Vehicular Ad Hoc Networks Connectivity Research Articles

5G handover issues and techniques for vehicular communications

<span lang="EN-US">Vehicular communication is gaining popularity, and seamless handover is critical to maintaining a stable and uninterrupted network connection between vehicles and roadside units. This paper investigates the advancements in handover approaches in vehicular networks, with a specific focus on 5G technology. Vehicular Ad-hoc Networks (VANETs) face challenges due to high mobility, dynamic network topology, and frequent information exchange. The paper discusses handover issues in 5G VANET environments, such as too-late and too-early handovers, wrong handover decisions, and unnecessary handovers. It also explores key performance indicators (KPIs) used in handover evaluation. The advancements in handover approaches presented in this paper pave the way for enhanced connectivity and communication management in 5G VANETs, contributing to the development of safer and more efficient intelligent transportation systems.</span>

Connectivity Analysis with Co-Channel Interference for Urban Vehicular Ad Hoc Networks

In urban vehicular ad hoc networks (VANETs), the complex channel environment and co-channel interference resulted in the uncertain delay of inter-vehicle packet transmission, which causes serious delay jitter. Connectivity is proposed as a key metric to describe this uncertainty. However, existing works lack a discussion of inter-vehicle connectivity in urban VANETs, particularly with regards to the process of transmitting packets between vehicles. In this paper, we analyze the connectivity probability of urban VANETs under co-channel interference with both complete and incomplete information. When the information is complete, we model the time-varying nature of co-channel interference and channel fading as delay jitter and analyze inter-vehicle connectivity in a time-varying environment. Then, when complete information is unavailable, we estimate the probability distribution of co-channel interference by combining the distribution of multiple parameters with the free space propagation model (Friss) model and Nakagami-m fading model. The expression for the connectivity performance of vehicle-to-vehicle (V2V) links is derived from the signal interference plus noise ratio (SINR) of the destination V2V link. Finally, we analyze the implications of various factors on connectivity, such as the transmit power of the signal, the arrival rate of packets, the number of channels and vehicles, and the distance between the transmitting vehicle and the receiving vehicle. The numerical analysis shows that co-channel interference and signal fading significantly affect inter-vehicle connectivity.

A Benchmark for Multi-Objective Routing in Vehicle Ad-Hoc Networks Using The Ant Colony Optimization Algorithm

The growing number of vehicles in cities has a great impact on our quality of life, such as air and noise pollution, traffic jams and traffic accidents. Cooperative Intelligent Transportation System (C-ITS) relies on communication technologies to provide innovative services and applications for transportation and traffic management. In the C-ITS context, users, roadside infrastructure and vehicles need to be connected and, for this purpose, a wide variety of wireless technologies can be used (e.g, vehicular WiFi, cellular and visible light communication). In this work we consider a VANET (Vehicular Ad-hoc NETwork) using vehicular WiFi (based on 802.11p). The communications in VANET networks have been studied for years and several routing algorithms have been developed for such a kind of network. However, a benchmark to compare the performance of such algorithms is still lacking. To fill this gap, the present work proposes a benchmark composed by instances of data routing for different scenarios in the VANET. Moreover, we propose a multi-objective algorithm based on ACO (Ant Colony Optimization) to compare with such benchmark. The results of simulations show the impact of several factors in the VANET connectivity, such as vehicle density, geographical location, propagation and fading models. The results are promising and indicate the importance of choosing appropriated simulation models.

A New Deployment Schema Using Dynamic Relay Vehicle to Improve VANETs Connectivity in Urban Environment

Vehicular ad-hoc network (VANETs) have emerged as promising technology to support traffic safety applications of intelligent transportation system (ITS). One of the most important challenges facing VANET is the connectivity, due to obstacles, high mobility, dynamic topology which leads to disconnection problem. Deploying road Sid unite (RSU) to improves VANET connectivity is considered as a highly cost solution. Previous researches suggested diverse RSU deployment schemes and algorithms to solve the RSU deployment issue in order to achieve better network connectivity with minimum number of RSU. In this paper we propose dynamic relay node as replacement to RSU with zero infrastructure. It’s Using key metrics of interest (such as connection duration, re-healing time, receiving time) we provide thorough visualization for network connectivity of urban VANETs with dynamic relay node. It is not only a low-cost solution, but it is practical solution since it does not require RSU installation or maintenance. Simulations are carried out in ns2 to evaluate the performance of dynamic relay node in urban environment. The proposed scheme proves its efficiency through increasing the vehicle density in the road and by increasing relay vehicle velocity. The result shows that the proposed scheme improve the network connectivity as the number of relays increased up to four dynamic relay nodes.

