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In large scale networks like Vehicular Ad-hoc Networks (VANETs), the full coverage of fixed infrastructure is hard to ensure, making network management difficult. Whether in infrastructure-less environments where the network connectivity is poor or where the infrastructure deployment is difficult, costly or not profitable. Recently, in the one side, Unmanned Aerial Vehicles (UAVs) have been used as a new flexible solution to assist infrastructure-less vehicular networks for the investigation of inaccessible areas. In the other side, several works have shown interest in the use of the emerging network paradigm of Software-Defined Networking (SDN) to facilitate the management and improve the performances of vehicular networks. In this paper, we propose a novel distributed SDN-based architecture for UAV-assisted infrastructure-less vehicular networks. The main goal is to fill the gap that no SDN-based architecture has been proposed for these networks. We focus particularly on a road safety use-case that incorporates UAVs to assist emergency vehicles in the exploration of affected zones in critical emergency situations. Moreover, we investigate how to achieve efficient data processing policy through a computation offloading/sharing decision-making problem. The main challenge is to reach the best tradeoff between computation delay and energy consumption for computation-intensive tasks in a delay-sensitive context. We formulate this decision problem as a two-player sequential game approach and design distributed computation algorithms to solve the problem. Numerical results show that data processing policy of distributed offloading/sharing algorithms achieves efficient computation performances in terms of delay and energy whilst ensuring until 28% gain of system cost and 95% better response time, compared to native computation scenarios and related data delivery UAV-assisted VANET works, respectively. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc networks (VANETs) are a significant field in the intelligent transportation system (ITS) for improving road security. The interaction among the vehicles is enclosed under VANETs. Many experiments have been performed in the region of VANET improvement. A familiar challenge that occurs is obtaining various constrained quality of service (QoS) metrics. For resolving this issue, this study obtains a cost design for the vehicle routing issue by focusing on the QoS metrics such as collision, travel cost, awareness, and congestion. The awareness of QoS is fuzzified into a price design that comprises the entire cost of routing. As the genetic algorithm (GA) endures from the most significant challenges such as complexity, unassisted issues in mutation, detecting slow convergence, global maxima, multifaceted features under genetic coding, and better fitting, the currently established lion algorithm (LA) is employed. The computation is analyzed by deploying three well-known studies such as cost analysis, convergence analysis, and complexity investigations. A numerical analysis with quantitative outcome has also been studied based on the obtained correlation analysis among various cost functions. It is found that LA performs better than GA with a reduction in complexity and routing cost. [ABSTRACT FROM AUTHOR]

This paper proposed a connectivity-based multi-lane geographic routing protocol (CGRP) for vehicular ad hoc networks. The proposed CGRP is based on an effective selection of road intersections through which a package must pass from source to destination. The cooperative connectivity probability and delay are taken into consideration when choosing the most suitable path for delay-sensitive safety traffic. Analytical expressions for cooperative connectivity probability is derived based on a three-lanes path model. Geographical forwarding is used to transfer packets between any two intersections on the path, reducing the path sensitivity to individual node movements. Furthermore, forwarding packets between two adjacent intersections also depend on geographic location information. Neighbor nodes’ priority are assigned according to position, speed, direction and other factors. Node with the highest priority will be selected as the next hop. Numerical and simulation results show that the proposed algorithm outperforms the exsiting routing protocols in terms of the end-to-end delay and the number of hops with a little cost of routing overhead in city environments. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc networks (VANETs) are under active development, thanks in part to recent advances in wireless communication and networking technologies. The most fundamental part in VANETs is to enable message authentications between vehicles and roadside units. Message authentication using proxy vehicles has been proposed to reduce the computational overhead of roadside units significantly. In this message authentication scheme, proxy vehicles that verify multiple messages at the same time improve roadside units’ efficiency. In this paper, first we show that the only proxy-based authentication scheme (PBAS) presented for this goal by Liu et al. cannot guarantee message authenticity, and also it is not resistant against impersonation and modification attacks and false acceptance of batched invalid signatures. Next, we propose a new identity-based message authentication scheme using proxy vehicles (ID-MAP). Then, to guarantee that it can satisfy the message authentication requirement, existential unforgeability of underlying signature against adaptively chosen-message and identity attack is proved under elliptic curve discrete logarithm problem in the random oracle model. It should be highlighted that ID-MAP not only is more efficient than PBAS since it is pairing-free and identity-based, and also it does not use map-to-point hash functions, but also it satisfies security and privacy requirements of VANETs. Furthermore, analysis shows that the required time to verify 3000 messages in ID-MAP is reduced by 76% compared to that of PBAS. [ABSTRACT FROM AUTHOR]

