Communications - Glossary
This glossary covers telecommunications terms and acronyms including company and
product specific terminology.
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2G
Second Generation Back to Top |
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3G
Third Generation Back to Top |
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3GPP
Third Generation Parnership Project (ETSI) Back to Top |
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AAL1
ATM Adaptation Layer, type 1 Back to Top |
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AAL2
ATM adaptation layer type 2 Back to Top |
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AAL5
ATM adaptation layer type 5 Back to Top |
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AALn
ATM Adaptation Layer n. Methods associated with formatting information into ATM cells. AAL1 is used for real-time constant bit rate serices, AAL2 for real-time variable bit rate services and AAL5 for packetized data. Back to Top |
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ABIS
The interface between the BTS and the BSC within a GSM architecture, usually configured using a 16kbps slot structure Back to Top |
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ABR
Available Bit Rate Back to Top |
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Access Control
Network managers define access control by requiring authentication of the user's identity before permitting or limiting entry to a computer network or server. Back to Top |
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ACTS
Automated Computer Time System, a NIST service that provides announced time via telephone. Back to Top |
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ADM
Add-Drop Multiplexer Back to Top |
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ADSL
Asymmetric Digital Subscriber Line. ADSL delivers more bandwidth downstream (from CO to customer) than upstream and is largely used in cost-sensitive consumer applications. Compare against SHDSL, SDSL, HDSL and VDSL Back to Top |
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Advanced Encryption Standard (AES)
Developed by NIST and private companies, this standard is 256-bit based and thus presents a strong defense for sensitive material Back to Top |
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Aging
The systematic change in frequency of an oscillator with time. Back to Top |
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AIS
Alarm Indication Signal Back to Top |
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AM
Amplitude modulation (AM) is a method of impressing information onto a carrier waveform. Back to Top |
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AMI
Alternate Mark Inversion Back to Top |
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AMPS
Advanced Mobile Phone Service. A standard system for analog signal cellular telephone service in the US and other countries. Back to Top |
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ANSI
ANSI (American National Standards Institute) is the primary organization for fostering the development of technology standards in the United States. Back to Top |
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API
Application Program Interface. This interface allows software developers to write their software so that it can communicate with the computer's operating system or other programs. Back to Top |
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APON
ATM-Asynchronous Transfer Mode, Passive Optical Networking. Back to Top |
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ASCII
American Standards Code Information Interchange, a code in which alphanumeric characters are represented as eight-digit binary numbers. Back to Top |
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ATIS
Alliance for Telecommunications Industry Solutions Back to Top |
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ATM
Asynchronous Transfer Mode. A technique for packetizing infomration into fixed length cells. These cells are made up of 53 octets of which 5 comprise a 'header' and 48 carry information. ATM supports statistical multiplexing, allowing multiple cell-streams to share a transmission pipe efficiently. Back to Top |
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AuC
Authentication Center Back to Top |
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Authentication
Method by which a person is verified to be who they say they are, by password or other means. Back to Top |
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Authorization
Method by which an authenticated person is allowed certain access to the system, via password or other means. Back to Top |
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AV
Analog Video or Audio Visual Back to Top |
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B-ICI
Broadband Inter-Carrier Interface Back to Top |
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B-ISDN
Broadband Integrated Services Digital Network Back to Top |
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B8ZS
Bipolar with 8 Zero Substitution Back to Top |
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BCD
Binary Coded Decimal. Also called packed decimal, this is the representation of each digit of a decimal number by four-bit binary numbers. So the number 29 would be encoded as 0010 1001. Back to Top |
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BER
Bit Error Rate Back to Top |
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BIPM
The averaging and steering of TAI is done by the Bureau International des Poids et Mesures (BIPM). Back to Top |
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BITS
Building Integrated Timing Supply, also known as a Synchronization Supply Unit (SSU) or Stand Alone Synchronization Equipment (SASE). Back to Top |
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BootP
Bootstrap Protocol Back to Top |
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BPON, WDM
Wave Division Multiplexing, Passive Optical Networking. Back to Top |
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BPV
Bi-Polar Violation Back to Top |
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BRI
Basic Rate Interface. See ISDN Back to Top |
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BSC
Base Station Controller Back to Top |
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BSS
Base Station Subsystem Back to Top |
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BTS
Base Transceiver Station Back to Top |
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C2P
Circuit to Packet Back to Top |
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CA
Certificate Authority/Certification Authority. This type of organization or company issues certificates that state the authenticity of the parties involved in an exchange or agreement, much like a notary public. The certificate also contains keys and other security information. Back to Top |
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CAS
Channel Associated Signaling Back to Top |
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CBO
Cesium Beam Oscillator. A highly-precise frequency source. Also known as a cesium clock or cesium atomic standard. Back to Top |
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CBR
Constant Bit Rate Back to Top |
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CBT
Cesium Beam Tube. The key component of a cesium-based atomic clock. Back to Top |
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CC
Composite Clock Back to Top |
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CCITT
Consultative Committee for International Telegraph and Telephone. International organization repsonsible for the development of communications standards. Now called the ITU-T. Back to Top |
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CCS
Common Channel Signaling. Signaling system used in telephone networks that separates signaling information from user data. Back to Top |
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CCS7
Common Channel Signaling, version 7 Back to Top |
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CD
Carrier Detect. A signal that indicates whether an interface is active. Also, a signal generated by a modem indicating that a call has been connected. Back to Top |
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CDMA
Code Division Multiple Access. A technique of multiplexing, also called direct sequence spread spectrum, in which bit streams are amplitude modulated onto pseudo-random chip streams. Back to Top |
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CDMA2000
3rd Generation Code Division Multiple Access Back to Top |
