Kuk-Hyun Cho

Survey of MAC Protocols for Vehicular Ad Hoc Networks

A vehicular ad hoc network is a special kind of mobile ad hoc network, and can be divided into two further types of networks, a vehicle-to-vehicle network or a vehicle-to-infrastructure network. However, unlike existing mobile ad hoc networks, vehicular ad hoc networks have unique characteristics, including high node mobility and a rapidly-changing topology. Vehicular ad hoc networks should be designed to accommodate these characteristics when we design them. To do this, many researchers have proposed Media Access Control protocols to improve the performance. Most of these studies deal with quick message transmission to support the high mobility of nodes, multiple channels for multiple connections in high-density urban node areas, and channel coordination. In this paper, we provide a survey of Media Access Control protocols for vehicular ad hoc networks and classify the existing Media Access Control protocols into the three major categories of time-based, dedicated short-range communication-based, and directional antenna-based. Moreover, we discuss the characteristics of these Media Access Control protocols and show their advantages and disadvantages. In addition we define some open issues and future work related to Media Access Control protocols for vehicular ad hoc networks.

Policy-Based Management for Self-Managing Wireless Sensor Networks

SUMMARY In a wireless sensor network (WSN), a large number ofsensor nodes are deployed over a wide area and multi-hop communica-tions are required between the nodes. Managing numerous sensor nodesis a very complicated task, especially when the energy issue is involved.Even though a number of ad-hoc management and network structuring ap-proaches for WSNs have been proposed, a management framework cov-ering the entire network management infrastructure from the messagingprotocol to the network structuring algorithm has not yet been proposed. Inthis paper we introduce a management framework for WSNs called SNOW-MAN (SeNsOr netWork MANagement) framework. It employs the policy-based management approach for letting the sensor nodes autonomously or-ganize and manage themselves. Moreover, a new light-weight policy dis-tribution protocol called TinyCOPS-PR and policy information base (PIB)are also developed. To facilitate scalable and localized management ofsensor networks, the proposed SNOWMAN constructs a 3-tier hierarchyof regions, clusters, and sensor nodes. The effectiveness of the proposedframework is validated through actual implementation and simulation us-ing ns-2. The simulation results reveal that the proposed framework allowssmaller energy consumption for network management and longer networklifetime than the existing schemes such as LEACH and LEACH-C for prac-tical size networks.

A Vehicle Communication Routing Algorithm Considering Road Characteristics and 2-Hop Neighbors in Urban Areas

V2V (Vehicle-to-Vehicle) is a special kind of VANET (Vehicular Ad-hoc Network), which has high mobility and frequent topology changes and causes the link breakage problem. To resolve this problem, geographic routing protocols such as greedy forwarding are proposed. However, the greedy forwarding approach selects the node closest to the destination node as the transfer node within the transmission range so that it may cause many problems owing to many intersections and many changes in vehicular traffic in urban areas. The paper proposes a greedy perimeter urban routing (GPUR) algorithm considering the presence of 2-hop neighbor nodes and the road characteristics. Simulation results using ns-2 reveal that the proposed GPUR algorithm significantly reduces the routing error problem and the probability of local maximum than the existing routing protocols.

Hierarchical Node Clustering Approach for Energy Savings in WSNs

This paper proposes an energy efficient clustering algorithm for self-organizing and self-managing WSNs, called SNOW cluster. It introduces region node selection as well as cluster head election based on the residual battery capacity of nodes to reduce the costs of managing sensor nodes and of the communication among them. SNOW cluster clusters periodically to select cluster heads that are richer in residual energy level, compared to the other nodes to achieve load balancing and extend the lifetime of every individual sensor nodes. After the cluster heads are selected, SNOW cluster selects the region nodes in the cluster heads based on the energy level of them and chooses gateway nodes between clusters based on their location information. The effectiveness of the proposed SNOW cluster algorithm is validated through actual implementation and simulation using ns-2. The simulation results reveal that the proposed framework allows smaller energy consumption for network management and longer network lifetime than the existing schemes such as LEACH and LEACH-C for practical size networks.

A Cluster Based Multi-Path Routing Protocol for Support Load-Balancing in Content-Centric Network

Content-Centric Network (CCN) is communication method based on contents to use voluminous information in internet and it is next generation internet technology to provide new paradigm. CCN is communicated by both interest packet and data packet. Interest packet is required content by user and data packet is responded data to contents. CCN use interest packet driven communication re-tracing routing path of interest packet. In CCN, unidirectional routing has low load-balancing only if data traffic is increasing. Therefore, turnaround time, which is time of transmission content to user, was increased by this problem. To resolve this problem, in this paper we proposed cluster based multi-path routing protocol for support load-balancing.

