Performance Of Vehicular Networks Research Articles

Secrecy performance evaluation and enhancement of vehicle-to-vehicle communications in the presence of big vehicles

Despite its significant role in providing and developing reliable and safe intelligent transportation services, the Internet of Vehicles faces several challenges and security threats, such as co-channel interference (CCI), node self-interference (SI), and eavesdropping. This paper investigates the secrecy performance of vehicular networks in terms of their secrecy outage probability (SOP) and average secrecy capacity (ASC) in the presence of an eavesdropper. The legitimate vehicles are assumed to operate in full-duplex mode. Hence, the impacts of CCI and SI are considered for practical modeling and performance evaluation. Moreover, the wireless communications among vehicles are assumed to be either subjected to Nakagami-m fading or Nakagami-N-Gamma shadowed fading due to the existence of a big vehicle and its location. Accordingly, closed-form mathematical expressions are derived for the SOP and the ASC. Furthermore, a power allocation (PA) model is proposed to improve the secrecy performance by maximizing the derived ASC. The numerical results validate the derived expressions by demonstrating the impact of the channel condition, the secrecy data rate threshold, the SI cancellation capability at the legitimate destination, the location of the eavesdropper, the location of the big vehicle, and the strength of shadowing on the SOP and the ASC. Also, it is shown that the proposed PA model can significantly enhance the secrecy performance.

Blind reconfigurable intelligent surface-aided fixed non-orthogonal multiple access for intelligent vehicular networks

In intelligent vehicular networks, vehicles should be able to communicate with their surroundings while traveling. This results in more efficient, safer, and comfortable driving experiences, as well as new commercial prospects in a variety of industries. Connected vehicles and autonomous vehicles expect 100% reliable connectivity without any compromise in quality. However, due to challenges such as difficult channel terrains in urban scenarios and dead zones, the reliability of current vehicle-to-infrastructure (V2I) and vehicle-to-vehicle communication systems cannot be guaranteed. The performance of vehicular networks can be considerably enhanced with reconfigurable intelligent surfaces (RIS). Non-orthogonal multiple access (NOMA) allows for massive connectivity with the surroundings. In vehicular networks, the RIS-assisted NOMA can ensure regulated channel gains, better coverage, throughput, and energy efficiency. In this work, a blind RIS-assisted fixed NOMA (FNOMA) system is proposed for a downlink V2I scenario. The closed-form analytical outage probability and throughput expressions are derived by considering RIS as an intelligent reflector and as a roadside unit. It is observed that the analytical and Monte Carlo simulation results are closely related. In simulations, it has been discovered that RIS-assisted FNOMA outperforms the traditional NOMA variants in terms of outage and throughput. Even without precise channel knowledge, blind RIS transmission outperforms traditional NOMA variants due to huge array gain. The increase in the number of reflective elements also results in a significant improvement in signal-to-noise ratio gains.

Quality-Aware Joint Caching, Computing and Communication Optimization for Video Delivery in Vehicular Networks

As being clear that the joint optimization of caching, computing, and communication (3 C) can significantly improve vehicular network performance, this paper investigates the quality-aware 3 C optimization for video delivery in vehicular networks. By incorporating the quality-awareness into 3 C models, we formulate both the quality-aware joint 3 C optimization problem and the quality-aware joint computing and communication (2 C) optimization problem with predetermined caching. By observing that the proposed 2 C and 3 C problems can be interpreted as submodular maximization problems with constraints, we propose a solution methodology using the submodularity and knapsack interpretation. Based on the proposed methodology, we then propose efficient solution approaches assuming batch input and streaming input, respectively. Complexity of the proposed solution approaches is analyzed. In addition, extensive simulations are conducted to evaluate the proposed solution approaches. Results show that our proposed approaches can outperform the reference schemes and improve the video delivery of vehicular networks.

