Multiplexing

Multiplexing

Multiplexing is a technique that enables broadband media to support multiple data channels. Multiplexing makes sense under a number of circumstances:

When media bandwidth is costly. A high-speed leased line, such as a T1 or T3, is expensive to lease. If the leased line has sufficient bandwidth, multiplexing can enable the same line to carry mainframe, LAN, voice, video conferencing, and various other data types.
When bandwidth is idle. Many organizations have installed fiber-optic cable that is used only to partial capacity. With the proper equipment, a single fiber can support hundreds of megabits—or even a gigabit or more—of data.
When large amounts of data must be transmitted through low-capacity channels. Multiplexing techniques can divide the original data stream into several lower-bandwidth channels, each of which can be transmitted through a lower-capacity medium. The signals then can be recombined at the receiving end.

Multiplexing refers to combining multiple data channels for transmission on a common medium. Demultiplexing refers to recovering the original separate channels from a multiplexed signal.

Multiplexing and demultiplexing are performed by a multiplexor (also called a mux), which usually has both capabilities.

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