Multiplexers and demultiplexers are used to combine and break the high rate data stream. Multiplexing can be achieved through:
Frequency Division Multiplexing (FDU)
Time Division Multiplexing (TDM)
Statistical Time Division Multiplexing (STDM)
Wavelength Division Multiplexing (WDU)
There are two basic types of transmission types:
Asynchronous
Synchronous
asynchronous communication A form of data transmission that involves a delay of seconds, minutes, or even days. Communication does not happen instantly.
synchronous communication Communication whose bits are sent and received in a timed method. Digital systems and networks rely on this method that results in faster transmissions, but it is also more complex and more expensive.
In asynchronous transmissions, the “building blocks” are bytes delineated by start and stop bits.
In synchronous transmissions, the “building blocks” are based on frames: blocks of bits separated by equal time intervals