Decentralized Resource Allocation-Based Multiagent Deep Learning in Vehicular Network

Resource allocation (RA) has a significant impact on vehicular network performance. With high mobility, RA is more challenging, as the number of vehicles in close proximity changes dynamically in the nonstationary environment. In this article, we propose a multiagent double deep Q-networks scheme to stabilize the system and maximize the sum-capacity of the vehicle-to-infrastructure (V2I) links, while satisfying the reliability and delay constraints for vehicle-to-vehicle (V2V) links. To avoid interference caused by unstable V2V links, a transmission mode selection is considered in the scheme design. In addition, we introduce a binarized weight algorithm to accelerate the deep neural network learning process and, therefore, improve the computational complexity of our scheme. Through extensive simulations and complexity analysis, we demonstrate that the proposed scheme yields excellent performance in terms of the sum-rate and probability rate of V2I and V2V communication modes. We also compare the proposed scheme with binarized weights with other algorithms in terms of accuracy evaluation.

GraTree: A gradient boosting decision tree based multimetric routing protocol for vehicular ad hoc networks

The Intelligent Transport System (ITS) is increasingly becoming a reality thanks to the incorporation of modern vehicles that, together with artificial intelligence techniques, can bring novel solutions to the smart city. Today, vehicles are embedded with different types of wireless devices that allow them to communicate with a wide range of telecommunication infrastructures located on streets, avenues, or roads. In this context, valuable data related to traffic management is transmitted and can be used for different purposes, such as assisting other vehicles on the road or improving the decisions made by traffic engineers. Vehicular Ad hoc NETworks (VANETs) enable wireless communications between vehicles, between vehicles and infrastructure, and also vehicles-to-everything, with the aim of generating smart mobility solutions and contributing to improve city services. However, routing information in VANETs is a challenging task, as vehicles are highly mobile, and their trajectories are uncertain and highly constrained by the city’s road map. In this regard, as the application of machine learning (ML) algorithms in wireless networks is increasing, the performance of vehicular networks can be improved by applying prediction-based techniques. In this work, we propose a multimetric ML-based routing protocol to select the best next-hop node for forwarding warning messages. For this purpose, we have considered the CatBoost framework, a gradient boosting algorithm on decision trees. Furthermore, we studied the importance of each routing metric and selected only the most relevant ones in our routing decisions. The performance evaluation shows the significant improvements obtained from our ML-based approach in terms of packet losses.

Hybrid adaptive MAC scheme for the broadcast of vehicular safety beacons

SummaryVehicular safety applications are based on broadcasting periodic safety beacons on the IEE802.11p control channel. The CSMA MAC scheme adopted in the IEE802.11p cannot ensure the strict timeline and the high reliability when broadcasting these real time and critical messages since it does not consider the high mobility of vehicles, the limited network resources, and the variant traffic densities. Therefore, the design of an effective MAC scheme that takes in consideration these parameters represents a challenging task. Furthermore, the fixed beaconing rate results an overload on the commination channel and collisions especially in dense situations that delay beacons broadcast. In this paper, we propose a novel hybrid MAC scheme for fast and reliable broadcast of safety beacons. At first, it relies on a time slot reuse policy that considers the mobility features of vehicles while reducing transmission collisions. In addition, it adapts mathematically the beaconing rate to the traffic density based on vehicular velocity at the aim of optimizing the performance of the wireless channel. Simulation results show that our proposal outperforms significantly the IEEE802.11p CSMA MAC scheme and upgrades the performance of vehicular networks in broadcasting periodic safety beacons.

PPTM: A Privacy-Preserving Trust Management Scheme for Emergency Message Dissemination in Space–Air–Ground-Integrated Vehicular Networks

Vehicular networks have tremendous potential to improve the road safety and traffic efficiency, and the adoption of the space–air–ground-integrated network (SAGIN) architecture in vehicular networks can greatly improve the performance of vehicular networks by leveraging the respective advantages of the space, air, and ground segments on coverage, flexibility, reliability, and availability, which results in space–air–ground-integrated vehicular networks (SAGIVNs). Trust management is an important tool for constructing trustworthy SAGIVNs, and privacy preservation is also a primary concern in SAGIVNs. They have conflicting requirements and a satisfactory balance between them is urgently required. In this article, we propose a novel privacy-preserving trust management (PPTM) scheme for the emergency message dissemination in SAGIVNs. The proposed scheme can realize precise trust management and strong conditional privacy preservation simultaneously with low communication overhead, and can provide strong applicability, strong robustness, and multiple other attractive features. Furthermore, the exhaustive theoretical analysis and simulation evaluation are detailed. The results reveal that the proposed scheme is significantly superior to the existing schemes in several aspects.

