Safety-related Messages Research Articles

Cooperative Antijamming Relaying for Control Channel Jamming in Vehicular Networks

Radio Frequency jamming attacks constitute a major threat to the availability of the vehicular networks. In particular, if the control channel is under persistent jamming attacks, the victim vehicles may fail to receive the safety related messages from the Road Side Unit, which can possibly cause tremendous economic loss and claim human lives. In this paper, we propose a cooperative relaying scheme to circumvent the control channel jamming problem in the vehicular networks, whereby the vehicles outside of the jamming area serve as relays to help forward the received control channel signal to the victim vehicles through another jamming-free service channel. By combining the signals from all relays using the selection combining or maximum-ratio combining methods, the spatial diversity provided by the relays can be effectively exploited to reduce the outage probability of the victim vehicles. Theoretical models are developed to characterize the performance of this cooperative antijamming relaying scheme, which take into account both the large-scale path loss and small-scale channel fading between relaying and victim vehicles under different jamming scenarios. We also propose a relay selection scheme to optimize the performance of the victim vehicles under the relay number constraint. Simulation results are provided to show the performance of the proposed cooperative relaying scheme and relay selection algorithm under different network settings.

The Relation between the Probability of Collision-Free Broadcast Transmission in a Wireless Network and the Stirling Number of the Second Kind

The broadcast performance of the 802.11 wireless protocol depends on several factors. One of the important factor is the number of nodes simultaneously contending for the shared channel. The Medium Access Control (MAC) technique of 802.11 is called the Distributed Coordination Function (DCF). DCF is a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) scheme with binary slotted exponential backoff. A collision is the result of two or more stations transmitting simultaneously. Given the simplicity of the DCF scheme, it was adapted for Dedicated Short Range Communication (DSRC) based vehicular communication. A broadcast mechanism is used to disseminate emergency and safety related messages in a vehicular network. Emergency and safety related messages have a strict end-to-end latency of 100 ms and a Packet Delivery Ratio (PDR) of 90% and above. The PDR can be evaluated through the packet loss probability. The packet loss probability PL is given by, PL = 1 − (1−Pe)(1−PC), where Pe is the probability of channel error and PC is the probability of collision. Pe depends on several environmental and operating factors and thus cannot be improved. The only way to reduce PL is by reducing PC. Currently, expensive radio hardware are used to measure PL. Several adaptive algorithms are available to reduce PC. In this paper, we establish a closed relation between PC and the Stirling number of the second kind. Simulation results are presented and compared with the analytical model for accuracy. Our simulation results show an accuracy of 99.9% compared with the analytical model. Even on a smaller sample size, our simulation results show an accuracy of 95% and above. Based on our analytical model, vehicles can precisely estimate these real-time requirements with the least expensive hardware available. Also, once the distribution of PC and PL are known, one can precisely determine the distribution of Pe.

A distributed time-limited multicast algorithm for VANETs using incremental power strategy

Efficient information dissemination is the pinnacle of Vehicular Ad-hoc Networks (VANETs). In case of delay-sensitive information such as safety-related messages, it is imperative to minimize the transmission delay and increase the message reliability in VANETs. In a previous work, we proposed a Time-Limited Reliable Broadcast Incremental Power (TRBIP) algorithm, which is a centralized heuristic to reduce transmission interferences for safety message dissemination in VANETs. By reducing the total transmission energy and the number of hops, TRBIP is able to reduce the transmission interference and thus-forth maximizes the reliability. Furthermore, in TRBIP, VANETs’ features such as vehicle mobility and frequent network fragmentation are also taken into account through store-carry-and-forward and the periodic multicast tree reconstruction strategies. However, multicast tree management is hard to maintain in urban environments due to the high density of nodes in VANETs (large trees), and is affected by the city streets organizations (intersections, roundabout, ... etc.). To address the afore-mentioned issues, in this paper we propose a Distributed version of Time-Limited Reliable Broadcast Incremental Power (DTRBIP) based on a road segmentation technique. Our proposal is extended to handle both delay-sensitive and delay-tolerant applications, and also both low and high dynamic VANETs scenarios respectively urban and highway environments. The results of the simulation conducted using NS-2 simulator advocate for the efficiency of our proposed method in term of reducing the total emission energy (at least by 150 dBm), reducing the average delay by 52%, increasing the packet delivery ratio by more than to 5%, and reducing the protocol overhead up to 3%. Obtained results show a clear enhancement compared to the previous solutions (i.e, RGRP-SA, RBIP, and TRBIP).

