Traffic-adaptive and interference-adaptive resource allocation schemes in GSM and DCS1800 systems under realistic traffic and propagation conditions: a case study

One of the key requirements of the evolution of present cellular systems (GSM) is the capability to cope with dynamic traffic and propagation conditions. It is well known that in the future microcellular urban systems (DCS1800) the usage of fixed channel allocation (FCA) schemes would be prevented, or at least made very difficult, by the high variability of the propagation conditions and consequently by the problem of identifying a regular pattern for channel re-use. Moreover, an FCA scheme would be inadequate to cope with traffic level fluctuations which are expected to vary dramatically especially in small cell or microcellular environments. Furthermore, the continuous incremental growth of subscribers could be better accommodated without reconsidering any frequency plan. These considerations drive us to investigate dynamic resource allocation policies in order to provide system operators with a flexible planning procedure capable of adapting the allocation of resources available at base stations according to the environmental conditions. We study dynamic allocation schemes in a realistic environment, focusing on the current GSM cellular network in the metropolitan area of Rome, starting from results of field prediction tools developed at CSELT. Due to the realistic propagation conditions, the cellular coverage is composed of different cell sizes (both small cells and macrocells) with irregular shapes. The paper shows the performance of different dynamic allocation policies and their advantage with respect to an FCA approach, by means of simulation results.