Connectivity analysis of directed highway vehicular ad hoc networks using graph theory

SummaryGraph theory is a promising approach in handling the problem of estimating the connectivity probability of vehicular ad hoc networks (VANETs). With a communication network represented as graph, graph connectivity indicators become valid for connectivity analysis of communication networks as well. In this article, we discuss two different graph‐based methods for VANETs connectivity analysis showing that they capture the same behavior as estimated using probabilistic models. The study is, then, extended to include the case of directed VANETs, resulting from the utilization of different communication ranges by different vehicles. Overall, the graph‐based methods prove a robust performance, as they can be simply diversified into scenarios that are too complex to acquire a rigid probabilistic model for them.

A cooperative game based mechanism for autonomous organization and ubiquitous connectivity in VANETs

Vehicular communications in Vehicular Ad-hoc NETworks (VANETs) play an interesting role in improving traffic flow on the roads. In such wireless networks, the vehicles cooperate with each other or with the roadside infrastructure to disseminate the data. In this paper, we introduce a mechanism based on coalitional game theory to study the cooperative transmission in VANETs. Each vehicle tries to access the Internet via gateways that can be either fixed or mobile. However, these gateways help the vehicles to access the Internet by cooperatively relaying the vehicles’ messages. Thus, two notions to indicate the availability of transmission between vehicles and gateways are introduced. These notions are chosen to deal with the highly dynamic topology in VANETs, namely the notion of an encounter and the notion of a link’s predicted lifetime. The problem is modelled as a non-transferable utility game. Then, an algorithm is proposed to dynamically form coalitions among the vehicles. Moreover, a probability of being active is set in terms of speed of the received vehicle. To evaluate the proposed solution, two scenarios are used: fixed gateways scenario and mobile gateways scenario. The numerical results show that the scenario of mobile gateways is more effective in terms of stimulating vehicles to regroup into coalitions. Hence, this helps the vehicles to access the Internet.

A study on modeling vehicles mobility with MLC for enhancing vehicle-to-vehicle connectivity in VANET

In Vehicular ad hoc networks (VANETs), vehicle-to-vehicle (V2V) is a significant mode of communication in which vehicles communicate with other moving vehicles with the aid of wireless transceivers. Due to the rapid mobility of vehicles, network connectivity over VANETs is frequently unstable, especially in sparse highways. This paper analyzes V2V connectivity dynamics by designing the microscopic mobility and lane changing decision model using an adaptive cursive control mechanism and recurrent neural network. Extensive simulators like SUMO and NS2 analyze the validity of this proposed model. The proposed analytical model provides a framework for examining the impact of mobility dependent metrics such as vehicle velocity, acceleration/deceleration, safety gap, vehicle arrival rate, vehicle density and network metric data delivery rate for characterizing the VANET connectivity of the proposed network. The simulation results synchronized those of the proposed model, which illustrated that the developed analytical model of this work is effective.

A Proof-of-Quality-Factor (PoQF)-Based Blockchain and Edge Computing for Vehicular Message Dissemination

Blockchain applications in vehicular networks can offer many advantages, including decentralization and improved security. However, most of the consensus algorithms in blockchain are difficult to be implemented in vehicular ad hoc networks (VANETs) without the help of edge computing services. For example, the connectivity in VANET only remains for a short period of time, which is not sufficient for highly time-consuming consensus algorithms, e.g., Proof of Work, running on mobile-edge nodes (vehicles). Other consensus algorithms also have some drawbacks, e.g., Proof of Stake (PoS) is biased toward nodes with a higher amount of stakes and Proof of Elapsed Time (PoET) is not highly secure against malicious nodes. For these reasons, we propose a voting blockchain based on the Proof-of-Quality-Factor (PoQF) consensus algorithm, where the threshold number of votes is controlled by edge computing servers. Specifically, PoQF includes voting for message validation and a competitive relay selection process based on the probabilistic prediction of channel quality between the transmitter and receiver. The performance bounds of failure and latency in message validation are obtained. This article also analyzes the throughput of block generation, as well as the asymptotic latency, security, and communication complexity of PoQF. An incentive distribution mechanism to reward honest nodes and punish malicious nodes is further presented and its effectiveness against the collusion of nodes is proved using the game theory. Simulation results show that PoQF reduces failure in validation by 11% and 15% as compared to PoS and PoET, respectively, and is 68 ms faster than PoET.

