Highway Vehicular Ad Hoc Networks Research Articles

Optimal Path Routing Protocol for Warning Messages Dissemination for Highway VANET.

In vehicular ad hoc networks (VANETs), helpful information dissemination establishes the foundation of communication. One of the significant difficulties in developing a successful dissemination system for VANETs is avoiding traffic fatalities. Another essential success metric is the transfer of reliable and secure warning messages through the shortest path, particularly on highways with high mobility. Clustering vehicles is a general solution to these challenges, as it allows warning alerts to be re-broadcast to nearby clusters by fewer vehicles. Hence, trustworthy cluster head (CH) selections are critical to decreasing the number of retransmissions. In this context, we suggest a clustering technique called Optimal Path Routing Protocol for Warning Messages (OPRP) for dissemination in highway VANETs. OPRP relies on mobility measured to reinforce cluster creation, evade transmission overhead, and sustain message authenticity in a high mobility environment. Moreover, we consider communication between the cluster heads to reduce the number of transmissions. Furthermore, the cluster head is chosen using the median technique based on an odd or even number of vehicles for a stable and lengthy cluster life. By altering traffic densities and speeds, OPRP is compared with prominent schemes. Simulation results revealed that OPRP offers enhanced throughput, end-to-end delay, maximizing packet delivery ratio, and message validity.

Fuzzy logic-based integrity-oriented file transfer for highway vehicular communications

Effective file transfer is fundamental to many applications in highway Vehicular Ad Hoc Networks (VANETs), e.g., social network applications, advertisement distributions, road traffic report, etc. However, due to the sparse development of roadside units (or access points) and the limited connection time between fast-moving vehicles, file transfer is susceptible to frequent interruptions, and accordingly resulting in incomplete file transfers. The incomplete file transfer leads to not only poor user performance with application playback failures, but also a colossal waste of bandwidth. To tackle this issue, in this paper, we consider a bi-directional highway vehicular network scenario where request vehicle and source vehicle are in the opposite direction, and propose a fuzzy logic-based cooperative file transfer scheme (FL-CFT). With the proposed scheme, the request file can be transferred completely from the source vehicle to request vehicle through multiple relay cluster members. As for the selection of relays, in general, finding an optimal relay subject to multiple constrains is an NP-complete problem that cannot be exactly solved in polynomial time. Accordingly, a fuzzy logic approach is utilized to optimally selects relays to help transfer the file and ensure the file integrity, which considers the relative velocity, distance, and predicted connection time among vehicles. The proposed scheme is self-organized and fully distributed, which does not require any assistance from roadside units (or access points). Simulation results show that FL-CFT outperforms the state-of-the-art file transfer schemes in file integrity on highway VANETs.

Drone-Based Highway-VANET and DAS Service

Wireless communications between vehicles are a focus of research in both the academic research community and automobile industry. Using unmanned aerial vehicles or drones in wireless communications and vehicular ad hoc networks (VANETs) have started to attract attention. This paper proposes a routing protocol that uses the infrastructure drones for boosting VANET communications to achieve a minimum vehicle-to-drone packet delivery delay. This paper also proposes a closed-form expression for the probability distribution of the vehicle-to-drone packet delivery delay on a two-way highway. In addition, based on that closed-form expression, we can calculate the minimum drone density (maximum separation distance between two adjacent drones) that stochastically limits the worst case of the vehicle-to-drone packet delivery delay. Moreover, this paper proposes a drones-active service that is added to the location service in a VANET. This service dynamically and periodically obtains the required number of active drones based on the current highway connectivity state by obtaining the maximum distance between each two adjacent drones while satisfying a probabilistic constraint for vehicle-to-drone packet delivery delay. Our analysis focuses on two-way highway VANET networks with low vehicular density. The simulation results show the accuracy of our analysis and reflect the relation between the drone density, vehicular density and speed, other VANET parameters, and the vehicle-to-drone packet delivery delay.

On the Analytical Calculation of the Probability Distribution of End-to-End Delay in a Two-Way Highway VANET

In several papers, analytical calculations of the mean value of the end-to-end delay in highway vehicular ad-hoc networks (VANETs) have been presented. Unfortunately, none of these papers presented calculations of the probability distribution of this delay, which is necessary to give probabilistically guaranteed upper bounds on the end-to-end delay in such VANETs. In a previous paper, we introduced the first analytical framework for the calculation of the probability distribution, and not only the mean, of the end-to-end delay in multi-lane one-way highway VANETs. This made it possible to provide guarantees of transmission in a given time frame with known confidence. In this paper, that previous work is extended to two-way multi-lane highways by taking into consideration vehicles travelling in both directions. The probability distribution of the end-to-end delay is calculated herein and its dependence on system parameters, such as speed distributions in the two directions, communication range, and vehicle densities, are analyzed. Computer simulations are used to verify the analytical model. The good agreement between simulation results and the analytical calculations demonstrates the correctness and accuracy of the proposed analytical model.

A Game Theory Approach for Platoon‐Based Driving for Multimedia Transmission in VANETs

Vehicular Ad Hoc Networks (VANETs) allow users, services, and vehicles to share information and will change our life experience with new autonomous driving applications. Multimedia will be one of the core services in VANETs and are becoming a reality in smart environments, ranging from safety and security traffic warnings to live entertainment and advertisement videos. However, VANETs have a dynamic network topology with short contact time, which leads to communication flaws and delays, increasing packet loss, and decreasing the Quality of Experience (QoE) of transmitted videos. To cope with this, neighbor vehicles moving on the same direction and wishing to cooperate should form a platoon, where platoon members act as a relay node to forward video packets in autonomous VANETs. In this article, we introduce a game theory approach for platoon‐based driving (GT4P) for video dissemination services in urban and highway VANET scenarios. GT4P encourages the cooperation between neighbor vehicles by offering reward (e.g., money or coupon) for vehicles participating in the platoon. In this sense, GT4P establishes a platoon by taking into account vehicle direction, speed, distance, link quality, and travel path, which reduces the impact of vehicle mobility on the video transmission. Simulation results confirm the efficiency of GT4P for ensuring video transmissions with high QoE support compared to existing platoon‐based driving protocols.

