Improved interface between link level and system level simulations applied to GSM

Advanced simulation tools are of paramount importance for development and analysis of proposed and existing functionality in cellular systems. The different time scales involved in analyzing an entire system make it generally impossible to use one single simulator. Instead, several layers of simulators are normally used together. A common combination of tools is a link level simulator and a system level simulator. This paper presents a novel method for interfacing between these two simulator types. The main idea is to extract more information than usual from the link level simulation, and to include multipath fading in a system level simulation that operates on TDMA burst level. The result is reduced total simulation time and increased accuracy, especially for simulation of services with bursty transmission characteristics, such as packet data. To illustrate the method, the speech quality for a GSM system with and without features such as frequency hopping is derived.