Fiber optic cables can be run anywhere from 2 kilometers to over 100 kilometers without signal regeneration, depending on the cable type and application. 163 describes criteria for the installation of optical fibre cables defined in Recommendation ITU-T L. 110 in remote areas with lack of usual infrastructure for installation including the procedures of cable-route planning, cable selection, cable-installation scheme selection. The NTT Group is investigating further coverage expansion of optical-fiber networks for 5G (fifth-generation mobile communications network) base-station demand and popularization of Internet-of-things devices. In extreme cold climates, cables may need to be buried at greater depths where there temperatures are colder and frost penetrates to. Fiber optic cable transmission distance is determined by two primary physical factors that affect signal quality as light travels through the fiber medium.