Simulation of quality of service mechanisms in the UMTS terrestrial radio access network

Supporting multiple traffic classes with different QoS (Quality of Service) constraints in third generation mobile systems is not a straightforward problem. This issue becomes critical at the access network interfaces, where transmission resources are usually expensive. One of the most important interfaces is the one that connects each base station with its controller, because there can be many instances of it. We have approached the dimensioning of this interface from the perspective of simulation, concretely for the UMTS (Universal Mobile Telecommunications System) access network. At this respect we have developed a simulation model capable of representing multi-service scenarios inside this particular UTMS interface. This tool can be fed with traffic of different types, representing the different traffic classes defined for UMTS, and is able to simulate traffic differentiation both at ATM (Asynchronous Transfer Mode) and AAL2 (ATM Adaptation Layer 2) level. In the paper we present simulation results showing how the simulator can aid us in the task of access network dimensioning with QoS constraints.