Vehicular Ad-hoc network is an emerging technology, which takes vehicles as nodes and forms a wireless network. The topology of such network changes rapidly as the nodes are in continuous motion with different speeds, leading to some serious issues that must be handled correctly in order to make VANETs reliable. One of the main problems associated with VANETs is Frequent Link Disconnection. There have been many designed for VANETs but Rapid change in topology has made it really problematic to design a routing protocol for VANETs that is efficient and effective in all terms. In this paper, we compared the four major VANET routing protocols, GPGR, GPSR, GPCR & HarpiaGrid in terms of Frequent Link Breakage with respect to velocity of nodes and the number of nodes. The results have proved, HarpiaGrid and GPGR are the better routing protocols than other two. If overhead cost is ignored, HarpiaGrid gives the outstanding performance. [ABSTRACT FROM AUTHOR]

With the remarkable progress of cooperative communication technology in recent years, its transformation to vehicular networking is gaining momentum. Such a transformation has brought a new research challenge in facing the realization of cooperative vehicular networking (CVN). This paper presents a comprehensive survey of recent advances in the field of CVN. We cover important aspects of CVN research, including physical, medium access control, and routing protocols, as well as link scheduling and security. We also classify these research efforts in a taxonomy of cooperative vehicular networks. A set of key requirements for realizing the vision of cooperative vehicular networks is then identified and discussed. We also discuss open research challenges in enabling CVN. Lastly, the paper concludes by highlighting key points of research and future directions in the domain of CVN. [ABSTRACT FROM PUBLISHER]

Recently, connected vehicles (CV) are becoming a promising research area leading to the concept of CV as a Service (CVaaS). With the increase of connected vehicles and an exponential growth in the field of online cab booking services, new requirements such as secure, seamless and robust information exchange among vehicles of vehicular networks are emerging. In this context, the original concept of vehicular networks is being transformed into a new concept known as connected and autonomous vehicles. Autonomous vehicular use yields a better experience and helps in reducing congestion by allowing current information to be obtained by the vehicles instantly. However, malicious users in the internet of vehicles may mislead the whole communication where intruders may compromise smart devices with the purpose of executing a malicious ploy. In order to prevent these issues, a blockchain technique is considered the best technique that provides secrecy and protection to the control system in real time conditions. In this paper, the issue of security in smart sensors of connected vehicles that can be compromised by expert intruders is addressed by proposing a blockchain framework. This study has further identified and validated the proposed mechanism based on various security criteria, such as fake requests of the user, compromise of smart devices, probabilistic authentication scenarios and alteration in stored user’s ratings. The results have been analyzed against some existing approach and validated with improved simulated results that offer 79% success rate over the above-mentioned issues.

“Vehicular Ad-hoc Networks„ (VANETs): As an active research area in the field of wireless sensor networks, they ensure road safety by exchanging alert messages about unexpected events in a decentralized manner. One of the significant challenges in the design of an efficient dissemination protocol for VANETs is the broadcast storm problem, owing to the large number of rebroadcasts. A generic solution to prevent the broadcast storm problem is to cluster the vehicles based on topology, density, distance, speed, or location in such a manner that only a fewer number of vehicles will rebroadcast the alert message to the next group. However, the selection of cluster heads and gateways of the clusters are the key factors that need to be optimized in order to limit the number of rebroadcasts. Hence, to address the aforementioned issues, this paper presents a novel distributed algorithm CDS_SC: Connected Dominating Set and Set Cover for cluster formation that employs a dominating set to choose cluster heads and set covering to select cluster gateways. The CDS_SC is unique among state-of-the-art algorithms, as it relies on local neighborhood information and constructs clusters incrementally. Hence, the proposed method can be implemented in a distributed manner as an event-triggered protocol. Also, the stability of cluster formation is increased along with a reduction in rebroadcasting by allowing a cluster head to be passive when all its cluster members can receive the message from the gateway vehicles. The simulation was carried out in dense, average, and sparse traffic scenarios by varying the number of vehicles injected per second per lane. Besides, the speed of each individual vehicle in each scenario was varied to test the degree of cohesion between vehicles with different speeds. The simulation results confirmed that the proposed algorithm achieved 99% to 100% reachability of alert messages with only 6% to 10% of rebroadcasting vehicles in average and dense traffic scenarios.

