What is WDM?
Transfer of information from one place to the other can be achieved using different transmission technologies or mediums which include copper cable lines, space and fibre optic cables etc. As there is only one medium, maximum data rate through it can only be achieved by simultaneous transmission of information through various techniques. These techniques are called multiplexing techniques. These are TDMA,FDMA,CDMA,OFDMA etc. WDM is also one such multiplexing technique.
This page describes what is WDM or Wavelength Division Multiplexing and WDM application.
Wavelength Division Multiplexing(WDM) is similar to the FDM(Frequency division multiplexing) technique.
This is because of their mathematical relationship as mentioned below.
Wavelength = C/Frequency , C is the Speed of Light
The difference between them is that in WDM light signals are multiplexed and transmitted through fibre optic cables. This results into higher data rate capacity as different light signals of different wavelengths will be carrying different data streams. This is because narrower band signals are combined to form wide band of light signal.
The basic concept in WDM is that it uses different optical carriers or colours to transmit different signals in a optic fibre. Optic fibre here is analogous to multi-lane highway. WDM is irrelevant to type of traffic to be carried and hence any type of traffic can travel over fibre optic cable e.g. ATM packets,SDH and IP data.
SONET/SDH functional capabilities and enormous bandwidth of DWDM lead to development of 32 and 96 channel WDM which can carry information at 320 Gbps to 1.2terabit per second transmission rates.
When the number of wavelength channels are more than 20, WDM is referred as DWDM or Dense WDM.