telecommunication Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

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

broadband internet access In telecommunications, broadband or high speed is the wide- bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Internet access. The transmission m ...

which uses the same infrastructure as

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 ...

(DSL) and fiber to the premises, cable Internet access provides network edge connectivity ( last mile access) from the

Internet service provider An Internet service provider (ISP) is an organization that provides a myriad of services related to accessing, using, managing, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, no ...

to an end user. It is integrated into the cable television infrastructure analogously to DSL, which uses the existing

telephone A telephone, colloquially referred to as a phone, is a telecommunications device that enables 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 ...

network. Cable TV networks and

telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

networks are the two predominant forms of residential 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 (''telecommunication'') between two or more points without the use of an electrical conductor, optical fiber or other continuous guided transm ...

, and

satellite internet access Satellite Internet access is Internet access provided through communication satellites; if it can sustain high-speed Internet, high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provide ...

Hardware and bit rates

Broadband cable Internet access requires a cable modem at the customer's premises and a cable modem termination system (CMTS) at a cable operator facility, typically a cable television headend. The two are connected via

coaxial cable Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...

to a hybrid fibre-coaxial (HFC) network. While

access network An access network is a type of telecommunications telecommunications network, network which connects subscribers to their immediate telecommunications service provider, service provider. It is contrasted with the core network, which connects l ...

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. Several standards have been used for cable internet, but the most common is Data Over Cable Service Interface Specification ( DOCSIS). A cable modem at the customer is connected via coaxial cable to an optical node, and thus into an HFC network. An optical node serves many modems as the modems are connected with coaxial cable to a coaxial cable "trunk" via distribution "taps" on the trunk, which then connects to the node, possibly using amplifiers along the trunk. The optical node converts the radio frequency (RF) signal in the coaxial cable trunk into light pulses to be sent through optical fibers in the HFC network. At the other end of the network, an optics platform or headend platform converts the light pulses into RF signals in coaxial cables again using transmitter and receiver modules,Data-Over-Cable Service Interface Specifications DOCSIS® 3.1 CCAP™ Operations Support System Interface Specification CM-SP-CCAP-OSSIv3.1-I25-220819. Cable labs. and the cable modem termination system (CMTS) connects to these coaxial cables. An example of an optics platform is the Arris CH3000. There are two coaxial cables at the CMTS for each node: one for the downstream (download speed signal), and the other for the upstream (upload speed signal). The CMTS then connects to the ISP's IP (Internet Protocol) network. Downstream, 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 DOCSIS 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, 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.

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 di ...

, satellite internet, or wireless broadband, a population of users share the available bandwidth. 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 buildi ...

, while some including cable internet and

passive optical network A passive optical network (PON) is a fiber-optic telecommunications network that uses only ''unpowered'' devices to carry signals, as opposed to electronic equipment. In practice, PONs are typically used for the '' last mile'' between Internet ...

(PON) also share the

. This arrangement allows the network operator to take advantage of

statistical multiplexing Statistical multiplexing is a type of digital communication link sharing, sometimes abbreviated as STDM. It is very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary num ...

, a bandwidth 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, or other bandwidth throttling 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