An Efficent Distributed Medium Access Control for V2I VANET

<p>Provisioning smart intelligent transport for vehicular ad hoc networks (VANETs) depends on dissemination of safety-related messages. The performance of VANET are highly affected due vehicle density, mobility and environmental condition. Recently several research has been under development, the design of a rapid, flexible, efficient and reliable medium access control (MAC) which address the precise constraint of smart intelligent transport system in the highly dynamic VANET environment. Extensive survey carried out in this work shows TDMA (Time division medium access) based MAC approach outperform carrier sense medium access/ collision avoidance CSMA\CA based approach. However, TDMA based approach incurs bandwidth wastages. To utilize bandwidth more efficiently cognitive radio (CR) technique is adopted for designing efficient MAC. However, the existing CR model incurs computation overhead and is not evaluated under different environmental condition such as rural, highway and urban (RHU). To overcome research challenges, this work present efficient decentralized distributed MAC (DMAC) that minimize collision and maximize throughput. Experiment are conducted to evaluate the performance of DMAC over state-of-art model in terms of throughput, success transmission and collision achieved. The outcome shows significant performance over state-of-model.</p>

Performance Analysis of the IEEE 802.11p Multichannel MAC Protocol in Vehicular Ad Hoc Networks.

Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. The safety applications require timely and reliable transmissions, while the non-safety applications require efficient and high throughput. In the IEEE 1609.4 protocol, operating interval is divided into alternating Control Channel (CCH) interval and Service Channel (SCH) interval with an identical length. During the CCH interval, nodes transmit safety-related messages and control messages, and Enhanced Distributed Channel Access (EDCA) mechanism is employed to allow four Access Categories (ACs) within a station with different priorities according to their criticality for the vehicle’s safety. During the SCH interval, the non-safety massages are transmitted. An analytical model is proposed in this paper to evaluate performance, reliability and efficiency of the IEEE 802.11p and IEEE 1609.4 protocols. The proposed model improves the existing work by taking serval aspects and the character of multichannel switching into design consideration. Extensive performance evaluations based on analysis and simulation help to validate the accuracy of the proposed model and analyze the capabilities and limitations of the IEEE 802.11p and IEEE 1609.4 protocols, and enhancement suggestions are given.

LIAP: A local identity-based anonymous message authentication protocol in VANETs

In vehicular ad hoc networks (VANETs), vehicle communicates with other nodes through an open wireless channel, which raises many potential safety issues. Both the public key infrastructure (PKI) and identity based authentication protocols can meet the requirements of security and privacy of VANETs. However, the receiver needs to check certificate revocation list (CRL) before certificate and signature verification in PKI-base schemes. The additional CRL checking reduces the authentication efficiency. In the identity-based schemes, every vehicle holds too many valid identities in order to protect privacy. It is complicated to revoke the membership of vehicle. To cope with the inherent issues, we propose a local identity-based anonymous message authentication protocol (LIAP) for VANETs, in which each vehicle and road side unit (RSU) is assigned a unique long term certification from the certificate authority (CA) in registration phase. RSU is in charge of managing and assigning the local master keys to every vehicle of entering its communication range. When vehicle meets a new RSU, they authenticate each other by their long certificates. The valid vehicle can obtain the local master keys from current RSU to generate the localized anonymous identity. To protect privacy, vehicle randomly chooses the anonymous identity to sign the safety-related message, which can be efficiently verified by the single or batch authentication manner. Finally, performance analysis and simulation show that LIAP is effective in terms of authentication speed and communication overhead.

New innovative educational method to prevent accidents involving young road users (aged 15-24) – European Road Safety Tunes

The article presents a new teaching method designed to improve road safety among young road users. Developed under “European Road Safety Tunes”, this international project was cofunded by EU DG MOVE. Its main aim is to improve road safety and minimize the number of road accidents, injuries and fatalities among road users who are 15-24 years old. The Safety Tunes method contains a series of workshops addressed to young vocational school students: cyclists, moped and motor riders and car drivers. The workshops incorporate peer and emotive education, and delivery of road safety related messages through different types of artistic forms. The topics tackled during class address awareness of possible risks and risk-behaviour, prevention of distraction and reduction in young fatalities and serious injuries on the road. All actions within the project are evaluated, both in terms of the impact of the workshops on students’ attitudes towards road safety problems and in terms of process assessment.