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CDSA
Common Data Security Architecture. This describes the security structure for the entire network. It is unique to each network because security is managed differently for each. Back to Top |
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CeNTU
Circuit emulation Network Termination Unit Back to Top |
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Certificate
Often called "digital certificates", this is a credential that includes security information and keys. Back to Top |
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Certificate Authority
Independent organization or vendor that acts as a notary, verifying the identification of involved parties, and issues certificates that contain identifying data. Back to Top |
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Certificate Extension
An extension of the X.509 standard that lets the certificate hold additional identifying information. Back to Top |
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Certificate Request Message
A certificate request message is composed of the certificate request along with other identifying data. Back to Top |
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Certification Path
A specified sequence of issued certificates necessary for the user to get their key. Back to Top |
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Certification Policy
This is how a CA defines its process for a user to obtain a certificate. Back to Top |
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Certification Revocation List
A CA maintains a list of certificates that have been cancelled but remain unused; revocation lists are vital when certificates have been stolen, for example. Back to Top |
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CES
Circuit Emulation Services Back to Top |
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CEV
Controlled Environment Vault Back to Top |
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chip
The carrier waveform in a DSSS is akin to a bit stream. Each 'bit' is called a chip to distinguish it from an information bit. Back to Top |
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CLE
Customer Located Equipment Back to Top |
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CLEC
Competitive Local Exchange Carrier Back to Top |
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Clock
Generator of frequencies which will be used to synchronize a network Back to Top |
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CMIP
Common Management Interface Protocol Back to Top |
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CMISE
Common Management Information Service Element Back to Top |
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CMTS
Cable Modem Termination System Back to Top |
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CN
Core Network Back to Top |
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CO
Central Office Back to Top |
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COFA
Change Of Frame Alignment Back to Top |
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Confidentiality
Keeping secret data from unauthorized eyes. Back to Top |
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Content Filtering
A filter that screens out data by checking, for example, URLs or key words. Back to Top |
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Coordinated Universal Time (UTC)
See UTC Back to Top |
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COTS
Commercial Off-The-Shelf. Products or services that are generally available and not built to customized specifications. Back to Top |
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cPCI
Compact Peripheral Component Interconnect - a bus standard Back to Top |
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CPE
Customer Premises Equipment Back to Top |
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CRC
Cyclic Redundancy Check Back to Top |
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Credential(s)
Much like a photo ID or birth certificate, electronic credentials (certificates) are recognized as proof of a party's identity and security level. Back to Top |
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CRM
See Certificate Request Message Back to Top |
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CRNC
Controlling RNC Back to Top |
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Cross-Certificate
Two or more CAs which issue certificates (cross-certificates) recognized in each others' domains. Back to Top |
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Cryptography
The method of encoding data so it can be accessed only by authorized individuals. See also: Encryption Back to Top |
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CSU
Customer Service Unit Back to Top |
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CSU/DSU
A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device that converts a digital data frame from a local area network (LAN) into a frame appropriate to a wide-area network (WAN) and vice versa. Back to Top |
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CWDM
Coarse wave-division multiplexing. An alternative enterprise access method. Back to Top |
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CWTS
China Wireless Telecommunications Standard Back to Top |
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D-AMPS
Digital AMPS Back to Top |
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Data Encryption Standard (DES)
Encryption method in which both the sender and receiver of a message share a single key that decrypts the message. Back to Top |
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DCLS
Direct Current Level Shift, or digital IRIG. Back to Top |
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Decryption
The transformation of unintelligible data ("ciphertext") into original data ("clear text"). Back to Top |
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Denial of Service
When a network is flooded with traffic, the systems cannot respond normally, so service is curtailed or denied. This is a favorite technique of network saboteurs. Back to Top |
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DES
Data Encryption Standard. Encryption method in which both the sender and receiver of a message share a single key that decrypts the message. Back to Top |
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DGPS
Differential Global Positioning System Back to Top |
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DHCP
Dynamic Host Configuration Protocol. Router or server software that assigns an IP address to each node in a network. Back to Top |
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Diffie-Hellman
A key-agreement algorithm used to create a random number that can be used as a key over an insecure channel. Back to Top |
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Digital Certificate
Digital Certificates are issued by a Certificate Authority, which verifies the identification of the sender. The certificate is attached to an electronic message, so the recipient knows the sender is really who they claim to be. Back to Top |
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Digital Fingerprint
Similar to digital signature, a digital fingerprint is the encryption of a message digest with a private key. Back to Top |
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Digital Signature
Like a digital certificate, a digital signature is verified by a Certificate Authority, and is attached to an electronic message so that it verifies that the sender is really who they claim to be. The difference between a digital certificate and a digital signature is found in how the message is encrypted and decrypted. Back to Top |
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Digital Signature Algorithm (DSA)
The asymmetric algorithm that is at the core of the digital signature standard. Back to Top |
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Digital Signature Standard (DSS)
A National Institute of Standards and Technology (NIST) standard for digital signatures, used to authenticate both a message and the signer. DSS has a security level comparable to RSA (Rivest-Shamir-Adleman) cryptography, having 1024-bit keys. Back to Top |
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Digital Time Stamp
See Time Stamp Back to Top |
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Directory
The directory is the storage area for network security information such as keys or server names. Back to Top |
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DLC
