Heterogeneous Vehicular Networks Research Articles

Congestion Game With Link Failures for Network Selection in High-Speed Vehicular Networks

Network selection is of critical importance for heterogeneous vehicular networks. However, it still faces network congestion and reliability challenges in high-speed vehicular networks, which are caused by users’ selfishness and link failures, respectively. To address these challenges, we propose a scheme called enhanced congestion game with link failures (E-CGF) to achieve optimal network selection. In E-CGF, a hidden Markov model is utilized to formulate the link failure probability. Considering link failures, users can use more than one radio network simultaneously to improve throughput performance by redundant transmission, which leads to an increase of transit cost. Accordingly, the goal of E-CGF is to make a compromise between achieved throughput and transit cost. We first prove the existence of Nash equilibrium in E-CGF and construct an efficient algorithm to find the optimal strategy. We then evaluate the effect of different parameters on the utility based on numerical analysis. Finally, we carry out extensive experiments based on real-world traces of link states from high-speed rails and compare with three typical algorithms. The results demonstrate that E-CGF outperforms others by alleviating network congestion and improving transmission reliability with a moderate trade-off between achieved throughput and transit cost.

Vehicular Wi-Fi Offloading in Heterogeneous Vehicular Networks: Techniques and Challenges

The increasing use of smartphones, tablets, and other vehicular network applications with varied capabilities and the associated growth in the use of all types of data-hungry multimedia services pose a significant challenge to cellular infrastructure operators. Vehicular Wi-Fi offloading (VWO) is one of the potential solutions for offloading cellular traffic. Several offloading techniques through vehicular ad-hoc networks are proposed in the literature. Thus, this paper reviews several state-of-the-art VWO techniques. We categorize the techniques based on the application requirements and the medium used for offloading. Two groups of techniques are identified. All techniques that depend on the roadside unit as offloading media are classified as vehicle-to-infrastructure-based techniques and those that depend on the opportunistic vehicle-to-vehicle (V2 V) network are called V2 V-based techniques. We present a comprehensive VWO architecture and VWO performance metrics derived from mobile-data offloading metrics. We also elucidate the important issues to be incorporated in designing VWO techniques together with future research directions in this domain.

A TDMA-Based Hybrid Transmission MAC Protocol for Heterogeneous Vehicular Network

A TDMA-Based Hybrid Transmission MAC Protocol for Heterogeneous Vehicular Network

Self-Sustaining Caching Stations: Toward Cost-Effective 5G-Enabled Vehicular Networks

In this article, we investigate the cost-effective 5G-enabled vehicular networks to support emerging vehicular applications, such as autonomous driving, in-car infotainment and location-based road services. To this end, self-sustaining caching stations (SCSs) are introduced to liberate on-road base stations from the constraints of power lines and wired backhauls. Specifically, the cache-enabled SCSs are powered by renewable energy and connected to core networks through wireless backhauls, which can realize "drop-and-play" deployment, green operation, and low-latency services. With SCSs integrated, a 5G-enabled heterogeneous vehicular networking architecture is further proposed, where SCSs are deployed along roadside for traffic offloading while conventional macro base stations (MBSs) provide ubiquitous coverage to vehicles. In addition, a hierarchical network management framework is designed to deal with high dynamics in vehicular traffic and renewable energy, where content caching, energy management and traffic steering are jointly investigated to optimize the service capability of SCSs with balanced power demand and supply in different time scales. Case studies are provided to illustrate SCS deployment and operation designs, and some open research issues are also discussed.

Emerging technologies and research challenges for intelligent transportation systems: 5G, HetNets, and SDN

With the rapid advance of the intelligent transportation system (ITS), the vehicular networks have a potential importance. Currently, these networks are suffering a major challenge due to the widespread demand for services associated with shipping safer, more efficient, cheaper, infotainment, and more sustainable. Researchers and companies are working to generate novel applications. Intelligent Transportation Systems that aim to reorganize the operation of vehicles. With the need for technological convergence in communications, it is necessary to refer of vehicular heterogeneous, autonomous, flexible and programmable networks. New emerging technologies open up interesting gaps for research and development of future networks. In this paper, we present an overview on wireless technologies and potential challenges to provide vehicle-to-x connectivity; such as the connected vehicles or self-driving cars, that will be the first robots that have a direct effect on the daily lives of millions of people. Particularly, we examine the 5G architecture designed with Software Defined Networking and their role in Heterogeneous Networks.

