By Engr: S Rehan ali shah MULTIPLEXING By Engr: S Rehan ali shah

Introduction of Multiplexing Whenever the transmission capacity of the medium linking two device is greater than the transmission needs of the device, the link can be shared. As a large water pipe can carry water to several separate house at once. Multiplexing is the set of technique s that allows the simultaneous transmission of multiple signals across a single data link. Figure shows the two possible ways of linking four pairs of devices.

In a multiplex system, n devices share the capacity of one link In a multiplex system, n devices share the capacity of one link. The four device on the left direct their transmission stream to a multiplexer (MUX). Which combines them into a single stream (many to one). At the receiving end , that stream fed into a demultiplexer (DEMUX). The word path refer to the physical link. The word channel refers to a portion of a path that carries a transmission b/w a given pair of device.

Categories of multiplexing

Frequency –division -Multiplexing FDM is an Analog technique that can be applied when the bandwidth of link is greater than the combined bandwidth of the signals to be transmitted. In FDM, signal generated by each device modulated different carrier frequencies , modulated signal are then combined into a single composite signal that can be transported by the link. The guard band…

FDM process In the illustration , the bandwidth of the resulting composite signal is more than three times the bandwidth of each input signal.

Demultiplexing The demultiplexer uses a series of filters to decompose the multiplexed signal into its constituent component signals

Wave-Division Multiplexing (WDM)