Frequency Division Multiplexing
Frequency division multiplexing (FDM) is an analogy technique that can be applied when the bandwidth of a link is greater than the combined bandwidths of the single to be transmitted. In FDM the bandwidth is devised into a number of frequency slots each of which can accommodate the single of an individual connection. The multiplexer assigns a frequency slot to each connection and uses modulation the place the single of the carries all the connections. The combined signal is transmitted and the de multiplexer recovers the single corresponding to each connection. Reducing the number of wires that need to be handled reduces the overall cost of the system.