Jezabel Molina-Gil

Cooperation Enforcement Schemes in Vehicular Ad-Hoc Networks

Vehicular Ad-hoc NETworks (VANETs) will provide many interesting services in the near future. One of the most promising is commercial application. In such a case, there will be necessary to motivate drivers to cooperate and contribute to packet forwarding in Vehicle-TO-Vehicle and Vehicle-TO-Roadside communications. This paper examines the problem, analyzes the drawbacks of known schemes, and proposes a new secure incentive scheme to stimulate cooperation in VANETs.

Design and Implementation of an Application for Deploying Vehicular Networks with Smartphones

A vehicular ad hoc network (VANET) is a wireless network that provides communications between nearby vehicles. Among the different types of information that can be made available to vehicles through VANETs, road traffic information is the most important one. This work is part of an experimental development of a wireless communication platform oriented to applications that allow improving road efficiency and safety, managing and monitoring road traffic, encouraging cooperative driving, and offering pedestrian services and other added-value uses. The proposed system consists of smartphones, sensors, and Wi-Fi hotspots 2.0, as well as complementary functionalities including access to network infrastructure via 3G, GPRS, and 4G. The developed wireless network prototype allows taking advantage of the potential benefits of VANETs. At the same time, the use of smartphones does not require large money investments either in public or restricted areas. The first implementations with smartphones have been useful to test the behaviour of the proposal in a real environment. We have also implemented a large-scale simulation by using NS-2 simulator. From the obtained data, we have estimated the minimum requirements necessary for the correct working of a VANET and the problems that can happen in case of possible attacks or communication overhead.

Flexible authentication in vehicular ad hoc networks

A Vehicular Ad-Hoc Network (VANET) is a form of Mobile ad-hoc network, to provide communications among nearby vehicles and between vehicles and nearby fixed roadside equipment. The key operation in VANETs is the broadcast of messages. Consequently, the vehicles need to make sure that the information has been sent by an authentic node in the network. VANETs present unique challenges such as high node mobility, real-time constraints, scalability, gradual deployment and privacy. No existent technique addresses all these requirements. In particular, both inter-vehicle and vehicle-to-roadside wireless communications present different characteristics that should be taken into account when defining node authentication services. That is exactly what is done in this paper, where the features of inter-vehicle and vehicle-to-roadside communications are analyzed to propose differentiated services for node authentication, according to privacy and efficiency needs.

A simulation study of new security schemes in mobile ad-hoc networks

This work provides both a new global authentication system for Mobile Ad-hoc NETworks and a study of its simulation with NS-2. The proposed scheme is constructed in a self-organizing manner, which implies the fulfillment of most requirements for this type of networks, such as adaptation to the changing topology of the network, public availability of broadcast communications and strength of access control.

Aggregation and probabilistic verification for data authentication in VANETs

Vehicular ad hoc networks are wireless networks in which traffic information is distributed from many sources to many destinations. Thus, their deployment requires data authentication mechanisms to detect any malicious behavior of users, such as modification or replay attacks. In this work we describe a new data aggregation protocol for such networks, which uses probabilistic verification to detect those attacks efficiently with minimal overhead and delay. The proposed algorithm also contains an additional security mechanism based on reactive groups created on demand, which ensures a priori that vehicles generate trustworthy information. This paper also provides a comprehensive analysis that includes NS2 simulations and a small-scale implementation with real devices, which show that the proposed protocol is robust.

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.

Stimulating cooperation in self-organized vehicular networks

A Vehicular Ad-hoc NETwork (VANET) is a special form of Mobile Ad-hoc Network designed to provide communications among nearby vehicles and between vehicles and nearby fixed roadside equipment. Its main goal is to improve safety and comfort for passengers, but it can also be used for commercial applications. In this latter case, it will be necessary to motivate drivers to cooperate and contribute to packet forwarding in Vehicle-to-Vehicle and Vehicle-to-Roadside communications. This paper examines the problem, analyzes the drawbacks of known schemes and proposes a new secure incentive scheme to stimulate cooperation in VANETs, taking into account factors such as time and distance.

Self-organized authentication architecture for Mobile Ad-hoc Networks

This work proposes a new architecture, called Global Authentication Scheme for Mobile Ad-hoc Networks (GASMAN), for fully distributed and self-organized authentication. In this paper apart from describing all the GASMAN components, special emphasis is placed on proving that it fulfils every requirement of a secure distributed authentication scheme, including limited physical protection of broadcast medium, frequent route changes caused by mobility, lack of structured hierarchy, etc. Furthermore, an extensive analysis through simulation experiments in different scenarios is described and discussed.

Study on an Indoor Positioning System for Harsh Environments Based on Wi-Fi and Bluetooth Low Energy

This paper presents a study of positioning system that provides advanced information services based on Wi-Fi and Bluetooth Low Energy (BLE) technologies. It uses Wi-Fi for rough positioning and BLE for fine positioning. It is designed for use in public transportation system stations and terminals where the conditions are “hostile” or unfavourable due to signal noise produced by the continuous movement of passengers and buses, data collection conducted in the constant presence thereof, multipath fading, non-line of sight (NLOS) conditions, the fact that part of the wireless communication infrastructure has already been deployed and positioned in a way that may not be optimal for positioning purposes, variable humidity conditions, etc. The ultimate goal is to provide a service that may be used to assist people with special needs. We present experimental results based on scene analysis; the main distance metric used was the Euclidean distance but the Mahalanobis distance was also used in one case. The algorithm employed to compare fingerprints was the weighted k-nearest neighbor one. For Wi-Fi, with only three visible access points, accuracy ranged from 3.94 to 4.82 m, and precision from 5.21 to 7.0 m 90% of the time. With respect to BLE, with a low beacon density (1 beacon per 45.7 m2), accuracy ranged from 1.47 to 2.15 m, and precision from 1.81 to 3.58 m 90% of the time. Taking into account the fact that this system is designed to work in real situations in a scenario with high environmental fluctuations, and comparing the results with others obtained in laboratory scenarios, our results are promising and demonstrate that the system would be able to position users with these reasonable values of accuracy and precision.

Self-Organized clustering architecture for vehicular ad hoc networks

Vehicular Ad Hoc NETworks (VANETs) are likely to be deployed in the near future. Then, they will become the platform for much of the relayed information in the Internet of Things. This paper proposes a new system based on 1-hop clustering to reduce the number of VANET communications in dense road traffic scenarios while maintaining the security of communications by combining public-key with secret-key cryptography. The proposed distributed clustering architecture creates a dynamic virtual backbone in the network, formed by Cluster-Heads and cluster-gateways, so that these nodes are responsible for the efficient message propagation in the network. The main aim of the described architecture is to balance both stability of backbone connections and cost/efficiency trade-off. Full definitions of all the architecture procedures are provided, including a cluster-head selection algorithm based on a version of the independent set problem and a secret-key agreement scheme that uses the generalized Diffie-Hellman protocol. Simulations show that the proposal improves network performance and security.