Telecommunications In
telecommunications, a broadband signalling method is one that handles a wide band of frequencies. "Broadband" is a relative term, understood according to its context. The wider (or broader) the
bandwidth of a channel, the greater the data-carrying capacity, given the same channel quality. In
radio, for example, a very narrow band will carry
Morse code, a broader band will carry speech, and a still broader band will carry
music without losing the high
audio frequencies required for realistic
sound reproduction. This broad band is often divided into channels or
frequency bins using
passband techniques to allow
frequency-division multiplexing instead of sending a higher-quality signal. In data communications, a
56k modem will transmit a data rate of 56 kilobits per second (kbit/s) over a 4-kilohertz-wide
telephone line (narrowband or
voiceband). In the late 1980s, the
Broadband Integrated Services Digital Network (B-ISDN) used the term to refer to a broad range of
bit rates, independent of physical modulation details. 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.
Computer networks Many
computer networks use a simple
line code to transmit one type of signal using a medium's full bandwidth using its
baseband (from zero through the highest frequency needed). Most versions of the popular
Ethernet family are given names, such as the original 1980s
10BASE5, to indicate this. Networks that use
cable modems on standard
cable television infrastructure are called broadband to indicate the wide range of frequencies that can include multiple data users as well as traditional television channels on the same cable. Broadband systems usually use a different
radio frequency modulated by the data signal for each band. 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==