What are the available cellular networks

What are radio cells and cellular networks like?

Cellular networks are the basis of mobile communication. To a certain extent, they form the basic infrastructure that enables calls to be made with the cell phone. The mobile phone operators have expanded the networks so well that citizens can use the mobile phone technology almost everywhere in Germany. Today, high quality voice and data transmission as well as expanded transmission capacities have become standard.

The German cellular networks use the frequency ranges of the older GSM and UMTS standards as well as those of the innovative LTE standard. The LTE standard was developed to further increase the data transmission rate and quality. Because with the introduction of the smartphone, data applications and the transmission of larger data volumes have become a matter of course.

EachCellular network is geographically divided into many contiguous areas, the so-called Radio cells. One therefore speaks of the cellular structure of the networks. The division into radio cells of limited size makes it possible to optimally use the limited number of available radio channels. Because the amount of available radio frequencies is severely limited in mobile communications by the state licensing. In a cellular network, the same frequencies or codes are therefore reused at a sufficient spatial distance.

Radio cells and their properties

The individual radio cells are usually honeycomb and extend over the entire federal territory. They have different sizes. The diameter of the cells ranges from less than 100 meters in city centers, where they may only supply a few houses or a subway station, to several kilometers in the country. So-called small cells are now being used more and more frequently in metropolitan areas. They can be installed in street lights, for example, and have a small radius which, however, increases the capacity of the networks.

Each radio cell is supplied by a permanently installed transmitter and receiver system - the so-calledCellular base station. To a certain extent, the base stations form the nodes of the mobile radio networks. The network operators in Germany currently operate around 124,000 base stations (source: Telecommunications Activity Report of the Federal Network Agency 2012-2013).

While the cell sizes do not change with GSM, the mobile radio cells with UMTS have a different characteristic: They “breathe”. Their spatial extent depends on the number of subscribers who make cell phone calls in a cell. Greater use reduces the usable cell accordingly. The capacity of an LTE radio cell is up to 200 active participants.

Requirements for the structure of cellular networks

In practice, the cell structure is derived from the numerous individual requirements that are placed on a modern cellular network. These are, for example, sufficient transmission capacity, high quality of voice and data transmission with low error rates and area-wide usability, which also includes supply within buildings.

Each cell can only supply a limited number of users. The continuously increasing demand for transmission capacities has meant that the operators have increased the number of mobile radio transmitters and thus also the number of radio cells. This makes it possible to reuse the frequencies or codes available in the network more frequently. Radio cells in which the same frequencies or codes are used, however, have to be far enough away from each other so that there is no mutual interference.

Depending on local demand, large and small cells are combined within a cellular network. In this way, high-load areas such as inner city areas, airports or train stations can be supplied in a more targeted and efficient manner. When cutting the cells, it should also be noted that the load can fluctuate very strongly over the day, week or year.

Smaller radio cells can also improve the transmission quality. Having the cells narrowly geographically restricted reduces the possibility of radio signal degradation.