• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.5A
• /
• pp.459-468
• /
• 2006

Current routing in sensor networks focuses on finding methods for energy-efficient route setup and reliable relaying of data from the sensors to the sink so that the lifetime of the network is maximized. The existing routing protocols do not have routing tables to determine a path when packets are transferred. A sensor network by a routing table increases a cost of maintaining and updating a path, because sensor nodes have characteristics to be mobile and constrained capacity and resources. This paper proposes a new routing algorithm by broadcasting a bitmap in order to reduce the number of messages transferred when routing paths are established. Each node has a routing table with a bitmap, which contains link information. A bitmap is formed two-dimensional array, which consists of each row and column represented with a bit. The node only updates its own bitmap if it receives a bitmap from another adjacent nodes after the broadcasting. There by, each node has a bitmap with partial links information not total links information on the network. The proposed routing algorithm reduces the number of messages for routing establishment at least 10% compared with the previous algorithms.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.2 no.2 s.3
• /
• pp.43-54
• /
• 2003

As the demand for ubiquitous mobile wireless Internet grows, vehicles are receiving a lot of attention as new networking platforms. The demand for 4G all-IP networks encourages vehicle networks to be connected using IPv6. By means of network mobility (NEMO) support, we can connect sensors, controllers, local ,servers as well as passengers' devices of a vehicle to the Internet through a mobile router. The mobile router provides the connectivity to the Internet and mobility transparency for the rest of the mobile nodes of an in-vehicle nv6 network. So, it is .important for the mobile router to assure reliable connection and a sufficient data rate for the group of nodes behind it. To provide reliability, this paper proposes an adaptive multihoming architecture of multiple mobile routers. Proposed architecture makes use of different mobility characteristics of different vehicles. Simulation results with different configurations show that the proposed architecture increases session preservation thus increases reliability and reduces packet loss. We also show that the proposed architecture is adaptive to heterogeneous access environment which provide different access coverage areas and data rates. The result shows that our architecture achieves sufficient data rates as well as session preservation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.49 no.1
• /
• pp.1-10
• /
• 2012

Mobility and quality of service (QoS) are becoming the more important issues in wireless communications. The traditional Internet service is expanding into new access media and applications. Since wireless communication services are accompanied by frequent handovers at remote sites, scalable and fast handover has become a prerequisite for ubiquitous communication. In this paper, the differentiated service (Diffserv) model is deployed in heterogeneous proxy mobile IPv6 (PMIPv6) networks to satisfy the QoS guaranteed service and fast handover requirements. The operational procedures for QoS guaranteed global roaming are presented. In addition, QoS management and handover cost evaluation schemes based on a mobile host's movement scope are proposed. This paper analyzes the reduction in handover delay in a network-based localized mobility management framework. We propose and analyze a PMIPv6 optimized with a global mobile access gateway (G-MAG), which is a network-based entity, to further improve the handover performance in terms of handover delay while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. The handover signaling procedures with host-based MIPv6 are compared with network-based proxy MIPv6 (PMIPv6) and fast PMIPv6 assisted by G-MAG to show how much handover delay reduction can be achieved. Analytical results show that the handover delay is significantly reduced.

• Journal of KIISE:Computing Practices and Letters
• /
• v.13 no.7
• /
• pp.442-453
• /
• 2007

A model-based integrated development tool for the development of USN application programs is proposed in this paper. The proposed tool has been implemented as a plug-in for Eclipse platform. The tool consists of Graphical User Interface, Modeler, Configuration Information Generator, Validity Checker, Source Code Generator and Templates Storage. Developers can implement USN applications from models of sensor networks using the tool. The developer can implement USN applications by automatic generation of execution code of each node in the sensor network after he/she designs a model of the sensor network. The configuration information of each node is automatically generated from the validated USN model. Then, the execution code is automatically generated using the configuration information and the predefined templates. Through the tool of this paper, developers can easily implement valid USN applications even if they do not know the details of low-level information. Also, a large number of application programs can be generated at once because application programs are generated from sensor network model instead of models of applications. Accordingly, the development effort of USN applications will be decreased and developers can consistently construct USN applications from USN models using the proposed tool.

• Journal of Korea Spatial Information System Society
• /
• v.11 no.1
• /
• pp.145-156
• /
• 2009

Ubiquitous City(U-City) in Korea is not a fantastic wonderland but an on-going real phenomenon. Many researchers so far have mainly dealt with a rosy future where U-City would potentially promise the high Quality of Life and positive economic effects. However, a suspicion of unexpected disadvantages can be able to take place in the bright future of U-City : the running cost of U-City. Without full consideration of it, descendants living in the U-City in near future will suffer from the heavy burden in operating the U-City. Given this circumstantial background, the aim of this study is to indicate potential solutions to address a sustainable U-City controlled by the virtuous cycled mechanism toward a self-sufficient city, which will illuminate a new paradigm of the city history. Solutions were sought from the several viewpoints, which were behavioral and institutional aspects, developing profitable business models and core technologies applicable to U-City, and building self-owned networks. Based on this preliminary study, further efforts and devotion to seeking virtuous-cycled U-City model will contribute to bringing a prominent future of U-City whose belongings will be able to manage to enjoy better quality of life.

