Vehicular Sensor Networks Research Articles

Vehicle location service scheme based on road map in Vehicular Sensor Networks

Vehicular Sensor Networks (VSNs) are merging for supporting communications between roadside sensor nodes and vehicles on for notifying environment events on roads to drivers and passengers. Geographic routing has been considered as an efficient and scalable approach to send sensing data from sensor nodes to vehicles. Fundamentally, geographic routing requires sensor nodes to be aware of the location information of vehicles. Since sensor nodes are deployed around roads and vehicles move on the roads, this field property of VSNs brings about a challenging issue to provide location service of vehicles. In this paper, we propose a quorum-based location service scheme to provide sensor nodes with the location information of vehicles in VSNs. For providing the location service, the proposed scheme exploits a crossing point between a quadrangular path quorum of a location update and a line path quorum of a location query by using the road map information. Then, the proposed scheme is extended to accommodate several considerations such as voids, multiple vehicles and sources, and energy depletion. The effectiveness of the proposed scheme is analyzed and validated by extensive numerical and simulation results.

Efficient Data Gathering and Estimation for Metropolitan Air Quality Monitoring by Using Vehicular Sensor Networks

Owing to the rising awareness of environmental protection and health, people put a high premium on air pollution in their living environment. It thus draws considerable attention to air quality monitoring in cities. The paper suggests using a vehicular sensor network (VSN) to tactically monitor metropolitan air quality and develops an efficient data gathering and estimation (EDGE) mechanism on VSN. EDGE has an objective to adaptively change data sampling rates of cars, such that the tradeoff between monitoring accuracy and communication cost is balanced. The monitoring accuracy is measured by the formal air quality index (AQI), whereas the communication cost considers the amount of sampling data and the monetary reward given to drivers. To do so, EDGE proposes dynamic grid partition based on the variation of pollutant concentration and computes the sampling rate by consulting car traffic in each grid. With the help of probabilistic reporting, it allows cars to collect air quality on more different positions and alleviate potential network congestion. Furthermore, EDGE applies the Delaunay triangulation to infer AQIs of the positions without any sensing data. Through simulation of urban mobility and industrial source complex, simulations are conducted based on practical metropolitan traffic and pollutant dispersion models. Experimental results demonstrate the significant effectiveness of the EDGE mechanism, under various scenarios.

Evaluation of a duty-cycled asynchronous X-MAC protocol for vehicular sensor networks

An asynchronous medium access control (MAC) duty-cycled protocols have higher energy efficiency and lower packet latency than synchronized ones due to reduced idle listening. Moreover, they provide efficient utilization of energy supplied to mobile sensors. They are considered very important in MAC protocols due to the adverse effects of hidden terminals which causes energy consumption in sensor networks. Therefore, in this paper, the impact of hidden terminals on the performance of an asynchronous duty-cycled MAC protocol X-MAC for vehicle-base sensor is investigated via analysis and simulations. We propose a Markov model to analyze the quality-of-service (QoS) parameters in terms of energy consumption, delay, and throughput. Our analytical model provides QoS parameter values that closely match the simulation results under various network conditions. Our model is more computationally efficient and provides accurate results quickly compared with simulations. More importantly, our model enables the designers to obtain a better understanding of the effects of different numbers of mobile sensor nodes and data arrival rates on the performance of an asynchronous MAC duty-cycled protocol.

Autonomous Car Parking System through a Cooperative Vehicular Positioning Network.

The increasing development of the automotive industry towards a fully autonomous car has motivated the design of new value-added services in Vehicular Sensor Networks (VSNs). Within the context of VSNs, the autonomous car, with an increasing number of on-board sensors, is a mobile node that exchanges sensed and state information within the VSN. Among all the value added services for VSNs, the design of new intelligent parking management architectures where the autonomous car will coexist with traditional cars is mandatory in order to profit from all the opportunities associated with the increasing intelligence of the new generation of cars. In this work, we design a new smart parking system on top of a VSN that takes into account the heterogeneity of cars and provides guidance to the best parking place for the autonomous car based on a collaborative approach that searches for the common good of all of them measured by the accessibility rate, which is the ratio of the free parking places accessible for an autonomous car. Then, we simulate a real parking lot and the results show that the performance of our system is close to the optimum considering different communication ranges and penetration rates for the autonomous car.

