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Glossary
Even experts need occasional help with telecom terms. We have combined glossaries from several sources to simplify finding the definitions you need.
1-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
AACS Access and Administration Control System.
ACU Antenna Coupling Unit.
ADC Analog-to-digital Converter. A device that converts an analog signal to a digital signal that represents equivalent information.
Address The unique number ID assigned to one host or interface in a network.
ADM Add/Drop Multiplexer. Digital multiplexing equipment that adds/removes individual signals to/from a collection of multiplexed signals in a network.
AGC Automatic Gain Control. A process that automatically adjusts gain as a function of a specified parameter, such as received signal level. AGC is used to help maintain a constant output level when the input signal level is changing.
AIS Alarm Indication Signal - The code generated by a regenerator upon loss of input signal or loss of frame. A signal transmitted in lieu of the normal signal to maintain transmission continuity and to indicate to the receiving terminal that there is a transmission fault that is located either at, or upstream from, the transmitting terminal.
AIS-L Line Alarm Indication Signal.
ALC Automatic Level Control. See AGC.
AMI Alternate Mark Inversion Signal. A pseudoternary signal, representing binary digits. Successive marks are of alternately positive and negative polarity and the absolute values of their amplitudes are normally equal. Spaces are of zero amplitude.
Analog signal A signal that has a continuous nature instead of pulsed or discrete.
ANSI American National Standards Institute.
APS Automatic Protection Switch or Automatic Protection Switching.
ARP Address Resolution Protocol.
ASCII American National Standard Code for Information Interchange.
ASIC Application Specific Integrated Circuit.
ATM Asynchronous Transfer Mode. A dedicated connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Relative to other related cells, each cell is processed asynchronously and queued before being multiplexed over the transmission path.
ATPC 1Automatic Transmit Power Control. A feature of digital microwave radio equipment that adjusts the transmitter output power based on path fading detected at the receiver. This feature reduces interference with neighboring systems and permits greater link density.
AUX Auxiliary services module.
Auxiliary Data Channel A data channel between microwave radio terminals that is outside the customer payload channel(s). The auxiliary data channel is normally transported in the radio overhead.
AWG American Wire Gauge. A wire diameter specification. The smaller the AWG number, the larger the wire diameter.
Azimuth The angle in the horizontal ground plane with respect to true North (such as, horizontal direction); used in reference to antenna alignment.
B
B1 Bit Interleaved Parity-8 (BIP-8). An RSOH byte for error checking the complete STM-1 signal at the end of a regenerator section.
B2 Bit Interleaved Parity-24 (BIP-24). MSOH bytes for error checking an STM-1 signal (minus the RSOH) at the end of the multiplexer section.
B3ZS Binary 3 zeros substitution. A ?1? is substituted for every 3 zeros.
B8ZS Binary 8 zeros substitution/Bipolar 8 zero substitution.
BAPT Bundesamtfur Post Und Telekommunikation (German Telecom Regulatory Agency).
BBER Background Block Error Ratio.
BBP Baseband Processing.
BCH Bose-Chaudhuri-Hochquenghem code. A multilevel, cyclic, error-correcting, variable-length digital code used to correct errors up to approximately 25% of the total number of digits.
Beamwidth The beamwidth of an antenna is defined as the angle between the two half-power (-3 dB) points on either side of the main lobe of radiation (half power beamwidth).
BER Bit Error Ratio or Bit Error Rate - The number of erroneous bits divided by the total number of bits transmitted, received, or processed over some stipulated period.
BML Business Management Level in the TMN model
BNC Type of coaxial connector.
BPDU Bridge Protocol Data Unit.
Bps Bits per second.
BSI British Standards Institute.
Bursty Traffic Communications data does not flow in a steady stream
C
Carrier Ethernet A ubiquitous, standardized carrier-class service defined by five attributes that distinguish Carrier Ethernet from LAN-based Ethernet: standardized services, scalability, reliability, quality of service, and service management.
CAS Channel Associated Signalling.
CBS Committed Burst Size.
CB-149 The Bell Core standard that was used before the ITU standard was adopted.
CCITT International Telegraph and Telephone Consultive Committee.
CCS Common Channel Signaling.
CDMA Code Division Multiple Access.
CE Conformit‚ Europ‚ene. The CE marking indicates that the product has been designed and manufactured in conformity with the essential requirements of all relevant EU (European Union) directives, and submitted to the relevant conformity assessment procedure.
CEMF Cisco Element Management Framework.
CEPT The European Conference of Postal and Telecommunications Administrations.
