1 Introduction
Today, the police in Germany communicates through analogue radio networks that are not compatible. This technique has two major disadvantages: the conversation can be bugged by criminals and spare parts become rare and expensive. A digital radio network provides encryption and is up to date, so spare are parts available. Moreover, it provides useful functionalities like data transmissions or priority calls that can improve the communication. Thus, most European countries have chosen a dedicated digital radio network for public safety and security. There are only two countries left still using analogue radio: Albania and Germany.
The floods at the river Elbe caused not only a lot of damage but also showed that the different organizations which were involved like police forces and German Armed Forces could not communicate directly. Additionally, the GSM network collapsed. Therefore, the Ministers of the Interior decided to use a digital radio network in 2000 that should be available in 2006 but the tender has not been started yet. This digital network should not only be used by police forces but also by fire brigades, rescue service, Federal Border Guard, the custom and governmental disaster relief organization THW.
A digital radio network consist of several base stations that cover the surface with areas in which they can send and receive radio that mobile device receive and send on the other side. These areas are called cells, each base station has got its own cell.
The base stations are connected to each other either by radio or by wire. So, an end user device in one cell can contact another end user device in another cell since the the base stations forward the data. If a an end user device leaves one cell and enters another one, the network should recognize it and should not terminate the call (handover). The base stations are controlled and administrated by headquarters.
Presently, there are three suitable techniques of digital radio networks: TETRA, Tetrapol and a combination of GSM and UMTS. The question must be raised which technique is favorable for Germany.