Thanks to the rapid development of vehicle-to-everything (V2X) and sensor technology, states of vehicles can be accurately measured and stored jointly in the cloud. These states can be viewed as a set of infinite attributes, such as the density around the motor vehicle, signal strength and so on. As such, the vehicle can be viewed as a moving object. The vehicle state can be measured, and its entropy is large. In vehicle networking, unicast communications between vehicles must be encrypted. The previous approach was to negotiate a session key through the Diffie-Hellman algorithm and then use the session key to encrypt the communications. This method not only needs to know in advance the peer IP of the communication, but it also needs a long time to establish a session key. Therefore, it is not suitable for vehicle networking. For the fast-changing vehicle networking, the session key establishment process should be shortened or even canceled. In this paper, we propose a method of Negotiation-free encryption for securing vehicular unicasting communications to improve the efficiency of vehicle ad hoc network transmissions.

Based on proxy re-signature and certificateless public key cryptography, a message authentication scheme for vehicular ad hoc network (VANET) is presented. By using the proxy re-signature technology, the trusted authority can convert a signature generated by on-board unit into one from the road-side unit on the same message. Hence, it not only effectively reduces the risk of tracking vehicle according to signature，but also ensures anonymous message communication in VANET. If the vehicle releases false news, the trusted authority can accurately track the true identity of the vehicle and recall illegal vehicles. Moreover, compared with Huang scheme, the proposal has higher security and lower communication overhead. [ABSTRACT FROM AUTHOR]

Internet of Vehicles (IoVs) is coming and will grow in next few years, VANETs (Vehicular Ad Hoc Networks) is evolving into the era of IoVs. Inevitably, VANETs need to communicate with WSNs (Wireless Sensor Networks). Real-time data transmission between vehicles and road-side sensor nodes has many application scenarios. However, due to different characteristics of VANETs and WSNs, real-time traffic data transmission is too complicated and slow when emergencies occurred in many RSUs-sparse (Road Side Units) areas. In this paper, we propose a broadcast authentication protocol, namely Paralleling Broadcast Authentication Protocol (PBAP), aiming at enhancing energy efficiency and providing network security in the direct communication between vehicles and WSNs. The simulation results demonstrate that the protocol can effectively extend lifetime of WSNs by improving the utilization rate of the keys and show nice properties in different channel loss ratio and different degrees of DoS attacks. The protocol can work well even in the area without RSUs. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the impacts of a reservation system for on-street parking. Such a system provides drivers looking for on-street parking with information on available parking spaces, thereby possibly reducing the need to cruise for parking and the accompanying negative externalities. The performance of the proposed system is studied using a highly detailed spatial agent-based simulation. The results of the simulations show that users of a reservation system benefit in terms of reduced search time and reduced walking distance under virtually all simulated circumstances. However, societal benefits are not as clear-cut. The benefit in search time for the users of the system comes at a cost to the regular drivers, which see a nearly identical increase in search time. In contrast, the positive impact on walking distance hardly influences walking distance for regular drivers. Hence, we conclude that the introduction of a reservation system for on-street parking results in a more efficient distribution of available parking spaces among drivers searching for parking. [ABSTRACT FROM AUTHOR]

