Base station
A base station is a stationary transmission device for radio signals from cellular networks , from cordless telephones and from wireless networks .
Cordless telephones
In the landline network , the term base station refers to the stationary part of a cordless telephone that is connected to the landline network with a cable. The task of the base station is to convert the signals from the telephone socket into radio signals and to transmit them to the handsets - and vice versa.
Previously, the transmission took place analogously according to the standard CT1 or later CT1 + (CT = cordless telephone). Digital transmission was later introduced with CT2. However, since CT1, CT1 + and CT2 partly transmit on the frequencies of the GSM standard and there were disruptions in the cellular network, the license to operate such cordless phones in Germany ended on December 31, 2008.
Today digital transmission is used in accordance with the DECT standard. DECT was defined for Europe by the European Telecommunications Standards Institute (ETSI).
Most of the time the base station is also a charging station and has an integrated answering machine . Up to 6 handsets can be registered on a base station and can also be used to make calls to one another.
There are also radio TAEs (i.e. sockets) that are registered with the base station and connect e.g. B. enable fax machines.
The radio communication between the cordless telephone and the base station takes place in Germany in the frequency range from 1880 to 1900 MHz with an average transmission power of 10 mW (peak power 250 mW). The average power increases with each registered handset and is a quarter of the value for active calls in the idle state. The permitted limit values for the radiation power density affecting the user are the same as those for cell phones (9.5 watts per square meter at 1900 MHz). While cell phones have power regulation, this is not provided for in the DECT standard.
Cellular
In the field of mobile radio , the term base station describes a fixed land radio station as a fixed radio station of the mobile land radio service . Typical radio applications include a. GSM , UMTS , WiMAX , LTE or TETRA network as a network element or location.
Locations
Since many transmitters are required in cellular mobile radio networks for area-wide coverage, these must be implemented at a wide variety of locations.
Many cell phone sites are on private or public buildings. For this purpose, antenna supports or a small tubular steel mast - possibly provided with a ladder - are placed on the flat or pitched roof. In some cases the antennas are also installed on the facade. Installation on or on buildings that are subject to monument protection is only possible in exceptional cases. Antenna supports and antennas can be hidden with appropriate cladding made of glass fiber reinforced plastic (GRP). This camouflage is often implemented as a chimney, which adapts in color and shape to the building or the existing chimneys.
Church towers can also carry transmission equipment for mobile communications. In most cases, the antennas are mounted behind the sound windows of the bell tower, so that they cannot be seen from the outside and do not affect the appearance of the tower. Due to the symbolism of church towers, antennae are not installed in the house of God in some places, many dioceses and communities have forbidden the rental of church properties for ethical reasons and environmental considerations for the neighborhood. This is not infrequently counterproductive, since church towers would often be the better (because higher) locations from the point of view of immission control and would relieve the neighborhood.
As a rule, transmitting antennas for mobile communications can be installed on the top of water towers without any problems, as these structures are very solid and are often designed to accommodate antennas for relay stations for BOS radio or similar radio services. Sometimes, however, cell phone antennas have to be disguised for reasons of monument protection or aesthetics. In the case of disused towers or towers with sufficient space, the technical unit is housed inside the tower, otherwise a container is required next to the tower.
As on water towers, cell phone antennas can also be installed on observation towers. In particular, if the tower already has antennas for other services (e.g. BOS radio services), their installation is usually not a problem. With some observation towers it must be noted that they are listed as historical monuments. In this case, the antennas are to be installed and colored so that they do not impair the appearance of the tower as much as possible.
In industrial areas and in places where suitably high roof locations are not available, cell phone antennas can be attached to existing chimneys. This option is often used by several mobile network operators at the same time, as it is an expensive location option. The chimney often has to be completely renovated before the antennas are installed. If the use of the chimney as a chimney has been abandoned, the installation of antennas represents a change of use that requires approval. The main use then changes from chimney to antenna carrier; in rare cases this use cannot be approved and prohibited by the authorities.
Mobile base transceiver stations (BTS, of Base Transceiver Station ) increase the capacity of the spot. For example, the existing BTS would quickly become overloaded at major events. Self-sufficient BTS are independent of supply lines. The picture below shows a BTS container. Two cell phone antennas radiate slightly inclined into a valley and communicate with cell phones in the vicinity. Two directional radio antennas maintain contact with the base station controller (BSC ) and forward the calls. The diesel generator on the right in the picture supplies the unit with electrical energy.