Integration of 4G LTE and DSRC (IEEE 802.11p) for Enhancing Vehicular Network Performance in IoV Using Optimal Cluster-Based Data Forwarding (OCDF) Protocol

<p>IoV is a known platform for exchanging data between vehicles and distinct networks through diverse communication media. Embedded technologies like IoT and Intelligent Transportation, are aimed to build smart networks for IoV to support diverse automated applications such as smart vehicle control, intelligent traffic control, and dynamic data services. However, in the smart domain, implementation of IoV has unresolved challenges. Synchronization of vehicles and humans is a crucial issue in making decisions. Therefore, proper understanding of the pertinent issues about IoV implementation that can improve the VNs performance are essential. DSRC and cellular networks are considered as potential alternatives for endorsing V2X communications. DSRC is employed for intelligent and automotive transportation applications through short-range data exchange between DSRC-components. Although spectrum assigned to DSRC alone will not be appropriate to satisfy huge information traffic needs for internet access in vehicles. Cellular networks offer potential solutions, attributing extensive range of cell coverage, broadly deployed infrastructure and greater capacity. Nevertheless, centralized characteristics of these networks limit the ability to handle low-latency communications that can challenge the efficacy of several safety applications. This paper reviews potential DSRC and wireless integrated solutions for efficient vehicular communications. In methodology, first we reviewed existing technologies that integrate DSRC with other wireless technologies and secondly, the study is carried out to highlight the limitations for each supporting vehicular communications. Thereby, the paper embeds a brief comparative analysis. Finally, an algorithm is proposed to integrate DSRC and 4G-LTE with a novel Optimal Clustering based Data Forwarding Protocol for efficient data transmission to attain better performance in IoV. The performance of the proposed algorithm is compared with the existing approaches using the NS-3 simulation tool. The obtained results demonstrate that the proposed algorithm outperforms over the existing approaches in terms of End to End Delay and throughput. </p>

BTMPP: Balancing Trust Management and Privacy Preservation for Emergency Message Dissemination in Vehicular Networks

As a potential application field of the sixth-generation (6G) communication technology and a promising part of massive Internet of Things (IoT), vehicular networks have attracted considerable attention from both academia and industry in recent years, where the cooperative safety applications are a significant branch. It is widely acknowledged that 6G is able to provide high-throughput and low-latency wireless communication capability for vehicular networks, support massive interconnectivity in vehicular networks with diverse service requirements, and significantly improve the performance of vehicular networks. Both trust management and privacy preservation play significant roles in vehicular networks, and there exists a tradeoff between them. For providing a satisfactory solution to balance the trust management and privacy preservation in vehicular networks, we put forward a novel scheme named as BTMPP (which is able to provide both the precise trust management and strong conditional privacy preservation simultaneously) in this article by leveraging the famous bloom filter (BF)-based private set intersection (PSI) technology. Furthermore, the theoretical analysis for the correctness, strong conditional privacy preservation capability, strong robustness, precise trust management, and the other features is detailed, and a series of simulations are conducted. The results reveal that the proposed scheme significantly outperforms the existing schemes in several aspects.