CEPT-1 ITU-T digital signal level 1 (2.048 Mbps) = E1
CEPT-2 ITU-T digital signal level 2 (8.448 Mbps) = E2
CEPT-3 ITU-T digital signal level 3 (34.368 Mbps) = E3
CEPT-4 ITU-T digital signal level 4 (139.264 Mbps)
CEPT-n Conference of European Posts and Telecommunications level n.
CES Carrier Ethernet Services.
CES Circuit Emulation Services.
CESR Carrier Ethernet Switch Router
CET Carrier Ethernet Transport.
CIR Committed Information Rate.
CLEC Competitive Local Exchange Carrier Market. A service provider that builds and operates communication networks in metropolitan areas, thus providing customers with an alternative to local telephone companies. USA terminology.
CLI Command Line Interface.
CMOS Complementary Metal Oxide Semiconductor.
CODEC Abbreviation of coder/decoder. A device that encodes and/or decodes a signal. For example, telcos use codecs to convert digital signals to analog signals - and vice-versa.
Commissioning A radio link is commissioned when customer traffic circuits have been connected and the link is completely ready to provide a data service.
Community String When configuring an SNMP agent, the community string (which is a name or combination of characters) is input as part of the configuration information. When a management system wants to communicate with the device, it authenticates using the community string. There are normally two community strings accommodated by a device, one for reading values and one for writing (setting) values. These are normally set to "Public" or "Private", but can be set to other values as a form of security.
Component The component replacement level describes the smallest field-replaceable parts of a system. For example, for a split-mount radio terminal, the IDU and ODU normally represent the lowest level of field replaceable items.
CORBA Common Object Request Broker Architecture.
CoS Class of Service.
CPE Customer Premise Equipment.
CRC Cycle Redundancy Check.
CS Cesium.
CSP Communication Service Providers.
CTB Cable Termination Block.
CTU Customer Termination Unit.
C-VLAN Customer VLAN.
D
D/A Digital to Analog.
DAC 1) For Eclipse: Digital Access Card; 2) Digital to Analog Converter.
DADE Differential Absolute Delay Equalization. An equalization process used to render a protected system hitless.
DART Digital Access Radio Technology. A digital microwave radio system.
dB The abbreviation for decibel; the standard unit of measure for relative signal power.
DB9 A standardized connector with 9 pins.
dBm db referenced to one milliwatt = 0 dBm. The standard unit of measure for absolute power values.
Dc Direct current; Harris Stratex Networks radios operate on dc power.
dc-dc Converter An electrical device used to convert direct current from one level to another.
DCE Data Communications Equipment.
DDS Direct Digital Synthesizer.
DEMUX De-multiplexer.
DFE Decision Feedback Equalizer.
DHCP Dynamic Host Configuration Protocol.
Diagnostic Controls or Functions Radio system features used for troubleshooting or testing the radio or radio link. Some examples: RF loopback, PA mute, and tributary loopback.
Diplexer A RF filter device used to separate the Tx and Rx signals at the transceiver antenna feed port.
Digital signal (DS) A signal format where the intelligence is transported as binary code.
Digital signal 1 (DS1) An ANSI digital signaling rate of 1.544 Mb/s, corresponding to the North American and Japanese T1 designator.
DC Direct Current
DLC Digital Loop Control.
DQPSK Differential Quadrature Phase Shift Keying.
DS1 Digital signal 1: an ANSI digital signaling rate of 1.544 Mb/s, corresponding to the North American and Japanese T1 designator.
DS3 Digital signal 3: an ANSI digital signal level 3 (44.736 Mbps), the North American T3 designator.
DSL Digital Subscriber Line.
DSTM Derived System Timing Mode, i.e., derived from incoming Ethernet frames.
DSx ANSI digital signal level x.
DTE Data Terminal Equipment. Devices acting as data source, data sink, or both. They typically connect to a network via a DCE.
Dual Link Two radio links operating in parallel, on different frequencies, and transporting different data.
DTM Derived Timing Mode. Recovered service clocks are derived from the incoming Ethernet frame.
DTMF Dual Tone Multi-frequency.
DTPC Dynamic Transmit Power Control. A feature enabling the regulation of a target receive signal level by remotely and proportionally controlling the corresponding transmitter output power level.
DUART Dual Universal Asynchronous Receiver-Transmitter.
DVM Digital Volt Meter.
DXR Digital Cross-Connect Radio. A legacy Harris Stratex Networks radio family.
E
E1 ITU digital signal level 1 (2.048 Mbps) = CEPT 1.
E3 ITU digital signal level 3 (34.368 Mbps) = CEPT 3.
