Real time traffic updates via UMTS: Unicast versus multicast transmissions

Real time traffic information systems represent a growing sector of the wireless communication industries. To provide traffic information to drivers in a short term, cellular systems represent the answer: on the one hand many vehicles are equipped with global positioning system (GPS) navigators integrating cellular devices; on the other a large percentage of people has smart phones integrating advanced positioning systems. In this paper we aim at evaluating the feasibility of real time traffic information transmission to drivers by exploiting the universal mobile telecommunication system (UMTS) as the enabling technology. In particular, we compare the performance in the downlink of a urban scenario of the UMTS adopted in unicast and multicast mode, in terms of service feasibility and impact on the capacity left for other services. Results, performed through a simulation platform integrating a vehicular simulator tool together with a UMTS network simulator, will show which between unicast and multicast has to be preferred as a function of the considered environment.