Vehicular Ad-hoc Network (VANET) is emerging technology which is considered one of the key research area in security applications. This paper surveys advancements made in group based Vehicular Ad-hoc Network security technologies for future directions in group management technologies (GMT) and also various secure message transmission (SMT) amongst the groups. This paper also presents a review of architecture, related technologies, trends, applications in VANET technologies with major focus security Ad here once tools. Although offering significant services and devices, VANET based healthcare still faces major challenges and open research issues which are discusses in the paper as well. [ABSTRACT FROM AUTHOR]

Intelligent Transport Systems applications for commercial vehicles are aimed at minimizing stops that are not strictly necessary (for weight control, licenses or approvals) and improved logistics for fleet operators, including the use of intermodal transport. This article addresses the development of a system that monitors and informs a road train, that forms in real-time, about the length of a selected route, the travel time on the route, and especially the route fuel consumption. By collecting information from fleets of trucks, the communication interface between the vehicle and the fleet monitoring and information system will cover a large area of interest. The system will receive data from the vehicles and after a specific processing stage, will display optimal routes in terms of fuel consumption. [ABSTRACT FROM AUTHOR]

Vehicular Ad-Hoc Network (VANET), a vital component of Intelligent Transportation Systems (ITS) technology, relies on communication between dynamically connected vehicles and static Road Side Units (RSU) to offer various applications (e.g., collision avoidance alerts, steep-curve warnings and infotainment). VANET has a massive potential to improve traffic efficiency, and road safety by exchanging critical information between nodes (vehicles and RSU), thus reducing the likelihood of traffic accidents. However, this communication between nodes is subject to a variety of attacks, such as Man-In-The-Middle (MITM) attacks which represent a major risk in VANET. It happens when a malicious node intercepts or tampers with messages exchanged between legitimate nodes. In this paper, we studied the impact on network performance of different strategies which attackers can adopt to launch MITM attacks in VANET, such as fleet or random strategies. In particular, we focus on three goals of MITM attacks—message delayed, message dropped and message tampered. The simulation results indicate that these attacks have a severe influence on the legitimate nodes in VANET as the network experience high number of compromised messages, high end-to-end delays and preeminent packet losses.

[Display omitted] • To present a new deep learning model called Optimized Recurrent Neural Network (O-RNN)-based performance prediction model of Internet of Things (IoT) regarding smart city application using Self Adaptive Honey Badger Algorithm (SA-HBA) for maximizing the performance of the IoT networks using various networks like Wireless Sensor Network (WSN), Radio Frequency Identification (RFID), Mobile Ad-hoc NETworks (MANET), Wireless Body Area Networks (WBAN), and Vehicular Ad-hoc NETwork (VANET). • To construct a new IoT performance prediction model using various networks like VANET, WBAN, MANET, RFID and WSN by suggesting a new SA-HBA to maximize the convergence rate of IoT network for smart city application. • To evaluate the efficiency of IoT networks by comparing with diverse heuristic and conventional prediction approaches regarding various performance measures like energy consumption, throughput, and packet loss ratio. Internet of Things (IoT) has been widely utilized as the major significant element of Information and Communications Technology (ICT) for feasible smart cities due to the capability of IoT for supporting sustainability in numerous domains. There is a need for fault avoidance via the continuous and dynamic utilization of network behavior for achieving the necessary quality of the IoT communication system that allows us to get sustainable enhancement in smart cities regarding IoT communication systems. While considering the IoT-assisted network, the basic part of the IoT model is considered a Wireless Sensor Network (WSN), especially for data management that consists of various sensor nodes in the smart city area. Moreover, every node in a WSN is considerably utilized for a specific reason and thus, every node is handled by a battery that increases the consumption of energy in the entire smart city scheme for processing the data regarding communication. On the other hand, there exist various limitations like scalability, communication latency, centralization, privacy, security, etc. Thus, this paper plans to develop the IoT and WSN-based smart city application using novel intelligent techniques, aiming for the optimal performance classification of the network. The infrastructure of IoT will consist of WSN, Vehicular Ad-hoc NETwork (VANET), Mobile Ad-hoc NETworks (MANET), Radio Frequency Identification (RFID), and Wireless Body Area Networks (WBAN). Here, the efficiency of the whole IoT system is acquired from the efficiency of the whole IoT module. Hence, the IoT network efficiency rates of the individual must be predicted in an earlier stage to predict the effectiveness of the complete IoT system. The efficiency of each network is forecasted with the help of the constraints such as energy consumption, gathered data size, transmitted data size, mobility, false positive, throughput, packet loss, and delay. The output from each network is considered as input to the Optimized Recurrent Neural Network (ORNN) for predicting the ending superiority of the whole IoT network. Here, the parameter tuning in the RNN is done by the Self Adaptive Honey Badger Algorithm (SA-HBA). The empirical outcomes confirmed that the designed method has forecasted and enhanced the superiority of a whole simulated IoT system in an accurate manner. Throughout the result analysis, the given designed method attains minimum energy consumption rate and also better prediction accuracy. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc network (VANET) is an emerging technology which can offer a wide variety of promising applications, such as safety-related and infotainment applications. However, VANET also raises important security and privacy concerns that must be properly addressed for widespread deployment. In this paper, we first proposed a provable secure pseudonym-based cryptosystem with a trusted authority, including a pseudonym-based encryption scheme, a pseudonym-based multi-receiver encryption scheme, a pseudonym-based signature scheme, and a pseudonym-based one-pass key establishment protocol. We then presented a secure and efficient data access scheme for VANET based on cooperative caching technology and the proposed pseudonym-based cryptosystem. The efficiency of data access was greatly improved by allowing the sharing and coordination of cached data among multiple vehicles, and the anonymity of vehicles, data confidentiality, integrity and non-repudiation were guaranteed by employing the proposed pseudonym-based cryptosystem. Simulation results have shown that the proposed data access scheme is suitable to the VANET environment. [ABSTRACT FROM AUTHOR]