E/I Energy to Interference ratio.
E/N Energy to Noise ratio.
ECC Error Correction Code.
EEPROM Electrically Erasable Programmable Read Only Memory
EIA Electronic Industries Association
EIR Excess Information Rate
EISA Extended Industry Standard Architecture - A 32-bit bus standard that supports the features of microchannel architecture. A special card is required for 32-bit operations that maintain compatibility with the older ISA (Industry Standard Architecture).
Electromagnetic Spectrum Though the electromagnetic spectrum was, by custom and practice, formerly divided into 26 alphabetically designated bands, the ITU formally recognizes 12 bands, from 30 Hz to 3000 GHz.
E-LAN An Ethernet service type that is based on a multipoint-to-multipoint EVC.
EM Element Manager.
EMC Electro-Magnetic Compatibility.
EMI Electromagnetic interference.
EML Element Management Level in the TMN model.
EMS Element Management System.
End-to-end delay The time it takes a signal to travel from point of transmission, to the point of reception.
EOW Engineering Orderwire (Voice and/or Data).
ERP Effective Radiated Power.
ES Errored Second.
ESCAN Extended SCAN Protocol. A Harris Stratex proprietary protocol that is more efficient and allows for faster communications than the SCAN protocol
ESD Electrostatic discharge.
ESR Errored Second Ratio.
Ethernet The term Ethernet refers to the family of local-area network (LAN) products covered by the IEEE 802.3 standard that defines what is commonly known as the CSMA/CD protocol. Data rates are defined for:
Ethernet 10 Mbit/s - 10Base-T Ethernet
Ethernet 100 Mbit/s - Fast Ethernet
Ethernet 1000 Mbit/s - Gigabit Ethernet
Ethernet 10000 Mbit/s - 10-Gigabit Ethernet
ETSI European Telecommunications Standards Institute. Provides international technical standards for wireless radios. Harris Stratex Networks radios are in compliance with all relevant ETSI standards.
EVC Ethernet Virtual Connection. An association of two or more UNIs that limits the exchange of frames to UNIs in the Ethernet Virtual Connection.
F
Fade margin The amount of attenuation a link can suffer before link performance is affected. Typically measured as the dB difference between the received signal strength and the receive threshold.
FCAPS Fault, Configuration, Accounting, Performance and Security functions in the TMN model.
FCC Federal Communications Commission. The FCC is an independent United States government agency, directly responsible to Congress. The FCC was established by the Communications Act of 1934 and is charged with regulating interstate and international communications by radio, television, wire, satellite and cable. The FCC's jurisdiction covers the 50 states, the District of Columbia, and U.S. possessions.
FCS Frame Check Sequence.
FD Frequency Diversity. A path protection mode. The main and standby radios are transmitting simultaneously and are tuned to different frequencies (at least two channels apart) to avoid interference. When a fault is detected on the active radio, the traffic is switched to the standby radio.
FEC Forward Error Correction. A system of error control for data transmission. It compensates for errors induced in the transmitted stream, by sending along with the primary data payload, additional information to correct for errors that occur in transmission.
FER Frame Error Ratio.
FFE Feed Forward Equalizer.
FIFO First In First Out.
FIR Finite Impulse Response filter. Designates one of two primary types of digital filters used in Digital Signal Processing (DSP) applications.
FLR Frame Loss Ratio. This is the measure of lost frames between the ingress UNI and the egress UNI. Frame Loss Ratio is expressed as a percentage.
FM Fault Management.
FPGA Field Programmable Gate Array.
Frame Short for "Ethernet Frame."
Frame Delay The time required to transmit a Service Frame from ingress UNI to egress UNI.
FSK Frequency-shift Keying. The modulating signal shifts the output frequency between predetermined values.
G
G.821 An ITU-T recommendation on error performance parameters and objectives for primary-rate (64 kbit/s) data circuits. It can be used for higher bit-rates, typically up to to 2 Mbit/s. G.821 is a bit-based system.
G.826 An ITU-T recommendation on error performance parameters and objectives for high-speed data circuits; circuits operating at 2 Mbit/s and above. G-826 is a block-based system.
Ga AsFET Gallium Arsenide Field Effect Transistor.
Gain The increase in signal power caused by a device or network (for example, the signal gain provided by an antenna).
GARP Generic Attribute Registration Protocol
GB Gigabyte.
GbE Gigabit Ethernet.
GHz Gigahertz.
Golden Cells These are sites where it is imperative that communications traffic continues at peak performance. They are typically sites where any communications down-time can mean significant loss of revenue, or a significant breach against a service level agreement (SLA).
