Cellular networks or Digital Cellur System (DCS) are radio networks for mobile communications and are the equivalent of public wide area networks. Cellular networks serve to supply mobile subscribers and must serve high subscriber densities in conurbations on the one hand and larger radio ranges in rural areas on the other. Both requirements can be met by cellular radio networks.
Currently, tele- and data communication from and to mobile terminals is carried out via base stations with transmitters and receivers. The coverage areas, i.e. the range of the respective base transmitters, make up the size of a radio cell. In theory, these radio cells are hexagonal in the form of a honeycomb plan, but in practice they are probably more circular with certain overlaps.
The radio cell sizeA radio cell consists of at least one transmitter/receiver pair and is defined as the space in which all transmitters and receivers use the same frequency and/or the same code. Depending on the extent of the individual radio cells, a distinction is made between picocells, microcells and macrocells, also known as large cells. metres and two kilometres and macrocells between two and 50 kilometres, whereby the carrier frequency of the transmitter plays a decisive role in the radio cell radius.
A special feature in mobile radio systems is the small cell network. In this cell structure, the mobile radio frequencies are better used by reducing the size of the radio cells. This is done by reducing the transmitting power to less than 10 watts, so that the coverage area then only has a diameter of 10 km to 20 km. The advantage is that the same transmission frequencies can be allocated much more often, the disadvantage is the high organisational effort required for handover.
Further characteristics of cellular networks are the automatic switching of the transmission when leaving a transmission area (handover) and the finding of a subscriber within the mobile network (roaming), even if the subscriber does not have a call connection during the search.