4.3 MultiplexingOutlinesFDMTDMWDM IntroductionDefinition1. The transmission of information from one or more source to one or more destination over the same medium.2. The process which two or more signals are combined for transmission over a single communications path.3. A process where multiple analog message signals or digital data streams are combined into one signal with the aim is to share an expensive resource.http://en.wikipedia.org/wiki/Multiplexing Contd...Make the communications ver economical b transmitting thousands of independent signals over a single transmission line.Three predominant was to multiplex1. !re"uenc Division Multiplexing #!DM$2. Time Division Multiplexing #TDM$3. %avelength Division Multiplexing #%DM$ Contd...Multiplexing allows several analog signals to be processed b one analog&to&digital converter #AD'$().g. *everal phone calls ma be transferred using one wire. The multiplexed signal is transmitted over a communication channel which ma be a phsical transmission medium. Contd...The multiplexing divides the capacit of the low&level communication channel into several higher&level logical channels+ one for each message signal or data stream to be transferred. A reverse process+ known as demultiplexing+ can extract the original channels on the receiver side. Contd...A multiplexing techni"ue ma be further extended into a multiple access method or channel access method.().g. Time Division Multiple Access #TDMA$Multiple access method makes it possible for several transmitters connected to the same phsical medium to share its capacit. Contd...'oncept of multiplexing Frequency Division Multiplexing (FDM,redominantl used in analog communications.%idel used in !M stereo broadcast.'ompatibilit with mono&receivers.-e"uires onl a slight increase in .%./reat advantage in increasing sstem capacit. Contd...Transmitting end of an !DM *stem Contd...,rocess()ach signal assigned s different carrier fre"uenc.(Modulated carrier fre"uencies are combined for transmission overa single line b M01.(At -x+ a D)M01 separates channels b their fre"uencies 2 routes them to the proper end users. Ti!e Division Multiplexing (TDM3ffers greater sstem improvement.'apable of combining various protocols 2 different tpes of signals onto a single high speed transmission link.().g. voice and dataMore efficient than !DM Contd...,rocess(The transmission must be digital in nature.(To transmit telephone conversations #voice is analog signal$Analog signal is converted to digital and transmitted -econverted into analog at the -x telephone. Contd...Drawbacks(/reater complexit.(/reater transmission .% re"uired. W"velengt# Division Multiplexing (WDM'ost effective wa to increase the capacit of fiber optic communications.Make use of the optical fiber4s available .% b multiplexing man wavelengths along a single mode optical fiber channel.)ach wavelength of light can transmit encoded information at the optimum data rate.