GPRS General packet radio service (GPRS) is a packet oriented mobile data service available to users of the 2G cellular communication systems global system for mobile communications (GSM), as well as in the 3G systems. In the 2G systems, GPRS provides data rates of 56-114 kbit/s.
GPS The Global Positioning System (GPS) is a global navigation satellite system (GNSS) developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing. It is the only fully functional GNSS in the world, can be used freely, and is often used by civilians for navigation purposes. It uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, which allow GPS receivers to determine their current location, the time, and their velocity. Its official name is NAVSTAR GPS. Although NAVSTAR is not an acronym,[1] a few backronyms have been created for it.
GSM Global Systems for Mobile.
GUI Graphical User Interface.
H
H.323 A standard approved by the ITU that defines how audiovisual conferencing data is transmitted across networks. In theory, H.323 should enable users to participate in the same conference even though they are using different videoconferencing applications.
HDB3 High Density Bipolar Order 3. The default method of encoding transmissions for E1 and E3 radios. Substitutes a 1 for every 3 zeros.
HDLC High-level Data Link Control. A bit-oriented synchronous data link layer protocol developed by ISO. HDLC specifies a data encapsulation method on synchronous serial links using frame characters and checksums.
HHT Handheld terminal.
Hitless Receive Switching A protected system configuration whereby if a fault occurs at the receiving end of the link, the traffic is switched to the standby radio without causing errors.
Hot Standby Hot Standby is a protected configuration whereby standby equipment is held ready to be switched immediately into service if the main equipment fails.
HPA High Power Amplifier.
HSB Hot-Standby Protection Mode.
HSC Hardware/Software Compatibility. Different hardware may require different software versions.
I
I/O Input / Output.
ICMP Internet Control Message protocol. An integral part of the Internet Protocol that handles error and control messages.
IDC Indoor Chassis.
IF Intermediate Frequency. The signal frequency or frequencies intermediate between the modem electronics and the transmitted/received frequencies.
IIOP CORBA's Internet Inter-ORB Protocol.
IDU Indoor Unit. The IDU s the control center of a split-mount radio system. It interfaces between the customer signals and the ODU.
IEEE Institute of Electrical and Electronics Engineers.
IETF Internet Engineering Task Force.
IGP Interior Gateway Protocol.
Intermodulation Intermodulation can occur in systems where multiple signals are present at the same point. Where there is a nonlinearity in the system any signal will generate harmonics, but when two signals are present, harmonics of both are produced. The harmonics of the two signals can intermix, resulting in further spurious signals that are known as intermodulation products. The result of an intermodulation signal can have a major impact on reception if it falls in a receive channel. As the number of signals increases and/or TX power increases, the probability of an intermodulation signal causing noise in a receive channel grows.
ITU International Telecommunications Union. A civil organization established to promote international standards for telecommunications.
INU Intelligent Node Unit. INU is the term used to describe the indoor unit of a Harris Stratex Networks Eclipse Node. The INU is a 1U chassis (the IDC) fitted with mandatory cards plus option cards. It supports up to three ODUs for three non-protected links, or one protected/diversity link and one non-protected link.
INUe Expanded Intelligent Node Unit. The Harris Stratex Networks term used to describe the 2U indoor unit of an Eclipse Node. The INUe supports up to six ODUs for six non-protected links, or up to three protected/diversity links.
IP Internet Protocol. A method or protocol by which data is sent from one device to another on the Internet.
IRU Indoor Radio Unit.
ISI Inter-Symbol Interference.
ISO International Standards Organization.
ITU-R International Telecommunication Union - Radio Communication Sector (formerly CCIR and IFRB).
ITU-T International Telecommunication Union - Telecommunication Standardization Sector (formerly CCITT).
K
K1 and K2 In an SDH system, K1 and K2 are MSOH bytes used for:
Controlling the multiplexer section protection switching. Signalling Alarm Indication Signal (AIS), Far End Remote Failure (FERF). Signalling Automatic Protection Switching (APS) alarms, when implemented.
L
L1 Layer 1.
L2 Layer 2.
LACP Link Aggregation Control Protocol.
LAG Link Aggregation Group.
LAN Local-area Network. A data network located on a user's premises within a limited geographical area. Ethernet is the most widely used LAN transport technology.
LBO Line Build-Out (I/O Cable Distance Compensator).
LED Light Emitting Diode.
Link A radio link comprises two terminals, one at each end of the link.
