A General Glossary of Telecommunications Terminology

Transcription

1 1 A General Glossary of Telecommunications Terminology Analog Electronic transmission of voice and data accomplished by adding signals of varying frequency, or amplitude, to carrier waves of a given frequency of alternating electromagnetic current. Dial-up modems utilize analog transmission techniques. Asymmetrical Digital Subscriber Loop (ADSL) One of the two-wire, copper-based Digital Subscriber Line (DSL) technologies which utilizes most of the available channel bandwidth above 4 KHz path to transmit and receive data. It is asymmetric in that it uses most of the available channel bandwidth to transmit downstream to the user and only a small part to receive information from the user. Asynchronous Transfer Mode (ATM) ATM is a layer 2, cell-based, fast-packet networking technology that provides a protocol for transmitting voice, data, and video applications over high-speed networks with access ports beginning at 1.5 MB/s through OC-12. ATM is a connection-oriented technology used in both Local Area Network (LAN) and Wide Area Network (WAN) environments that utilizes a fixed cell size of 53 octets for transmission across the network, and provides various qualities of service depending on the application s needs. Backbone - A network element with a central cabling scheme and/or high speed connections linking multiple network nodes. Bandwidth The transmission rate or the amount of data that can be transferred over a specific connection. High speed connections usually range from at least 256 KB/s per second to more than 10 GB/s per second. Bit - Short for binary digit, the smallest unit of information on a machine. A single bit can hold only one of two values: 0 or 1. A byte is composed of eight consecutive bits. Bits per second (Bps) - Abbreviation of bits per second, the standard measure of digital data transmission speeds. Broadband - Refers to telecommunication that provides multiple channels of data, voice and video over a single communications medium, typically using some form of frequency or wave division multiplexing. When referring to Connect efforts, broadband

2 is minimally defined as symmetrical 1.5 MB/s or asymmetrical > 1MB/s downstream and 384K upstream. Broadband over Power Lines (BPL) An overlay technology that allows Internet data to be transmitted over low and medium voltage utility power lines. Cable (Television) Modem A device that is designed to allow the transmission of data over coaxial cable television lines to achieve fast access to the Internet and provide an Ethernet user interface. Cable Modems utilize an industry standard protocol called Data Over Cable Service Interface Specification (DOCSIS). Similar to Asymmetrical Digital Subscriber Loop (ASDL), cable modems can offer asymmetrical transmission rates of up to 6+ Mbps downstream and up to 384 KB/s upstream depending on network configuration. Central Office (CO) Typically a telephone company building where subscriber lines (local loops) are connected to network switching equipment. The Central Office has voice and data switching equipment that can switch calls and networks locally or to long-distance carrier phone and data lines. It also provides a collocation space for other service providers such as a Competitive Local Exchange Carrier (CLEC). Coaxial Cable A transmission cable composed of an insulated central conductor wrapped in another cylindrical conductor and then wrapped an another insulating, outer protective layer. Coax has the capacity to support very high bandwidth transmission rates. Competitive Local Exchange Carrier (CLEC) - A telecommunications service provider that competes with an Incumbent Local Exchange Carrier (ILEC) such as a Regional Bell Operating Company (RBOC) like Verizon to deliver similar access services. Dial-Up Connection Analog modem technology that uses an existing local telephone line and is limited to the 400 Hz to 4 KHz frequency range and provides transmission rates between 2.4 KB/s and 56 KB/s. Digital Electronic technology that generates, stores, and processes data in terms of two states: positive is represented by the number 1 and non-positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0 s or 1 s. Each of these state digits is referred to as a bit. Digital Subscriber Line (DSL) - A copper-based technology for providing continuously available ("always on") high-bandwidth connection utilizing existing copper telephone lines. Various types of DSL include Asymmetric Digital Subscriber Line (ADSL) a twowire service, and High-bit-rate Digital Subscriber Line (HDSL) a four-wire service (see HDSL). ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. Assuming the home or small business is close enough to a telephone company central office that 2

