Multiplexing

It is the backbone of communication both analog as well as digital. Multiplexing means sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal(A mixture of all the signals needed to be sent) and then recovering the separate signals at the receiving end. In analog transmission(example telephone line), signals are commonly multiplexed using frequency-division multiplexing (FDM), in which the carrier bandwidth is divided into sub channels of different frequency widths, each carrying a signal at the same time in parallel.

In digital transmission, signals are commonly multiplexed(combined) usingtime-division multiplexing (TDM), in which the multiple signals(more than one) are carried over the same channel in alternating time slots. In some optical fiber networks, multiple signals are carried together as separate wavelengths of light in a multiplexed signal using dense wavelength division multiplexing(DWDM).