Liquid Bandwidth Liquid bandwidth refers to the Eclipse ability to seamlessly assign capacity to Ethernet and to companion E1/DS1 or STM1/OC3 traffic. This scalability is enabled by the unique universal modem design built into Eclipse. It does not distinguish between the type of data to be transported, Ethernet or TDM; data is simply mapped into byte-wide frames to provide a particularly efficient and flexible wireless transport mechanism, with the result that when configured for Ethernet and/or TDM, the full configured capacity is available for user throughput.
LLC Logical Link Control.
LMCDR Low-medium capacity data radio.
LMT Local Maintenance Terminal.
LNA Low Noise Amplifier.
LO Local Oscillator.
LOF Loss of Frame or Loss of Frame Alignment.
LOH Line Overhead. Contains the media's framing, routing protocol, and network-layer protocol overhead.
Loopback A diagnostic function designed to assist testing of system components by routing traffic back to the direction it came from.
LOS 1) Loss of signal; 2) Line of Sight.
LSP Label Switched Path.
LSR Label Switched Router.
LTE Line Termination Equipment.
M
MAC Media Access Control.
MAC address Media Access Control address. A unique number assigned to every layer 2 Ethernet device in the world.
MIS Management Information System. An organized assembly of resources that collects, processes, and distributes data.
Mbps Megabits Per Second. Also Mbit/s.
Mapper A device or logic that implements a mapping function.
MEF Metro Ethernet Forum.
MEN Metro Ethernet Network.
Message Board Scratch pad text area that allows radio users to leave each other messages.
MGB Master Ground Bar.
MHSB Monitored Hot Standby.
MHz Megahertz = 1 million hertz.
MIB Management Information Base. A file that describes the information that can be accessed for each network device. The MIB is required by SNMP.
MMIC Microwave Monolithic Integrated Circuit.
MIS Management Information System. An organized assembly of resources that collects, processes, and distributes data.
MMC MultiMediaCard. A compact, removable standard for storing and retrieving digital information in small, low-power devices. MultiMediaCards use flash technology for reusable recording, and ROM technology for read-only applications.
Modulator/Demodulator A device used to convert digital signals into analog signals suitable for transmission over analog communications channels and/or recover digital signals from analog signals.
MPLS Multi-Protocol Label Switching.
MSOH Multiplexer Section Overhead. Part of an SDH frame.
MSPP Multi Service Provisioning Platform
MSU Multiplexer Switching Unit.
MTBF Mean Time Between Failure. The average time (usually expressed in years) over which a component operates without failure.
MTBO Mean Time Between Outages. A function of MTBF, MTTR and the probability that the monitoring circuits detect a failure. The only circuits considered in the MTBO calculations are the ones that impact traffic.
MTR Mean Time to Restore.
MTTR Mean Time to Repair. The average time taken to repair or replace a failed device.
Multiplex A multiplexer sends/receives two or more signals over the same channel.
Mute When a transmitter is muted, it is prevented from transmitting.
MUX Multiplexer. A device that combines two or more information-carrying channels for transmission over one channel, by using frequency division or time division techniques.
N
Native Ethernet The process used to map Ethernet over a transport media whereby the Ethernet format and its structure are retained ?untouched? during transmission. This is distinct from the mechanism of encapsulation, where Ethernet frames are encapsulated within other formats such as E1/DS1, E3/DS3 or SDH/SONET frames.
NBI North Bound Interface.
NE Network Element.
NEL Network Elements Level in the TMN model.
NMI Network Management Interface.
Network Operator The organization responsible for installing and maintaining a radio network.
NML Network Management Level in the TMN model.
NMC Network Management Centre.
NMS Network Management System.
NOC Network Operations Center.
Node A network device or device-grouping that is mid-point in a network, as distinct from a terminal device that is at the end/edge of a network.
Nonprotected A 1+0 configuration in which there is only one set of equipment.
O
O&M Overhead and Maintenance.
Object Class The object class identifies the radio type to which the object belongs.
Object Group A group of network elements created using user-defined selection criteria.
OC-n Optical Carrier Level n. The optical signal that results from an optical conversion of a synchronous transport signal n (STS-n). This is the signal that will form the basis of the interface.
ODU Outdoor Unit. ODU generally refers to the outdoor transceiver unit that is co-located with an antenna in a split-mount radio system.
OEM Original Equipment Manufacturer
OFDM Orthogonal frequency-division multiplexing (OFDM) — essentially identical to Coded OFDM (COFDM) and Discrete multi-tone modulation (DMT) — is a frequency-division multiplexing (FDM) scheme utilized as a digital multi-carrier modulation method. A large number of closely-spaced orthogonal sub-carriers are used to carry data. The data is divided into several parallel data streams or channels, one for each sub-carrier. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth.
