Multiplexing is the set of techniques that allows simultaneous transmission of multiple signals across a single data like. It is methods for efficient utilization of system resources. Whenever the transmission capacity of a medium linking two devices is greater than the transmission needs of the devices the link need to be shared by multiplexing.
In a multiplexed systems n devices share the capacity of the link. Single are a multiplexed using two basic techniques. Frequency Division multiplexing ( FDM) and time Davidson multiplexing ( TAM) is subdivided into synchronous ( usually) just called TDM) and asynchronous TDM also called statistical TDM or concentrator.
classification of multiplexing techniques