Cellular transmission towers and masts
Use of existing transmission towers
Mobile radio transmission and reception devices can be installed on existing transmission towers (e.g. on television or telecommunications towers) or transmission masts (e.g. on television converters ).
Depending on the design of the antenna support and the space available, the devices are housed in an existing tower pulpit or in a building next to the tower.
Special masts for cellular communications
Freestanding masts often have to be erected for cellular base stations. They are reinforced concrete, steel pipe or steel framework structures. Guyed masts are uncommon in Germany because they require more space because of the guy foundations. Concrete towers are heavier than steel towers, but require less maintenance (rust protection).
The towers erected for mobile radio transmitters are usually no higher than 70 meters and often also carry directional radio antennas up to 3 m in diameter for radio link connections to larger radio relay nodes or to other base stations.
Antennas for other radio services are also often on the cell phone mast (e.g. VHF and TV converters ).
In contrast to larger telecommunications towers, conventional cell phone towers do not have high operating rooms. All technical devices are either housed in a container or in one or more technical cabinets next to the tower. Many antenna supports from around 15 meters in height have round or angular maintenance platforms for the antenna systems.
At the request of the municipality on whose territory they are located, some transmission towers for mobile communications were equipped with a viewing platform accessible to the public via stairs. In Germany you can find such towers in Schöppingen , in the Fort Fun amusement park , in the Müritz National Park , Groß Reken Melchenberg , on the Schomberg and on the Gräbersberg in Alpenrod . There are also some such towers in the Czech Republic.
The Rottenbuch radio tower is also a special cell phone tower because, unlike other cell phone towers , it is a wooden structure.
For large events such as the Oktoberfest , most network providers also set up additional channel capacities by setting up temporary BTS. Steel masts are erected here, which are usually shared by several network providers.
Overhead line masts
Transmission devices for mobile radio (usually including a directional radio link to a larger network node) are also often installed on overhead line masts . As a rule, masts of 380 kV lines are used for this due to the required height and for structural reasons, but it is also not uncommon for mobile radio stations to be set up on higher and more stable masts of 220 and 110 kV lines. Masts of traction power lines are only rarely used for this
Cell phone antennas for smaller cell phone stations can also be installed on pylons of overhead lines for medium voltage (10–30 kV) and even low voltage (0.4 kV)
The transmitting and receiving devices are usually housed in a container or a switch cabinet under or next to the mast.
Chimneys
Large chimneys can also carry cell phone antennas. If the chimney has maintenance platforms, these are usually attached there. Mounting on the shaft is also possible. If the chimney is no longer to be used as such, the antennas can also be attached to the top. There are also dummy chimneys made of plastic for roof mounting, inside of which cell phone antennas can be installed.
building
Cellular antennas are installed on suitable buildings on the roofs of the same. Often these are clearly visible because this is the cheapest option.
Camouflaged antennas
The network providers are forced to camouflage many antennas on the one hand because of protests and on the other hand because of the desired network expansion. Monument protection or the protection of the landscape can also be a reason to hide the antennas. There are, for example, plastic chimney stacks to camouflage antennas on roofs.
The installation of cell phone antennas on listed buildings offers the opportunity to finance their maintenance through rental income.
There are cell phone towers whose appearance is modeled on trees and which should therefore blend in better with the landscape. Such constructions are commercially available in different variants, depending on the climate of the installation site in different versions (palm, pine, etc.).
Micro cells
At certain points in the city centers, the network utilization is significantly increased. For this reason, some network operators set up so-called microcells . These have a very limited range of rarely more than 200 meters. They only serve to relieve neighboring radio cells. The antennas are installed at a low height, for example on the facades of buildings, in neon advertising, on street lamps or on advertising pillars.
So-called indoor micro cells (also known as picocells) are used in heavily frequented buildings such as shopping centers, exhibition halls, train stations or airport terminals.
There are also mobile microcells that can be transported in a vehicle and set up on certain occasions (e.g. at concerts or football games).
Tunnel radio coverage
Many network providers also want to offer their customers an underground network supply. Here, several underground stations, each with several antennas, are usually combined to form a BTS. Due to the great distance and the associated high attenuation of the mobile radio signal, the supply usually takes place via an optical repeater network . The (analog) mobile radio signal is not distributed via coaxial cables, but rather via fiber optic cables . In a central operating room, in which the base stations of the network operator and the master unit are housed, the analog RF signal is converted electrically / optically and from there distributed via fiber optics to the individual remote units, which then optically / electrically again convert back, amplify and radiate via antennas or slotted cables . Another advantage of this technology is that several remote units can be supplied with the same frequency, i. H. the radio cell can extend over several subway stations. This makes it possible to save base stations.