Digital Loop Carrier Back to Top |
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DOCSIS
Digital Subscriber Line Access Multiplexer Back to Top |
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DOS
Disk Operating System Back to Top |
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DPLL
Digital Phase-Locked Loop Back to Top |
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DPRAM
Dual Port RAM Back to Top |
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DS-n
Digital Signal at level n (e.g., DS-1, DS-3, etc.) used in the US and Japan Back to Top |
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DS0
Digital Signal, level 0 Back to Top |
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DS1
Digital Signal, level 1 Back to Top |
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DS2
Digital Signal, level 2 Back to Top |
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DS3
Digital Signal, level 3 Back to Top |
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DSA
Digital Signature Algorithm. DSA is a public-key method based on the discrete logarithm problem. Back to Top |
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DSLAM
A Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and puts the signals on a high-speed backbone line using multiplexing techniques. Back to Top |
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DSS
Digital Signature Standard. A National Institute of Standards and Technology (NIST) standard for digital signatures, used to authenticate both a message and the signer. DSS has a security level comparable to RSA (Rivest-Shamir-Adleman) cryptography, having 1024-bit keys. DSA is the Digital Signature Standard. Back to Top |
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DSSS
Direct Sequence Spread Spectrum. See CDMA. Back to Top |
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DSU
Data Service Unit Back to Top |
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DSX-n
Digital Signal Cross-Connect level n Back to Top |
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DUS
Do not Use for Sync Back to Top |
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DWDM
Dense Wavelength Division Multiplexing Back to Top |
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DXC
Digital Cross Connect Back to Top |
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E-n
Digital Signal at level n (e.g., E-1, E-2. E-3, etc.) used in Europe Back to Top |
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E1
E1 (or E-1) is a European digital transmission format devised by the ITU-TS and given the name by the Conference of European Postal and Telecommunication Administration (CEPT). It's the equivalent of the North American T-carrier system format. Back to Top |
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E911
Enhanced 911. Specification that requires the ability to estabish the physical location of a mobile handset when transmitting to/from a wireless base station. Back to Top |
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EDGE
Enhanced Data rates for GSM Evolution Back to Top |
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EFM
Ethernet in the First Mile. General discussion surrounding the use of Ethernet prototol as the terminating technology to the home. Back to Top |
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EIR
Equipment Identity Register Back to Top |
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Element Manager (ENMTMS)
Software that manages the components of an application. Back to Top |
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EMC
Electro-Magnetic Compatibility Back to Top |
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EMI
Electro-Magnetic Interference Back to Top |
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Encryption
The transformation of clear data (clear text) into unintelligible data (ciphertext). Back to Top |
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ENMTMS
See Element Manager Back to Top |
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EOC
Embedded Operation Channels. Part of the SHDSL specification Back to Top |
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Ephemeris
Time obtained from observing the motion of the moon around the earth. Back to Top |
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EPON
Ethernet Passive Optical Networking. Back to Top |
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ESD
Electro-Static Discharge Back to Top |
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ESF
Extended Superframe Format Back to Top |
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ETSI
European Telecom Standards Institute Back to Top |
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Eurocard
European Packaging Specifications (IEC 60297, IEEE 1101.1, IEEE 1101.10, IEEE 1101.11) Back to Top |
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FCC
Federal Communications Commission - The US Government bureau responsible for regulating the communications industry Back to Top |
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FDD
Frequency Division Duplex Back to Top |
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FDL
Facility Data Link Back to Top |
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FDM
Frequency-division multiplexing (FDM) is a scheme in which numerous signals are combined for transmission on a single communications line or channel. Each signal is assigned a different frequency (subchannel) within the main channel. Back to Top |
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FDMA
Frequency Division Mutiple Access Back to Top |
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FIFO
First In First Out Back to Top |
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FIPS
Federal Information Processing Standards. These are a set of standards for document processing and for working within documents. Some commonly-used FIPS standards are 140-1, -2, -3, and -4, and 180. Back to Top |
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Firewall
Software and hardware systems that protect an internal network from outside data that could be harmful to the network, such as a virus sent via the Internet. Back to Top |
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FM
Fault Management Back to Top |
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FN
Fiber Node Back to Top |
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FTP
File Transfer Protocol Back to Top |
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FTTC
Fiber to the Curb. Using fiber transmission up to customer premises. Back to Top |
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FTTH
Fiber to the Home Back to Top |
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FWA
Fixed Wireless Access Back to Top |
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G.shdsl
See SHDSL Back to Top |
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Galileo
A satellite-based radio navigation system run by the European Space Administration (ESA), the European Commission and the European Organization for the Safety of Air Navigation. Using 27 satellites and three spares, Galileo is expected to be complete Back to Top |
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GDOP
Geometric Dilution of Precision Back to Top |
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GGSN
Gateway GPRS support node Back to Top |
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GHz
A GigaHertz is one billion (109) cycles per second Back to Top |
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GLONASS
Glonass is a Soviet space-based navigation system comparable to the American GPS system. The operational system contains 21 satellites in 3 orbital planes, with 3 on-orbit spares. Glonass provides 100 meters accuracy with its C/A (deliberately degraded) signals and 10-20 meter accuracy with its P (military) signals. Back to Top |
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GMT
Greenwich Mean Time, the mean solar time of the meridian of Greenwich, England. This was the primary basis for calculating standard time throughout the world until 1972 when it was superceded by UTC. Back to Top |
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GOS
Grade Of Service Back to Top |
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GPIB
General Purpose Interface Bus, IEEE 488 Back to Top |
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GPRS
General Packet Radio Service Back to Top |
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GPS
Global Positioning System. Originally designated the NAVSTAR (Navigation System with Timing And Ranging) Global Positioning System, GPS was developed by the US Department of Defense to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces. Back to Top |