CU-CVIS Test Bed: A Test Bed of Cooperative Vehicle- Infrastructure System in Chang’an University

With the rapid development of information technology, there is an increasing interest in connected vehicle and related technology. Compared to the large number of simulation studies on connected vehicle, there appeared to be few empirical studies on the performance of networks and applications due to the lack of suitable hardware facilities. Therefore, Chang’an University started to build a cooperative vehicle-infrastructure system test bed with different types of ITS scenarios and communication systems such as 4G-LTE and VANET (Vehicular Ad Hoc Network), which was called CU-CVIS test bed and located in its Weishui campus. In this paper, the architecture and detailed functions of CU-CVIS test bed are presented. Firstly, some important connected vehicle test beds in the world are introduced. Next, based on the demand of applications on connected vehicle, details of CU-CVIS test bed, such as architecture of the test bed, construction of 4G-LTE and DSRC communication systems and result of performance test, are described. The characteristics of CU-CVIS test bed are also presented. Finally, the vision and developing strategy of the test bed in the future are discussed with opportunities and challenges. It can be concluded that CU-CVIS can simulate various connected vehicle scenarios with reliable heterogeneous vehicular network and support future empirical study on connected vehicle and other related technologies.

Predict and prevent from misbehaving intruders in heterogeneous vehicular networks

The great evolution of communication technologies and potential availability of network access mediums and service providers have led to the appearance of heterogeneous network concept. This paradigm refers to the seamless and ubiquitous interoperability between multi-coverage protocols with different access techniques. A heterogeneous vehicular network (HetVNet) is a heterogeneous network where a vehicle is a smart node equipped with various communication technologies such as Dedicated Short Range Communication (DSRC) and cellular network (3G/4G). The purpose of HetVNet is ensuring a wide area coverage to all vehicles in a large scale network, thus achieving the Always Best Connected (ABC) paradigm where the best continuous connectivity is offered to clients. In addition, HetVNet enables the acquisition and processing of a large amount of data from wide geographical areas via smart vehicles to offer various categories of services to drivers and passengers. There are many challenges in HetVNet and security is one of them since, on one hand, vehicles exchange vital data (about congestions, accidents, hazards, road-works, etc.) and on the other hand they form a specific network with particular characteristics (frequent fragmentation, dynamic topology, no centralized authority, etc.). Intrusion detection systems (IDS) act as a second wall of defense when cryptography is broken and already proved their effectiveness against both external and internal intruders. Therefore, in this research work we propose and implement an intrusion detection and prediction scheme able to detect and especially predict the future misbehavior of a malicious vehicle. The attack prediction technique proposed in this paper is based on a game theory to prevent the occurrence of malicious vehicles. Moreover, the proposed detection scheme detects the most dangerous attacks that target a HetVNet such as false alerts and Sybil attacks. This detection uses a rules-based technique to model a normal behavior of a vehicle. Simulations performed using NS-3 show that our scheme exhibits a high accuracy prediction, faster attack detection, and a low communication overhead compared to current detection frameworks.

A congestion avoidance game for information exchange on intersections in heterogeneous vehicular networks

Recently, the concept of HetVNET (Heterogeneous Vehicular NETwork) is greatly motivated by the fact that present wireless networks not only offers their attractive benefits, but also bring their shortcomings together. In this paper, by integrating the GIS (Geographic Information System), GPS (Global Position System), Sensor network, Vehicular Ad Hoc Networks (VANETs) and other localization technologies into our work, we propose a RoS (Requirement of Safety) aware services scheduling in the HetVNET to improve the packets delivery ratio, increase the spectral efficiency and alleviate the packet congestion as well. In addition, through utilizing the SINR-based (Signal to Interference plus Noise Ratio) utility and social optima searching strategy, our proposed algorithm outperforms the IEEE 802.11p in terms of the throughput as well as service miss ratio with the EDF (Earliest Deadline First) queuing mechanism. In addition, to reflect the increased transmission opportunities, the channel busy ratio under different configurations is also compared with a previous work DynB (Dynamic Beaconing).

