INFORMATION AND COMMUNICATION TECHNOLOGIES AND SERVICES VOLUME: 13 | NUMBER: 4 | 2015 | SPECIAL ISSUE Vehicular Traffic Optimization in VANETs: a Proposal for Nodes Re-routing and Congestion Reduction Mauro TROPEA, Amilcare Francesco SANTAMARIA Department of Computer Science Engineering, Modeling, Electronics and Systems, University of Calabria, Via P. Bucci 42/C, 870 36 Arcavacata di Rende (CS), Italy mtropea@dimes.unical.it, afsantamaria@dimes.unical.it DOI: 10.15598/aeee.v13i4.1495 Abstract. Recently, vehicular networking has grown up in terms of interest and transmission capability, due to the possibility of exploiting the distributed commu- nication paradigm in a mobile scenario, where moving nodes are represented by vehicles. The different ex- isting standards for vehicular ad-hoc networks, such as DSRC, WAVE/IEEE 802.11p, have given to the research community the possibility of developing new MAC and routing schemes, in order to enhance the quality and the comfort of mobile users who are driving their vehicles. In this paper, we focus our attention on the optimization of vehicular traffic flowing, where the vehicle-2-roadside device is available. As shown in the next sections, the proposed idea exploits the informa- tion that is gathered by road-side units with the main aim of redirecting traffic flows (in terms of vehicles) to less congested roads, with an overall system opti- mization, also in terms of Carbon Dioxide emissions reduction. Several campaigns of simulations have been carried out to give more effectiveness to our proposal. Keywords 802.11p, congestion, DSRC, traffic flow, VANET, WAVE. 1. Introduction Vehicular Ad-hoc NETworks (VANETs) represent a new and modern paradigm of communication, where the nodes are able to communicate in a distributed manner, based on the Ad-hoc paradigm [1]. Each node is equipped with a wireless device, the On-Board Unit (OBU), which is able to interact with the mobile user, especially for comfort/security applications, trade and infotainment services. The OBU devices are able to realize the pure Ad-hoc communication networking in VANETs, indicated with Vehicle-2-Vehicle (V2V) com- munication. The complete architecture also provides the, so-called, Road-Side Units (RSUs) which can also be any equipment-certified packet forwarding, such as GSM, WLAN, and WiMAX towers. These devices realized the, so-called, Vehicle-2-Infrastructure (V2I) paradigm. The RSUs are very useful for guaranteeing the complete coverage of an area when some distributed nodes are disconnected, giving the driver the possibil- ity of still being able to receive the needed information. In this way, the road safety is improved, also because emergency vehicles can act more speedily; VANETs are able to broadcast real-time alerts to drivers about the risks of their planned journey and their immediate sur- roundings [2]. In addition, if a danger situation is cre- ated or, at a particular place, an emergency vehicle is needed to come quickly, VANETs give the chance to improve the effectiveness of the needed operations, by exploiting the effects of dedicated protocols and algo- rithms [3], [4]. For instance, if the cars involved in accidents can advise the event instantly to the emer- gency services, a ready and timely intervention can be immediately scheduled. If also the near cars can re- ceive the update, they would reduce inconveniences: platooning would be really helpful in order to leave the right space on the roads for the emergency vehicles, without time wastages. V2V communication allows the development of new applications and one of the main desires of drivers is also to avoid congested roads during their journeys and traveling. In this paper, we focus our attention on the optimization of traffic flowing in a vehicular environment with V2I capability. The pro- posed idea enables the considered vehicular network to re-route all the vehicles on new paths toward des- tinations, avoiding useless time wastages and reducing the creation of harmful Carbon Dioxide (CO 2 ) emis- c  2015 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 376