Self-Sorting-Based MAC Protocol for High-Density Vehicular Ad Hoc Networks

The implementation of safety applications in vehicular ad hoc networks (VANETs) depends on the dissemination of safety-related messages. A self-sorting MAC protocol is proposed for high-density scenarios. The protocol allows vehicles to sort with others in a collision-tolerance manner before data transmission. The vehicles establish a logic queue by the self-sorting process, and the queue is able to access the channel once the length reaches the set threshold. Vehicles in the queue will access the channel by time-division multiple access when the queue occupies the channel. A queue will compete for accessing the channel on behalf of all the nodes in the queue, which greatly alleviates the contention for access from all nodes. In contrast with completely random access, the slot a queue selects to access the channel depends on the completion time of the self-sorting process. In this case, the queue accomplishing the self-sorting process first can avoid collisions with other queues, since they are still in the self-sorting process. The performance of the proposed protocol is evaluated compared with other typical MAC protocols in VANET. The analysis and simulation results in highway and city scenarios show that the proposed protocol can significantly reduce packets loss and delay especially in dense scenarios.

Dependability of Decentralized Congestion Control for Varying VANET Density

IEEE 802.11p is an amendment to the IEEE 802.11 standard for Wireless Access in Vehicular Environments (WAVE). Lower layer wireless transmission formats and protocols are defined for both vehicle-to-infrastructure and vehicle-to-vehicle communication links to support cooperative intelligent transport systems. The medium access control (MAC) layer uses carrier sensing as a means for detecting the busy state of the radio channel before transmitting. In heavily loaded vehicular ad hoc networks (VANETs), the channel access delay, when attempting to access the channel, unpredictably increases when it is sensed as busy. The European Telecommunications Standards Institute (ETSI) defines safety-related messages. These messages require a dependable behavior of the communication link. In this context, dependable behavior translates to the reliable delivery of data packets within a specified deadline regardless of changes in traffic density. Unfortunately, the WAVE amendment does not fulfill the requirements for such dependable behavior. This contribution reports on performance evaluations by simulation studies of the WAVE MAC and the decentralized congestion control (DCC) mechanism specified by the ETSI in addition to the existing enhanced distributed channel access. The simulation scenario under study is a two-VANET-merging highway situation. The MAC protocol has to adapt to variable traffic densities in this scenario. The performance is evaluated in terms of coverage range and MAC-to-MAC delay reliability and DCC state stability. Furthermore, a novel performance indicator is defined, evaluated, and discussed, which the authors of this work have named data novelty. Finally, a multistate-active DCC mechanism is proposed, which achieves a dependable behavior.

Token Based Trust Computation in VANET

In vehicular ad hoc network or VANET, the safety related messages broadcast by vehicles is used by other vehicles to make critical decisions. This may trap a vehicle taking wrong decision with dire consequences and authenticated vehicles or malicious vehicles may also broadcast wrong messages. This necessitates those messages of vehicles to be trusted after authentication process of vehicles, especially in the absence of centralized authority. In this paper, token based trust computation based on network connectivity duration of vehicles in VANET is proposed. The proposed technique is based on travelling time association among vehicles or network connectivity of vehicle at the time of driving on the road. We present simulations of the proposed technique that verify its correctness and reliability in the presence of infrastructure and absence of infrastructure. Results show that the efficacy of the proposed scheme and makes it viable for secure and lightweight trusted communication in a VANET.

Information theory based performance analysis and enhancement of Safety applications and cluster design in VANET

Safety applications in vehicular ad hoc network (VANET) are handled by broadcast to disseminate safety related messages, due to lack of stable topology. The mobility of vehicles leads to significant performance degradation, especially in dense and dynamic scenarios. This paper presents an informat

Reliable and Swift Message Broadcast Method in Vehicular Ad Hoc Networks

A vehicular ad hoc network (VANET) could deliver safety-related messages reliably within a short time to increase road safety. Since safety-related messages should be sent to a set of unspecified receivers, they are delivered by broadcast method. However, the broadcast method specified in the IEEE 802.11p does not have a collision avoidance procedure and receivers do not acknowledge when they receive a broadcast frame. In addition, frames could be lost and corrupted. Therefore, as the portion of nodes that do not receive a broadcast frame increases, the effectiveness of a safety application decreases. To tackle the problem, we propose a reliable and swift message broadcast method (RSMB). In RSMB, to expedite message dissemination process, a relay node is selected in a distributed manner considering the progress made to a frame and the delay requirements of an application. In addition, a relay node broadcasts a message multiple times to assure that the probability that the other nodes successfully receive the message at least once is larger than a given threshold value. Since the number of rebroadcasts is regulated based on the successful message reception probability, the additional bandwidth needed to increase the reliability of broadcast is reasonably small.