Design of authentication protocol for wireless sensor network-based smart vehicular system

The design of authentication protocol for a smart vehicle system is proposed, where vehicles are equipped with sensors and the sinks are placed along the road to receive and/or send data to sensors. The user monitors the vehicles by collecting data from sinks and performs analysis of the data by taking necessary action (if needed). Moreover, the system is using sensors in vehicles to provide a user-friendly platform to communicate with users. Now, the exchange of authentication message between authenticated entities are two important issues for successful implementation of a smart vehicular system. In the proposed vehicular system, there are three entities involve namely users, sink and sensor. In the same architecture, there is two set of communication between user to sink and sink to sensor are needed. In short, we have proposed an architecture of data traffic/movement in vehicular sensor network and authenticate the entities. In addition, we have analyzed our protocol with respect to security attacks and found that it is strongly protected against security attacks. Furthermore, the proposed protocol is relatively better in terms of overhead such as computation and communication.

Protocols and applications in vehicular sensor networks for driving safety, driving efficiency, and data services

Protocols and applications in vehicular sensor networks for driving safety, driving efficiency, and data services

Efficient data collection for self-organising traffic signal systems based on vehicular sensor networks

The development of traffic signal systems based on vehicular sensor networks (VSNs) requires new methods to enable real-time collection and processing of the data registered by sensor-equipped vehicles. Owing to the large amounts of sensor readings, there is a necessity of selecting the data that have to be transferred to control nodes. Moreover, the control nodes need an appropriate algorithm to effectively utilise the information which is delivered from individual vehicles. This paper presents an approach, which enables efficient collection and utilisation of the detailed data from VSN for controlling traffic signals in a road network. A self-organising control strategy is used in the analysed system. The amount of transmitted data is reduced by taking into account uncertainties estimated at control nodes. Results of simulation experiments show that the proposed approach outperforms state-of-the-art methods in terms of data transfers and average vehicle delay.

Integrity-Oriented Content Offloading in Vehicular Sensor Network

In this paper, an integrity-oriented content offloading ( ICO ) problem with variable modulation and coding schemes is proposed for relay-assisted vehicular sensor network. To accurately describe the link duration properties, a finite-state Markov chain-based model is built by jointly considering the mobility and radio propagation characteristics. Considering the ICO problem is NP-hard, our solution divides it into two offloading sub-problems with direct link and relay-assisted path, respectively. These two sub-problems are solved heuristically, and the corresponding results are combined to achieve a near-optimal result as the ICO scheme. While the analytical model is validated by Monte Carlo simulations and chi-square goodness fit test, the performance of our proposed ICO scheme is verified through simulations and comparisons, showing that our ICO solution can reduce the integral content offloading time compared with two other selected schemes and an upper performance bound.

BIG-CCA: Beacon-Less, Infrastructure-Less, and GPS-Less Cooperative Collision Avoidance Based on Vehicular Sensor Networks

This paper proposes a lane-level beacon-less, infrastructure-less, and GPS-less cooperative collision avoidance (BIG-CCA) framework for preventing rear-end collisions. The BIG-CCA framework applies vehicular sensor networks to prevent chain vehicle collisions, which are common road accidents that occur when vehicles make sudden stops. BIG-CCA enables vehicles equipped with only onboard sensors to prevent such accidents. Based on extensive research, BIG-CCA is the first lane-level CCA solution that provides the following features: 1) BIG-CCA does not maintain a list of neighboring vehicles through beacons and, thus, the overall signaling overhead can be reduced to conserve bandwidth; 2) BIG-CCA does not use the GPS positions of vehicles to facilitate collision avoidance and, thus, the inaccuracy and unavailability of a GPS can be avoided; and 3) BIG-CCA does not rely on costly roadside infrastructures but employs only vehicle-to-vehicle communications to form warning groups for vehicles driving along in the same lane. BIG-CCA consists of a distributed grouping mechanism and a receiver-based forwarding scheme. Vehicles join or leave a warning group through only single-hop transmissions with the low overhead of group maintenance. When sudden braking occurs in a warning group, the proposed receiver-based forwarding scheme can specify a single forwarder without message contention. The performance of BIG-CCA is evaluated by conducting mathematical analysis and computer simulations, which outperform existing methods. An Android-based prototype is also implemented to verify the feasibility of BIG-CCA.