Ohm The unit of electrical resistance. A potential difference of one volt across a circuit resistance of 1 ohm produces a current of one ampere.
OMM Optical Multimode
OSM Optical Single Mode
Orderwire An auxiliary communications channel provided for use by maintenance and service personnel, typically allowing both voice and/or data transmission between radio terminals.
Oscillator An electronic circuit designed to produce an ideally stable alternating voltage or current.
OSI Open Systems Interconnection
OSPF Open Shortest Path First. An OSI layer 3 dynamic routing protocol.
OSS Operations Support System.
P
PA Power Amplifier.
PAM Pulsed Amplitude Modulation.
Path A radio path refers to the path traversed by the signal between two radios.
PBT Provider Backbone Transport.
PCA Printed Circuit Assembly.
PCB Printed Circuit Board.
PCM Pulse-code Modulation. Modulation in which a signal is sampled, quantized and then digitized for transmission. PCM is the basic method of encoding an analog voice signal into digital form using8-bit samples.
PCR Paperless Chart Recorder. A software based diagnostic tool that stores operational data from a remote radio and provides view capability to the user.
PCS Personal Communications Service. A set of capabilities that provides a combination of terminal mobility, personal mobility, and service profile management.
PDA Personal Digital Assistant
PDH Plesiosynchronous Digital Hierarchy. A multiplexing scheme of bit stuffing and byte interleaving. It multiplexes the lower level 64 kbit/s circuits into a successively higher order 2 Mbit/s, 34 Mbit/s, 140 Mbit/s and 565 Mbit/s aggregate rates.
PDU Protocol Data Unit.
Ping A message used to determine whether an IP address is accessible on a network.
PIU Plug-In Unit
PLL Phase-locked Loop. A circuit that controls an oscillator so that it maintains a constant phase angle relative to a reference signal.
PLT Party Line Telephone.
PM Performance Management.
PMA Protection Multiplex Adaptor.
PN Part Number.
Pointer A part of the SDH/SONET overhead that locates a floating payload structure.
Ppm Parts per million.
PPP Point-to-Point Protocol. A TCP/IP routing protocol that allows communications over serial communications lines without the use of other adapters, such as modems.
PRBS Pseudo-Random Binary Sequence.
PRC Primary Reference Clock.
PROM Programmable Read Only Memory.
Protection Switch A unit that controls protection switching in hot-standby, diversity or ring protected devices.
Proxy An entity that performs information preparation and exchange on behalf of a device it is representing.
PRS Primary Reference Source
PSTN Public switched telephone network.
PSU Power Supply Unit.
P-VLAN Provider VLAN.
PW Pseudo-Wire.
Q
QAM Quadrature Amplitude Modulation. A method of modulating digital signals using both amplitude and phase coding.
QoS Quality of Service.
QPSK Quadrature Phase Shift Keying. A method of modulating digital signals using four phase states to code two digital bits per phase shift.
R
RAC Radio Access Card.
RFI Radio Frequency Interference.
RAS Remote Access Server.
RCS Reverse Channel Switching. A feature set that provides protection against potential far-end transmitter silent failure.
RDI-L Remote Defect Indication - Line.
Restricted Area A location qualified in accordance with IEC Standard 60950-1 as providing an access that can only be gained by Skilled Persons or users who have been instructed about the reasons for the restriction applied to the location and about any precautions to be taken; and access achieved through the use of a Tool, lock and key, or other means of security, and is controlled by the authority responsible for the location.
RF Radio Frequency.
RFCOH Radio Frame Complementary Overhead. Refers to data that is added to a data transmission unit.
RFU Radio Frequency Unit.
Rigger The member of the radio installation team responsible for installing the antenna and cabling on the transmission tower.
RIM Radio Interface Module
RIP Routing Information Protocol. An OSI layer 3 dynamic routing protocol.
RMA 1) Return Material Authorization; 2) Radio Modem Adaptor
RMS Rack Mounting Space.
Router A layer 3 network device that interconnects networks. It directs data between two or more networks using information held in the IP header to decide whether to foward a packet, and over which network interface to send a packet, for it to reach its destination.
Routing Protocol A protocol used between routers to exchange routing information. OSPF and RIP are the two most common dynamic routing protocols.
RPC Radio Processing Card.
RPR Resilient Packet Ring.
RS Revertive Switching. A process that sends traffic back to the original working system after the system returns online.