Comprehensive Performance Evaluation of VANETs for Safety-Related Applications

In vehicular ad hoc networks (VANETs), broadcast communication is an effective approach to disseminate the safety-related messages to inform the neighboring vehicles. However, the characteristics of broadcast environments lead to poor reliability of the messages. This paper focuses on the comprehensive evaluation to investigate the performance of the safety-related applications, from which we could obtain the optimum performance and ensure quality of service of VANETs. The proposed comprehensive evaluation scheme comprises three parts, with the first applying an analytic hierarchy process (AHP) to decide the relative weights of access categories according to the user preferences, i.e. safety-related applications; the second using the entropy and its combination with AHP to determine the weights of performance metrics; and the third adopting the grey relation analysis to rank the alternatives. The analysis results show that the proposed comprehensive evaluation scheme can obtain the optimum performance and also effectively investigate on capabilities and constraints of VANETs.

Multi‐hop delay reduction for safety‐related message broadcasting in vehicle‐to‐vehicle communications

In vehicle-to-vehicle (V2V) communications, low delay and long propagation distance are very important for multi-hop safety-related message broadcasting. Most earlier studies focused on one-hop broadcasting while little attention has been paid to multi-hop delay and propagation distance. In this study, a new model for analysing the connectivity probability, average hop count and one-hop delay of multi-hop safety-related message broadcasting in V2V communications is built, taking into account the following factors: propagation distance, one-hop transmission range, distribution of vehicles, vehicle density, average length of vehicles and minimum safe distance between vehicles. Simulation results demonstrate that the proposed model can provide better performance in terms of multi-hop delay and there exists an optimal one-hop transmission range to minimise the multi-hop delay. After that, A new scheme is proposed to track the optimal one-hop transmission range by using a Genetic Algorithm. With this scheme, vehicles are allowed to adjust the one-hop transmission range based on vehicle density to reduce the multi-hop delay. The proposed scheme is validated by simulations using realistic vehicular traces.

Do Facial Characteristics Influence Acceptance of Health And Safety Messages?

Do Facial Characteristics Influence Acceptance of Health And Safety Messages? Ian Parker, Ass. Prof Jacques Oosthuizen, Dr Leesa Costello Abstract Physiognomy is the art of judging temperament and character from outward appearance. The aim of this study was to legitimize the expectations of facial physiognomy in audience interpretation and recall of safety related messages. Mixed methods were utilized to describe and analyse data for free facial and image description and the recall of facts presented in the image testimonial. Facial physiognomy was explored along four dimensions ranging from more trustworthy/less trustworthy and more dominant/less dominant dimensions and these images were introduced along with a printed message on electrical safety (n=100). Remarkable interactions between a source-credibility subscale and perceived dominance scale suggests that there is an innate frame of reference used by humans whereby decision judgments are made based on another person’s facial physiognomy. Furthermore, there is an atypical innate and perhaps evolved, or socialized, response with respect to whether humans will approach or avoid another person based on their facial physiognomy and people do make decision judgments based on dominance, trustworthiness, approach or avoidance behaviour and recall of information differs based on somatic facial characteristics when presented with an avatar of a human face in a workplace safety advertisement. The physiognomic appearance of an endorser can influence the believability and attitude components of potential target audiences; and thus, the impact of the intended message. Full Text: PDF DOI: 10.15640/ijhs.v3n1a5

A Feasibility Study and Development Framework Design for Realizing Smartphone-Based Vehicular Networking Systems

Designing and distributing effective vehicular safety applications can help significantly reduce the number of car accidents and assure the safety of many precious lives. However, despite the efforts from standardization bodies and industrial manufacturers, many studies suggest that it will take more than a decade for full deployment. We start this work with the hypothesis that smartphones may be suitable platforms for catalyzing the distribution of vehicular safety systems. Specifically, smartphones connected to their respective cellular networks can report sensing data to back-end application servers and exchange safety-related messages. This paper first evaluates the performance of the vehicular ad-hoc networking standards and the hardware platforms that implement them. Next, we perform empirical evaluations on the performance of cellular networks to confirm their applicability in vehicular networking. Based on our observations, we present the VoCell application development framework. VoCell, comprehends a set of components that eases the development of smartphone applications for vehicular networking applications. Using VoCell, developers can easily access internal and external sensing components and share this data to servers. We present a number of example applications developed using VoCell and evaluate their effectiveness in local and highway environments using a pilot deployment. We envision that VoCell can act as a building block for enabling new smartphone-based systems for vehicular networking applications.

