How to build vehicular ad-hoc networks on smartphones

Vehicular ad-hoc networks have been defined in the literature as communications networks that allow disseminating information among vehicles to help to reduce traffic accidents and congestions. The practical deployment of such networks has been delayed mainly due to economic and technical issues. This paper describes a new software application to detect traffic incidents and exchange information about them, using only smartphones, without any central authority or additional equipment. Both road safety and communication security have been taken into account in the application design. On the one hand, the interface has been designed to avoid distractions while driving because it operates automatically and independently of the driver, through voice prompts. On the other hand, communication security, which is essential in critical wireless networks, is provided through the protection of attributes such as authenticity, privacy, integrity and non-repudiation. All this is achieved without increasing the price of vehicles and without requiring the integration of new devices neither in vehicles nor on roads. The only prerequisite is to have a smartphone equipped with Wi-Fi connectivity and GPS location in each vehicle. The proposed application has been successfully validated both in large-scale NS-2 simulations and in small-scale real tests to detect traffic congestions and empty parking spaces.