long haul network (LHN)
The term Long Haul Network (LHN) is used for optical long-haul networks that span large distances, in some cases this can be several thousand kilometers. They differ from other networks in that there are long distances between their nodes and that they have extremely high bandwidth requirements.
These networks are optical networks that use the diverse techniques of wavelength division multiplexing(WDM) and optical amplifiers( OA). For example, EDFA amplifiers, which are used to amplify and regenerate signal distortion due to chromatic dispersion( CD), can easily bridge distances of 500 km or more.
Distances can be increased to over 6,000 km with Very Long Haul( VLH) and Ultra Long Haul( ULH) techniques, at multi-terabit data rates.
The approach using wavelength division multiplexing and optical amplifiers is much less expensive than electrical regenerators. In addition, wavelength division multiplexing eliminates the need for new optical fibers.