Multiplexing: An Intro to How it Works
Multiplexing is a way of sending multiple signals or information streams over a any other network device without having to dedicate a connection for each pair. Feb 27, paper examines the modulation and multiplexing techniques for accomplishing the task of . also be done by enforcing a global relationship. May 26, Multiplexing basically involves taking multiple signals and This spreading code modulation increases the bandwidth required for the signal.
This coded transmission typically is accomplished by transmitting a unique time-dependent series of short pulses, which are placed within chip times within the larger bit time.
All channels, each with a different code, can be transmitted on the same fiber or radio channel or other medium, and asynchronously demultiplexed. Advantages over conventional techniques are that variable bandwidth is possible just as in statistical multiplexingthat the wide bandwidth allows poor signal-to-noise ratio according to Shannon-Hartley theoremand that multi-path propagation in wireless communication can be combated by rake receivers. Telecommunication multiplexing Multiple access method[ edit ] A multiplexing technique may be further extended into a multiple access method or channel access methodfor example, TDM into time-division multiple access TDMA and statistical multiplexing into carrier-sense multiple access CSMA.
A multiple access method makes it possible for several transmitters connected to the same physical medium to share its capacity. Multiplexing is provided by the Physical Layer of the OSI modelwhile multiple access also involves a media access control protocol, which is part of the Data Link Layer.
Code-division multiplexing CDM is a technique in which each channel transmits its bits as a coded channel-specific sequence of pulses.
Difference Between Modulation and Multiplexing
All channels, each with a different code, can be transmitted on the same fiber and asynchronously demultiplexed. Early experiments allowed two separate messages to travel in opposite directions simultaneously, first using an electric battery at both ends, then at only one end.
Inthe quadruplex telegraph developed by Thomas Edison transmitted two messages in each direction simultaneously, for a total of four messages transiting the same wire at the same time. Telephony[ edit ] In telephonya 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.
The multiplexed signal is then carried to the central switching office on significantly fewer wires and for much further distances than a customer's line can practically go.
This is likewise also true for digital subscriber lines DSL. Fiber in the loop FITL is a common method of multiplexing, which uses optical fiber as the backbone. Asynchronous Transfer Mode is often the communications protocol used.
IPTV also depends on multiplexing. Demultiplexer media file In video editing and processing systems, multiplexing refers to the process of interleaving audio and video into one coherent data stream. In digital videosuch a transport stream is normally a feature of a container format which may include metadata and other information, such as subtitles.
The audio and video streams may have variable bit rate.
A demuxer is software that extracts or otherwise makes available for separate processing the components of such a stream or container. This can result in empty slots and underutilization of the multiplexed communication channel. In STDM, if a sender is not ready to transmit in a cycle, the next sender that is ready can transmit.
This reduces the number of wasted slots and increases the utilization of the communication channel.
Multiplexing - Wikipedia
STDM data blocks are known as packets and must contain header information to identify the receiving destination. Frequency Division Multiplexing In frequency division multiplexing FDMeach signal is assigned its own frequency range or channel within a larger frequency band. Frequency ranges for channels cannot overlap. Frequency bands are often separated by an unused block of the frequency spectrum to reduce interference.
FDM is used mainly for analog transmissions. It can be used over both wired and wireless mediums. FM is a band that occupies the frequency range from 88 MHz to MHz within the larger radio frequency spectrum.
Each radio station transmits at the frequency assigned to its channel for example, The TV transmission cable carries all available channels at their assigned frequencies. When you choose a cable channel with your remote control, the set-top box processes the signal at the frequency assigned to that channel.
Code Division Multiplexing In code division multiplexing CDMsignals from multiple senders are transmitted in an assigned frequency band. CDM uses a principle known as spread spectrumin which transmitted signals are spread out over all frequency channels in the assigned band.
Modulation is the way a source of information transmits that information through a carrier. For example, look at human speech. A person, the source of information, transmits… data by modulating the air with sound waves in a way that is understandable to other humans.
What is the relationship between multiplexing and modulation
In this case the air is the carrier. An example is the communications backbone between two cities. A fast, high bandwidth optical line joins the cities together, but when it reaches either city's limits, it is split up into many individual phone or data circuits. The bottom line is that modulation is how a source manipulates the carrier where as multiplexing is combining multiple circuits into a single, faster line and then separating them again.
What is the Difference between encoder and multiplexer?