• 정보처리학회논문지C
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• 제15C권1호
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• pp.9-18
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• 2008

센서 노드의 프로그램 변경을 통한 센서 네트워크 공격을 방지하는 것은 중요한 센서 네트워크 관련 보안요소들 중 하나이다. 이를 해결하기 위해 각 센서 노드 내에서 실행 중인 코드가 변경되지 않았음을 검증하는 소프트웨어 기반 검증(attestation) 기술이 사용되고 있다. 그러나 현재 제안되고 있는 소프트웨어 기반 검증 기법은 신뢰할 수 있는 검증자가 존재하지 않는 센서 네트워크 환경에 대한 고려가 부족할 뿐만 아니라, 망의 변화가 없는 정적인 환경에 중점을 두어 설계되었기 때문에 센서 네트워크 환경에 적합하지 않다. 본 논문에서는 SWATT(Software-based ATTestation) 기법을 이용하여 센서 네트워크 환경에 적합한 상호 검증 프로토콜을 제안한다. 제안 기법은 신뢰 노드가 존재하지 않는 센서 네트워크 환경에서 이웃한 센서 노드에게 자신의 존재를 주기적으로 알리되, SWATT 기법을 이용하여 이를 인지한 이웃 센서 노드와 상호 검증을 수행하도록 한다. 이를 통해 신뢰할 수 있는 검증자가 없는 센서 네트워크 환경에서 악의적인 공격으로 인해 변경된 프로그램을 실행하는 센서 노드를 식별할 수 있으며, 결과적으로 검증된 센서 노드들만으로 이루어지는 네트워크 구성이 가능하도록 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.901-920
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• 2015

Wireless Sensor Networks (WSNs) are widely used in geographically isolated applications like military border area monitoring, battle field surveillance, forest fire detection systems, etc. Uninterrupted power supply is not possible in isolated locations and hence sensor nodes live on their own battery power. Localization of sensor nodes in isolated locations is important to identify the location of event for further actions. Existing localization algorithms consume more energy at sensor nodes for computation and communication thereby reduce the lifetime of entire WSNs. Existing approaches also suffer with less localization coverage and localization accuracy. The objective of the proposed work is to increase the lifetime of WSNs while increasing the localization coverage and localization accuracy. A novel intelligent unmanned aerial vehicle anchor node (IUAN) is proposed to reduce the communication cost at sensor nodes during localization. Further, the localization computation cost is reduced at each sensor node by the proposed intelligent arc selection (IAS) algorithm. IUANs construct the location-distance messages (LDMs) for sensor nodes deployed in isolated locations and reach the Control Station (CS). Further, the CS aggregates the LDMs from different IUANs and computes the position of sensor nodes using IAS algorithm. The life time of WSN is analyzed in this paper to prove the efficiency of the proposed localization approach. The proposed localization approach considerably extends the lifetime of WSNs, localization coverage and localization accuracy in isolated environments.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.357-360
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• 2007

An asset tracking using wireless sensor network is concerned with geographical locations of sensor nodes. The limited size of sensor nodes makes them attractable for tracking service, at the same time their size causes power restrictions, limited computation power, and storage restrictions. Due to such constrained capabilities, the wireless sensor network basically assumes the failure of sensor nodes. This causes a set of concerns in designing asset tracking system on wireless sensor network and one of the most critical factors is location uncertainty of sensor nodes. In this paper, we classify the location uncertainty problem in asset tracking system into following cases. First, sensor node isn't read at all because of sensor node failure, leading to misunderstanding that asset is not present. Second, incorrect location is read due to interference of RSSI, providing unreliable location of asset. We implemented and installed our asset tracking system in a real environment and continuously monitored the status of asset and measured error rate of location of sensor nodes. We present experimental results that demonstrate the location uncertainty problem in asset tracking system using wireless sensor network.

