Mobiles Funken : Simulation von Mobilfunknetzen
Handys haben unseren Alltag erobert: Fast jede(r) Deutsche besitzt eins. Die Simulation von Mobilfunknetzen ist vor allem angesichts ihrer zunehmenden Komplexität der Systeme – Stichworte sind hier zum Beispiel Internationalisierung und Kompatibilität – sinnvoll. So ist es möglich, bei Plänen für Weiterentwicklungen und Ausbau alle zu berücksichtigenden Parameter mit einzubeziehen.
Digital cellular networks have experienced a rapid growth since their introduction in the early nineties of the last century. Nowadays mobile phones belong to the personal belongings for the daily life of many people. However, digital cellular networks are very complex systems, and their development and deployment costs a lot of money. Due to their complexity it is not possible to overlook all parameters and their influence on system performance from scratch. The only feasible way of evaluating such complex systems in detail is by means of computer simulations. However, again because of the complexity a single simulation for the whole system, which takes every aspect of the system into account, is not possible. Instead, one splits the system in a link level simulator and a system level simulator. The link level simulator covers all details of a single link between one or more transmit antennas and one or more receive antennas. A core component of the link level simulator is the channel model, which models the properties of the mobile channel between the antennas. Because of the great variability of mobile channels only statistical channel models are promising. But also of the kind of statistical models there exist a large variety. In this paper simulations are shown which were performed at the Department of Communication Technologies at the University Duisburg- Essen. There are examples of channel impulse responses shown as they are experienced by the base stations and mobile stations. It is demonstrated that both types of stations typically experience very different channels. Furthermore, there are link level simulations. These show the influence of different algorithms on the bit error ratio in nonfading and fading channels. Finally, there are simulation results shown which demonstrate the behavior of a whole mobile network.