Performance enhancement of safety message communication via designing dynamic power control mechanisms in vehicular ad hoc networks

AbstractIn vehicular ad hoc networks (VANETs), transmission power is a key factor in several performance measures, such as throughput, delay, and energy efficiency. Vehicle mobility in VANETs creates a highly dynamic topology that leads to a nontrivial task of maintaining connectivity due to rapid topology changes. Therefore, using fixed transmission power adversely affects VANET connectivity and leads to network performance degradation. New cross‐layer power control algorithms called (BL‐TPC 802.11MAC and DTPC 802.11 MAC) are designed, modeled, and evaluated in this paper. The designed algorithms can be deployed in smart cities, highway, and urban city roads. The designed algorithms improve VANET performance by adapting transmission power dynamically to improve network connectivity. The power adaptation is based on inspecting some network parameters, such as node density, network load, and media access control (MAC) queue state, and then deciding on the required power level. Obtained results indicate that the designed power control algorithm outperforms the traditional 802.11p MAC considering the number of received safety messages, network connectivity, network throughput, and the number of dropped safety messages. Consequently, improving network performance means enhancing the safety of vehicle drivers in smart cities, highway, and urban city.

Stochastic performance modeling and analysis of multi service provisioning with software defined vehicular networks

Tremendous growth of traffic in Vehicular Ad hoc NETworks (VANET) in recent days leads into enormous delay in data transfer. To overcome this, we use Software Defined Vehicular Networks (SDVN) as a promising solution with reliable multi-hop cooperative data dissemination (MHCDD) for data traffic forwarding in the network of end to end connectivity. In SDN based system, data forwarding in a road side unit is through cooperatively data dissemination. The intermittent connectivity in VANET dynamically changes because of the vehicular mobility, thereby causing SDN and RSU controller to link/connection failures. However, in multi-hop data traffic forwarding from source to destination node through RSU and SDN switches in which controllers control the data traffic for Virtual Network Customization (VNC). In this paper, we introduce Software defined-VANETs (SD-VANETs) to improve the network resource utilization by providing the network connectivity for dynamic network topology. Here, we analyze the network model using M/M/1 and M/M/m queueing models, which are proposed to effectively minimize the delay and enhance the throughput in multi-server queueing system of the SDVN. To achieve this, we propose a novel solution with enhancement of the SDVN system reliability in terms of service rate which is based on service level agreement.

Study on Connectivity Probability of Vanets Under Adverse Weather Conditions at 5.9 Ghz

Vehicular ad hoc networks (VANETs) are an important part of the next generation of intelligent transportation. For multimedia information transmissions, VANETs require high speed and a low-delay link between the vehicles. This paper focuses on a connectivity analysis of VANET high-speed and low-delay connections under different traffic densities and adverse weather conditions. In this paper, a channel measurement at 5.9 GHz under two kinds of traffic densities is first carried out. Then, the measured data for the path loss are used in the VANET model for the connectivity probability. Finally, we consider the influence of adverse weather conditions on the wireless signal and simulate the influence on the high-speed and low-delay data connectivity of VANETs. The results show that adverse weather will have a certain impact on vehicle-to-vehicle (V2V) communication.

Effect of Traffic Light Scenario on VANETs Connectivity with Low Penetration Rate

Traffic light with Vehicular Ad-Hoc Networks (VANETs) has been developed recently. Many issues and challenges come up with this development that required an investigation. One of the most prominent challenges is connectivity under low penetration of vehicles with VANET technology. Traffic light scenario has been proposed in this field to overcome low penetration problem, but no studies have been done on their connectivity. In this paper, VANET connectivity with traffic light scenarios had been investigated. The most significant metric in this investigation is penetration rate, more specifically low values of it. Connectivity measurements, i.e. reachability, connection duration and re-healing time had been studied with real-time simulation. Three traffic light scenarios had been considered; no traffic light, normal traffic light and intelligent traffic light. The effect of these scenarios on VANET connectivity had been analyzed with low penetration rate and important conclusions had been stated for future works.