Performance Analysis of DSRC-Based Vehicular Safety Communication in Imperfect Channels

Vehicle-to-vehicle (V2V) communication empowers vehicles to share information by broadcasting basic and critical safety messages. Dedicated short-range communication (DSRC), the medium access control (MAC) layer of which utilizes the IEEE 802.11p protocol, is a promising candidate technology for vehicular communication. Safety applications usually demand safety message dissemination to be prompt and reliable. To satisfy these strict requirements, the MAC layer of vehicular safety communication tends to adopt Distributed Coordination Function (DCF) or single-class Enhanced Distributed Channel Access (EDCA) without request-to-send/clear-to-send (RTS/CTS), acknowledgment (ACK) and retransmission mechanisms as the access scheme. As far as we know, although many numerical models have been provided to understand the IEEE 802.11 DCF performance, there is no precise model that examines the performance of vehicular safety communication exploiting such an access scheme in imperfect channels with different incoming traffic loads. In this paper, we settle this problem by developing an analytical model where the impacts of various incoming traffic loads, packet length distribution, hidden terminal effects, node mobility, the MAC layer queuing system, and the faulty radio channels are all included which no one has done this before. The experimental and numerical results reveal that the constructed model can exactly forecast the vehicular network performance of packet delay, delivery rate, and reception rate under different traffic and channel circumstances.

Analysis and Design of Functional Device for Vehicular Cloud Computing

Relay technology application becomes prevalent nowadays, as it can effectively extend the communication distance, especially for vehicular networks with a limited communication range. Combined with vehicular cloud (VC), transmission efficiency can be improved by offloading partial data. Hence, designing a vehicle relay algorithm and implementation embedded vehicle device is critical. In this paper, VC is considered to deal with the complexity computation in our proposed system model. Without a loss of generality, an end-to-end vehicle communication with one assisted vehicle is analyzed firstly on a transmission link based on VC. Here, the signal-to-noise ratio (SNR) on the receiving end and link outage probability is obtained to enhance the link reliability. The VC computing helps us further simplify computational complexity. Subsequently, an embedded vehicle-enabled device is designed to achieve the optimal path relay selection in realistic vehicular environments. In the functional device framework, we display an optimal path relay selection algorithm according to the link quality. Finally, the performance of the transmission link on the outage probability related with SNR is verified in the simulation results. Meanwhile, the effect of the relay gain is also analyzed. The application of a vehicle-enabled embedded device could improve the performance of vehicular networks.

Road-Aware Estimation Model for Path Duration in Internet of Vehicles (IoV)

In Internet of Vehicles (IoV), numerous routing metrics have been used to assess the performance of routing protocols such as, packet delivery ratio, throughput, end-to-end delay and path duration. Path duration is an influential design parameter, among these routing metrics, that determines the performance of vehicular networks. For instance, in highly dynamic scenarios, it can be used to predict link life time in on-demand routing protocols. In this paper, we propose an infrastructure-assisted hybrid road-aware routing protocol which is capable of enhanced vehicle-to-vehicle and vehicle-to-infrastructure communication. A remarkable aspect of the proposed protocol is that it establishes a link between path duration and fundamental design parameters like vehicular velocity, density, hop count and transmission range. Although, a lot of research has been previously performed, a well defined analytical model for IoV is not available in the literature. Precisely, a relation between path duration and vehicular velocity has not been validated in the previous studies. Experimental results show that the increased packet delivery ratio with reduced end-to-end delay can be achieved by the prediction of path duration. Proposed model for path duration is validated by getting experimental results from network simulator 3 (NS3) and analytical results from MATLAB. In addition, SUMO simulator was used to generate real time traffic on the roads of Gangnam district, South Korea.