• Journal of KIISE:Information Networking
• /
• v.34 no.3
• /
• pp.218-225
• /
• 2007

As the research on home network technologies, sensor network technologies, and ubiquitous network technologies makes rapid progresses, wireless ad-hoc network have attracted a lot of attention. A wireless mobile ad-hoc network is a temporary network formed by a collection of wireless mobile nodes without the aid of any existing network infrastructure or centralized administration, and it is suitable for ubiquitous computing environments. In this paper, we suggest an extension scheme of a wireless mobile ad-hoc network based on limited multiple paths source routing protocol. This scheme reduces the overhead of route re-establishment and re-registration by maintaining link/node non-disjoint multiple paths between mobile hosts in a wireless mobile ad-hoc network or a mobile host in a wireless mobile ad-hoc network and a base station supporting fixed network services. By maintaining multiple paths, our scheme provides short end-to-end delay and is reliable extension scheme of a wireless mobile ad-hoc network to a fixed network. In this paper, our simulations show that our scheme outperforms existing schemes with regards to throughput and end-to-end delay. Also we show that our scheme outperforms multi-paths approach using disjoint routes with regards to routing overhead.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.45 no.4
• /
• pp.64-72
• /
• 2008

Researchers nowadays are trying to implement u-Healthcare (ubiquitous Healthcare) systems for real-time monitoring and analysis of patients' status through a low-cost and low-power wireless sensor network. u-Healthcare system has an aim to provide reliable and fast medical services for patients regardless of time and space by transmitting to doctors a large quantity of vital signs collected from sensor networks. Existing u-Healthcare systems can merely monitor patients' health status. However, it is not easy to derive physiologically meaningful results by analyzing rapidly vital signs through the existing u-Healthcare systems. We introduce a Grid computing technology for deriving the results by analyzing rapidly the vital signs collected from the sensor network. Since both sensor network and Grid computing use different protocols, a gateway is needed. In addition, we also need to construct a gateway which includes the functions such as an efficient management and control of the sensor network, real-time monitoring of the vital signs and communication services related to the Grid network for providing u-Healthcare services effectively. In this paper, to build an advanced u-Healthcare system by using these two technologies most efficiently, we design and present the results to implement a SensorGrid gateway which connects transparently the sensor network and the grid network.

• Journal of Korea Spatial Information System Society
• /
• v.9 no.1
• /
• pp.45-57
• /
• 2007

Recently, the development of sensor devices has accelerated researches on advanced technologies like Wireless Sensor Networks. Moreover, spatial sensors using GPS lead to the era of the Ubiquitous Computing Environment which generally uses spatial information and non-spatial information together. In this new era, a real-time processing system for spatial sensor data is essential. In this reason, new data processing systems called DSMS(Data Stream Management System) are being developed by many researchers. However, since most of them do not support geometry types and spatial functions to process spatial sensor data, they are not suitable for the Ubiquitous Computing Environment. For these reasons, in this paper, we designed and implemented a spatial DSMS by extending STREAM which stands for STanford stREam datA Manager, to solve these problems. We added geometry types and spatial functions to STREAM in order to process spatial sensor data efficiently. In addition, we implemented a Spatial Object Manager to manage shared spatial objects within the system. Especially, we implemented the Simple Features Specification for SQL of OGC for interoperability and applied algorithms in GEOS to our system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.27 no.5
• /
• pp.517-528
• /
• 2009

Korean Land Spatialization Program (KLSP) is a R&D program of the National GIS Project for developing ubiquitous GIS technologies under control of Ministry of Land, Transport and Maritime Affairs. The first program from 2006 to 2012, initiated with $132 million of national fund and $42 million of private matching fund. Aiming 'Innovation of the GIS technology for the ubiquitous Korean land', KLSP consists of five core research projects and one research coordination project. The coordination project's purpose is to practically utilize and commercialize the results of core research projects. Korean Land Spatialization Group (KLSG) is planning a test-bed for testing, integrating, and exhibit- ing the KLSP's outcomes. Integrations of the outcomes are mandatory for the successful KLSG Test-Bed. The main objective of this paper is to introduce KLSP test-bed and three methodologies for integration of the outcomes in KLSP. As a plan of integrations, especially, this paper proposes SWE SOS (Sensor Observation Service) prototype to achieve interoperability of the geo-sensor networks.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.6
• /
• pp.143-153
• /
• 2011

The goal of Ubiquitous Sensor Network(USN) environments is to provide users high quality services based on a variety of sensors. In this environment, sensor devices, sensor nodes and sensor networks are heterogeneous and have various characteristics. Therefore it is important for interoperability to define a metadata for describing USN resources. The OGC(Open Geospatial Consortium) proposes SensorML(Sensor Model Language) as a standard language for modeling sensors. However, SensorML provides a framework for describing a processing model among sensors rather than describing information of sensors. Therefore, to describe a USN metadata is not main purposes of SensorML. This paper defines a USN metadata which describes information about sensor device, sensor node, and sensor network. Also the paper proposes a method for efficiently storing and searching the USN metadata and implements a USN metadata management system based on our method. We show that our metadata management system is reasonable for managing the USN metadata through performance evaluation. Our USN metadata keeps the interoperability in USN environments because the metadata is designed on SensorML. The USN metadata management system can be used directly for a USN middleware or USN application.