Vehicular Ad-hoc Networks (VANETs) are seen as the key enabling technology of Intelligent Transportation Systems (ITS). In addition to safety, VANETs also provide a cost-effective platform for numerous comfort and entertainment applications. A pragmatic solution of VANETs requires synergistic efforts in multidisciplinary areas of communication standards, routings, security and trust. Furthermore, a realistic VANET simulator is required for performance evaluation. There have been many research efforts in these areas, and consequently, a number of surveys have been published on various aspects. In this article, we first explain the key characteristics of VANETs, then provide a meta-survey of research works. We take a tutorial approach to introducing VANETs and gradually discuss intricate details. Extensive listings of existing surveys and research projects have been provided to assess development efforts. The article is useful for researchers to look at the big picture and channel their efforts in an effective way. [ABSTRACT FROM AUTHOR]

Efficient data delivery accompanied with low end-to-end delay is important in vehicular ad-hoc networks and optimal route selection is vital to improve these performance metrics. Different routing algorithms are proposed in VANETs. This paper reviews and analyzes these algorithms briefly and based on the analysis, a new opportunistic-based routing algorithm (OSTD) is proposed for urban scenarios. The proposed algorithm severely considers the type of vehicular distribution in the calculation of utility function. This utility function is used to evaluate the routes in the network. The reason of such a severe consideration is expressed and evaluated in the paper. Vehicle's driving path predictability is also used in the algorithm to forward the packet to a more suitable next hop, as vehicular mobility is the reflection of human social activity. Simulation results show that OSTD achieves a higher delivery ratio and lower end-to-end delay and packet loss compared to the other well-known protocols. [ABSTRACT FROM AUTHOR]

In a vehicular ad hoc network (VANET), the performance of the communication protocol is heavily influenced by the vehicular density dynamics. However, most of the previous works on VANET performance modeling paid little attention to vehicle distribution or simply assumed homogeneous car distribution. It is obvious that vehicles are distributed nonhomogeneously along a road segment due to traffic signals and speed limits at different portions of the road, as well as vehicle interactions that are significant on busy streets. In light of the inadequacy, in this paper, we present an original methodology to study the broadcasting performance of 802.11p VANETs with practical vehicle distribution in urban environments. First, we adopt the empirically verified stochastic traffic models, which incorporate the effect of urban settings (such as traffic lights and vehicle interactions) on car distribution and generate practical vehicular density profiles. Corresponding 802.11p protocol and performance models are then developed. When coupled with the traffic models, they can predict broadcasting efficiency, delay, and throughput performances of 802.11p VANETs based on the knowledge of car density at each location on the road. Extensive simulation is conducted to verify the accuracy of the developed mathematical models with the consideration of vehicle interaction. In general, our results demonstrate the applicability of the proposed methodology on modeling protocol performance in practical signalized road networks and shed insights into the design and development of future communication protocols and networking functions for VANETs. [ABSTRACT FROM PUBLISHER]

