thumb|Fixed broadband subscriptions (per 100 people)
In telecommunications, broadband or high speed is the wide-bandwidth data transmission that uses signals at a wide spread of frequencies or several different simultaneous frequencies. It is used in fast Internet access where the transmission medium can be coaxial cable, optical fiber, wireless Internet (radio), twisted pair cable, or satellite.
Originally used to mean "using a wide-spread frequency" and for services that were analog at the lowest level, in the context of Internet access, "broadband" is now often used to mean any high-speed Internet access that is seemingly always "on" and is faster than dial-up access over traditional analog or ISDN PSTN services.
The ideal telecommunication network has the following characteristics: broadband, multi-media, multi-point, multi-rate and economical implementation for a diversity of services (multi-services). The Broadband Integrated Services Digital Network (B-ISDN) was planned to provide these characteristics. Asynchronous Transfer Mode (ATM) was promoted as a target technology for meeting these requirements. or in the context of audio noise reduction systems, where it indicated a single-band rather than a multiple-audio-band system design of the compander. Later, with the advent of digital telecommunications, the term was mainly used for transmission over multiple channels. Whereas a passband signal is also modulated so that it occupies higher frequencies (compared to a baseband signal which is bound to the lowest end of the spectrum, see line coding), it is still occupying a single channel. The key difference is that what is typically considered a broadband signal in this sense is a signal that occupies multiple (non-masking, orthogonal) passbands, thus allowing for much higher throughput over a single medium but with additional complexity in the transmitter/receiver circuitry.
The term became popularized through the 1990s as a marketing term for Internet access that was faster than dial-up access (dial-up being typically limited to a maximum of 56 kbit/s). This meaning is only distantly related to its original technical meaning.
Since 1999, broadband Internet access has been a factor in public policy. In that year, at the World Trade Organization Biannual Conference called "Financial Solutions to Digital Divide" in Seattle, the term "Meaningful Broadband" was introduced to the world leaders, leading to the activation of a movement to close the digital divide. Fundamental aspects of this movement are to suggest that the equitable distribution of broadband is a fundamental human right.
Personal computing facilitated easy access, manipulation, storage, and exchange of information, and required reliable data transmission. Communicating documents by images and the use of high-resolution graphics terminals provided a more natural and informative mode of human interaction than do voice and data alone. Video teleconferencing enhances group interaction at a distance. High-definition entertainment video improves the quality of pictures, but requires much higher transmission rates.
These new data transmission requirements may require new transmission means other than the present overcrowded radio spectrum. A modern telecommunications network (such as the broadband network) must provide all these different services (multi-services) to the user.
Differences from old telephony
Conventional telephony communication used:
- the voice medium only,
- connected only two telephones per telephone call, and
- used circuits of fixed bit-rates.
Modern services can be:
- multimedia,
- multi-point, and
- multirate.
These aspects are examined individually in the following three sub-sections.
Multimedia
A multimedia call may communicate audio, data, still images, or full-motion video, or any combination of these media. Each medium has different demands for communication quality, such as:
- bandwidth requirement,
- signal latency within the network, and
- signal fidelity upon delivery by the network.
The information content of each medium may affect the information generated by other media. For example, voice could be transcribed into data via voice recognition, and data commands may control the way voice and video are presented. These interactions most often occur at the communication terminals, but may also occur within the network. The various forms of digital subscriber line (DSL) services are broadband in the sense that digital information is sent over multiple channels. Each channel is at a higher frequency than the baseband voice channel, so it can support plain old telephone service on a single pair of wires at the same time. However, when that same line is converted to a non-loaded twisted-pair wire (no telephone filters), it becomes hundreds of kilohertz wide (broadband) and can carry up to 100 megabits per second using very high-bit rate digital subscriber line (VDSL or VHDSL) techniques.
Modern networks have to carry integrated traffic consisting of voice, video and data. The Broadband Integrated Services Digital Network (B-ISDN) was designed for these needs. The types of traffic supported by a broadband network can be classified according to three characteristics:
- Bandwidth is the amount of network capacity required to support a connection.
- Latency is the amount of delay associated with a connection. Requesting low latency in the quality of service (QoS) profile means that the cells need to travel quickly from one point in the network to another.
- Cell-delay variation (CDV) is the range of delays experienced by each group of associated cells. Low cell-delay variation means a group of cells must travel through the network without getting too far apart from one another.
Cellular networks utilize various standards for data transmission, including 5G which can support one million separate devices per square kilometer.