Connectivity probability analysis of VANETs at different traffic densities using measured data at 5.9 GHz

Vehicular Ad Hoc Networks (VANETs) is one of the most important applications in the fifth generation. The stable connection between the vehicles can guarantee the construction of VANETs. This study55This study is an extension of work originally presented in the 16th edition of International Conference on Intelligent Transport Systems (ITS) Telecommunications, IEEE ITST2018, Lisboa,Portugal, October 2018.stresses on the connectivity probability analysis under different vehicle density. Firstly, this study investigates the matched path loss models under four kinds of traffic flow conditions: high, medium traffic density in urban areas and two low traffic density in suburb areas based on the analysis of measured vehicle-to-vehicle (V2V) data at 5.9 GHz. Secondly, based on the measured path loss and small-scale fading data, we build a VANETs model considering single-hop link connectivity and signal blocking phenomenon in multi-hop link. Finally, the VANETs connectivity probability under different traffic flows is obtained as well as the obstruction considered effective communication coverage. The results show that the integrated VANETs connectivity model based on measured data can accurately reflect the V2V communication environment under real conditions.

UAV-Assisted Supporting Services Connectivity in Urban VANETs

To keep the services and applications of intelligent transportation system stable and active, vehicular ad hoc networks (VANETs) are considered as an essential building block to maintain and manage its features. A wide deployment of VANETs is possible only after addressing numerous research challenges. One of the most complicated issues consists of designing a routing strategy, taking into consideration several serious constraints, and especially in a network such as VANET. The severity of these issues would be increased significantly when a VANET is deployed over an urban area, where we distinguish the high mobility of nodes and existing obstructions (e.g., buildings, bridges, tunnels, etc.). In this paper, an efficient routing solution based on a flooding technique is conceived to make the data delivery more reliable and to guarantee robust paths. Vehicles can cooperate in ad hoc fashion with existing unmanned aerial vehicles (UAVs). This kind of collaboration provides reliable routing paths and ensures alternative solutions in the case of path failures. Furthermore, a prediction technique is used to expect the expiration time of each discovered path. To limit the overhead over the network, all control packets are characterized by their static size making the originality of this work. Based on the simulation outputs, we discuss the performances of the proposed approach as compared with other dedicated previous schemes in terms of several metrics. The obtained results demonstrate that the hybrid communication between vehicles and UAVs based on the proposed flooding technique is perfectly suited to improve the data delivery process.

Improvised dynamic network connectivity model for Vehicular Ad-Hoc Networks (VANETs)

The Road traffic modeling in Vehicular Ad Hoc Networks (VANETs) may require disseminating information to specific geographical areas like Road Intersection. The communications, network connectivity and routing are the central issues in VANETs. The Vehicular Ad Hoc Network (VANETs) have high mobility and high density of mobile nodes. Managing this mobility is very important to ensure routing efficiency and network connectivity in VANETs. VANETs are characterized by topology changes and link disconnections. The research challenges for applications of VANETs remains to design of intelligent algorithms for dynamic network connectivity and efficient routing problem in VANETs becomes a challenging event because of the active nature of mobile clients. In this paper, we have proposed an appropriate routing protocol for VANETs based on the dynamic network connectivity behavior of urban traffic at road crossings or Intersection. The dynamic network connectivity model for VANETs is based on parallel processing concept are essential for designing an efficient routing protocol for VANETs at Road Intersection in urban scenarios. Our simulation result showed that different control mechanisms are applied at road crossings and we likened the performance of our proposed scheme with the competitive schemes (Modeling Urban Traffic (MUT) Scheme, Dynamic Connectivity Scheme (DCS), Cellular Automaton Model for Car Traffic (CAMCT) and Dynamic Connectivity-Aware Routing for Internet-based Services (D-CAR)) in terms of Inter-vehicle spacing, number of vehicles in one road block and distance from road crossings or Intersection against varying node density.

Effect of non-cooperative vehicles on path connectivity in vehicular networks: A theoretical analysis and UAV-based remedy

A fully-connected Vehicular Ad-hoc Network (VANET) contributes tremendously to the improvement of the travel experience of commuting passengers. However, the existence of an end-to-end multi-hop path across VANET highly depends on the willingness of vehicles to cooperate with one another when it comes to data forwarding. Unlike the existing VANET connectivity studies that focused solely on fully-cooperative vehicular environments, this paper develops a mathematical model to explain the effect of non-cooperative vehicles on the end-to-end connectivity through the roadway segments of a VANET.First, this work characterizes some of the fundamental traffic-theoretic properties of VANETs in the presence of non-cooperative vehicles. Then, it proposes to alleviate the detrimental effect of non-cooperation on end-to-end path connectivity by exploiting Unmanned Aerial Vehicles (UAVs) as store-carry-and-forward nodes in a VANET. Through both mathematical analysis and extensive simulations, the role that UAVs can play in enhancing end-to-end path connectivity is quantified in the context of a hybrid, UAV-assisted VANET architecture.