3 offers DSL service, it may be able to receive data at rates up to 6.1 MB/s megabits (millions of bits) per second. Typically, individual connections will provide from 768 KB/s to 3 MB/s downstream and about 128 KB/s upstream. A DSL line can carry both data and voice signals and the data part of the line is continuously connected to the network. A DSL line is limited by line quality and distance from the Central Office. Depending on the Digital Subscriber Line Access Multiplier (DSLAM) equipment and the line quality, DSL service often may not reach past 20,000 cable feet from the Central Office. Digital Subscriber Line Access Multiplier (DSLAM) The switching equipment located in the Central Office or Remote Terminal that allows for Digital Subscriber Line (DSL) service to subscribers. Not all Central Offices are equipped with DSLAMs. Ethernet (1) a baseband local area network specification invented and developed jointly by Xerox, Intel, and Digital Equipment Corporation. Ethernet networks operate at 10, 100, and 1000 MB/s using Carrier Sense Multiple Access / Collision Detect (CSMA/CD) to run over coaxial, Cat.5, or fiber optic cables; (2) a very common and most preferred method of networking computers in a LAN environment. Fiber Optic Cable - A transmission medium that uses long, thin strands of glass or plastic fibers, rather than copper wire, to transport data or voice signals. The signal is imposed on the fiber via pulses (modulation) of light from a laser or a light-emitting diode (LED). Because of its high bandwidth and lack of susceptibility to interference, fiber optic cable is used in long-haul and local distribution networks. Fiber to the Premises (FTTP) A telecommunications networking service that utilizes fiber to each subscriber to deliver high bandwidth services. Frame Relay (FR) - A layer 2, connection-oriented, packet-switching protocol for connecting devices on a Wide Area Network (WAN). It used Permanent Virtual Circuit (PVC) technology to create point to point, full, and partial mesh connections between FR network nodes. FR networks in the U.S. support data transfer rates at 56 KB/s through 45 MB/s. FR utilizes existing DDS, T-1, and T-3 lines owned by a service provider. Gigabits Per Second (GB/s) A digital transmission speed of a billion bits per second. Gigahertz (GHz) An analog transmission speed of a billion cycles per second. High-bit-rate Digital Subscriber Line (HDSL) A four-wire, symmetrical, copperbased Digital Subscriber Line (DSL) technology with the same upstream and downstream speeds. It has comparable speed to a T-1 and is the most common local loop technology deployed by the local service providers to deliver T1s. Hertz (Hz) The speed or frequency of cycles in an analog transmission. 3

4 Hotspot An access point for a short-range, public wireless broadband access that is often located in populated areas, such as airports, libraries, or hotels. Hub The intelligent wiring center to which all devices, printers, scanners, PCs, etc. are connected within a segment of a local area network (LAN). Incumbent Local Exchange Carrier (ILEC) - A telecommunications service provider such as a Regional Bell Operating Company (RBOC) like Verizon. Integrated Services Digital Network (ISDN) - A set of standards for digital transmission over ordinary telephone copper wire or other media. Home and business users who install an ISDN adapter (in place of a modem) can achieve transmission speeds up to 128 KB/s. ISDN specifies three distinct transmission channels referred to as 2B+D. There are two 64 KB/s bearer channels for data transmission which can be bonded to achieve 128 KB/s, and a 16 KB/s data channel for line control. Internet Service Provider (ISP) A company that provides access to the Internet to subscribers for a fee. Kilohertz (KHz) A measure of analog transmission speed of a thousand cycles per second. Kilobits Per Second (KB/s) - A measure of digital transmission speed of a billion bits per second. Local Area Network (LAN) A network of devices, such as computers, printers and scanners, connected by wires or wireless for a small area, such as a floor, department or small cluster of buildings. A system of LAN s connected are called a Wide Area Network (WAN). Last-mile technology (also known as First-mile technology ) - Any telecommunications technology, such as wireless radio, that carries a signal from the local Central Office along the relatively short distance (hence, the "last mile") to and from the home or business, telecommunications infrastructure at the neighborhood level. In many communities, last-mile technology represents a major challenge to highbandwidth applications such as fast Internet access, with web pages full of multimedia effects, videoconferencing, etc. Local Multipoint Distribution Services (LMDS) - Fixed wireless technology that operates in the 28 GHz band and offers line-of-sight coverage for distances up to 3 to 5 kilometers. At a maximum, it can deliver data and telephony services to 80,000 customers from a single node. LMDS is considered one possible solution for bringing high-bandwidth services to homes and offices within the "last mile" of connectivity, an area where cable or optical fiber may not be convenient or economical. 4

