• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.473-493
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• 2019

5G vehicular communication is one of key enablers in next generation intelligent transportation system (ITS), that require ultra-reliable and low latency communication (URLLC). To meet this requirement, a new hybrid vehicular network structure which supports both centralized network structure and distributed structure is proposed in this paper. Based on the proposed network structure, a new vehicular network utility model considering the latency and reliability in vehicular networks is developed based on Euclidean norm theory. Building on the Pareto improvement theory in economics, a vehicular network uplink optimization algorithm is proposed to optimize the uplink utility of vehicles on the roads. Simulation results show that the proposed scheme can significantly improve the uplink vehicular network utility in vehicular networks to meet the URLLC requirements.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1229-1234
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• 2012

Vehicular communications have been receiving much attention in intelligent transport systems (ITS) by combining communication technology with automobile industries. In general, vehicular communications can be used for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication by adopting IEEE802.11p/1609 standard which is commonly known as wireless access in vehicular environments (WAVE). WAVE system transmits signal in 5.9GHz frequency band with orthogonal frequency division multiplexing (OFDM) signaling. In this paper, we consider physical layer issues in vehicular communications. We first overview the physical (PHY) layer of WAVE standard and properties of 5.9GHz signals, and then physical layer issues to provide reliable communication link are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.529-546
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• 2012

To address the need for autonomous control of remote and distributed mobile systems, Machine-to-Machine (M2M) communications are rapidly gaining attention from both academia and industry. M2M communications have recently been deployed in smart grid, home networking, health care, and vehicular networking environments. This paper focuses on M2M communications in the vehicular networking context and investigates areas where M2M principles can improve vehicular networking. Since connected vehicles are essentially a network of machines that are communicating, preferably autonomously, vehicular networks can benefit a lot from M2M communications support. The M2M paradigm enhances vehicular networking by supporting large-scale deployment of devices, cross-platform networking, autonomous monitoring and control, visualization of the system and measurements, and security. We also present some of the challenges that still need to be addressed to fully enable M2M support in the vehicular networking environment. Of these, component standardization and data security management are considered to be the most significant challenges.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.122-131
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• 2013

We address the problem of effective vehicular routing in hostile scenarios where malicious nodes intend to jeopardize the delivery of messages. Compromised vehicles can severely affect the performance of the network by a number of attacks, such as selectively dropping messages, manipulating them on the fly, and the likes. One of the best performing solutions that has been used in static wireless sensor networks to deal with these attacks is based on the concept of watchdog nodes (also known as guard nodes) that collaborate to continue the forwarding of data packets in case a malicious behavior in a neighbor node is detected. In this work, we consider the beacon-less routing algorithm for vehicular environments routing protocol, which has been previously shown to perform very well in vehicular networks, and analyze whether a similar solution would be feasible for vehicular environments. Our simulation results in an urban scenario show that watchdog nodes are able to avoid up to a 50% of packet drops across different network densities and for different number of attackers, without introducing a significant increase in terms of control overhead. However, the overall performance of the routing protocol is still far from optimal. Thus, in the case of vehicular networks, watchdog nodes alone are not able to completely alleviate these security threats.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.1057-1062
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• 2014

Vehicular communications can be applied for transmission of various safety messages or Intelligent Transportation Systems(ITS) applications by combining vehicle/road technology with Information and Communication Technology(ICT). In this paper, we represent measurement results of radio characteristics of vehicular communications using IEEE 802.11p based system in urban environments. Radio characteristics are based on the packet error rate (PER) and received spectrum mask. Using measurement results, we discuss implementation issues of vehicular communication systems for supporting reliable services.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.10
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• pp.1589-1594
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• 2013

Vehicular communication is one of representative convergence technology which combines information technology and vehicle industry. Wireless Access in Vehicular Environments (WAVE) technology is vehicular communication standard which is widely used in the world. In this paper, we introduce service realization of WAVE based vehicular communication systems in the practical testbed. We review the overall WAVE based systems in brief and introduce the testbed. Then, we investigate various applications using vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. Based on realization of systems, we discuss practical implementation issues and the convergence area of WAVE systems.

• Information and Communications Magazine
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• v.31 no.3
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• pp.103-116
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• 2014

This paper proposes the design of Vehicular Cyber-Physical Systems (called VCPS) based on vehicular cloud for smart road networks. Our VCPS realizes mobile cloud computing services where vehicles themselves or mobile devices (e.g., smartphones and tablets of drivers or passengers in vehicles) play a role of both cloud server and cloud client in the vehicular cloud. First, this paper describes the architecture of vehicular networks for VCPS and the delay modeling for the event prediction and data delivery, such as a mobile node's travel delay along its navigation path and the packet delivery delay in vehicular networks. Second, the paper explains two VCPS applications as smart road services for the driving efficiency and safety through the vehicular cloud, such as interactive navigation and pedestrian protection. Last, the paper discusses further research issues for VCPS for smart road networks.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.207-216
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• 2013

Vehicular ad-hoc networks (VANETs) are self-organizing, self-healing networks which provide wireless communication among vehicular and roadside devices. Applications in such networks can take advantage of the use of simultaneous connections, thereby maximizing the throughput and lowering latency. In order to take advantage of all radio interfaces of the vehicle and to provide good quality of service for vehicular applications, we developed a seamless flow mobility management architecture based on vehicular network application classes with network-based mobility management. Our goal is to minimize the time of flow connection exchange in order to comply with the minimum requirements of vehicular application classes, as well as to maximize their throughput. Network simulator (NS-3) simulations were performed to analyse the behaviour of our architecture by comparing it with other three scenarios. As a result of this work, we observed that the proposed architecture presented a low handover time, with lower packet loss and lower delay.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.237-244
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• 2011

Vehicular communications extend their application areas by combining communication technologies with roads/vehicles, and one of major applications is Smart Highway project. Smart Highway is a new advanced highway system which enhances the current highway system in Korea by improving reliability, safety and convenience. In this paper, we introduce wireless access technologies for vehicular communications especially focusing on Smart Highway. We first introduce the overall communication system architecture and the basic service and communication requirements for Smart Highway. Then, we discuss wireless access technologies including L2-level hand-over scheme. In addition, the results of experimental measurements of Wireless Access in Vehicular Environments (WAVE) system are introduced.

• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.26-32
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• 2014

Vehicular-to-anything (V2X) technology is attractive for wireless vehicular ad-hoc networks (VANETs) because it allows for opportunistic choice of a vehicular protocol between vehicular-to-vehicular (V2V) and vehicular-to-infrastructure (V2I) communications. In particular, achieving seamless connectivity in a VANET with nearby network infrastructure is challenging. In this paper, we propose a density-based opportunistic broadcasting (DOB) protocol, in which opportunistic connectivity is carried out by using the nearby infrastructure and opposite vehicles for solving the problems of disconnection and long end-to-end delay times. The performance evaluation results indicate that the proposed DOB protocol outperforms the considered comparative conventional schemes, i.e., the shortest path protocol and standard mobile WiMAX, in terms of the average end-to-end delay, packet delivery ratio, handover latency, and number of lost packets.