Vehicular Ad-hoc Network (VANET), a subset of Mobile Ad-hoc networks (MANETs), is one of the emerging technologies of Road Transportation system. In recent years, the aspect of Vehicular Ad-hoc Network (VANET) is becoming an interesting research area as it is characterized as self-configured wireless network. The design of routing protocols in VANETs is play a vital role and necessary issue for the Vehicle to Vehicle Communication Technology. The existing routing protocols of MANETs are suitable for VANET with changes in configuration of protocol. The routing protocols fall into two major categories of topology-based and position-based routing. We discussed different kinds of existing routing protocols with two major categories, the advantages and limitations of each which will helps to enhance the existing routing protocols for the suitability of Vehicular Ad-hoc Networks. We implemented three existing routing protocols and the testing results stated that the performance of each in aspects of various parameters such as Packet Delivery Ratio, Throughput and End-End Delay using Network Simulator. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc networks (VANETs) display many characteristics that are different from the traditional wireless networks, e.g. the rapidly changing topology and short-lived link. The vehicle communication stack is thus redesigned differently from the traditional TCP/IP architecture in order to accommodate these diversities. The network layer bears the function of the reliable routing and delivery of packets from sources to destinations over a highly dynamic path. We investigate the network layer within the vehicle communication stack and present an abstraction approach, with aims at filling the gap between the simplified and the very detailed models by incorporating more realistic routing protocols and network topologies. We study how the network dynamics, as monitored by multiple network performance indicators (e.g. transmission delay, path length, throughput, and loss rate), is affected by various combinations of routing algorithms, packet sizes, moving speeds, communication ranges, processing rates, boundary conditions, and movement patterns. The proposed suite can be modified and expanded easily to incorporate more features of the real VANET, e.g. traffic light control. [ABSTRACT FROM AUTHOR]

To improve environment monitoring in VANET, Compressed Sensing as a novel and effective signal transforming technology is a suitable tool in the process of gathering data and transmitting information. In traditional CS, comprehensive data collection is a prerequisite for sensing environments fully. However, it is difficult to obtain well-round information due to the lack of monitoring infrastructures and realize precise structures of variable signals in real situations. In this paper, two effective hybrid compressive matrices HCMs based on distributed compressed sensing (DCS) is proposed for the exponential distribution and the Passion distribution. Actual experiments show that signals could be obtained stably when sampling in a certain space and time, and reconstructed accurately. [ABSTRACT FROM AUTHOR]

Nowadays, with the increasing number of vehicles in the urban environment, finding a parking space has become an important and challenging issue. Vehicles may have to spend a lot of time looking for a parking space, which can lead to excessive fuel consumption, area traffic congestion, increased air pollution, and even driver impatience and immorality. To solve this problem, this article has used Roadside-to-Vehicle/Vehicle-to-Roadside (R2V/V2R), Roadside-to-Roadside (R2R) and Parking-to-Roadside/Roadside-to-Parking (P2R/R2P) communication in Vehicular Ad-hoc Network (VANET) and learning automata with variable actions to select and reserve the most suitable parking space. The performance of the proposed method was evaluated using computer simulation. The simulation results showed the efficiency of the proposed method in terms of improving service quality, reducing computational overhead, and making optimal use of parking resources in the city compared to existing methods. The proposed algorithm helps reduce air and noise pollution by reducing traffic congestion caused by parking space searches, and also helps increase the use of parking facilities efficiently. [ABSTRACT FROM AUTHOR]