An Empirical Study on the Temporal Structural Characteristics of VANETs on a Taxi GPS Dataset

In recent years, vehicular ad hoc networks (VANETs) have received significant interests from both academia and industry because of the ubiquitous communication capabilities they provide. VANETs are expected to support a wide range of applications that may influence our daily life, ranging from road safety applications to entertainment ones. A key to the development of protocols and algorithms for intervehicle communication and services lies in the knowledge of the structural properties of the VANET communication graph. Nonetheless, previous researches represented the VANET communication graph as a set of snapshots and tracked the evolution of some metrics on snapshots at certain time intervals. They neglected to take into account the temporal property of VANETs, which in many real scenarios plays a pivotal role. In this paper, we mainly explore the temporal structural characteristics of VANETs. A time-extended model is first presented to capture the temporal property of VANETs. Based on the model, some key metrics are defined to describe the structural characteristics of VANETs in various aspects. We then employ a real and large-scale urban taxi GPS dataset to provide a comprehensive study of the temporal structural characteristics involved with time-ordered paths, reachability, and connectivity of VANETs. These results are helpful in designing better protocols and algorithms to achieve reliable and low-latency communications.

One Dimensional Vehicular Ad-hoc Network Connectivity Analysis Under Fading Conditions

Inter vehicle headway distance and channel fading are the two important highly random factors affecting the connectivity of vehicular ad-hoc networks (VANET). In this paper we investigate the combined effect of vehicle headway distance and channel fading on network connectivity. We develop a mathematical model for connectivity based on inter arrival time and channel parameters. The effect of channel fading is incorporated in to the analysis by using stochastic geometric method. We investigate on the Inter arrival time based power distribution which primarily determines connectivity probability and mean number of connected nodes in the network.

Modeling the Impact of Mobility on the Connectivity of Vehicular Networks in Large-Scale Urban Environments

The connectivity of moving vehicles is one of the key metrics in vehicular ad hoc networks (VANETs) that critically influences the performance of data transmission. Due to lack of in-depth analysis of real-world vehicular mobility traces, we do not understand the connectivity in realistic large-scale urban scenarios. Specifically, the mechanism of how the mobility of networked vehicles impacts the network connectivity remains unknown. In this paper, we aim to unveil the underlying relationship between the mobility and connectivity of VANETs. To achieve this goal, we employ some key topology metrics, including component speed and component size, to characterize mobility and connectivity. In our investigation of a large-scale real-world urban mobility trace data set, we discover, to our surprise, that there exists a dichotomy in the relationship between component speed and size. This dichotomy indicates that mobility destroys the connectivity with a power-law decline when the component speed is larger than a threshold; otherwise, it has no apparent impact on connectivity. Based on this observation, we propose a mathematical model to characterize this relationship, which agrees well with empirical results. Our findings thus offer a comprehensive understanding of the relationship between mobility and connectivity in urban vehicular scenarios, and based on this, helpful guidelines can be provided in the design and analysis of VANETs.

Connectivity-Sensed Routing Protocol for Vehicular Ad Hoc Networks: Analysis and Design

With the fast development of vehicular ad hoc networks (VANETs), various VANET applications, especially safety and infotainment service, have stronger requirements for reliable network connectivity. Intermittent connectivity has become a thorny problem in VANETs, which causes unreliable vehicle to vehicle (V2V) connection due to high vehicle mobility. In this paper, we have studied the network connectivity using a stochastic analysis model and then we prove average intervehicle distance influences VANET connectivity greatly. Based on our analysis, we propose a connectivity-sensed routing protocol (CSR) for VANETs in urban scenario. CSR utilizes vehicle distribution information collected by intersection infrastructure to help vehicles select a road not only with progress to destination but also with better network connectivity. Moreover, simulation results demonstrate that the CSR protocol achieves much lower end-to-end delay, higher delivery rate, and higher throughput than traditional routing protocols.