A Distance-Aware Safety-Related Message Broadcasting Algorithm for Vehicular Networks

A new distance-aware broadcasting algorithm was proposed to enhance the propagation distance in the latency time of safety-related message broadcasting. The IEEE 802.11p standard states that if the medium is detected as idle, a station would defer its transmission within a backoff time to avoid collisions with other stations. The backoff times follow uniform distribution over [0, CW]. In this way, fairness among all the stations can be guaranteed. However, propagation distance was ignored and in safety-related message broadcasting fairness is not the most important issue. In the proposed algorithm, the lengths of backoff times are generated from a nonuniform distribution. They are related with the distances between the source station and its forwarding stations. The farthest forwarding station has the highest probability to forward messages. Performance of the proposed algorithm is analyzed by using a 2D Markov chain. Analytical and simulation results demonstrate that the proposed algorithm can enhance the performance of safety-related message broadcasting in terms of propagation distance, which is reflected by the successful transmission probability. The proposed algorithm does not need additional waiting time, RTS/CTS, and ACK, therefore having better compatibility with the IEEE 802.11p standard than earlier distance-aware algorithms.

Prioritized Optimal Channel Allocation Schemes for Multi-Channel Vehicular Networks

The IEEE 1609.4 standard has been proposed to provide multi-channel operations in wireless access for vehicular environments (WAVE), where all channels are periodically synchronized into control and service intervals. Communication device in each vehicle will stay at the control channel for negotiation and contention during the control interval, and thereafter switch to one of the service channels for data transmission in the service interval. In this paper, based on the concept of cognitive radio (CR), the vehicles are categorized into primary providers (PPs) that intend to transmit safety-related messages and secondary providers (SPs) with non-safety information to be delivered. The prioritized optimal channel allocation (POCA) approaches are proposed to improve channel utilization of IEEE 1609.4 standard for multi-channel vehicular networks. Prioritized channel access is analyzed in the POCA schemes in order to increase the transmission opportunity of PPs. Moreover, depending on whether the CR network is distributed or centralized, the optimal channel-hopping sequence and optimal channel allocation is assigned for SPs based on dynamic programming and linear programming technique, respectively. These schemes are designed to consider optimal load balance between both channel availability and channel utilization within the throughput constraints of PPs. With the adoption of proposed POCA schemes, simulation results show that maximum throughput of SPs can be achieved with guaranteed quality-of-service requirement for PPs.

Performance Analysis for Priority-Based Broadcast in Vehicular Networks

Transportation safety is one of the most important applications of vehicular ad hoc networks which is based on IEEE 802.11p. When a vehicle is in an emergency situation, a safety-related message is transmitted to the neighboring vehicles and infrastructures. Vehicles and infrastructures exchange periodic messages on vehicle position, traffic information, and so forth to provide various services. When the traffic load is very high, the emergency message cannot be delivered immediately. To overcome this situation, a priority-based transmission scheme is considered to guarantee the transmission of the emergency message. In this paper, the performance of vehicular communication networks is analyzed in two perspectives. Firstly, an analytical Markov chain model for vehicle-to-vehicle (V2V) ad hoc communication networks is proposed for broadcasting messages with priority based on the IEEE 802.11p wireless access for vehicular environments (WAVE) standard. Secondly, an analytic queuing model for vehicular communication networks is proposed to evaluate the network performance to deal with safety and nonsafety messages.

Performance and Reliability Analysis of IEEE 802.11p Safety Communication in a Highway Environment

Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications are gaining increasing importance in vehicular applications. Dedicated short-range communication (DSRC) is a fundamental set of short-to-medium-range communication channels and a set of protocols and standards that are specifically designed for V2V and V2I communications. IEEE 802.11p is a protocol that has been standardized as the medium access control (MAC) layer of the DSRC standard. Due to the highly dynamic topology and low delay constraints in vehicular ad hoc networks (VANETs), direct (or one-hop) broadcast on the control channel (CCH) is an effective approach to inform the neighborhood of safety-related messages. The 802.11p enhanced distributed channel access (EDCA) mechanism allows four access categories (ACs) in a station for applications with different priorities according to their criticalities for the vehicle's safety. This paper focuses on the analysis of the 802.11p safety-critical broadcast on the CCH in a VANET environment and improves the existing work by taking several aspects into design consideration. Extensive performance evaluations based on the NS-2 simulator help to validate the accuracy of the proposed model and analyze the capabilities and limitations of the standard 802.11p broadcast on the CCH.