Broadening Understanding on Managing the Communication Infrastructure in Vehicular Networks: Customizing the Coverage Using the Delta Network

Over the past few decades, the growth of the urban population has been remarkable. Nowadays, 50% of the population lives in urban areas, and forecasts point that by 2050 this number will reach 70%. Today, 64% of all travel made is within urban environments and the total amount of urban kilometers traveled is expected to triple by 2050. Thus, seeking novel solutions for urban mobility becomes paramount for 21st century society. In this work, we discuss the performance of vehicular networks. We consider the metric Delta Network. The Delta Network characterizes the connectivity of the vehicular network through the percentage of travel time in which vehicles are connected to roadside units. This article reviews the concept of the Delta Network and extends its study through the presentation of a general heuristic based on the definition of scores to identify the areas of the road network that should receive coverage. After defining the general heuristic, we show how small changes in the score computation can generate very distinct (and interesting) patterns of coverage, each one suited to a given scenario. In order to exemplify such behavior, we propose three deployment strategies based on simply changing the computation of scores. We compare the proposed strategies to the intuitive strategy of allocating communication units at the most popular zones of the road network. Experiments show that the strategies derived from the general heuristic provide higher coverage than the intuitive strategy when using the same number of communication devices. Moreover, the resulting pattern of coverage is very interesting, with roadside units deployed a circle pattern around the traffic epicenter.

Drone Assisted Vehicular Networks: Architecture, Challenges and Opportunities

This article introduces the DAVN, which provides ubiquitous connections for vehicles by efficiently integrating the communication and networking technologies of drones and connected vehicles. Specifically, we first propose a comprehensive architecture of the DAVN and outline its potential services. By cooperating with vehicles and infrastructures, drones can improve vehicle-to-vehicle connectivity, infrastructure coverage, network information collection ability, and network interworking efficiency. We then present the challenges and research opportunities of DAVNs. In addition, a case study is provided to demonstrate the effectiveness of DAVNs by leveraging our designed simulation platform. Simulation results demonstrate that the performance of vehicular networks can be significantly enhanced with the proposed DAVN architecture.

Comparison of propagation and packet error models in vehicular networks performance

Over the years, we have witnessed how wireless communications and transportation technologies converge. Likewise, the research on the so-called vehicular ad hoc networks (VANETs) makes more and more sense. Due to the high costs and effort of deploying vehicles in real scenarios, network simulation is a popular alternative when studying the performance of vehicular networks. However, the dynamism of such environments makes their simulation a rarely simple task. In fact, many parameters have to be considered by VANET simulation, such as a dynamic topology, omnipresent obstacles, traffic flow, different mobility models, traffic lights, changing vehicular speeds, etc. Unsurprisingly, the way how some events are modeled in a simulation might bias the performance measures of vehicular communications. Accordingly, in this paper, we concentrate on assessing the impact of packet error modeling on VANET simulations. With this aim, we measure different parameters such as losses, end-to-end delay, and number of hops over a realistic urban scenario. We also test three different densities of nodes and three channel capacities. The performance metrics obtained after our simulations suggest that, in the best cases, the basic packet error model may obtain reliable results (i.e., results similar to those from a realistic error model). This evaluation is performed over a multi-hop scenario in which the antenna is configured with high sensitivity values. This simple technique bases on the assumption that interference levels will not exceed the SINR (Signal to Interference and Noise Ratio) threshold when errors begin to appear. This requirement may not be met in all simulations, for example in simulations with very high traffic load.

Full Duplex AF and DF Relaying Under Channel Estimation Errors for V2V Communications

In this paper, we investigate the outage performance of full-duplex (FD) and half-duplex (HD) vehicle to vehicle (V2V) networks. We consider two vehicular communication scenarios with the assistance of roadside unit (RSU), i.e., RSU-to-vehicle-to-vehicle (RVV) and vehicle-to-RSU-to- vehicle (VRV) scenarios. In particular, we analyze the outage performance of vehicular networks with the amplify-and-forward (AF) and decode-and-forward (DF) protocols under the effect of residual loop-back-interference (LBI) and channel estimation errors. For RVV scenario, the upper bounds for the outage probability of the AF based FD and HD relaying over double Rayleigh fading channels are derived. Moreover, we derive the approximate closed form expressions for the outage probability of the DF based FD and HD relaying protocol over Rayleigh fading channels; For VRV scenario, the exact closed-form expressions for the outage probability of the AF and DF relaying protocols are presented in case of FD and HD modes. Furthermore, we derive the approximate closed-form expressions for the outage probability of hybrid FD/HD mode on AF and DF relaying protocols. The numerical and simulation results corroborate our theoretical ones and quantify the impact of the data rates, channel estimation errors and the residual LBI on the system performance.