5 Local Exchange Carrier (LEC) - The term for the public telephone company in the U.S. that provides local service. Some of the largest LEC are the Bell Operating Companies (BOC) which were grouped into holding companies known collectively as the Regional Bell Operating Companies (RBOC) when the Bell System was broken up by a 1986 Consent Decree. Local Loop - The link between the subscriber's equipment and the line-terminating equipment in the telephone exchange. Metropolitan Area Network (MAN) A group of data devices that can communicate with each other within a city or a large campus area covering many city blocks. Megabits per Second (MB/s) - A measure of digital transmission speed of a million bits per second. Megahertz per Second (MHz) A measure of analog transmission speed of a million cycles per second. Multi-channel/Multi-point Microwave Distribution System (MMDS) - A wireless broadband technology for voice, data, video or Internet access over licensed and unlicensed channels, with channels in 6 MHz allotments. Node - The point at which a piece of user equipment connects to the network. Packet - A group of data and control bits that is transmitted as a unit. Plain Old Telephone Service (POTS) Refers to the standard telephone service in most homes. Point-to-Point Network architecture that allows the transmission of data between two locations. Point-to-Multipoint - A communications network that provides a path from one location to multiple locations (from one to many). Points of Presence (POP) - A term used by Internet service providers to indicate the number of geographical locations from which they provide access to the Internet. Remote Terminal (RT) An extension of Central Office switching equipment. The location at which there is a transition between a telecommunications common carrier and the local lines serving the individual customers. Quality of Service (QoS) - Term for the set of parameters and their values which determine the performance of a given circuit or network. 5

6 Satellite Technology - Electronic communication via a satellite link. Satellite networks are composed of a hub, satellites and receiving antennas on dishes. Served Community A municipality that has access to Digital Subscriber Line (DSL) and cable broadband technologies. Symmetrical Digital Subscriber Line (SDSL) One of the two-wire, copper-based Digital Subscriber Line (DSL) technologies that provides identical data transmission rates both downstream and upstream (transmit & receive). Synchronous Optical NETwork (SONET) A family of standard fiber optic transmission rates from MB/s to GB/s created to provided the flexibility to transport many digital signals with varying capacities and provide a transmission d esign standard above 45 MB/s. SONET architectures allows for the drop and insert capability between various SONET network nodes, as well as a ringed design which provides network service redundancy in the case of a fiber break. T-1/T-Carrier System Also known as DS-1, this technology can be used to transmit voice, data, video and Internet. The T-carrier system uses four copper wires to provide duplex capability (two wires for receiving and two for sending at the same time). It supports a symmetrical bandwidth of MB/s. The T-1 digital stream can be used as a unified transmission pipe for a single network port or can be used for voice transmission supporting KB/s channels/paths. TCP/IP - Internet Protocol (IP) / Transport Control Protocol (TCP) A combination of protocols that makes up the Internet s networking protocol. IP is a layer 3 connectionless protocol that, when combined with TCP, a layer 4 connection-oriented protocol, provides reliable transmission of packet data over IP networks. Triple Play A three-way service bundle of voice and/or Voice over Internet Protocol (VoIP) services, broadband Internet access, and cable television/video-on-demand services. Trunk - In telephone systems, a line that carries multiple voice or data channels between two Central Office switching systems. In digital communications, a trunk is often a T-carrier system. Unbundled Network Elements (UNE) Parts of the telecommunications network that Incumbent Local Exchange Carriers (ILEC) are required to offer for sale through a collocation agreement to Competitive Local Exchange Carriers (CLEC) on an unbundled basis as defined by the Telecommunications Act of Underserved Community - A municipality that has very limited access to Digital Subscriber Line (DSL) and/or cable broadband technologies. 6

7 Unserved Community - A municipality that does not have access to Digital Subscriber Line (DSL) or cable broadband technologies. Voice over Internet Protocol (VoIP) This technology allows voice conversations to be carried over the Internet as opposed to traditional phone lines. WDM (Wavelength Division Multiplexing) - WDM is a fundamental passive optical component for optical system sending several signals through one WDM with different wavelengths of light. There are two distinct WDM architectures, CWDM and DWDM. CWDM (Coarse Wavelength-Division Multiplexing) allows eight or fewer channels to be stacked in the 1550 nm region of optical fiber, the C-Band. DWDM (Dense Wavelength- Division Multiplexing) is able to transmit many of closely spaced wavelengths in the 1550 nm (nanometers) region over a single optical fiber. Wavelength spacings are usually 100 GHz or 200 GHz. Wide Area Network (WAN) - A network which encompasses interconnectivity between devices over a wide geographic area. Wireless Fidelity (WiFi) Term used to describe any wireless network that connects users to an access point using an a/b/g (WiFi speeds) standard network. Wireless LAN (WLAN) - In which a mobile user can connect to a Local Area Network (LAN) through a wireless (radio) connection. A standard specifies the technologies for wireless LANs, which includes an encryption method. Worldwide Interoperability for Microwave Access (WiMax) Broadband wireless networks that are based on the Institute of Electrical and Electronics Engineers, Inc (IEEE) standard, which ensures compatibility and interoperability between broadband wireless access equipment. Wireless Mesh Network (WMN) A Wireless Local Area Network (WLAN) that has redundant connections among multiple nodes and users. Wireless Internet Service Provider (WISP) A company that provides Internet access to subscribers for a fee over a wireless connection. 7