Protection of remote radio units

Electrical Power & Protection

October 2014 Electrical Power & Protection

With the commercial introduction of UMTS technology in 2003, mobile data communication gained in importance besides voice communication. As the demand for data volumes grew, so did the global demand for bandwidth.

The increasing use of smartphones and other mobile terminal equipment leads to a significantly higher utilisation of existing conventional mobile networks.

The motivation for mobile network operators to rely on modern and innovative technology are the high investment costs for new network infrastructures and system technology, as well as high maintenance and operating costs for existing mobile radio stations. Their aim is to reduce maintenance and operating costs and increase the availability and reliability of mobile radio stations for an ever growing number of mobile phone users.

Mobile network operators and system technology manufacturers worldwide increasingly use remote radio head/unit technology for UMTS (3G) and LTE (4G). Remote radio heads/units (RRHs/RRUs) are a refinement of the third mobile radio generation.

Remote radio head technology is not only used for commercial mobile radio applications, but also for the digital radio systems of security authorities (BOS) such as police and emergency medical services since these systems require high reliability and availability.

Conventional mobile radio stations

Conventional mobile radio stations use coaxial cables, also referred to as waveguide cables. A clear disadvantage of this technology is the high transmission loss (up to 50%), depending on the cable length and cross section. Moreover, the complete radio transmission technology is integrated in the base station/radio base station (RBS). This requires permanent cooling of the technical rooms and leads to increased energy consumption and maintenance costs.

Mobile radio stations with remote radio heads/units

Remote radio heads/units incorporate the high frequency technology which was originally integrated centrally in the base station. The signal is generated directly at the antenna and then transmitted. Therefore, the RRHs/RRUs are installed directly at the antennas, thus reducing loss and increasing the transmission speed. Another benefit is that less air conditioning is required due to the self cooling of the remote radio heads. Optical fibre cables allow transmission of data between the base station and the remote radio heads/units for up to 20 km. The use of remote system technology and modern base-stations saves energy as well as lease and location related costs due to the reduced number of technical rooms.

External lightning protection

The antennas of such systems are often installed on rented roof space. The operator of the antennas and the building owner usually agree that the placement of the antennas must not present an additional risk for the building. For the lightning protection system, this means that no partial lightning currents may enter the building in case of a lightning strike.

The air termination tip must be insulated when attached to the radio tower by means of a supporting tube made of nonconductive material. The height of the air termination tip depends on the radio tower and possible electrical equipment of the antenna system and radio base-station. In case of buildings with several antenna systems, several isolated air termination systems must be installed.

To learn more about radio base-station protection using Dehn’s DEHNvap CSP combined surge arresters, download the full White Paper http://instrumentation.co.za/+C18490

For more information contact Alexis Barwise, Dehn Protection South Africa, +27 (0)74 505 0312, [email protected], www.dehn-africa.com

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Protection of remote radio units

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