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Glossary of Terms

If you do not find the information you need here, please also check the Frequently Asked Questions page.   

4G - Abbreviation for fourth-generation wireless, the stage of broadband mobile communications that will supersede the third generation (3G). Specifies a mobile broadband standard offering both mobility and very high bandwidth. Usually refers to LTE and WiMax technology.

Actual Speed - Refers to the data throughput delivered between the network interface unit (NIU) located at the end-user's premises and the service provider Internet gateway that is the shortest administrative distance from that NIU. In the future, the technical definition of "actual speed" should be crafted by the FCC, with input from consumer groups, industry and other technical experts, as is proposed in Chapter 4 of the National Broadband Plan. The technical definition should include precisely defined metrics to promote clarity and shared understanding among stakeholders. For example, "actual download speeds of at least 4 Mbps" may require certain achievable download speeds over a given time period. Acceptable quality of service should be defined by the FCC.

Asymmetric Digital Subscriber Line (ADSL) -  A technology that transmits a data signal over twisted-pair copper, often over facilities deployed originally to provide voice telephony. Downstream rates are higher than upstream rates - i.e., are asymmetric. ADSL technology enables data transmission over existing copper wiring at data rates several hundred times faster than analog modems using an ANSI standard.

Broadband - In general usage, the term broadband is a label applied to any telecommunications technology offering a better data transmission rate than that available over a standard voice-grade telephone line (which is 56 Kbps and usually less). In 2008, the Federal Communications Commission (FCC) defined broadband using a set of tiered speeds, with Tier 1 being characterized as "First Generation Data". Tier 2 (768 Kbps) is now the minimum data transmission rate for "Basic Broadband." Tiers 3 through 8 reflect the range of broadband service speeds currently available or expected to be available from Internet broadband service providers.




200 Kbps up to 768 Kbps


768 Kbps to 1.5 Mbps


1.5 Mbps to < 3.0 Mbps


3.0 Mbps to < 6.0 Mbps


6.0 Mbps to < 10.0 Mbps


10.0 Mbps to < 25.0 Mbps


25.0 Mbps but < 100.0 Mbps


100.0 Mbps and beyond

                        FCC Broadband Service Speed Tiers
                                         [FCC 08-89]

Cable Modem - A cable modem is a device that enables you to connect to the internet using a local cable television line. Cable Modem DOCSIS 3.0 uses a third-generation equipment.

Census Block - The smallest level of geography designated by the U.S. Census Bureau, which may approximate actual city street blocks in urban areas. In rural districts, census blocks may span larger geographical areas to cover a more dispersed population.

Census tract - A small, relatively permanent statistical subdivision of a county, designed to contain roughly 1,000 to 8,000 people who are relatively homogeneous with respect to their demographics, economic status and living conditions.

Central Office (CO) - A telephone company facility in a locality to which subscriber home and business lines are connected on what is called a local loop. The central office has switching equipment that can switch calls locally or to long-distance carrier phone offices. In other countries, the term public exchange is often used.

Confidence Value - The Confidence value (between 0% and 100%) represents an estimate of the likelihood that the provider’s coverage area is correct, based on factors such as: (a) the fact that the provider validated that their coverage area displays properly and accurately (some providers do not participate in the validation step); (b) the extent to which the provider's coverage area aligns with third-party data resources; and, (c) comments collected from the public via the Feedback tool in this web application. A 0% confidence value could be the result of several factors, including a lack of coverage area validation by the broadband Internet service provider.

Data Over Cable Service Interface Specification (DOCSIS) - A cable modem standard from the CableLabs research consortium (www.cablelabs.com), which provides equipment certification for interoperability. DOCSIS supports IP traffic (Internet traffic) over digital cable TV channels, and most cable modems are DOCSIS compliant. Some cable companies are currently deploying third-generation (DOCSIS 3.0) equipment. Originally formed by four major cable operators and managed by Multimedia Cable Network System, the project was later turned over to CableLabs.

Digital Signal 1 (DS-1) - Also known as T1; a T-carrier signaling scheme devised by Bell Labs. DS-1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. DS-1 is the logical bit pattern used over a physical T1 line; however, the terms DS-1 and T1 are often used interchangeably. Carries approximately 1.544 Mbps, and would be classified as Tier 3..

Digital Subscriber Line (DSL) - A generic name for a group of enhanced speed digital services generally provided by telephone service providers. DSL services run on twisted-pair copper wires, which can carry both voice and data signals.

Digital Subscriber Line Access Multiplexer (DSLAM) - Technology that concentrates or aggregates traffic in DSL networks. Located in the central office or in a remote terminal.