Requirements of the types of traffic
The types of traffic found in a broadband network (with examples) and their respective requirements are summarised in Table 1.
{| class="wikitable"
|+ Table 1: Network traffic types and their requirements
The total bandwidth of the medium is larger than the bandwidth of any channel.
The 10BROAD36 broadband variant of Ethernet was standardized by 1985, but was not commercially successful.
The DOCSIS standard became available to consumers in the late 1990s, to provide Internet access to cable television residential customers. Matters were further confused by the fact that the 10PASS-TS standard for Ethernet ratified in 2008 used DSL technology, and both cable and DSL modems often have Ethernet connectors on them.
TV and video
A television antenna may be described as "broadband" because it is capable of receiving a wide range of channels, while e.g. a low-VHF antenna is "narrowband" since it receives only 1 to 5 channels. The U.S. federal standard FS-1037C defines "broadband" as a synonym for wideband. "Broadband" in analog video distribution is traditionally used to refer to systems such as cable television, where the individual channels are modulated on carriers at fixed frequencies. In this context, baseband is the term's antonym, referring to a single channel of analog video, typically in composite form with separate baseband audio. The act of demodulating converts broadband video to baseband video. Fiber optic allows the signal to be transmitted farther without being repeated. Cable companies use a hybrid system using fiber to transmit the signal to neighborhoods and then changes the signal from light to radio frequency to be transmitted over coaxial cable to homes. Doing so reduces the use of having multiple head ends. A head end gathers all the information from the local cable networks and movie channels and then feeds the information into the system.
However, "broadband video" in the context of streaming Internet video has come to mean video files that have bit-rates high enough to require broadband Internet access for viewing. "Broadband video" is also sometimes used to describe IPTV Video on demand.
Alternative technologies
Power lines have also been used for various types of data communication. Although some systems for remote control are based on narrowband signaling, modern high-speed systems use broadband signaling to achieve very high data rates. One example is the ITU-T G.hn standard, which provides a way to create a local area network up to 1 Gigabit/s (which is considered high-speed as of 2014) using existing home business and home wiring (including power lines, but also phone lines and coaxial cables).
In 2014, researchers at Korea Advanced Institute of Science and Technology made developments on the creation of ultra-shallow broadband optical instruments.
Internet broadband
In the context of Internet access, the term "broadband" is used loosely to mean "access that is always on and faster than the traditional dial-up access".
A range of more precise definitions of speed have been prescribed at times, including:
- "Greater than the primary rate" (which ranged from about 1.5 to 2 Mbit/s) —CCITT in "broadband service" in 1988.
- "Internet access that is always on and faster than the traditional dial-up access"
- 4 Mbit/s downstream, 1 Mbit/s upstream —Federal Communications Commission (FCC), 2010
- 50 Mbit/s downstream, 10 Mbit/s upstream —Canadian Radio-television and Telecommunications Commission (CRTC)
Broadband Internet service in the United States was effectively treated or managed as a public utility by net neutrality rules until being overturned by the FCC in December 2017.
Speed qualifiers
A number of national and international regulators categorize broadband connections according to upload and download speeds, stated in Mbit/s (megabits per second).
{|class="wikitable sortable"
|-
! Term !! Regulator(s) !! Minimal download<br/> speed (Mbit/s) !! Minimal upload<br/> speed (Mbit/s) !! Notes
|-
| Full fibre / FTTP/H||Ofcom || 100 || 1 ||
|-
| Gigabit||Ofcom || 300 || 1 ||
|-
| Ultra-fast / Gfast||EU || 30 || ||
|-
| Superfast||Ofcom || 30 || 1 ||
|-
| Superfast||FCC || 100 || 20 ||
|-
| Broadband||Ofcom || 10 || 1 ||
|-
|Broadband
|CRTC
|50
|10
|
|}
In Australia, the Australian Competition and Consumer Commission also requires Internet service providers to quote speed during night time and busy hours
Global bandwidth concentration
[[File:GlobalBandwidthConcentration.jpg|thumb|500px|Global bandwidth concentration: 3 countries have almost 50% between them; 10 countries almost 75%. In 2014, only three countries (China, the US, and Japan) host 50% of the globally installed telecommunication bandwidth potential. The U.S. lost its global leadership in terms of installed bandwidth in 2011, being replaced by China, which hosts more than twice as much national bandwidth potential in 2014 (29% versus 13% of the global total).