Delay-Optimal Virtualized Radio Resource Scheduling in Software-Defined Vehicular Networks via Stochastic Learning

Due to the high density of vehicles and various types of vehicular services, it is challenging to guarantee the quality of vehicular services in current Long-Term Evolution (LTE) networks in a cost-efficient manner. Fortunately, with the development of fifth-generation (5G) technology, the installation of a large number of small cells is foreseen as one of the practical ways to achieve the low-delay requirement in vehicular environments. However, it may cause a huge operating expense and capital expenditure to mobile network operators due to the limited backhaul capacity and the explosion of signaling. In this paper, we integrate software-defined networking and radio resource virtualization into an LTE system for vehicular networks, i.e., software-defined heterogeneous vehicular network (SERVICE) . Based on this proposed system framework, a delay-optimal virtualized radio resource scheduling scheme is proposed via stochastic learning. The delay optimal problem is formulated as an infinite-horizon average-cost partially observed Markov decision process (POMDP). Then, an equivalent Bellman equation is derived to solve it. The proposed scheme can be divided into two stages, i.e., macro virtualization resource allocation (MaVRA) and micro virtualization resource allocation (MiVRA). The former is executed based on large timescale variables (traffic density), whereas the latter is operated according to short timescale variables (channel state and queue state). Simulation results show that the proposed scheme outperforms traditional schemes.

Cost-Efficient Sensory Data Transmission in Heterogeneous Software-Defined Vehicular Networks

Sensing and networking have been regarded as key enabling technologies of future smart vehicles. Sensing allows vehicles to be context awareness, while networking empowers context sharing among ambients. Existing vehicular communication solutions mainly rely on homogeneous network, or heterogeneous network via data offloading. However, today’s vehicular network implementations are highly heterogeneous. Therefore, conventional homogeneous communication and data offloading may not be able to satisfy the requirement of the emerging vehicular networking applications. In this paper, we apply the software-defined network (SDN) to the heterogeneous vehicular networks to bridge the gaps. With SDN, heterogeneous network resources can be managed with a unified abstraction. Moreover, we propose an SDN-based wireless communication solution, which can schedule different network resources to minimize communication cost. We investigate the problems in both single and multiple hop cases. We also evaluate the proposed approaches using traffic traces. The effectiveness and the efficiency are validated by the results.

Visible light communications as a complementary technology for the internet of vehicles

The paradigm of connected vehicles is moving from research to implementation, thus enabling new applications that start from safety improvement and widen to the so called Internet of vehicles (IoV). The candidate enabling technologies in the radio frequency (RF) bands are cellular and short range technologies. However, the limited bandwidth shared among several applications pushes researchers to look at new technological solutions. To this end, an option is provided by visible light communication (VLC). Based on the use of the light emission diodes (LEDs) that are already available on the majority of vehicles, VLC would enable short range communication in large, unlicensed, and uncongested bands with limited costs. In this work we first highlight the main properties of VLC in vehicular networks and revise the state of the art focusing on both the IEEE 802.15.7 standard and on the performance demonstrated by field tests that have been conducted worldwide. Then, we discuss the limitations of using VLC for pure vehicular visible light networks (VVLNs) and its application as complementary technology, to be implemented with other wireless standards in future heterogeneous vehicular networks. Finally, we show numerical results provided by simulations in a realistic urban scenario focusing, as a case study, on the crowd sensing vehicular network application with VLC added to short range IEEE 802.11p technology. Results demonstrate that the addition of VLC improves the performance of a conventional vehicular network based only on IEEE 802.11p.