Design and Analysis of an Infrastructure-Less Framework for Lane Positioning, Tracking, and Requesting through Vehicular Sensor Networks

In this letter, we design and analyze an infrastructure-less framework for lane positioning, tracking, and requesting through vehicle-to-vehicle communications. The proposed framework involves applying vehicular sensor networks to localize the lane position of vehicles on road segments. It enables vehicles equipped with image sensors to detect the current lane location without using a global positioning system, which may give an inaccurate location, and without the need for roadside infrastructures, which can be costly. Through image sensors, the proposed framework can maintain the recognition of the lane position of a vehicle. By using vehicle-to-vehicle communications, the proposed framework enables lane position information to be requested from other vehicles in the same lane when required. The proposed framework facilitates the development of innovative applications for the next-generation intelligent transportation systems that rely on high positioning accuracy, such as lane-level cooperative collision avoidance, dynamic traffic control, and intelligent personal navigation systems. An analytical model is derived for estimating the positioning success ratio of the proposed framework. The analytical and simulation results show that the proposed framework can significantly improve the positioning success ratios by cooperative lane requesting.

Survey on protocols and applications for vehicular sensor networks

This article surveys protocols and applications for the driving safety and efficiency in vehicular sensor networks. Nowadays, most vehicles are equipped with Global Positioning System navigation systems in the form of a dedicated navigator or smartphone app. Also, the government regulation requires vehicles to be equipped with dedicated short-range communication device for the communications among vehicles or between vehicles and infrastructure for a safety purpose. Because of this trend, many applications in vehicular networks can be envisioned for the safety of drivers and pedestrians as well as driving efficiency and fuel saving. To support these applications, protocols in physical, link, and network layers are designed and tailored for the optimal performance. This article summarizes and analyzes the state-of-art articles in the protocols and applications for vehicular sensor networks in order to shed the light of research direction on the audience in vehicular sensor networks.

Directed broadcasting with mobility prediction for vehicular sensor networks

This article suggests a new directed broadcasting method with mobility prediction of moving vehicles in vehicular sensor networks (VSNs). VSNs can play a critical role to ensure prompt delivery of real-time sensing data and be able to prevent various road dangers. The suggested method is particularly for vehicle safety communication (VSC) on highway roads by using directed broadcasting between vehicles. In VSNs, broadcasting is the most suitable communication mechanism for VSC. The simplest broadcasting mechanism is flooding, which introduces the redundant message retransmission and the broadcast storm problem. It is because all vehicles rebroadcast the messages in flooding. The broadcast storm problem can be addressed with selective flooding schemes which select rebroadcast vehicles to perform rebroadcasting. However, selective flooding schemes cannot promise enough reliability for VSC because of the highly dynamic topology and frequent disconnections of vehicular networks. Fast movement and frequent topology changes cause repeated link breakages and it increases the packet loss rate of vehicular networks. In this article, we propose a mobility prediction-based directed broadcasting (MPDB) protocol to achieve a reliable broadcasting in VSNs. MPDB protocol broadcasts emergent messages only to the rear vehicles on the same road. MPDB protocol consists of two phases: (i) mobility prediction phase and (ii) broadcasting phase. The mobility prediction can be acquired through periodical beaconing. In mobility prediction phase, each vehicle gets its rear vehicle set on the same road through neighbour’s position, inter-vehicle distance, relative speed and moving direction. In broadcast phase, MPDB protocol selects a vehicle having the largest link available time (LAT) values acquired by the mobility prediction as a rebroadcast vehicle among the rear vehicle set acquired in previous phase. By using LAT for broadcasting propagation, MPDB protocol can intensify the reliability of the message dissemination and also prevent the broadcast storm problem in vehicular networks. The simulation results show that MPDB protocol has better performance improvement in terms of average packet rate and packet delay.