Location information is very important for many applications of vehicular networks such as routing, network management, data dissemination protocols, road congestion, etc. If some reliable prediction is done on vehicle's next move, then resources can be allocated optimally as the vehicle moves around. This would increase the performance of VANETs. A Kalman filter is employed for predicting the vehicle's future location in this paper. We conducted experiments using both real vehicle mobility traces and model-driven traces. We quantitatively compare the prediction performance of a Kalman filter and neural network-based methods. In all traces, the proposed model exhibits superior prediction accuracy than the other prediction schemes. [ABSTRACT FROM AUTHOR]

The emergence of Intelligent Transportation Systems has given new hope and an unprecedented number of promising benefits to the transportation industry. However, these benefits are accompanied with inherent challenges due to the higher mobility of the vehicular nodes. One of the major problems faced is the induced Doppler shift in the carrier frequency of the transceiver node. This paper attempts to decrypt the effect of the Doppler shift impact in a Vehicle-to-Vehicle or Vehicle-to-Infrastructure communication system. Mobile nodes that are moving at a relative speed of 25 to 250 km/h are considered. Using a variable Modulation Code Scheme, the degradation effect in term of Bit Error Rate is analyzed under variable signal strength condition. Using the principle of Monte-Carlo, intense simulations are carried with a 95% Confidence Interval. Using the approximation technique, the results obtained from simulations prompted the derivation of a mathematical model. Considering the Bit Error Rate threshold limit defined by the standard, multiple simulation results are optimized to derive the composite result called the Doppler shift signature. A complete mathematical model of the Doppler shift signature accounting for all channel realizations when the Improved Direct Derivation Method is used in a Vehicular Ad-hoc Network is derived and compared against the actual. To assess and explore the effectiveness of the proposed model, several tests are conducted to evaluate the performance of the signature model against other existing rate adaptations, such as Adaptive Modulation Code, Binary phase-shift keying, and Constant. The results from simulation tests demonstrate that the proposed model in conjunction with the Improved Direct Derivation Method offers more than 200% improved throughput compared to its peers Adaptive Modulation Code, Binary phase-shift keying, and Constant. [ABSTRACT FROM AUTHOR]

The paper proposes a scheme on constructing a vehicular ad-hoc network based on cluster chains. In the cluster construction algorithm, the distance from a potential cluster head to its neighbor cluster associate node is used as a metric to elect a cluster head, so the number of the cluster heads is minimized. In the cluster-chain construction algorithm, the distance from a potential cluster associate node to its neighbor cluster head is used as a metric to elect a cluster associate node, so the number of the nodes in a cluster chain is minimized. The cluster/cluster-chain repair algorithm maintains the cluster/cluster-chain stability. The cluster/cluster-chain merging algorithm has no effects on the topology of the corresponding cluster chains, so the cluster-chain stability is enhanced. The performances of the proposed scheme and the existing scheme are analyzed, and the performance parameters include the cluster size, the cluster formation delay, the cluster stability, and the cluster-chain stability. And the analytical results show that the performance of the proposed scheme is better. [ABSTRACT FROM AUTHOR]

Abstract: The practical deployment of vehicular networks is still a pending issue. In this paper we describe a new self-organized method of authentication for VANETs, which allows their widespread, fast and secure implementation. Our proposal does not involve any central certification authority because the nodes themselves certify the validity of public keys of the other nodes. On the one hand we propose an algorithm that each node must use to choose the public key certificates for its local store. On the other hand, we also describe a new node authentication method based on a cryptographic protocol including a zero-knowledge proof that each node must use to convince another node on the possession of certain secret without revealing anything about it, which allows non-encrypted communication during authentication. Thanks to the combination of the aforementioned tools, the cooperation among vehicles can be used for developing several practical applications of VANETs, such as detection and warning about abnormal traffic conditions. One of the most interesting aspects of our proposal is that it only requires existing devices such as smartphones, because the designed schemes are fully distributed and self-organized. In this work we include an analysis of both an NS-2 simulation and a real device implementation of the proposed algorithms, which enables us to extract promising conclusions and several possible improvements and open questions for further research. [Copyright &y& Elsevier]