed wireless technology that is one solution for bringing high-bandwidth services to homes and offices within the “last mile” of connectivity.
Local Number Portability (LNP)
A system that allows local telephone numbers to be transferred to competitive local exchange carriers. This allows the subscriber to change local phone companies without experiencing a change in phone numbers.
Programming developed by an individual cable TV system specifically for the community it serves.
A device used to supply a stable single frequency to an upconverter stage of a downconverter. The local oscillator signal is mixed with the carrier wave to change its frequency. [Arr11]
Television signals that are received at locations that are within the station's Predicted Grade B Contour. Cable systems must carry all commercial local signals in their areas.
This term has different definitions depending on the application format: A DVB- HTML locator is a link, expressed in the syntax in IETF RFC 2396 , which provides an unambiguous pointer to a DVB-HTML document accessible to the MHP in a specific transport stream. The scheme specified should resolve to one of the available transports signaled for the DVB-HTML application. For signed DVB-HTML applications, the schemes HTTP and HTTPS may use the return channel. This version of the specification does not include a scheme for transporting independent locators; future versions are expected to do so. This term in the DVB-HTML context should not be confused with the DVB-J class of the same name.
A component of a connector, used to seize and retain the cable outer conductor. [Arr11]
A theft-proof connector used in a cable system where it becomes necessary to terminate both RF signal and 60 Hz AC power. [Arr11]
A directional antenna in which the size and spacing of the elements increase logarithmically from one end of the antenna to the other. [Arr11]
Logical Link Control (LLC)
The LLC network protocol sublayer is the part of the data link layer that uses the services of the Medium Access Control (MAC) Layer to provide services to the Network Layer. See also Logical Link Control Procedure.
Logical Link Control Procedure
In a local area network (LAN), or a metropolitan area network (MAN), that part of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared.
This term refers to a communication terminating outside the local telephone service area of the originating party. Since 1984 in the U.S., the term generally has meant service across local access and transport areas (LATAs).
1. In public switched networks, regarding circuits that span long distances, such as the circuits in inter-LANA, interstate, and international communications. 2. In military use, communications among users on a national or worldwide basis. Long-haul communications are characterized by a higher level of users, more rigorous performance requirements, longer distances between users, including worldwide distances, higher traffic volumes and densities, larger switches and trunk cross sections, and fixed and recoverable assets. Usually pertains to the U.S. Defense Communications System. [Fib111]
The distance east or west of the prime meridian, measured in degrees. [Arr11]
An optical waveguide mode with boundary condition determined along the length of the optical cavity. [Fib111]
A type of fiber optic cable construction where the fiber is contained within a loose tube in the cable jacket. [Fib111]
Loose-tube Fiber Construction Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/l
Long Range Navigation mode C. Provides navigation and very accurate time information via radio. [Arr11]
Line Of Sight
Power dissipated in a device, cable, or network expressed in decibels. See attenuation. [Arr11]
An accounting of overall attenuation in a system. See optical link loss budget. [Fib111]
1) Reduction of the storage size of digital data by employing one or more appropriate algorithms in such a way that the data can be recovered without losing integrity. 2) Reduction of the amount of data that needs to be transmitted per unit time though an analogous real-time process that does not compromise the ability to completely restore the data. [Fib111]
Reduction of the bit-rate for an image signal by using algorithms that achieve a higher compression than lossless compression. Lossy compression presents loss of information and artifacts that can be ignored when comparing to original image. Lossy compression takes advantage of the subtended viewing angle for the intended display, the perceptual characteristics of the human eye, the statistics of image populations, and the objective of the display. 2) Removal of redundant bits from an image in video technology producing a minor loss of image quality. [Fib111]
That portion of the electromagnetic spectrum from 54 to 88MHz, NTSC television channels 2 to 6. [Arr11]
Low Noise Amplifier (LNA)
An electronic device that amplifies weak satellite signals while keeping any received noise and interference to a minimum. The unit is mounted on a feedhorn and is rated in degrees Kelvin. [Arr11]
Low Noise Block Downconverter (LNB)
An electronic device used on satellite antennas that amplifies and converts weak satellite signals to a lower band of frequencies. The unit is mounted on a feedhorn and is rated in degrees Kelvin. [Arr11]
Low Noise Converter (LNC)
A combination Low Noise Amplifier and down converter built into one antenna-mounted package. [Sat07]
At an altitude of 200 to 300 km this orbit is used for certain types of scientific or observation satellites, which can view a different part of the Earth beneath them on each orbit revolution, as they overfly both hemispheres. [Sat07]
Low Pass Filter (LPF)
Replaces the regular filter (used for one-way transmission) on a drop, and enables a subscriber to have 2-way service. The LPF allows low frequencies to pass, but blocks out higher frequencies.
Low Power Satellite
Satellite with transmit RF power below 30 watts. [Sat07]
Low Power Television
Broadcast medium that is similar to commercial TV but limited in broadcast coverage area by its low power signal.
Common HFC frequency assignment in which upstream (to head-end) is below 42MHz and downstream (to customer) is above 54MHz.
Low VHF Band
The part of the frequency band allocated by the FCC for VHF broadcast television, including NTSC television channels 2 through 6, or 54 through 108 MHz.
Low Pass Filter
Left/Right baseband audio outputs from stereo system
Local Access and Transport Area Switching Systems Generic Requirements
That portion of the NTSC color television signal which contains the luminance or brightness information.
A three-letter abbreviation with multiple meanings, as described below:
M2M (Eclipse), an implementation of the Object Management Group's QVT standard for model transformation
Many-to-many (data model), as an entity-relationship model
Machine-to-Machine, a word describing the field of machine-to-machine communications
Made2Manage, a software application by Consona Corporation
M2M Data Mining, a research project exploiting Mobile-to-Mobile (M2M) technologies to support pervasive and ubiquitous data mining through mobile devices [Wik119]
Media Access Control
Medium Access Control
Message Authentication Code
MAC (A, B, C, D2)
Multiplexed Analog Component color video transmission system. Subtypes refer to the various methods used to transmit audio and data signals. [Sat07] A video standard developed by the European community. An enhanced version, HD-MAC delivers 1250 lines at 50 frames per second, HDTV quality. [Fib111]
Media Access Control Address
Media Access Control Procedure
Media Access Control Sublayer
M2M is the field of machine-to-machine communications.
In a fiber, all macroscopic deviations of the fiber’s axis from a straight line that will cause light to leak out of the fiber, causing signal attenuation. [Fib111]
Macrobend Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/m
A computer responsible for processing and/or storing e-mail. It is the electronic equivalent of a post office. E-mail accounts exist on a mail server, where e-mail messages are stored until retrieval by the e-mail client.
The major link from the headend to feeder lines.
A male adapter has a pin which inserts on a female receptacle. [Arr11]
Male Splice Adapter
A housing to housing coupling connector designed to eliminate the need for coaxial jumpers and permit cascadability of taps, etc. [Arr11]
MAN (Metropolitan Area Network)
A network covering an area larger than a local area network. A series of local area networks, usually two or more, that cover a metropolitan area. [Fib111]
Network Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/m
Management Information Base (MIB)
An SNMP-defined data structure used for storing and retrieving information to and from network elements.
Mandatory Ordinary Keycodes
The Mandatory Ordinary Keycodes are guaranteed to always be available to the application that has focus. The set of mandatory keycodes includes keycodes required by the MHP specification in the minimum platform capabilities section as the minimum set of input events.
Man-Machine Interface (MMI)
Another term for User Interface.