An Efficient Conditional Privacy-Preserving Authentication Scheme for Vehicular Sensor Networks Without Pairings

Constructing intelligent and efficient transportation systems for modern metropolitan areas has become a very important quest for nations possessing metropolitan cities with ever-increasing populations. A new trend is the development of smart vehicles with multiple sensors able to dynamically form a temporary vehicular ad hoc network (VANET) or a vehicular sensor network (VSN). Along with a wireless-enabled roadside unit (RSU) network, drivers in a VSN can efficiently exchange important or urgent traffic information and make driving decisions accordingly. In order to support secure communication and driver privacy for vehicles in a VSN, we develop a new identity-based (ID-based) signature based on the elliptic curve cryptosystem (ECC) and then adopt it to propose a novel conditional privacy-preserving authentication scheme based on our invented ID-based signature. This scheme provides secure authentication process for messages transmitted between vehicles and RSUs. A batch message verification mechanism is also supported by the proposed scheme to increase the message processing throughput of RSUs. To further enhance scheme efficiency, both pairing operation and MapToPoint operation are not applied in the proposed authentication scheme. In comparison with existing pseudo-ID-based authentication solutions for VSN, this paper shows that the proposed scheme has better performance in terms of time consumption.

A GTS Allocation Scheme to Improve Multiple-Access Performance in Vehicular Sensor Networks

The IEEE 802.15.4 protocol is designed to flexibly support both real-time and contention-based services. When the beacon model is enabled, guaranteed time slot (GTS) scheduling can provide contention-free access to latency-sensitive services based on the time-division multiple-access mechanism. This characteristic makes IEEE 802.15.4 the appropriate candidate for vehicular sensor networks in which mobile nodes need to exchange packets with roadside units (RSUs) within a limited duration. In this paper, using network calculus theory, we analyzed the relationship between time-slot utilization and the corresponding access parameters, such as packet arrival rate, burst size, and vehicles' mobility extent. Then, for a given number of vehicles preparing to access an RSU, we proposed a time-sensitive weighted round-robin (TS-WRR) scheduler to improve the multiple-access performance, which can take the service delay requirement, packet arrival rate, and vehicular mobility level into account. Next, the weight determination and time-slot allocation strategy of the TS-WRR scheduler were issued in detail, which incorporate the special limitations and application requirements in a vehicle-to-infrastructure (V2I) communication environment. To make our model feasible for testing, we also elaborately demonstrated the implementation procedure with pseudocode and simulator design. Numerical results show that our TS-WRR scheduler outperforms some classic schedulers such as First-Come First-Served and WRR, as well as two latest works, i.e., implicit GTS allocation scheme and adaptive real-time GTS allocation mechanism in terms of delay guarantee and GTS utilization maximization in vehicular sensor networks.

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture.

Delay-Optimal Data Forwarding in Vehicular Sensor Networks

Vehicular Sensor Network (VSN) is emerging as a new solution for monitoring urban environments such as Intelligent Transportation Systems and air pollution. One of the crucial factors that determine the service quality of urban monitoring applications is the delivery delay of sensing data packets in the VSN. In this paper, we study the problem of routing data packets with minimum delay in the VSN, by exploiting i) vehicle traffic statistics, ii) anycast routing and iii) knowledge of future trajectories of vehicles such as buses. We first introduce a novel road network graph model that incorporates the three factors into the routing metric. We then characterize the packet delay on each edge as a function of the vehicle density, speed and the length of the edge. Based on the network model and delay function, we formulate the packet routing problem as a Markov Decision Process (MDP) and develop an optimal routing policy by solving the MDP. Evaluations using real vehicle traces in a city show that our routing policy significantly improves the delay performance compared to existing routing protocols.