The RF signal is emitted into the tunnel tubes via slotted cables along the tube walls or via directional antennas , which are usually placed at the tunnel entrances.
Other locations
Cellular antennas can also be installed in very unusual locations. In the USA, the installation of cell phone antennas on artificial trees is widespread.
Picture gallery
Cellular station on a house.
Cellular antennas on a tower.
Cellular antennas on a church tower.
Monument-compliant cell phone antennas on a church tower
BTS on a chimney.
Mobile BTS
Device cabinets for GSM and 3G BTS
Self-sufficient BTS
Antenna disguised as a palm tree
Microcell for LTE and UMTS
Device container
High voltage pylon with base station
Horse head observation tower with transmission systems for GSM, UMTS and LTE
criticism
Criticism is made of the growing number of masts and the image of the masts in the landscape. The increased radio wave intensity in the environment ( electromagnetic environmental compatibility ) is also criticized.
Apart from the fact that the increased density of the base stations reduces the transmission power of the cell phone at the ear, the radio wave energy density of the cell phone base stations is often estimated to be more dramatic than it is in comparison to the cell phones themselves and also in comparison with other sources: while cell phones are based of the radio waves absorbed in the body are assessed (limit value 2 watts per kilogram of body tissue), the power flux density at the location of people is decisive in radio transmission systems such as cell phone base stations . Depending on the transmission frequency, it is 4.5 to 10 watts per square meter. They are derived from the basic restriction for the general public of 0.08 watts per kilogram of body tissue. In the city of Regensburg, in connection with the expansion of the mobile network, forecasts were made to exhaust the limit values at various locations, with up to 15.2% of the permitted limit values being reached or expected after expansion at various locations (schools, children's homes, etc.).
It is often criticized that every mobile network operator sets up its own transmission masts and that no agreements are made to merge several transmitters on one mast. On the other hand, possible rental income attracts many to give permission for their property or house to have antennas installed there. This can lead to differences with the neighborhood.
Depending on the legal situation, politicians have more or fewer rights to intervene in a regulatory manner. In Austria, politicians have relatively few opportunities to intervene in structural or landscape protection, which is why the federal state of Lower Austria wanted to introduce a so-called cell phone mast tax from 2006 . However, following an agreement with the Austrian network operators, the levy was abolished before it was applied for the first time.
sabotage
In autumn 2016, cables were cut at 20 base stations in part of Styria and flight warning lights were damaged. In December, a 23-year-old suspect was arrested on account of serious damage to critical infrastructure and disruption of air traffic safety.
In 2020, there was an increasing number of arson attacks on cell towers in several European countries . Apparently these are motivated by conspiracy theories that assume a connection between the 5G expansion and the Covid-19 pandemic .
Web links
- Images from GSM transmitters
- Cellular radio station lists
- Federal Network Agency - Search for transmitter mast locations in Germany
- Bundesnetzagentur - mobile radio - station search
- Transmitter register for Austria
Individual evidence
- ↑ https://emf3.bundesnetzagentur.de/pdf/DECT-BNetzA.pdf Message from the Federal Network Agency on DECT cordless telephony, accessed on May 31, 2020
- ↑ VO Funk, 2012 edition, Article 1.71, definition: stationary land station / ortsfeste land radio station
- ^ [1] Vanessa Könecke: Why cell phone masts are camouflaged as chimneys , message from the company t-online from April 27, 2019
- ↑ [2] Message from komFOUR GmbH & Co. KG: How are the limit values for mobile communications determined? , accessed on May 30, 2020
- ↑ [3] Matthias Wuschek: Electromagnetic immissions in the vicinity of mobile radio transmission systems , accessed on May 30, 2020
- ↑ Cell phone mast requires the consent of the owner
- ↑ Sabotage on transmitter masts: perpetrators captured orf.at, December 23, 2016, accessed December 23, 2016.
- ↑ Because of coronavirus: Conspiracy theorists are flaring more and more 5G masts. April 18, 2020, accessed April 19, 2020 .
- ↑ Mobile communications: Burning 5G masts: Corona conspiracy theory is spreading. Retrieved April 19, 2020 .