Recommendation ITU-T K.120 provides guidelines for lightning protection and earthing of miniature base stations. A miniature base station is a new type of radio base station, which is different from a distribution base station (DBS) in many respects. The change of installation environment is the critical factor to affect the lightning protection of miniature base stations.
Miniature base stations have low radio frequency (RF) power and a small volume in size, which makes them suitable for the coverage of hotspots and/or blind areas for improving communication quality. Miniature base stations are ordinarily installed in residential or densely populated urban areas (unconventional telecommunication site), for example, ceiling (indoor), external wall, advertising board, rooftop, street light, low-voltage power pole, and so on, where the installation, wiring and earthing is difficult.
In comparison, distribution base stations, within the domain of macro-base stations, have high RF power and a large volume in size, which is suitable for wide area coverage. Usually a DBS is installed in a conventional telecommunication environment, where the installation, wiring and earthing is easier. Though some installation scenarios are covered by Recommendation ITU-T K.97, lightning protection of miniature base stations are not fully specified in the ITU-T K series of Recommendations.
The purpose of this Recommendation is to give guidance on the protection of miniature base stations against lightning surge, especially for those which are in unexposed environments (to lightning) and unconventional telecommunication sites.
Protection of miniature base stations is achieved by either surge protective devices and/or components or isolation of interfaces. For those where earthing is not available or it is difficult, the base station can be unearthed (floating), as long as the safety measures against electric shock are considered adequately. Bonding configurations of the protection module and of the optical fibre cable are also illustrated.
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