Soft-defined heterogeneous vehicular network: architecture and challenges

Heterogeneous Vehicular NETworks (HetVNETs) can meet various quality-of-service (QoS) requirements for intelligent transport system (ITS) services by integrating different access networks coherently. However, the current network architecture for HetVNET cannot efficiently deal with the increasing demands of rapidly changing network landscape. Thanks to the centralization and flexibility of the cloud radio access network (Cloud-RAN), soft-defined networking (SDN) can conveniently be applied to support the dynamic nature of future HetVNET functions and various applications while reducing the operating costs. In this paper, we first propose the multi-layer Cloud RAN architecture for implementing the new network, where the multi-domain resources can be exploited as needed for vehicle users. Then, the high-level design of soft-defined HetVNET is presented in detail. Finally, we briefly discuss key challenges and solutions for this new network, corroborating its feasibility in the emerging fifth-generation (5G) era.

Meeting Always-Best-Connected paradigm in heterogeneous vehicular networks: A graph theory and a signaling game analysis

Due to the high mobility of vehicles and the dynamic topology changes of vehicular networks, it is difficult to satisfy drivers needs through a single wireless network. Consequently, by integrating different wireless access networks such as LTE and IEEE 802.11p, the vehicular network is expected to be a good platform called Heterogeneous Vehicular Network that can meet various vehicular user requirements. In such networks, vehicles need to have mechanisms in place to decide which access network is the most suitable for every application that the vehicular user requires. Always-Best-Connected is considered as a special concept to allow users getting connected to Internet using the access network that best suits their needs or profile at any point in time. Clearly, this concept provides multiple access networks simultaneous for mobile users moving in heterogeneous access network environment. In this paper, we propose two approaches called graph theory-based approach, and signaling game-based approach. The first approach is based on graph theory while the second one based on signaling game theory to compute the suitable path which provides Always-Best-Connected service for a smart vehicle moving in vehicular networks.

Internet of Vehicles: Motivation, Layered Architecture, Network Model, Challenges, and Future Aspects

Internet of Things is smartly changing various existing research areas into new themes, including smart health, smart home, smart industry, and smart transport. Relying on the basis of “smart transport,” Internet of Vehicles (IoV) is evolving as a new theme of research and development from vehicular ad hoc networks (VANETs). This paper presents a comprehensive framework of IoV with emphasis on layered architecture, protocol stack, network model, challenges, and future aspects. Specifically, following the background on the evolution of VANETs and motivation on IoV an overview of IoV is presented as the heterogeneous vehicular networks. The IoV includes five types of vehicular communications, namely, vehicle-to-vehicle, vehicle-to-roadside, vehicle-to-infrastructure of cellular networks, vehicle-to-personal devices, and vehicle-to-sensors. A five layered architecture of IoV is proposed considering functionalities and representations of each layer. A protocol stack for the layered architecture is structured considering management, operational, and security planes. A network model of IoV is proposed based on the three network elements, including cloud, connection, and client. The benefits of the design and development of IoV are highlighted by performing a qualitative comparison between IoV and VANETs. Finally, the challenges ahead for realizing IoV are discussed and future aspects of IoV are envisioned.

On Achieving Seamless IP Communications in Heterogeneous Vehicular Networks

The supporting infrastructure and communications technologies for vehicular networking contexts are heterogeneous by nature. Large coverage access networks, such as 3G/4G, coexist with wireless local area networks and dedicated short-range communications. In such a scenario, we investigate the seamless provision of mobile Internet access and general IP services over the heterogeneous network, in particular for loosely coupling architectures. We propose a hybrid global mobility scheme that allows for the ongoing IP sessions to be transferred across dissimilar radio access networks that may belong to different administrative domains. In order to achieve the global mobility, our scheme combines host- and network-based mobility. The solution focuses on urban vehicular scenarios and enables seamless communications for in-vehicle networks, passengers with mobile devices, and users of public transportation commuting along the system. By means of analytical evaluations and simulations of realistic urban vehicular scenarios, we show that our hybrid scheme can achieve seamless IP communications for mobile Internet access over the heterogeneous vehicular network.