A Graph-based Performance Analysis of the 802.11p MAC Protocol for Safety Communications in Highway Vehicular Ad Hoc Networks

A Graph-based Performance Analysis of the 802.11p MAC Protocol for Safety Communications in Highway Vehicular Ad Hoc Networks

SIRC: A Secure Incentive Scheme for Reliable Cooperative Downloading in Highway VANETs

In this paper, we propose a secure incentive scheme to achieve fair and reliable cooperative (SIRC) downloading in highway vehicular ad hoc networks (VANETs). SIRC can stimulate vehicle users to help download-and-forward packets for each other and consists of cooperative downloading and forwarding phase. During the cooperative downloading phase, SIRC utilizes “virtual checks” associated with the designated verifier signature to ensure fair and secure cooperation. Meanwhile, to minimize the payment risk of the client vehicle, partial prepayment strategy is adopted, i.e., the vehicles involved in downloading packets can only obtain part of the check before the client vehicle confirms the packet reception. During the cooperative forwarding phase, a profit-sharing model associated with an aggregating Camenisch–Lysyanskaya (CL) signature can stimulate cooperation and reduce the authentication overhead. In addition, we develop a reputation system to encourage cooperation and punish malicious vehicles. The aggregating CL signature and the symmetric cryptosystem are applied to resist various attacks, including injection/removing attack, free riding attack, submission refusal attack, and denial of service attacks. Extensive simulation results are given to show that the proposed SIRC can achieve a high download success rate and low average download delay with moderate cryptographic computation and communication overhead.

Accurate Probability Distribution of Rehealing Delay in Sparse VANETs

In this letter, rehealing delay is analyzed for disconnected highway vehicular ad-hoc networks (VANETs). In the analysis, cluster length is first approximated by a simple but accurate, exponential-like mixed random variable. The relation between two successive network disconnections is then discussed to obtain the steady-state probability distribution of rehealing delay. Simulations show that the proposed analysis significantly outperforms previous works in terms of accuracy.

Vehicle Mobility and Communication Channel Models for Realistic and Efficient Highway VANET Simulation

Developing real-time safety and nonsafety applications for vehicular ad hoc networks (VANETs) requires understanding of the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANETs. Using various key metrics of interest, including node degree, neighbor distribution, number of clusters, and link duration, we provide a realistic analysis of the VANET topology characteristics over time and space for a highway scenario. In this analysis, we integrate real-world road topology and real-time data extracted from the freeway Performance Measurement System (PeMS) database into a microscopic mobility model to generate realistic traffic flows along the highway. Moreover, we use a more realistic, recently proposed, obstacle-based channel model and compare the performance of this sophisticated model to the most commonly used and more simplistic channel models, including unit disk and lognormal shadowing models. Our investigation on the key metrics reveals that both lognormal and unit disk models fail to provide realistic VANET topology characteristics. We therefore propose a matching mechanism to tune the parameters of the lognormal model according to the vehicle density and a correlation model to take into account the evolution of the link characteristics over time. The proposed method has been demonstrated to provide a good match with the computationally expensive and difficult-to-implement obstacle-based model. The parameters of the proposed model have been validated to depend only on the vehicle traffic density based on the real data of four different highways in California.

A multi-hop broadcast protocol design for emergency warning notification in highway VANETs

Multi-hop broadcast transmission is used in vehicular ad hoc networks (VANETs) to alert all vehicles within a geographical area of an emergency situation. However, the successful dissemination of multi-hop warning messages beyond the transmission range of a vehicle faces three major issues: (i) the broadcast storm, (ii) the severe interference with the existing periodic single-hop safety messages, and (iii) the hidden nodes. In this paper, we propose an efficient time-slotted multi-hop broadcast protocol that significantly reduces the number of required transmissions, while ensuring a timely and successful delivery of the warning messages. To alleviate the broadcast storm problem, we select only a subset of vehicles on the road to serve as the potential relay nodes. Each of these ‘segment leaders’ is responsible for forwarding the warning messages arrived in its own road segment. To avoid interfering with the safety messages transmitted periodically, we propose to allocate separate time slots for the warning messages. We also devise a signaling mechanism that ensures the reliable delivery of these multi-hop messages. Simulation results confirm that the developed protocol substantially outperforms existing schemes in terms of the number of required multi-hop transmissions and the dissemination delay. At the same time, the proposed solution maintains a high reception rate and low end-to-end delay for the single-hop safety messages.

Probability Distribution of End-to-End Delay in a Highway VANET

Vehicular ad-hoc networks (VANETs) are wireless ad-hoc networks formed by vehicles in motion on a road or highway. The performance of VANETs has been analyzed in several studies. However, these studies determined the expected value of the information propagation speed and the end-to-end delay in highway VANETs. In this letter, we find the probability distribution of the end-to-end information propagation delay of a message in a store-carry-forward highway VANET, and show that these results agree closely with those from computer simulations. Using the derived probability distribution, we calculate the probability that the end-to-end delay is less than a given threshold.