# Managing Emergency Situations in VANET Through Heterogeneous Technologies Cooperation
## 2 Related Work  
Many protocols and applications have been proposed in literature to deal with traffic physical security and comfort, especially after the incredible development of VANETs technologies. However, very few of them tend to integrate the available technologies, in order to exploit their advantages. For example, several applications have been developed to improve road safety by using GPS and users advisories: to reduce and optimize the time needed by an emergency vehicle, the accident detection is made by a direct connection with the car control unit, while calling directly the emergency number or sending data to a dedicated server [11]. HD traffic [12] is another solution developed by TomTom, allowing to receive up-to-date information related to the path the vehicle is following, collecting data from other devices that use this service. In [13], the authors provide an overview of an innovative approach for effective cross-network information dissemination (quick and inexpensive) of traffic alerts using VANET network architecture. In [14; 15; 16; 17; 18] the authors describe a new intelligent street lighting system integrated with VANET technology in the smart city context. The paper proposes a system able to tune the LED lamp automatically according to environment luminance changes. In [19] the authors develop a Traffic Management System (TMS) solution that incorporates the progress in the _Internet of Things_ (IoT) technologies. The aim of [20] is to propose a route planning algorithm able to dynamically calculate the route that meets the shortest travelling time or the lowest fuel consumption criteria using information from Google Map. In [21] the authors proposed a dynamic traffic light control scheme, in order to reduce vehicles CO\({}_{2}\) emissions. In the proposed scheme, vehicles can pass through intersections with less waiting time and fewer numbers of stops. Other works that propose solution for traffic lighting control based on traffic analysis are [22; 23; 24]. In [25] the authors address the road safety issue in VANET and by proposing a framework called _Attention Assist Framework_ (AAF). In [26] the authors propose a detailed analysis on ITS that may help to improve actual solutions. The work in [27] deals with the _Adaptive Speed Limits_ (ASLs) which is a technique for enhancing the driving conditions on the roads. The variable speed limit with notification in-vehicle driver is an important factor that can outperform dynamic roadside speed limit signs in terms of safety. The authors present a framework outlining the system-level design and the implementation for an ASL system with an interactive in-vehicle display supporting communication units. The authors in [28] presented a strategy to reduce traffic congestion using the _Vehicle-To-Vehicle_ (V2V) communication. Periodically emitted beacons are used to analyze traffic flow and to warn other drivers of a possible distribution of traffic. The vehicles that receive such a warning, are told to keep a larger gap to their predecessor. In [29] the authors, on the basis of a hybrid ITS which utilizes both vehicular ad hoc networks and cellular systems, propose a real-time path-planning algorithm able to reduce average vehicle travel cost for avoiding congestion. The work in [30] presents a routing protocol that uses Real-Time traffic information gathered through the exchange of messages between vehicles. This protocol creates road-based paths consisting of successions of road intersections that have an high probability of connectivity among them. Another work that faces with safety issues is [31]: in this idea the vehicles collaborate in order to avoid collision. In [32; 33; 34], we have paid attention to the network layer of VANET, trying to reduce the co-channel interference during data exchange between the vehicles. Instead, in this paper we have focused the study on a new distributed architecture and a necessary protocol for managing dangerous situations in VANET networks.