Mobile telephones and base stations Mobile telephones and base stations
Mobile telephones and base stations

Mobile network operation and base stations

GSM (Global System for Mobile Communication) is currently Finland's most comprehensive system.

GSM is also called the second-generation system, or 2G. The first-generation system, or 1G, was NMT (Nordic Mobile phone), which has already been decommissioned. 3G or UMTS has faster data transfer than GSM, so it is suitable for multimedia and data applications. 3G is also used to transmit conventional calls and SMS messages. The LTE (Long Term evolution), or 4G, system enables data transfer that is even faster than 3G. For the time being, the 4G network is only used for data transfer. 3G and 4G phones have better power control than GSM phones.

Mobile network operation

The mobile network consists of base stations and a fixed network. The telephone call or information is transmitted from the mobile phone as a radio signal to the nearest base station and then to the fixed network either directly or via a microwave link.

The size and shape of the cell formed by the base station depends on the frequency range, power, and radiation patterns of the base station antennas, and on the terrain. In sparsely populated areas, the cell size is generally larger and the power of base station transmitters is higher because wider coverage is required. In urban areas, there can be multiple base stations in one area, because only a limited number of calls and data can be processed by a single base station at once. There may be base station antennas from several operators in the same transmission location. In practice, the base station network covers the whole of Finland, i.e. there is at least one base station within a radius of a few kilometres from almost any point.

Base station types    

In cities and urban areas, so-called macro cell base stations serving a large area are often located on the rooftops of buildings. More base station masts are used in sparsely populated areas. Macro cell base sta-tions are narrow, high panels with a beam in the shape of a horizontal fan and directed at the horizon. The exposure limits of the population may be exceeded in the middle of the beam approximately 10 me-tres from the antenna. Bystanders must not have access to this area. The antennas do not radiate much downwards or backwards, so even high-power antennas can be safely installed on a wall or rooftop.

 

Macro cell base station antennas on the edge of a rooftop

Macro cell base station antennas on the edge of a rooftop

Micro cell base stations point diagonally downwards from the rooftop or the wall of the building. They run traffic within a radius of a few hundred metres. The exposure limits of the population may be ex-ceeded at a distance of a few dozen centimetres in front of the antenna. Base station antennas must be installed so that they cannot be touched through the ventilation windows or balconies. In practice, mi-cro cell antennas also only radiate forward and very little in other directions.    

Pico cell base stations are usually compact elements attached to the wall right below the ceiling. They provide better signal strength of local shadow areas, such as the interior of buildings. As the transmis-sion power is low, the exposure from the pico cell base stations does not exceed the exposure limit val-ues for the population even at arm’s length.

Base station type Macro cell Micro cell Pico cell
Operating radius Several kilometres 100–1,000 m Less than 100 m
Transmission power Up to a few hundred watts A few watts Less than 1 W
Operating area Urban areas, countryside, city City Dense urban construction, building interiors
Antenna location On rooftops and masts On rooftops and walls On ceilings and walls
Distance at which exposure may exceed the limit values Approx. 10 m (in front of antenna) Less than 30 cm (in front of antenna) Not even at arm’s length

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