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GSM
GSM (Global System for Mobile communication) is a digital mobile telephone system that is widely used in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephone technologies (TDMA, GSM, and CDMA). Back to Top |
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Hack/crack
"Hackers" are unauthorized programmers who write code that enables them to break into a computer network or program. "Crackers" are unauthorized programmers whose goal it is to break into computer networks or programs protected by security software or hardware. Back to Top |
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HAE
Host Application Equipment Back to Top |
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Hash
Also called "hash function" or hashing, used extensively in many encryption algorithms. Hashing transforms a string of characters usually into a shorter, fixed-length value or key. Back to Top |
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HDB3
High-Density Bipolar of order 3 Back to Top |
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HDSL
High-data-rate Digital Subscriber Line. A DSL technology that delivers 1.544 Mbps each way (symmetrically) over two copper twisted pairs. Compare against SHDSL, SDSL, ADSL and VDSL Back to Top |
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HDT
Host Digital Terminal Back to Top |
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HE
Head-End Back to Top |
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HFC
Hybrid Fiber Coax (SMFCB) Back to Top |
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HLR
Home Location Register Back to Top |
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Holdover
When a clock that is locked to a PRS-traceable input loses that input, it enters a holdover mode where the frequency drift is related to the quality, or stratum level, of its oscillator. Back to Top |
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HSCSD
High Speed Circuit Switched Data Back to Top |
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HTML
HyperText Markup Language, the computer language used to create pages for the World Wide Web. Back to Top |
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HTTP
HyperText Transfer (or Transport) Protocol, the protocol most often used to transfer information from World Wide Web servers to users of the Web. Back to Top |
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Hz
Hertz. A measure of frequency relating to cycles per second. Back to Top |
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IAD
Integrated Access Device. CPE (customer premises equipment) that terminates xDSL, ISDN, T1 or other transmission protocol. Back to Top |
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Identity Certificate
The hash creates a message digest based on the contents of the message. The message is then encrypted using the publisher's private key, then it is appended to the original message. Back to Top |
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IEC
Inter-exchange Carrier Back to Top |
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IEEE
Institute of Electrical and Electronic Engineers, an international organization that sets standards for electrical and computer engineering. Back to Top |
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IETF
Internet Engineering Task Force, an international organization which sets standards for Internet protocols in their Request for Comment (RFC) papers. Back to Top |
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IKE
Internet Key Exchange, a security system that uses a private key and an exchange key that encrypts private keys. Passwords are delivered via the Internet. Back to Top |
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ILEC
Incumbent Local Exchange Carrier. Often referred to as the 'Baby Bells'. Back to Top |
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IMT-2000
International Mobile Telecommunications 2000 Back to Top |
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IN
Intelligent Network Back to Top |
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In-band Authentication
When you use PKI for authentication, it is called in-band authentication. See also: out-of-band authentication. Back to Top |
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Integrity
Data that has retained its integrity has not been modified. Back to Top |
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IP
Internet Protocol Back to Top |
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IPSec
Internet Protocol Security describes the IETF protocols that protect the secure exchange of packets on the IP layer. Back to Top |
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IRIG
The InterRange Instrumentation Group is the IRIG standards steering committee. IRIG is a serial time format standard. Back to Top |
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Irrefutability
In the time security world, irrefutability means the source of the message cannot be disproved. Back to Top |
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ISA
Industry Standard Architecture; desktop PC adapter board specification Back to Top |
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ISDN
Integrated Services Digital Networks. There are two basic types of ISDN service: Basic Rate Interface (BRI) and Primary Rate Interface (PRI). BRI consists of two 64 kb/s B channels and one 16 kb/s D channel for a total of 144 kb/s. PRI is intended for users with greater capacity requirements. Typically the channel structure is 23 B channels plus one 64 kb/s D channel for a total of 1536 kb/s. In Europe, PRI consists of 30 B channels plus one 64 kb/s D channel for a total of 1984 kb/s. Back to Top |
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ITU
International Telecommunications Union, the international organization that sets standards for data communication. Back to Top |
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ITU-T
International Telecom Union -Telecom Standardization Sector Back to Top |
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Iu
Interface Between RNC and CN Back to Top |
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Iub
Interface Between Node B and RNC Back to Top |
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Iur
Interface between two RNCs Back to Top |
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IXC
Inter eXchange Carrier. A long distance telecomunications service provider. Back to Top |
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Jitter
Short-term variations of a timing signal from its ideal positions in time Back to Top |
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JTF
The Jitter Transfer Function (JTF) of a network element indicates the degree to which an output is affected by input jitter (i.e. amplified or attenuated) Back to Top |
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kbit
A kilobit is 1024 or 210 bits Back to Top |
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Key
An alphanumeric string that encrypts and decrypts data. Back to Top |
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Key Escrow
A secure storage maintained by a trusted third party, which holds keys. Back to Top |
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Key Generation
Creation of a key. Back to Top |
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Key Management
The process by which keys are created, authenticated, issued, distributed, stored, recovered, and revoked. Back to Top |
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Key Pair
An integrated pair of keys, one public, one private. Back to Top |
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Key Recovery
A method that allows messages to be decrypted even if the original key is lost. Back to Top |
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kHz
A kilohertz is 1000 cycles per second Back to Top |
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L1 Band, L2 Band
Each Navstar GPS satellite currently transmits in two dedicated frequency bands: L1 and L2, which are centered on 1575.42 and 1227.6 MHz respectively. L1 carries one encrypted signal, as does L2, both being reserved for the military. L1 also carries one unencrypted signal, for civilian use. Back to Top |
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LAN
Local Area Network Back to Top |
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LATA
