telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that ...

s, cable Internet access, shortened to cable Internet, is a form of

broadband Internet access Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Inte ...

which uses the same infrastructure as a

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

. Like

digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

and

fiber to the premises Fiber to the ''x'' (FTTX; also spelled "fibre") or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic ...

services, cable

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, p ...

access provides network edge connectivity ( last mile access) from the

Internet service provider An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise priva ...

to an end user. It is integrated into the

infrastructure analogously to DSL which uses the existing

telephone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into e ...

network. Cable TV networks and telecommunications networks are the two predominant forms of

residential A residential area is a land used in which housing predominates, as opposed to industrial and commercial areas. Housing may vary significantly between, and through, residential areas. These include single-family housing, multi-family resi ...

Internet access. Recently, both have seen increased competition from fiber deployments,

wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...

, and

mobile Mobile may refer to: Places * Mobile, Alabama, a U.S. port city * Mobile County, Alabama * Mobile, Arizona, a small town near Phoenix, U.S. * Mobile, Newfoundland and Labrador Arts, entertainment, and media Music Groups and labels * Mobile ( ...

networks.

Hardware and bit rates

Broadband cable Internet access requires a cable modem at the customer's premises and a

cable modem termination system A cable modem termination system (CMTS) is a piece of equipment, typically located in a cable company's headend or hubsite, which is used to provide high speed data services, such as cable Internet or Voice over Internet Protocol, to cable subsc ...

(CMTS) at a cable operator facility, typically a

cable television headend A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. A headend facility may be staffed or unstaffed and is typically surrounded by some type of security ...

. The two are connected via

coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...

or a

hybrid fibre-coaxial Hybrid fiber-coaxial (HFC) is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s. In a hybrid fib ...

(HFC) plant. While

access network An access network is a type of telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to one another. The access network may be further ...

s are referred to as '' last-mile'' technologies, cable Internet systems can typically operate where the distance between the modem and the termination system is up to . If the HFC network is large, the cable modem termination system can be grouped into hubs for efficient management.

Downstream Downstream may refer to: * Downstream (bioprocess) * Downstream (manufacturing) * Downstream (networking) * Downstream (software development) * Downstream (petroleum industry) * Upstream and downstream (DNA), determining relative positions on DNA ...

, the direction toward the user, bit rates can be as high as 1

Gbit/s In telecommunications, data-transfer rate is the average number of bits ( bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mu ...

. Upstream traffic, originating at the user, ranges from 384 kbit/s to more than 50 Mbit/s, although maximum effective range seems to be unknown. One downstream channel can handle hundreds of cable modems. As the system grows, the CMTS can be upgraded with more downstream and upstream ports, and grouped into hub CMTSs for efficient management. Most ''Data Over Cable Service Interface Specification'' (

DOCSIS Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable televisio ...

) cable modems restrict upload and download rates, with customizable limits. These limits are set in configuration files which are downloaded to the modem using the

Trivial File Transfer Protocol Trivial File Transfer Protocol (TFTP) is a simple lockstep File Transfer Protocol which allows a client to get a file from or put a file onto a remote host. One of its primary uses is in the early stages of nodes booting from a local area netwo ...

, when the modem first establishes a connection to the provider's equipment. Some users have attempted to override the bandwidth cap and gain access to the full bandwidth of the system, by uploading their own configuration file to the cable modem - a process called

uncapping Uncapping, in the context of cable modems, refers to a number of activities performed to alter an Internet service provider's modem settings. It is sometimes done for the sake of bandwidth (i.e. by buying a 512kbit/s access modem and then altering ...

Shared bandwidth

In most residential broadband technologies, such as cable Internet,

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

satellite internet Satellite Internet access is Internet access provided through communication satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high d ...

, or

wireless broadband Wireless broadband is telecommunications technology that provides high-speed wireless Internet access or computer networking access over a wide area. The term comprises both fixed and mobile broadband. The term broadband Originally the wor ...

, a population of users share the available

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

. Some technologies share only their

core network A backbone or core network is a part of a computer network which interconnects networks, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same buildin ...

, while some including cable internet and

passive optical network A passive optical network (PON) is a fiber-optic telecommunications technology for delivering broadband network access to end-customers. Its architecture implements a point-to-multipoint topology in which a single optical fiber serves multiple e ...

(PON) also share the

. This arrangement allows the network operator to take advantage of

statistical multiplexing Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...

, a

sharing technique which is employed to distribute bandwidth fairly, in order to provide an adequate level of service at an acceptable price. However, the operator has to monitor usage patterns and scale the network appropriately, to ensure that customers receive adequate service even during peak-usage times. If the network operator does not provide enough bandwidth for a particular neighborhood, the connection would become saturated and speeds would drop if many people are using the service at the same time, or drop out completely. Operators have been known to use a

bandwidth cap A data cap, often erroneously referred to as a bandwidth cap, is an artificial restriction imposed on the transfer of data over a network. In particular, it refers to policies imposed by an internet service provider in order to limit customers' u ...

, or other

bandwidth throttling Bandwidth throttling consists in the intentional limitation of the communication speed (bytes or kilobytes per second) of the ingoing (received) data and/or in the limitation of the speed of outgoing (sent) data in a network node or in a network ...

technique; users' download speed is limited during peak times, if they have downloaded a large amount of data that day.

References

{{DEFAULTSORT:Cable Internet Access Internet access Digital cable

Hardware and bit rates

Shared bandwidth

See also

References