Wireless Communications Enabling Smart Mobility: Results from the Project PEGASUS Alessandro Bazzi, Barbara M. Masini, Gianni Pasolini, and Oreste Andrisano CNR-IEIIT and DEIS, University of Bologna @WiLab Bologna, Italy Email: {alessandro.bazzi, barbara.masini, gianni.pasolini oreste.andrisano}@unibo.it Abstract—Wireless communications for real time traffic information are considered to efficiently provide smart mobility in congested cities. In this work, we aim at summarizing objec- tives the results of the Italian project PEGASUS, where wireless communications have been exploited, in real time, to: i) acquire traffic information directly from vehicles (uplink) and ii) re- transmit updated information to interested vehicles (downlink) after a proper processing at a control center. Specifically we focus on i) the uplink collection of data from vehicles through the universal mobile telecommunication system (UMTS), ii) the downlink transmission of updated information to vehicles through UMTS, iii) the cellular resource saving through the exploitation of short range communications based on wireless access in vehicular environment (WAVE)/IEEE 802.11p, and iv) the impact of updated information on travel time. Results are provided through the development of an integrated simu- lation platform that jointly takes into account vehicular traffic behavior in urban environment, data processing at the control center, and performance of the communication networks at the different layers of the protocol pillar. Keywords-Intelligent transportation systems (ITS); real time services; simulations in realistic scenarios. I. I NTRODUCTION Keeping traffic moving is a challenge that governments, industries and researchers are facing worldwide nowadays. Effective solutions can only be obtained with a capillary real time knowledge of the traffic conditions and a prompt communication to the drivers; without updated and dynamic traffic information, only particular events or repetitive sit- uations can be handled. The creation of an infrastructure for communication between vehicles, service centers and sensors, is thus one of the main needs identified by interna- tional institutions, service providers and car manufacturers to address with satisfactory results the problems generated by traffic, justifying the big efforts that are being pushed both in Europe and in the rest of the world [1]. To this scope, dif- ferent wireless access technologies could be exploited, from short-range ad-hoc networks to cellular systems. Regarding the former ones, wireless access in vehicular environment (WAVE) [2], based on IEEE 802.11p [3] represents the future for vehicle-to-vehicle (V2V) communications. This technology, well suited for safety applications, entertain- ment, gateway access, and road charging, can also be used for traffic management service, on condition that a connection to a remote control center is available. Vehicles, in fact, must periodically collect their position and speed and send such data to a control center, that is in charge of retransmitting back aggregated traffic information. Even in the case that all vehicles were equipped with such technolo- gies, the need for an infrastructure makes the adoption of IEEE 802.11p for traffic management services a long term solution, due to the investment that the deployment of a communication infrastructure requires. Hence, thinking to short term, cellular systems appear as the only feasible solution, already guaranteeing high penetra- tion and wide coverage worldwide, also allowing continuity of service at vehicular speeds. And this is particularly true noting that, on the one hand, the last generation of on board navigators are already equipped with a cellular interface, and, on the other hand, smart phones embed navigation functionalities (often for free). However, the expected in- crease of vehicles equipped with on board units (OBUs) could lead to an overload of the cellular access network, and, consequently, to a degradation of the quality of service provided to voice and data users [4]. This work is carried out in the framework of the Italian project PEGASUS [5] and aims at summarizing the obtained results. Most of them have been already published (see, e.g., [4], [6], [7], [8], [9], [10]), but this is the first paper that summarizes the project as a whole. PEGASUS relies on over one million vehicles already equipped with OBU periodically transmitting their position and speed to a control center. Considering this scenario, we focus on i) the uplink transmission of data from vehicles through cellular systems, ii) the downlink transmission of updated traffic information to vehicles through cellular systems, iii) the exploitation of short range V2V and vehicle-to-roadside (V2R) communica- tions to save cellular resources, and iv) the impact of updated traffic information on travel time. In particular, firstly focusing on the universal mobile telecommunications system (UMTS) as the enabling tech- nology for uplink and downlink information, we aim at: • investigating the feasibility of the acquisition of small but frequent amount of data from many vehicles (uplink performance). Is the UMTS capacity sufficient for these kinds of multiple connections? 141 Copyright (c) IARIA, 2012. ISBN: 978-1-61208-229-5 MOBILITY 2012 : The Second International Conference on Mobile Services, Resources, and Users