RSL Received Signal Level. The signal level at the receiver input (from the antenna). RSL is usually expressed in dBm.
RSOH Regenerator Section Overhead. Part of an SDH frame.
RSSI Received Signal Strength Indicator. The raw indicator of signal level at the receiver input (from the antenna). Usually expressed as a voltage, RSSI is usually converted to dBm and presented as an RSL.
RSTP Rapid Spanning Tree Protocol.
RU Rack Unit, 1 standard EIA rack unit (44.5 mm / 1.75 inch)
Rx Receive.
S
SAW Surface Acoustic Wave (filter).
SASE Stand Alone Synchronisation Element
SD Space Diversity.
SDH Synchronous Digital Hierarchy. An international standard for synchronous data transmission. SDH uses a multiplexing structure that enables direct access to individual 2 Mbit/s data streams from within the higher order aggregate line signals.
SDLC Synchronous Data Link Control. A bit-oriented, full-duplex serial protocol that has spawned numerous similar protocols, including HDLC and LAPB.
Service Provider An organization providing ethernet service(s).
SES Severely Errored Seconds.
SESR Severely Errored Second Ratio.
SI System International units.
SNMP Simple Network Management Protocol A networking management protocol used to monitor network-attached devices. SNMP allows messages (protocol data units) to be sent to various parts of a network. Upon receiving these messages, SNMP-compatible devices (agents) return data stored in their Management Information Bases.
Skilled Person A skilled person in the microwave radio installation and maintenance industry is considered to have the necessary knowledge and practical experience of electrical and radio engineering to competently and safely carry out their work. They must have a full understanding of the various hazards that can arise from working on and around radio installations and be competent to take responsibility for their safety and the safety of any other personnel under their immediate supervision.
SLA Service Level Agreement. A contract between a subscriber and an (ethernet) service provider specifying the agreed upon service level commitments and related business agreements.
SLIP Serial-Line Internet Protocol.
SLS Service Level Specification.
SMA Services Management Adaptor.
SML Service Management Level in the TMN model.
SMS Short Message Service.
SNCP Subnetwork Connection Protection. Designates path-switched SDH rings that employ redundant, fiber-optic transmission facilities. Organized in pairs, one fiber transmits in one direction while the backup fiber transmits in the other. If the primary ring fails, the backup takes over.
SNR Signal-to-noise ratio.
SONET Synchronous Optical Network. An ANSI standard for synchronous data transmission on optical media that is the equivalent of SDH, described above.
Space Diversity A protection mode. The main and standby radios are set up in Hot Standby mode, but are connected to their own antennas. Both antennas, separated by a specific distance, are receiving the signal transmitted from the online radio at the other end of the link. If a fault occurs in the receiving end of the link, the traffic is switched to the standby radio without causing errors (hitless receive switching). As in Hot Standby mode, a fault detected in the online transmitter causes that transmitter to mute and the standby transmitter to unmute.
SSC Software-Software Compatibility.
SSL Secure Sockets Layer.
SSU Synchronisation Supply Unit
Static Routing Static routing requires manual configuration of the routing table within Layer 3 routers. Data is forwarded within a network via a fixed path defined by the static routes - it cannot adjust to changing line conditions, unlike dynamic routing.
STDM Statistical Time Division Multiplexing. Time slots are assigned to signals dynamically to make better use of bandwidth.
STM-0 ITU digital signal level used in Synchronous Digital Hierarchy (SDH) equivalent to a 51.84 Mbps data rate.
STM-1 ITU digital signal level used in Synchronous Digital Hierarchy (SDH) equivalent to a 155.52 Mbps data rate.
STM-N Synchronous Transport Module-level N (Nx155.52 Mbps) where N = 1, 4, 16 or 64.
STP Spanning Tree Protocol.
STS-N Synchronous Transport Signal-level N (Nx51.84 Mbps) where N = 1, 3, 12, 48, or 192.
Subnet A portion of a network sharing a particular subnet address.
Subnet Mask A 32-bit combination used to describe which portion of an address refers to the subnet and which part refers to the host.
SU Switch Unit.
SWR Standing Wave Ratio.
T
T-R Spacing The difference in MHz between transmit and receive frequencies for duplex radios.
T1 A digital carrier system for DS1 signals. T1 is a term for a digital facility used to transmit a DS1 formatted digital signal at 1.544 megabits per second. The 'T' is about the carrier facility and the 'DS' is about the signal format, which includes the muxed relationship between DS0, DS1, DS2, and DS3.
