Multiplexing

Multiplexing is the process of combining many signals, usually from slow devices, onto one very fast communications link. This sharing is achieved by a device called a Multiplexor (MUX) that organises the signals that are sent and by a corresponding device, a Demultiplexor (DEMUX), at the other end separating the signals again.
]]Next: The Multiplexing Solution
The Multiplexing Solution

When multiplexing is successfully implemented it is transparent to the end users. As far as they are concerned they are directly connected to the receiving system and are not sharing the channel with anyone else.
A multiplexor is specialist communication hardware that combines many signals to permit use of a single communications link. The bandwidth of a multiplexor depends on the number of users using the link. Another term used to describe multiplexor is concentrator.
In order to allow users access to a single link a system must be set up to ensure that all users are given equal access. This can be achieved by either giving users a time slice of the channel or some of the frequency space. The use of multiplexing has been the backbone of telephone systems around the world.
Click on this link to review the wikipedia resource on multiplexing.
Next: Types of Multiplexing
Types of Multiplexing

There are two basic forms of multiplexing used: * Time division multiplexing (TDM) * Frequency division multiplexing (FDM)
Next: Time Division Multiplexing
Time Division Multiplexing

Time Division Multiplexing works by the multiplexor collecting and storing the incoming transmissions from all of the slow lines connected to it and allocating a time slice on the fast link to each in turn. The messages are sent down the high speed link one after the other. Each transmission when received can be separated according to the time slice allocated.
Theoretically, the available speed of the fast link should at least be equal to the total of all of the slow speeds coming into the