Ontology-Based Methodology for Managing Heterogeneous Wireless Sensor Networks:

With the growing interest in ubiquitous technologies recently, many studies have been conducted in order to manage wireless sensor network, which is the central component in ubiquitous environment. To manage a certain wireless sensor network, a variety of techniques can be applied and thereby the network can be managed. However, it is very complicated and time-consuming to incorporate and manage more than a heterogeneous wireless sensor network since each network has different data, meanings, and terms. Instead of conducting verification through examining the detailed technology or simulation in order to manage a variety of wireless sensor networks, we suggest a methodology which manages data coming from the various sensors mentioned above, a technique by which those data from various sensor networks are managed in each different network, and a methodology which manages sensor networks where management languages exist. This paper defined the network-related terminology using Protégé for the tools and definitions necessary for ontology-based methodology, thereby defined OWL and the related rules, and suggested a methodology for incorporated management. In addition, this study showed that the methodology presented in this study has expandability and it can incorporate and manage a variety of wireless sensor networks.

Measuring the Performance of Packet Size and Data Rate for Vehicular Ad Hoc Networks

Since 2004, Vehicular Ad-hoc Networks (VANETs) is core technology of Intelligent Transportation System (ITS), in which standardize the Wireless Access in Vehicle Environments (WAVE) based on IEEE 1609 and IEEE 802.11p. WAVE is a field of study to provide safety service and information to person such as driver and passenger. Recently, many researchers have been proposed resolution for high velocity and rapid topology change. However, it assume equal to packet size. Therefore, this assumption could not provide various services for VANETs due to limited data packet size. To do resolve this problem, in this paper, we analyzed transmission rate of differences data packet in VANETs environment and proposed future research about improving transmission method according to difference packet size.

An EJB-based platform for policy-based qos management of diffserv enabled next generation networks

Unlike IntServ where resource reservation and admission control is per-flow based using RSVP, DiffServ supports aggregated traffic classes to provide various QoS to different classes of traffics. However, it is possible to lead to serious QoS violations without a QoS management support. Therefore, a QoS management system that can manage differentiated QoS provisioning is required. This paper proposes and implements a policy-based QoS management platform for differentiated services networks, which specifies QoS policies to guarantee dynamic QoS requirements. High-level QoS policies are represented as valid XML documents and are mapped into EJB beans of the EJB-based policy server of the platform. The policy distribution and the QoS monitoring are processed using SNMP.

Clustering based Routing Algorithm for Efficient Emergency Messages Transmission in VANET

Abstract Vehicle Ad hoc Network (VANET) is next-generation network technology to provide various services using V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure). In VANET, many researchers proposed various studies for the safety of drivers. In particular, using the emergency message to increase the efficiency of traffic safety have been actively studied. In order to efficiently transmit to moving vehicle, to send a quick message to as many nodes is very important via broadcasting belong to communication range of vehicle nodes. However, existing studies have suggested a message for transmission to the communication node through indiscriminate broadcasting and broadcast storm problems, thereby decreasing the overall performance has caused the problem. In addition, theses problems has decreasing performance of overall network in various form of road and high density of vehicle node as urban area. Therefore, this paper proposed Clustering based Routing Algorithm (CBRA) to efficiently transmit emergency message in high density of vehicle as urban area. The CBRA managed moving vehicle via clustering when vehicle transmit emergency messages. In addition, we resolve linkage problem between vehicles according to various form of road. The CBRA resolve link brokage problem according to various form of road as urban using clustering. In addition, we resolve broadcasting storm problem and improving efficacy using selection flooding method. simulation results using ns-2 revealed that the proposed CBRA performs much better than the existing routing protocols.

Policy-based differentiated QoS provisioning for DiffServ enabled IP networks

This paper proposes and implements a policy-based QoS management platform for DiffServ enabled IP networks, which specifies QoS policies to guarantee QoS requirements. The proposed platform integrates the function of policy-based management and QoS monitoring by extending the original IETF policy-based management architecture. High-level QoS policies are represented as valid XML documents and are translated to EJB beans in the EJB-based policy server of the platform. The policy distribution and the QoS monitoring are processed using SNMP. This paper also describes the implementation of Linux-based DiffServ routers with DiffServ MIB and analyzes the experimental results using a video streaming system.