Reliable and efficient autonomous driving: the need for heterogeneous vehicular networks

Autonomous driving technology has been regarded as a promising solution to reduce road accidents and traffic congestion, as well as to optimize the usage of fuel and lane. Reliable and highly efficient vehicle-to-vehicle and vehicle-to-infrastructure communications are essential for commercial autonomous driving vehicles to be on the road before 2020. The current article first presents the concept of heterogeneous vehicular networks (HetVNETs) for autonomous driving, in which an improved protocol stack is proposed to satisfy the communication requirements of not only safety but also non-safety services. We then consider and study in detail several typical scenarios for autonomous driving. In order to tackle the potential challenges raised by the autonomous driving vehicles in HetVNETs, new techniques from transmission to networking are proposed as potential solutions.

Dynamic Performance Analysis of Uplink Transmission in Cluster-Based Heterogeneous Vehicular Networks

As an emerging technology, vehicular networks have evolved into an indispensable part of intelligent transport systems (ITS). Thus, this paper focuses on the performance analysis of the cluster-based heterogeneous vehicular networks (C-HetVNETs) with dynamic data arrival rate and different vehicle densities. Different from the previous studies, which mainly focus on network capacity in just one wireless-technology-supported vehicular network, such as dedicated short-range communication (DSRC) or Third-Generation Partnership Project (3GPP) long-term evolution (LTE), we focus on the different performance metrics of uplink transmission in C-HetVNET. First, we develop a framework of C-HetVNET by employing the cluster mechanism. Then, the performance analysis models of intracluster and intercluster communications are designed based on a Markov queuing model. Due to the explosion of state space, model decomposition and iteration techniques are proposed to handle this problem. Based on the developed analytical model, the performance metrics of different scheduling schemes, in terms of throughput, delay, dropping probability, and queue length, are studied and compared. The performances of C-HetVNETs under different vehicle densities and data arrival rates are obtained via analysis and simulations, which give a useful guideline for network configuration of C-HetVNETs. The proposed analytical model can be also used for heterogeneous or two-tier network analysis and validation of network simulators under various traffic conditions. In addition, we investigate the performances of LTE networks used for vehicular communications for the purpose of performance comparison.

An Adaptive Live Streaming Mechanism for Heterogeneous Vehicular Networks

With the popularity of vehicular networks, how to maintain high quality of the seamless live streaming service is a great challenge. In this work, an adaptive seamless live streaming dissemination system for heterogeneous vehicular networks to tackle this challenging issue is presented. First, differential service is presented in this work to ensure that paid users can satisfy the live steaming service. Based on users’ service-level agreement, an adaptive bandwidth allocation policy is proposed in this work to attain seamless handoff. In addition, because vehicles enter into the areas of hotspots, we also present a mechanism not only to prevent the insufficient bandwidth in advance, but also to make sure the paid users have higher priority than free users to obtain the seamless streaming service. When an unavoidable congestion occurs, we compress the streaming videos with a Region of Interest approach based on the content and characters of the video in order to maintain the service quality of paid users and reduce the required bandwidth for the streaming services. A series of simulation results show that our mechanism achieves better performance in terms of bandwidth utilization, packet loss ratio, and blocking probability. The capability of self-adaption in volatile real-time vehicular environment assists in the effectiveness and practicability of our proposed approach.

Optimizing Unsatisfactory Handover Trigger in Heterogeneous Vehicular Networks

In heterogeneous vehicular networks, the communications among moving vehicles (MV) and between vehicles and the roadside infrastructures have posed a challenge for providing continuous mobility services. FMIPv6 looking toward the support of a timely and precise link layer (L2) trigger provides a fundamental mobility management approach. The time stamp of L2 trigger hence is crucial for guaranteeing the handover performance but is difficult to be obtained in the practical application scenarios. The unsatisfactory handover trigger includes the late L2 trigger and the premature L2 trigger. The former would cause a missed detection deteriorating the perceived quality of service, and the latter would cause a false alarm with serious performance loss and resources waste. To address this issue, we propose a solution to optimize the unsatisfactory handover trigger (O-UHT), including promptly determining the unsatisfactory handover trigger and elaborately developing the specific measures to reduce the performance loss caused by the above two cases. The simulations conducted on NS-2 platform have verified the efficiency.

A Fast Safety Message Transmission Mechanism for Heterogeneous Vehicular Networks

A Fast Safety Message Transmission Mechanism for Heterogeneous Vehicular Networks