Local Access and Transport Area - This was created by the 1984 divestiture and defines the geographic area over which the LEC may provide toll calls. The area is often smaller than that covered by a long distance area code. Back to Top |
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LCD
Liquid Crystal Display Back to Top |
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LDAP
The Lightweight Directory Access Protocol allows access to a directory service. Back to Top |
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Leap Second
The time error that accumulates between the earth's rotation and actual measured time is added (or deleted) as a leap second from UTC time on the last day of June or December in any year in which a leap second is needed to keep in step with the rotation of the earth. Back to Top |
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LEC
Local Exchange Carrier Back to Top |
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LED
Light Emitting Diode Back to Top |
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LMU
Location Management Unit. Equipment in a wireless base station that isolates the location of an individual handset. Back to Top |
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Local loop
The part of a telephone line which runs from a subscriber's premises to the telephone company's local exchange Back to Top |
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LORAN-C
LOng RAnge Navigation, version C. A long-range radio navigation position-fixing system consisting of an array of fixed stations that transmit precisely synchronized signals to mobile receivers. Back to Top |
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LOS
Loss Of Signal Back to Top |
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M12
Multiplexer/demultiplexer, DS1 to DS2 Back to Top |
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M13
Multiplexer/demultiplexer, DS1 to DS3 Back to Top |
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M23
Multiplexer/demultiplexer, DS2 to DS3 Back to Top |
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MAC
A Message Authentication Code is a function that takes a variable length input and a key to produce a fixed-length output. Back to Top |
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MAN
Metropolitan Area Network Back to Top |
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Master clock
'A generator which generates an accurate frequency signal for the control of other generators'. Also known as a PRC. Back to Top |
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Mbit
Megabit Back to Top |
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Mbps
Megabits per second. One million bits transmitted each second. Back to Top |
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ME
Mobile Equipment Back to Top |
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Message Digest
The hash of a message. See also Hash. Back to Top |
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MHz
A MegaHertz is one million (1,000,000) cycles per second Back to Top |
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MIB
Management Information Base, a database on the network that tracks, records, and corrects performance for each device on the network. Back to Top |
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MIME
Multimedia Internet Mail Extensions Back to Top |
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MPLS
Multiprotocol Label Switching. A standards-approved technology for speeding up network traffic flow and making it easier to manage. Works with IP, ATM and frame relay. Back to Top |
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MS
Mobile Station Back to Top |
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MSC
Mobile Services switching Center Back to Top |
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MSO
Multisystem Operator. A cable service provider. Back to Top |
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MTBF
Mean Time Between Failure, a measure of reliability. The longer the time span between failures, the more reliable the device. Back to Top |
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MTIE
Maximum Time Interval Error Back to Top |
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MTTR
Mean Time To Repair Back to Top |
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Multiplexing
Process during which two or more signals are combined into one; at the other end, signals are "unbundled" by a demultiplexer. TDM is Time Division Multiplexing, FDM is Frequency Division Multiplexing, and CDMA is Code Division Multiple Access. Back to Top |
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Mxy
Muliplexer/demultiplexer, DSx to DSy (e.g. M12 is DS1 to DS2). Back to Top |
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NE
Network Element Back to Top |
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NEBS
Network Equipment Building Standard Back to Top |
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NEC
National Electrical Code Back to Top |
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Network Synchronization
A generic concept that depicts the way of distributing a common time and/or frequency to all elements in a network. Back to Top |
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NI
Network Interface Back to Top |
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NIST
National Institute of Standards and Technology, the National Measurement Institute in the United States. In the form of FIPS documents, NIST produces standards for security and cryptography. Back to Top |
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NIU
Network Interface Unit Back to Top |
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NLOS
Non-line-of-sight. A term referring to wireless services which don't require a clear open path between sites. Back to Top |
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NMA
Network Maintenance and Analysis (Bellcore) Back to Top |
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NMI
National Measurement Institute(s), the national authority in each country that is recognized as the source of official time. Back to Top |
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NMIServer
National Measurement Institute Server Back to Top |
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NMS
Network Management Software (or System) Back to Top |
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NNI
Network Node Interface Back to Top |
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NOC
A Network Operations Center monitors and manages a network's performance. Back to Top |
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Node B
UMTS base station Back to Top |
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Node Clock
A clock distributing synchronization information to one or more network elements Back to Top |
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Non-repudiatable
The Trusted Time time stamp has an audit trail back to its time source, during which the sender of the transaction is authenticated. Therefore, the sender cannot deny the time of the transaction. Back to Top |
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Notarization
Certification of the identity of the party in a transaction based on identifying credentials. Back to Top |
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ns
A nanosecond is one billionth (10-9) of a second Back to Top |
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NSS
Network Switching Subsystem Back to Top |
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NT1
Network Terminating equipment - type 1 (ISDN) Back to Top |
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NTMS
Network Time Management System Back to Top |
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NTP
Network Time Protocol provides a reliable way of transmitting and receiving time over TCP/IP networks and is useful for synchronizing the internal clock of computers to a common time source. Back to Top |
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OAM
Operations, Administration and Maintenance. Part of the ATM specification Back to Top |
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OAM&P
Operations, Administration, Maintenance & Provisioning Back to Top |
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OC-n
Optical Carrier level n (e.g., OC-1, OC-3, OC-9, OC-12, etc.) Back to Top |
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OCSP
Online Certificate Status Protocol, a method for validating digital certificates and signatures. Back to Top |
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OFDM
Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies. Back to Top |
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OID
