Road safety applications envisaged for Vehicular Ad Hoc Networks (VANETs) depend largely on the dissemination of warning messages to deliver information to concerned vehicles. The intended applications, as well as some inherent VANET characteristics, make data dissemination an essential service and a challenging task in this kind of networks. This work lays out a decentralized stochastic solution for the data dissemination problem through two game-theoretical mechanisms. Given the non-stationarity induced by a highly dynamic topology, diverse network densities, and intermittent connectivity, a solution for the formulated game requires an adaptive procedure able to exploit the environment changes. Extensive simulations reveal that our proposal excels in terms of number of transmissions, lower end-to-end delay and reduced overhead while maintaining high delivery ratio, compared to other proposals.

The dissemination of video information contents migth enhance the performances of safety-related applications in vehicular ah-hoc networks (VANETs). A major problem concerns the high sensitivity of the compressed video streams to the severe channel conditions in wireless ad-hoc networks. The reliable dissemination of video contents in mobile environments is recognized as one of the main challenges for the developing and deploying of VANETs. To improve the robustness of dissemination, we propose RCP+ (Road-Casting Protocol) scheme for distributing high-definition video contents in VANETs. RCP+ is a cross layer dissemination mechanism for video safety messages that specifically addresses highway scenarios with zero infrastructure support. Also, a comparison of one of the most popular and widely spread video encoder H.264/AVC with respect to the recently released video coding scheme H.265/HEVC is presented. The comparison is performed by means of simulations showing differences between encoding algorithms in terms of perceived quality. The results indicate a better performance of HEVC based encoding algorithm in comparison to AVC in VANET environments.

Video content delivery for vehicular ad hoc networks (VANETs) is envisioned to be of high benefit for road safety, traffic management as well as for providing value-added vehicle services. In this paper, we evaluate five existing dissemination mechanisms in a realistic urban scenario. We also propose RCP+ as a renovated mechanism for adaptative video streaming over VANETs. RCP+ is a cross layer dissemination mechanism for video safety messages that specifically addresses urban scenarios with zero infrastructure support. Through simulations, we compare our proposal with other distributed dissemination mechanisms. The performance evaluation shows that our proposal mechanism is more suitable for video transmission in realistic urban scenarios. The results also indicate that a modified frame coding approach provides many opportunities for multimedia services.

Location privacy is a critical aspect of vehicular networks. Privacy schemes adopt diverse methods to minimize vehicle traceability. These schemes include pseudonym periodical changes, silent periods, context-based approaches, and cooperative pseudonym changes. It is important to maintain a discontinuity in the information sent by the vehicle to avoid reconstructing the vehicle trace. In this paper, we propose three privacy schemes that use SLOW as a baseline and combine it with other techniques: SLOW-based random silent periods, SLOW-based cooperative pseudonym change, and SLOW-based context-aware privacy scheme. These proposed schemes aim to enhance the original scheme by restricting their operations with intervals and thresholds and improving the management of silent periods. We evaluate the proposed schemes' performance in terms of traceability, computation time, pseudonym usage, and silence time. Results show that our schemes improve the original scheme in most tested metrics. The average improvement in traceability is 70%. Furthermore, our schemes reduce the silent period of the SLOW scheme by 17.40% on average.