Multiplexing

multiplexedmultiplexmultiplexesdemultiplexensembledemultiplexingmuxedensemblesMultiple Channel Per Carriermultiplexer
In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium.wikipedia
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Telecommunication

telecommunicationscommunicationstelecom
In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium.
Such transmission paths are often divided into communication channels which afford the advantages of multiplexing.

George Owen Squier

George O. SquierGeneral George SquierGeneral George O. Squier
In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910.
His biggest contribution was that of telephone carrier multiplexing in 1910 for which he was elected to the National Academy of Science in 1919.

Wavelength-division multiplexing

wavelength division multiplexingWDMdense wavelength division multiplexing
A variant technology, called wavelength-division multiplexing (WDM) is used in optical communications.
In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light.

Shared medium

shares a medium
In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium.
A multiplexing scheme divides up the capacity of the medium.

Polarization-division multiplexing

polarization multiplexing
Polarization-division multiplexing uses the polarization of electromagnetic radiation to separate orthogonal channels.
Polarization-division multiplexing (PDM) is a physical layer method for multiplexing signals carried on electromagnetic waves, allowing two channels of information to be transmitted on the same carrier frequency by using waves of two orthogonal polarization states.

Computer network

networknetworkingcomputer networking
In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium.
Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers.

Orbital angular momentum multiplexing

orbital angular momentum based multiplexing
Orbital angular momentum multiplexing is a relatively new and experimental technique for multiplexing multiple channels of signals carried using electromagnetic radiation over a single path.
Orbital angular momentum (OAM) multiplexing is a physical layer method for multiplexing signals carried on electromagnetic waves using the orbital angular momentum of the electromagnetic waves to distinguish between the different orthogonal signals.

Channel access method

multiple accesschannel accessmultiple access method
Carrier sense multiple access and multidrop communication methods are similar to time-division multiplexing in that multiple data streams are separated by time on the same medium, but because the signals have separate origins instead of being combined into a single signal, are best viewed as channel access methods, rather than a form of multiplexing.
A channel access method is based on multiplexing, that allows several data streams or signals to share the same communication channel or transmission medium.

Medium access control

media access controlMACEMAC
Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer.
Within that data link layer, the LLC provides flow control and multiplexing for the logical link (i.e. EtherType, 802.1Q VLAN tag etc), while the MAC provides flow control and multiplexing for the transmission medium.

Time-division multiplexing

TDMtime division multiplexingtime slot
Time-division multiplexing (TDM) is a digital (or in rare cases, analog) technology which uses time, instead of space or frequency, to separate the different data streams. Émile Baudot developed a time-multiplexing system of multiple Hughes machines in the 1870s.
This form of signal multiplexing was developed in telecommunications for telegraphy systems in the late 19th century, but found its most common application in digital telephony in the second half of the 20th century.

Multiplexer

demultiplexermultiplexersMUX
A device that performs the multiplexing is called a multiplexer (MUX), and a device that performs the reverse process is called a demultiplexer (DEMUX or DMX).
Multiplexing

Acoustic telegraphy

harmonic telegraphacoustic telegraphharmonic (multi-signal) telegraphs
Several workers were investigating acoustic telegraphy, a frequency-division multiplexing technique, which led to the invention of the telephone.
Acoustic telegraphy (also known as harmonic telegraphy) was a name for various methods of multiplexing (transmitting more than one) telegraph messages simultaneously over a single telegraph wire by using different audio frequencies or channels for each message.

Émile Baudot

BaudotBaudot, Emile
Émile Baudot developed a time-multiplexing system of multiple Hughes machines in the 1870s.
He invented a multiplexed printing telegraph system that used his code and allowed multiple transmissions over a single line.

OSI model

OSIOSI Reference Modellayer 2
Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer.

Data link layer

layer 2Data linkdatalink layer
Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer.
The uppermost sublayer, LLC, multiplexes protocols running at the top of data link layer, and optionally provides flow control, acknowledgment, and error notification.

Physical layer

physicalPHYlayer 1
Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer.
Multiplexing

Phased array

phased array radarphased-arrayphased-array radar
In wireless communications, multiplexing can also be accomplished through alternating polarization (horizontal/vertical or clockwise/counterclockwise) on each adjacent channel and satellite, or through phased multi-antenna array combined with a multiple-input multiple-output communications (MIMO) scheme.
Synthetic array heterodyne detection is an efficient method for multiplexing an entire phased array onto a single element photodetector.

Statistical time-division multiplexing

statistical multiplexingstatistical multiplexerstatistical time division multiplexing
Multiple variable bit rate digital bit streams may be transferred efficiently over a single fixed bandwidth channel by means of statistical multiplexing.
In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or data streams.

Optical fiber

fiber opticfiber opticsfibre optic
Fiber in the loop (FITL) is a common method of multiplexing, which uses optical fiber as the backbone.
Depending on the application, fiber may be used because of its small size, or the fact that no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using different wavelengths of light for each sensor, or by sensing the time delay as light passes along the fiber through each sensor.

Telephony

digital telephonytelephonedigital
In telephony, a customer's telephone line now typically ends at the remote concentrator box, where it is multiplexed along with other telephone lines for that neighborhood or other similar area.
Although analog carrier systems existed that multiplexed multiple analog voice channels onto a single transmission medium, digital transmission allowed lower cost and more channels multiplexed on the transmission medium.

Television channel

channeltelevision channelsTV channel
Cable TV has long carried multiplexed television channels, and late in the 20th century began offering the same services as telephone companies.
Digital television channels are the same as their analog predecessors for legacy reasons, however through multiplexing, each physical radio frequency (RF) channel can carry several digital subchannels.

DVB-T

DigitalterrestrialDVB-T (where available)
This may involve several standard definition television (SDTV) programmes (particularly on DVB-T, DVB-S2, ISDB and ATSC-C), or one HDTV, possibly with a single SDTV companion channel over one 6 to 8 MHz-wide TV channel.
Source coding and MPEG-2 multiplexing (MUX): Compressed video, compressed audio, and data streams are multiplexed into MPEG program streams (MPEG-PS's). One or more MPEG-PS's are joined together into an MPEG transport stream (MPEG-TS); this is the basic digital stream which is being transmitted and received by TV sets or home Set Top Boxes (STB). Allowed bitrates for the transported data depend on a number of coding and modulation parameters: it can range from about 5 to about 32 Mbit/s (see the bottom figure for a complete listing).

Transmission Control Protocol

TCPTCP/IPACK
Some web proxy servers (e.g. polipo) use TDM in HTTP pipelining of multiple HTTP transactions onto the same TCP/IP connection.
This provides the application multiplexing and checksums that TCP does, but does not handle streams or retransmission, giving the application developer the ability to code them in a way suitable for the situation, or to replace them with other methods like forward error correction or interpolation.

Electrical telegraph

telegraphelectric telegraphtelegraph line
The earliest communication technology using electrical wires, and therefore sharing an interest in the economies afforded by multiplexing, was the electric telegraph.
This was the harmonic telegraph, a form of frequency-division multiplexing.

ISDB

ISDB-TISDB-SIntegrated Service Digital Broadcasting-Terrestrial
This may involve several standard definition television (SDTV) programmes (particularly on DVB-T, DVB-S2, ISDB and ATSC-C), or one HDTV, possibly with a single SDTV companion channel over one 6 to 8 MHz-wide TV channel.
This is also much like another digital radio system, Eureka 147, which calls each group of stations on a transmitter an ensemble; this is very much like the multi-channel digital TV standard DVB-T.