Object Identifier Back to Top |
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OLT
Optical Line Termination: a broadband multi-service device that controls the flow of information to and from all subscribers through the optical port. Back to Top |
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Online validation
A way of validating a key each time before it is used to verify that it has not expired or revoked. Back to Top |
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ONT
Optical Network Termination, used in fiber to the home (FTTH) to terminate the optical signal at the customer premise and provide the electrical interface to the customer equipment. Back to Top |
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ONU
Optical Network Unit Back to Top |
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OOF
Out Of Frame Back to Top |
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OPTXS
ATIS Optical Transport and Synchronization Committee (formerly T1X1) Back to Top |
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OS
Operating System Back to Top |
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OSF
Open Systems Foundation Back to Top |
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OSI
Open System Interconnect Back to Top |
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OSI
Operations System Interface Back to Top |
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OSMF
The Open Synchronization Media Framework (OSMF) is a protocol that gives telecom service providers the ability to remotely manage their synchronization networks and isolate synchronization related problems. Back to Top |
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OSS
Operational Support System Back to Top |
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Out-of-band Authentication
When authentication is performed using relatively insecure methods, such as over the telephone, it is called out-of-band authentication. In-band authentication, which uses PKI, is preferred. See In-band Authentication. Back to Top |
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PABX
A private automatic branch exchange (PABX) is an automatic telephone switching system within a private enterprise. Back to Top |
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Passive fiber splitters
devices that are approximately the size of a pen that allow the fiber to be split without a reduction in the bit rate. Back to Top |
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PBX
Private Branch Exchange Back to Top |
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PCI
Peripheral Component Interconnect, a local bus that supports high-speed connection with peripherals. It plugs into a PCI slot on the motherboard. Back to Top |
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PCISIG
PCI Special Interest Group Back to Top |
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PCM
Pulse Code Modulation Back to Top |
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PCS
Personal Communications Services Back to Top |
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PDA
Personal Digital Assistant Back to Top |
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PDH
Plesiochronous Digital Hierarchy Back to Top |
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PDOP
Position Dilution of Precision Back to Top |
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PICMG
PCI Industrial Computer Manufacturers Group Back to Top |
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PKCS
Public Key Cryptography Standards. These standards allow compatibility among different cryptographic products. Back to Top |
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PKI
Public Key Infrastructure. The PKI includes the Certificate Authority (CA), key directory, and management. Other components such as key recovery, and registration, may be included. The result is a form of cryptography in which each user has a public key and a private key. Messages are sent encrypted with the receiver's public key; the receiver decrypts them using the private key. Back to Top |
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PKIX
Extended Public Key Infrastructure, of PKI with additional features approved by the IETF. Back to Top |
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PLB
Private Label Branch Back to Top |
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PLL
Phase-Locked Loop Back to Top |
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PM
Performance Monitoring Back to Top |
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PMC
PCI Mezzanine Card Back to Top |
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Policy
A company's security policy. Back to Top |
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PON
Passive Optical Network Back to Top |
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POP
Point Of Presence Back to Top |
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POTS
Plain Old Telephone Service Back to Top |
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ppm
parts per million Back to Top |
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pps
Pulse per second Back to Top |
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PRC
Primary Reference Clock Back to Top |
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PRI
Primary Rate Interface. See ISDN. Back to Top |
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Primary Reference Source
Equipment that provides the highest quality sync for telecom networking as required by international standards. Typically derive source timing from GPS or CDMA signals or from stand-alone sources such as cesium. Back to Top |
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Private Key
This is a secret key, known to only of the parties involved in a transaction. Back to Top |
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PRN
Psuedo/Random Noise Code Back to Top |
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PRR
Primary Reference Receiver Back to Top |
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PRS
Primary Reference Source Back to Top |
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PSTN
Public Switched Telephone Network Back to Top |
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PTT
Post, Telephone and Telegraph. Government agency (largely outside North America) that provides both local and long distance telephone services. Back to Top |
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Public Key
Messages are sent encrypted with the recipient's public key, which is known to others; the recipient decrypts them using their private key. Back to Top |
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Public Key Certificate
Certificate in the form of data that holds a public key, authentication information, and private key information. Back to Top |
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PVC
Permanent Virtual Circuit Back to Top |
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PXI
PCI eXtensions for Instrumentation Back to Top |
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Qbus
Digital Equipment Corporation Bus Back to Top |
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QoE
Quality of Experience: a subjective term associated with the end user's perception of next generation services. Back to Top |
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QoS
Quality of Service. An expression of transmission error rates, often established by a network policy server. Back to Top |
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RA
A Registration Authority does not issue certificates, but does the required identification for certain certificate data. Back to Top |
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RAM
Random Access Memory Back to Top |
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RAN
Radio Access Network Back to Top |
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Resolution
Resolution of a time code refers to the smallest increment of time, whether it is days, hours, seconds, or other. Back to Top |
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Revocation
The withdrawing of a certificate by a Certificate Authority before its expiration date or time. Back to Top |
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Risk Management
The tasks and plans that help avoid security risk, and if security is breached, helps minimize damage. Back to Top |
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RJ-xx
In the U. S., telephone jacks are also known as registered jacks, sometimes described as RJ-XX, and are a series of telephone connection interfaces (receptacle and plug) that are registered with the U.S. Federal Communications Commission (FCC). RJ-11 is the designation for a common phone jack while RJ-45 is an Ethernet connection. Back to Top |