Cognitive Radio Assisted OLSR Routing for Vehicular Sensor Networks

Vehicular Sensor Network (VSN) emerged due to recent developments in Wireless Sensor Network (WSN) and functioning as a way for observing metropolitan environments and enabling vehicles to share relevant sensor data to assist safety, convenience and commercial applications. Data dissemination is an important aspect of these networks and requires timely delivery of important sensor information. In VSNs, rapid mobility of the vehicles causes recurrent topography modifications. The possibility of on-demand protocols that makes routing decisions reactively in Vehicular Networks are restricted owing to its structural instability and current routing protocols, operating in a table-driven fashion like OLSR are unable to cope up with the high demands imposed by vehicular applications. Furthermore, sensor data transmissions are accompanied by rapid fluctuations in the convention of licensed spectrum and acquire more number of channels to transmit huge bandwidth data and result in spectrum scarcity. Existing works on OLSR protocol failed to examine spectrum conditions and calculate utilization of channel. Cognitive Radio (CR) is a possible solution for guiding OLSR to discover unused frequency bands and utilize them opportunistically. This paper presents an optimal OLSR routing for efficient data communication using Cognitive Radio enabled Vehicular Sensor Networks (CR-VSNs). The proposed model was tested under simulated traffic of Chennai urban road map. Delay is observed to be minimal for data communications in CR-VSN.

Hardware platform for wide-area vehicular sensor networks with mobile nodes

In recent years, Wireless Sensor Networks have experienced significant growth, mainly motivated by the development of standard communication protocols and the availability of low cost microcontrollers and wireless transceivers, resulting in low-power small-size sensing and data processing capable devices, and wireless communication links. In this paper, a hardware platform for the deployment of a heterogeneous multi-tiered Sensor Network architecture supporting highly mobile nodes covering wide geographic areas for automotive applications is proposed. In the presented network architecture, the low level system consists of an IEEE 802.15.4 based Wireless Sensor Network fully composed of compatible devices that support all the standard functionalities. As a novelty, some extensions are proposed to release part of the topological restrictions of IEEE 802.15.4 communication protocol which limit the development of WSN for applications with wide area coverage and high mobility requirements. The proposed hardware platform has been implemented and experimentally validated and characterized in vehicular applications to monitor and communicate specific environmental parameters in a heavy transport fleet.

Finding Lane Positions of Vehicles: Infrastructure-Less Cooperative Lane Positioning Based on Vehicular Sensor Networks

In this article, we proposed an infrastructureless cooperative lane positioning (ICLP) framework using vehicle-to-vehicle (V2V) communications. The ICLP framework applies vehicular sensor networks (VSNs) to localize lane positions of vehicles on roads. ICLP allows the vehicles equipped with image sensors to detect the current located lane without utilizing global positioning system (GPS) locations and roadside infrastructures. Through image sensors, ICLP can keep recognizing the lane position for a vehicle. In addition, ICLP can request lane position information from other vehicles in the same lane as necessary, based on V2V communications. ICLP makes innovative applications of intelligent transportation systems relying on accurate positioning possible, such as lane-level cooperative collision avoidance, dynamic traffic control, and intelligent personal navigation. An Android-based prototype is implemented to verify the feasibility and superiority of our framework. The experimental results show that ICLP can achieve high positioning success ratios and provide accurate lane positions for vehicles.

Sensor Communications towards Intelligent Vehicle Networking

Sensor technologies have been widely used to make transportation clean, efficient, connected, and safe. Roadside wireless sensor and networking technology represents a costeffective solution and can leverage the deployment of the system as a whole. Sensors installed in cars continuously gather important information, such as air bags, distance detection, mechanical and electronic parts, tire pressure, collision force, and passengers’ conditions. Transmission of such information between cars can be used to implement differentiated mobile services. As a consequence, Wireless Vehicular Sensor Network (VSN) has been widely accepted in developing the next generation intelligent transportation application systems as well as connected vehicles networking. However, VSN does not operate like the traditional wireless sensor network (WSN). For example, the motion of the vehicle, the environment of the roads, and other uncertain traffic conditions all pose challenges to the system. For safety reason, the vehicle-vehicle and vehicle-gateway communication modes must be stable. Therefore, how to keep link stability becomes an important issue. This special issue is in response to the increasing convergence of distributed sensor networks. Papers selected for this special issue represent recent progresses in the field, including works on mobility architectures, vehicle communications and networking, algorithms in wireless sensor networks, and services and applications in distributed systems. All of these papers not only provide novel ideas and state-of-the-art techniques in the field but also stimulate future research in the sustainable environment. 2. Architecture and Mobility