5G Software Defined Vehicular Networks

With the emerging of the fifth generation (5G) mobile communication systems and software defined networks, not only the performance of vehicular networks could be improved but also new applications of vehicular networks are required by future vehicles, e.g., pilotless vehicles. To meet requirements from intelligent transportation systems, a new vehicular network architecture integrated with 5G mobile communication technologies and software defined network is proposed in this paper. Moreover, fog cells have been proposed to flexibly cover vehicles and avoid frequently handover between vehicles and road side units (RSUs). Based on the proposed 5G software defined vehicular networks, the transmission delay and throughput are analyzed and compared. Simulation results indicate that there exist a minimum transmission delay of 5G software defined vehicular networks considering different vehicle densities. Moreover, the throughput of fog cells in 5G software defined vehicular networks is better than the throughput of traditional transportation management systems.

Deployment of vehicular networks in highways using 802.11p and IPv6 technologies

Most of the previous and current vehicular communication deployments, testbeds and, in general, experimental efforts come from research contributions evaluating particular solutions in the area. We have had to wait until recent days to see great testing campaigns in vehicular cooperative systems, coming from research projects supported by national or international funding. This paper reviews the deployment and operation of communication infrastructures in one of the major European projects in this area, i.e., European field operational test on safe, intelligent and sustainable road operation FOTsis. A key advance of FOTsis has been the integration of IEEE 802.11p and IPv6 technologies following the ISO/ETSI guidelines in cooperative systems for vehicle to infrastructure V2I communications. This work reports our main findings providing an interoperable IPv6 access to vehicular services, describes the main test-sites, provides vehicular network performance tests, and summarises our experience in these deployments. Our recommendations pave the way for future large-scale vehicular communication deployments in the V2I segment, which is expected to be the most relevant in the short and medium term.

Deployment of vehicular networks in highways using 802.11p and IPv6 technologies

Most of the previous and current vehicular communication deployments, testbeds and, in general, experimental efforts come from research contributions evaluating particular solutions in the area. We have had to wait until recent days to see great testing campaigns in vehicular cooperative systems, coming from research projects supported by national or international funding. This paper reviews the deployment and operation of communication infrastructures in one of the major European projects in this area, i.e., European field operational test on safe, intelligent and sustainable road operation (FOTsis). A key advance of FOTsis has been the integration of IEEE 802.11p and IPv6 technologies following the ISO/ETSI guidelines in cooperative systems for vehicle to infrastructure (V2I) communications. This work reports our main findings providing an interoperable IPv6 access to vehicular services, describes the main test-sites, provides vehicular network performance tests, and summarises our experience in these deployments. Our recommendations pave the way for future large-scale vehicular communication deployments in the V2I segment, which is expected to be the most relevant in the short and medium term.

Optimal road side units placement model based on binary integer programming for efficient traffic information advertisement and discovery in vehicular environment

Road side units (RSUs) are considered to be one of the most important components in vehicular networks to send and receive data from other components inside the networks. Regarding the fact that vehicular network performance and vehicular environment coverage are highly related, the maximum coverage via RSUs improves the efficiency of vehicular networks. However, because of high costs of RSU placement, it would be impossible to have full coverage through RSUs. Hence, it would be necessary to optimally install a limited number of RSUs in the most appropriate locations. In this article, the problem of RSU placement is formulated to binary integer programming. The objective of the present study is to find locations which have higher impacts on efficiency of vehicular networks. The objective function is minimising the costs of RSU placement. Moreover, coverage of the most important locations by RSUs has been applied in the form of optimization constraints. The performance of the given mechanism has been assessed by real traces. Simulation results indicate that the method is able to find optimal locations of RSUs in highway and urban environments. Furthermore, the results show that by optimal RSU placement inside the environment, the performance of vehicular network is improved.