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RNC
Radio Network Controller for UMTS Back to Top |
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RSA
The RSA (Rivest-Shamir-Andleman) algorithm is used to create digital signatures. Back to Top |
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S/MIME
Secure Multipurpose Internet Mail Extensions. The standard for secure messaging. Back to Top |
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SA
Selective Availability (GPS accuracy limits for civilian users) Back to Top |
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SAASM
Selective Availability Anti-Spoofing Module Back to Top |
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SAN
Storage Area Network Back to Top |
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SASE
Stand-Alone Synchronization Equipment. See BITS. Back to Top |
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Sbus
Sun(TM) Bus Back to Top |
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SDA
Space, Defense and Avionics Back to Top |
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SDH
Synchronous Digital Hierarchy Back to Top |
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SDM
Service Delivery Management (SDM) is network management software that encompasses performance, fault and provisioning measurements. Back to Top |
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SDSL
Single-line Digital Subscriber Line. Non-standard method to deliver 1.544 Mbps (symmetric)over a single copper pair. Compare against SHDSL, HDSL, ADSL and VDSL Back to Top |
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SDV
Switch Digital Video (BMFB or BMFS) Back to Top |
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SEC
SDH Equipment Clock Back to Top |
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SF
Superframe Format Back to Top |
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SGSN
Serving GPRS support node Back to Top |
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SHA-1
Secure Hash Algorithm, which has a larger message digest, making it more secure against certain hacker attacks. Back to Top |
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SHDSL
Symmetric High-speed Digital Subscriber Line. A 2.3 Mbps ISO standard for transmission over one copper wire pair. Generally used for business applications. Compare against HDSL, SDSL, ADSL and VDSL Back to Top |
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Smart Card
A card the size of a credit card, which holds a microprocessor that stores information. Back to Top |
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SMC
SONET Minimum Clock Back to Top |
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SMTP
Simple Mail Transfer Protocol Back to Top |
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SNMP
Simple Network Management Protocol is the Internet standard protocol for network management software. It monitors devices on the network, and gathers device performance data for management information (data)bases ("MIB"). Back to Top |
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SNR
Signal to Noise Ratio Back to Top |
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Solar Time
Time based on the revolution of the earth around the sun. Back to Top |
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SONET
Synchronous Optical NETwork Back to Top |
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SPE
Synchronous Payload Envelope Back to Top |
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SS7
Signaling System 7. Standard CCS system, developed by Bellcore, used with BISDN and ISDN. Back to Top |
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SSL
Secure Sockets Layer, a protocol that allows secure communications on the World Wide Web/Internet. Back to Top |
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SSL Client
Authentication Part of the SSL "handshake" process, when the client responds to server requests for a key. Back to Top |
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SSL Server
Authentication Part of the SSL "handshake" process, when the server informs the client of its certificate (and other) preferences. Back to Top |
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SSL-LDAP
Secure Sockets Layer-Lightweight Directory Access Protocol. Back to Top |
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SSM
Sync Status Messaging Back to Top |
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SSU
Synchronization Supply Unit. See BITS. Back to Top |
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STFP
Sbus Time & Frequency Processor Back to Top |
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STL
Studio-Transmitter Links Back to Top |
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STM-n
Synchronous Transport Module level n Back to Top |
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Stratum Level
The performance levels of frequency sources, or clocks, are classified in terms of stratum levels. Stratum 1, the highest, represents a source with an intrinsic accuracy of better than 1 x 10-11. Other levels defined are Stratum 2E, 2, 3E, 3 and 4 corresponding to lower levels of intrinsic accuracy. Back to Top |
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STS-n
Synchronous Transport Signal level n Back to Top |
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SVC
Switched Virtual Circuit Back to Top |
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SVN
Satellite Vehicle Number Back to Top |
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Sysplex Timer
The Sysplex Timer provides a synchronized Time-of-Day clock for multiple attached computers. Back to Top |
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T1
The T1 (or T-1) carrier is the most commonly used digital line in the United States, Canada, and Japan. In these countries, it carries 24 pulse code modulation (PCM) signals using time-division multiplexing (TDM) at an overall rate of 1.544 Mbps. Back to Top |
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TA
Technical Advisory Back to Top |
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TAI
International Atomic Time, (Temps Atomique International), results from the averaging and coordination of several hundred of the best atomic clocks around the world. Back to Top |
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TCCert
Time Calibration Certificate Back to Top |
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TCG
Time Code Generator Back to Top |
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TCP/IP
A mainstay of the Internet, the Transmission Control Protocol (TCP) provides dependable communication and multiplexing It is connection-oriented, meaning it requires a connection be established data transfer. It sits on top of the Internet Protocol (IP), which provides packet routing. This is connectionless, meaning each data packet has its source and destination data embedded, so it can bounce around a network and still get to its destination. Back to Top |
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TD-CDMA
Time Division-Code Multiple Access Back to Top |
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TDD
Time Division Duplex Back to Top |
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TDEV
Time DEViation Back to Top |
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TDM
Time-division multiplexing (TDM) is a method of putting multiple data streams in a single signal by organizing the composite signal into many segments, each having a very short duration. Each individual data stream is reassembled at the receiving end based on the timing. Back to Top |
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TDMA
Time Division Multiple Access Back to Top |
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TDOA
Time Difference of Arrival. A technique for triangulating on the location of a mobile handset from multiple wireless base stations. Used for E911 services. Back to Top |
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TDOP
Time Dilution of Precision Back to Top |
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Telnet
Telnet is a terminal emulation application protocol that enables a user to log in remotely across a TCP/IP network to any host supporting this protocol. Back to Top |
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TFP
Time & Frequency Processor Back to Top |
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TFTP
Trivial File Transfer Protocol Back to Top |