T3 T3 is a term for a digital facility used to transmit a DS3 formatted digital signal at 44.7 megabits per second. The 'T' is about the carrier facility and the 'DS' is about the signal format, which includes the muxed relationship between DS0, DS1, DS2, and DS3.
TAE Transversal Adaptive Equalization.
TCP/IP Transmission Control Protocol/Internet Protocol. Protocols that define connectivity across computer platforms interconnected via the Internet. The TCP protocol is responsible for an error free connection between two computers, while the IP protocol is responsible for the data packets sent over the network.
TCM Trellis-Coded Modulation. A bandwidth-efficient scheme that combines error-correction coding with modulation. The redundancy thus introduced by the coding does not expand the bandwidth, since the parity bits are absorbed by the extended signal constellation. Two-dimensional (2D) TCM uses dependency between in-phase and quadrature symbols, while four-dimensional (4D) TCM introduces dependency between symbols of two successive intervals.
TCXO Temperature Controlled Crystal Oscillator.
TDM Time Division Multiplexing. Examples of TDM services include Nx64 k/bits, DS1, DS3, E1, E3, OC3, STM1, OC12, and STM3.
TELNET A terminal emulation program for TCP/IP networks such as the Internet. The Telnet program runs on your computer and connects your PC to a server on the network. You can then enter commands through the Telnet program and they will be executed as if you were entering them directly on the server console. This enables you to control the server and communicate with other servers on the network. To start a Telnet session, you must log in to a server by entering a valid username and password. Telnet is a common way to remotely control Web servers.
TFTP Trivial File Transfer Protocol.
TIM Tributary Interface Module.
TMN Telecommunications Management Network.
Tombstone A database stored in non volatile memory.
Trap A program interrupt, usually caused by some exceptional situation in the user program. In most cases, the operation system performs some action, then returns control to the program. Used for event notification with SNMP.
Tree View Transistor-Transistor Logic. It is often applied to a network where the core of the network is the trunk, and the various end-user connections are the leaves.
Trib Tributary.
TTL A common semiconductor technology for building discrete digital logic integrated circuits. It originated from Texas Instruments in 1965.
Tx Transmit.
U
UDP/IP Universal Datagram Protocol/Internet Protocol. Used primarily for short, broadcast messages, such as for SNMP messaging. UDP does not guarantee reliability or ordering in the way that TCP does. Datagrams may arrive out of order, appear duplicated, or go missing without notice. Avoiding the overhead of checking whether every packet actually arrived makes UDP faster and more efficient than TCP, at least for applications that do not need guaranteed delivery. Time-sensitive applications often use UDP because dropped packets are preferable to delayed packets.
UNI The UNI is the physical interface or port that is the demarcation between the customer and the service provider.
UTC Coordinated Universal Time. A time format used when a time zone independent time and date is required. Identical to Greenwich mean time (GMT) for most purposes.
V
V.24 Serial data communication interface. Also called RS-232.
VC Virtual Container.
VCO Voltage Controller Oscillator. An electronic circuit designed to produce an ideally stable alternating voltage.
Vdc Volts, direct current.
VDE Video Display Emissions.
VF Voice Frequency signal.
VGA Video graphics array. A display standard for IBM PCs.
Viterbi Viterbi is “convolutional code” which is used in data correction circuits. It operates on serial data, one or a few bits at a time, unlike block codes such as Reed-Solomon, which operate on relatively large message blocks (typically greater than 100 bytes).
VLAN Virtual Local Area Network.
VLAN ID VLAN Identifier
VLSI Very Large Scale Integration.
VCO Voltage Controlled Oscillator.An electronic circuit designed to produce an ideally stable alternating voltage.
VPLS Virtual Private LAN Service.
VPN Virtual Private Network.
VSWR Voltage Standing Wave Ratio.
VT100 A port on the IDU for making a connection to the NMI card.
W
WAN Wide-area Network. A network that provides telecommunication services to a geographic area larger than that served by a local area network or a metropolitan area network.
WAP Wireless Application Protocol.
WMT Web-based Maintenance Terminal.
WR-xx The designation for a specific size of waveguide used to transmit the microwave RF signal.
X
XPD Cross-Polar Discrimination.
XPIC Cross Polarized Interference Cancellation
1-9
1+1 protected system Two transceivers are used at each end of a link to protect against transmission failure. If a data transmission fails on the operating transceiver, it is transferred to the backup transceiver. With a 1+1 protected microwave radio link, the protection mechanism normally allows receiver switching independently of the transmitter, and vice-versa.
1U Standard Electronic Industries Association size for a single rack unit (44.5 mm / 1.75 in.)
