Multiplexing and Inverse Multiplexing

Mustafa Ashurex, Scott HansenBA 479

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Multiplexing is sending multiple signals or streams of data on an information line at the same time in the form of a single, more complex signal and then separating the signals at the receiving end.

Multiplexing

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Inverse Multiplexing is combining multiple low speed streams of data to form a single higher-speed data stream. The sending and receiving ends use an inverse multiplexer with one high speed input stream. 

Inverse Multiplexing

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Each signal is assigned a different frequency (sub-channel) within the main channel

Frequency Division

•A typical analog Internet connection via a twisted pair telephone line requires approximately three kilohertz (3 kHz) of bandwidth for accurate and reliable data transfer.

•Suppose a long-distance cable is available with a bandwidth allotment of three megahertz (3 MHz). This is 3,000 kHz, so in theory, it is possible to place 1,000 signals, each 3 kHz wide, into the long-distance channel.

•Each input signal is sent and received at maximum speed at all times

•For many connections, a lot of bandwidth is required

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Frequency Division

Each data stream is put into a single signal by separating the signal into many segments, each with a very short duration. Each individual data stream is reassembled at the receiving end based on the timing.

Time Division

•Flexible

•Careful engineering and implementation necessary

•Bandwidth can be wasted

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Time Division

Assume that a 3,000-hertz tone is applied to each of the six channels in the transmitter. Assume also that the rotating switch turns fast enough to sample, in turn, each of the six channels 2.4 times during each cycle of the 3,000-hertz tone. The speed of rotation of the switch must then be 2.4 X 3,000 or 7,200 rotations per second. This is the optimum sampling for a practical system.

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Time Division

When the transmitter and receiver switches are synchronized, the signals will be fed in the proper sequence to the receiver channels. The samples from transmitter channel one will be fed to receiver channel one.

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Employs a buffer memory which temporarily stores the data during periods of peak traffic, allowing STDM to waste no high speed line time with inactive channels.

Statistical Time Division

•Flexible

•Doesn’t waste bandwidth

•Increased complexity

Demo

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Multiple signals are carried together as separate wavelengths of light

Dense Wavelength Division

•Up to 80 (and theoretically more) separate wavelengths or channels of data can be multiplexed into a light stream transmitted on a single optical fiber

•In a system with each channel carrying 2.5 Gbps (billion bits per second), up to 200 billion bits can be delivered a second by the optical fiber

•Different data formats being transmitted at different data rates can be transmitted together.

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Dense Wavelength Division

Inverse

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• Performs multiplexing at the network layer using the MP or MPP protocol.

• One data packet is send over the first channel, the next is send over the second channel, and so on, until all the packets are distributed over all the available channels.

• The receiving end adjusts for network-induced delay and reassembles the data packets into their proper order.

Packet-level

Inverse

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• Used in Telecommuting applications

• Provides load balancing

• Allows Scalability

Packet-level

Inverse

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• Performs multiplexing at the physical layer using the AIM and BONDING protocols.

• A data stream is sliced into portions, then the data steams are distributed over all the available circuits.

• The receiving end adjusts for network-induced delay and reassembles the data streams into their proper order.

Circuit-level

Inverse

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• Used in Applications that require transparent digital circuits – videoconferencing– bulk file transfer applications

• Allows Scalability

Circuit-level

Sou

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• http://www.tpub.com/neets/book17/75h.htm

• http://www.webopedia.com/TERM/D/DWDM.htm

• http://www.fiber-optics.info/articles/dwdm.htm

• http://en.wikipedia.org/wiki/Wavelength_division_multiplexing

• http://en.wikipedia.org/wiki/Time-division_multiplexing

• http://www.atis.org/tg2k/_time-division_multiplexing.html

• http://telecom.tbi.net/mux1.html

• http://en.wikipedia.org/wiki/Frequency_division_multiplexing

• http://www.its.bldrdoc.gov/fs-1037/dir-016/_2344.htm

• http://www.answers.com/topic/frequency-division-multiplexing

• http://www.totaltele.com/Glossary.aspx

• http://www.fotech.com.tr/sozluk/i.htm

• http://whatis.techtarget.com/definition/0,,sid9_gci214323,00.html

• http://en.wikipedia.org/wiki/Inverse_multiplexing

• http://www.networkworld.com/details/806.html?def