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TIE
Time Interval Error Back to Top |
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Time Stamp
A record mathematically linking a document to a time and date. Back to Top |
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Time Stamp Request
The client computer or application sends a time stamp request to the stamp server. Back to Top |
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Time Stamping Authority
A third party which provides authenticated time to the security process. Back to Top |
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TL1
Transaction Language 1 Back to Top |
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TLS
Transport Layer Security, security that protects the OSI layer that is responsible for reliable end-to-end data transfer between end systems. Back to Top |
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TMN
Telecommunication Management Network Back to Top |
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TNM
Telecommunications Network Management (AT&T) Back to Top |
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Tool box
A group of software applications that have similar functions. Back to Top |
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TPC
Third Party Certificate. See Certificate. Back to Top |
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TPCA
Third Party Certification/Certificate Authority. See Certificate Authority. Back to Top |
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TR
Technical Reference Back to Top |
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Transaction
An activity, such as a request or an exchange. Back to Top |
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Triple-DES
Also called Triple Data Encryption Algorithm (TDEA) Data Encryption Standard is an algorithm that encrypts blocks of data. Back to Top |
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Trust
In the network security context, trust refers to privacy (the data is not viewable by unauthorized people), integrity (the data stays in its true form), non-repudiation (the publisher cannot say they did not send it), and authentication (the publisher--and recipient--are who they say they are). Back to Top |
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TSA
See Time Stamp Authority Back to Top |
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TSG
Timing Signal Generator. See BITS, SSU. Back to Top |
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TSR
See Time Stamp Request Back to Top |
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TSS
See Time StampServer Back to Top |
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TTL
Transmitter-Transmitter Links Back to Top |
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TVAR
Time VARiance Back to Top |
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UBR
Unassigned or Unknown Bit Rate Back to Top |
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UDP
User Datagram Protocol Back to Top |
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UDP/IP
User Datagram Protocol/Internet Protocol Back to Top |
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UE
User Equipment Back to Top |
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UI
Unit Interval (inverse of a signals' symbol rate) Back to Top |
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UMTS
Universal Mobile Telecommunications Service is a third-generation (3G) broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 Mbps Back to Top |
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USNO
U.S. Naval Observatory, in Washington, D.C., where the atomic clock that serves as the official source of time for the United States is maintained. Back to Top |
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UT1
The time scale derived from the earth's rotation - needed for celestial navigation and surveying Back to Top |
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UTC
The international time standard is called Universal Coordinated Time or, more commonly, UTC, for "Universal Time, Coordinated". This ITU standard has been in effect since 1972. UTC is maintained by the Bureau International de l'Heure (BIH) which forms the basis of a coordinated dissemination of standard frequencies and time signals. Back to Top |
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UTRAN
UMTS Terrestrial Radio Access Network Back to Top |
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Uu
UMTS air interface Back to Top |
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Vault
Secure data storage facility. Back to Top |
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VBR
Variable Bit Rate Back to Top |
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VCXO
Voltage -controlled Crystal Oscillator Back to Top |
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VDSL
Very-high-data-rate Digital Subscriber Line. High speed (13 to 52 Mbps) low range asymetric DSL technology. Compare against SHDSL, SDSL, ADSL and HDSL Back to Top |
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Verification
The process of making sure the identity of the parties involved in a transaction is what they claim it to be. Back to Top |
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VF
Voice Frequency Back to Top |
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ViiP
Video over IP. Similar to Voice over IP but typically at higher and constant bit rates (CBR). Back to Top |
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Virus
An unwanted program that hides "behind" legitimate code, and which is activated when the legitimate program is activated. Back to Top |
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VISA
Virtual Instrument Software Architecture Back to Top |
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VITA
VMEbus International Trade Association Back to Top |
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VLR
Visitor Location Register Back to Top |
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VME
Versa Module Europe; VMEbus specification governed by the VSO Back to Top |
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VOD
Video On Demand Back to Top |
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VoIP
Voice over IP. A set of facilities for managing the delivery of voice information over a packet-switched network. Back to Top |
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VPN
Virtual Private Network, a way that authorized individuals can gain secure access to an organization's intranet, usually via the Internet. Back to Top |
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VPP
VXI Plug & Play Specification Back to Top |
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VSO
VITA Standards Organization Back to Top |
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VT
Virtual Tributary (for SONET systems) Back to Top |
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VXCO
Voltage-controlled Crystal Oscillator Back to Top |
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VXI
VME Extensions for Instrumentation Back to Top |
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W3C
Based at the Massachusetts Institute of Technology (MIT), this international organization creates standards for the World Wide Web. Back to Top |
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WAN
Wide Area Network Back to Top |
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WAP
Wireless Application Protocol, a worldwide standard for applications used on wireless communication networks. Back to Top |
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WCDMA
Wide-band Code Division Multiplex Access Back to Top |
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WML
Wireless Markup Language. An HTML-equivalent for low-bandwidth and/or small screen format wireless phones and PDAs Back to Top |
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WPKI
Wireless Public Key Infrastructure. Back to Top |
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WTLS
Wireless Transport Layer Security Back to Top |
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WWW
World Wide Web Back to Top |
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X.509
The ITU's X.509 standard defines a standard format for digital certificates, the most-widely used PKI standard. Back to Top |
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X.509 v3 Certificate Extension
The X.509 standard with extended features approved by the IETF. Back to Top |
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xDSL
Generic name for the various types of DSL service. See ADSL, HDSL, SDSL, SHDSL and VDSL. Back to Top |