Fiber to the Node (FTTN) - A high-capacity bandwidth approach that uses both fiber and copper wires. Optical fiber is used from the core of the telco or CATV network to an intelligent node in the neighborhood where copper wire is used for the connection to the end-user, with one node serving perhaps many residences or small businesses. The few 100 meters or so of the local loop from the node to the premises generally is either unshielded twisted pair (UTP) in a telco application or coaxial cable (coax) in an HFC application, although some form of wireless technology is also possible. Known as Fiber to the Neighborhood, or Fiber to the Cabinet (FTTCab), as well.

Fiber-to-the-Premise (FTTP) - A fiber-deployment architecture in which optical fiber extends all the way to the customer's premise. Also known as Fiber to the Home (FTTH) or Fiber to the Building (FTTB). Typically using PON for residential deployments.

Fixed Wireless (FW) - Wireless service that uses fixed CPE in addition to (or, possibly, even instead of ) mobile portable devices to deliver data services. FW solutions have been deployed as a substitute for wired access technologies. For example, it is being used commercially in the U.S. by Clearwire with WiMAX and Stelera with HSPA, and globally by Telstra with HSPA.

Housing Units (HU) - Includes a house, an apartment, a mobile home, a group of rooms or a single room that is occupied (or if vacant, is intended for occupancy) as separate living quarters.

Hybrid Fiber Microwave (HFM) - A network (usually wireless) whereby the backhaul transport elements of the network are a mixture or combination of fiber-optic facilities and wireless microwave transport.

Hybrid Fiber Coaxial (HFC) - Another term for cable systems, which are a combination of fiber (Middle and Second Mile) and coaxial cable (Last Mile).

Internet Service Provider (ISP) - A company that provides a connection to the public Internet, often owning and operating the Last-Mile connection to end-user locations.

Last Mile - Refers generally to the transport and transmission of data communications from the demarcation point between the end user's internal network and the carrier's network at the customer premise to the first point of aggregation in the carrier's network (such as a remote terminal, wireless tower location, or HFC node).

Middle Mile - Refers generally to the transport and transmission of data communications from the central office, cable headend or wireless switching station to an Internet point of presence.

Mobile Wireless - Service that is broadcasted via a cellular signal to a mobile receiver.

Node splitting - In a cable system, adding infrastructure so that subscribers previously served by a single node are moved to multiple nodes, reducing the number of subscribers per node.

Point to point (P2P) - A type of fiber to the premise network in which each endpoint is connected to its serving office via a dedicated fiber optic strand.

Provider - Owns and operate most of the facilities used to deliver services to customers, such as transmission equipment, switches, cables, towers and radios. Other service providers may lease facilities or resell purchased services from a facilities-based provider's network. Service Resellers are not listed on this map.Satellite - Internet connectivity provided by satellite using a dish network, rather than through a cable or subscriber line. 

Spectrum Allocation - The amount of spectrum dedicated (or allocated) to a specific use; in wireless, spectrum allocation is typically made in paired bands, with one band for upstream and the other for downstream.

Spectrum Band - The frequency of the carrier wave in wireless communications. Radios can transmit on different frequencies in the same area at the same time without interfering; frequency marks the division of different parts of spectrum for different uses. Frequency is measured in Hertz (Hz); the range of frequency typically used for radio communications is between 10,000 (10 kHz) and 30,000,000,000 Hz (30 GHz). Different frequencies have different natural properties: Lower frequencies travel farther and penetrate solids better, while higher frequencies can carry more information (faster data rates, etc.) The best balance of these properties for the purpose of cell phones is in the range of roughly 700-2,500 MHz. A specific range of frequencies allocated for a specific purpose is called a "band."

Street Segment - A line on a map that represents the street, road, or highway between two known points. It is used to store address range information for one form of geocoding functionality (geocoding can also use address points to query against mapped information).

Symmetric Digital Subscriber Line (SDSL) - Transmits a data signal over twisted-pair copper wires, but the bandwidths are equal for download and upload so the download and upload rated speeds are the same.

Very high bit rate Digital Subscriber Line (VDSL) - A form of DSL similar to ADSL but providing higher speeds at shorter loop lengths.

Voice Over Internet Protocol (VOIP) - A family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony and broadband phone.

Wireless ISP (WISP) - An Internet service provider that provides fixed or mobile wireless services to its customers. Using Wi-Fi or proprietary wireless methods, WISPs provide last mile access, often in rural areas and areas in and around smaller cities and towns. The largest provider of wireless broadband in the U.S. is currently Clearwire Corporation, a WISP that uses an early version of WiMAX to deliver the Internet to customers in the U.S., Ireland, Belgium and Denmark (see WiMAX - Worldwide Interoperability for Microwave Access).

Wireless Priority Service (WPS) - A federal program that authorizes cellular communications service providers to prioritize calls over wireless networks. Participating service providers typically deploy WPS in stages until service is available in most coverage areas and functionality has reached full operating capability.