• Journal of Information Processing Systems
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• 제1권1호
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• pp.49-54
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• 2005

With the recent advances in Micro Electro Mechanical System (MEMS) technology, low cost and low power consumption wireless micro sensor nodes have become available. However, energy-efficient routing is one of the most important key technologies in wireless sensor networks as sensor nodes are highly energy-constrained. Therefore, many researchers have proposed routing protocols for sensor networks, especially cluster-based routing protocols, which have many advantages such as reduced control messages, bandwidth re-usability, and improved power control. Some protocols use information on the locations of sensor nodes to construct clusters efficiently. However, it is rare that all sensor nodes know their positions. In this article, we propose another cluster-based routing protocol for sensor networks. This protocol does not use information concerning the locations of sensor nodes, but uses the remaining energy of sensor networks and the desirable number of cluster heads according to the circumstances of the sensor networks. From performance simulation, we found that the proposed protocol shows better performance than the low-energy adaptive clustering hierarchy (LEACH).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권7호
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• pp.3480-3500
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• 2017

Accurate locating for the mobile target remains a challenge in various applications of wireless sensor networks (WSNs). Unfortunately, most of the typical localization algorithms perform well only in the WSN with densely distributed sensor nodes. The non-localizable problem is prone to happening when a target moves into the WSN with sparsely distributed sensor nodes. To solve this problem, we propose a collaborative and predictive localization algorithm (CPLA). The Gaussian mixture model (GMM) is introduced to predict the posterior trajectory for a mobile target by training its prior trajectory. In addition, the collaborative and predictive schemes are designed to solve the non-localizable problems in the two-anchor nodes locating, one-anchor node locating and non-anchor node locating situations. Simulation results prove that the CPLA exhibits higher localization accuracy than other tested predictive localization algorithms either in the WSN with sparsely distributed sensor nodes or in the WSN with densely distributed sensor nodes.

• Journal of Communications and Networks
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• 제11권4호
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• Smart Structures and Systems
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• 제7권5호
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• pp.393-416
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• 2011

Hybrid acceleration-impedance sensor nodes on Imote2-platform are designed for damage monitoring in steel girder connections. Thus, the feasibility of the sensor nodes is examined about its performance for vibration-based global monitoring and impedance-based local monitoring in the structural systems. To achieve the objective, the following approaches are implemented. First, a damage monitoring scheme is described in parallel with global vibration-based methods and local impedance-based methods. Second, multi-scale sensor nodes that enable combined acceleration-impedance monitoring are described on the design of hardware components and embedded software to operate. Third, the performances of the multi-scale sensor nodes are experimentally evaluated from damage monitoring in a lab-scaled steel girder with bolted connection joints.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제4권7호
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• pp.235-238
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• 2015

IEEE 802.15.4는 무선 센서노드들 사이의 연결을 가능하게 하는 대표적인 표준이다. 그러나 이 IEEE 802.15.4를 기반으로 하는 무선 센서네트워크는 기본적으로 숨은노드 충돌에 매우 취약하다는 약점을 갖고 있는데 이는 무선 센서네트워크 자체가 제한된 통신 반경과 짧은 배터리 수명을 갖고 있기 때문이다. 본 논문에서는 IEEE 802.15.4 기반의 무선 센서네트워크에서 노드들의 클러스터링을 통한 숨은노드 충돌 회피 및 성능향상 기법을 제안하다. 이 방법에서 사용되는 클러스트링은 각각의 무선 센서노드들이 갖고 있는 채널 품질 정보를 바탕으로 수행된다. 그리고 클러스터에 어느 정도의 무선자원을 할당해야 하는 문제도 다룬다.

• 대한전자공학회논문지TC
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• 제45권9호
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• pp.13-19
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• 2008

Sensor network에서의 망동기화는 센서 노드들을 하나의 시각에 동기화시킴으로써, 센서 노들들이 수집해서 보내는 센서 정보들이 의미있는 정보들이 되도록 돕는 망의 기본적인 요소이다. 센서 노드들이 망동기화 되어 있지 않으면, 센서 노드돌이 보내오는 시각정보와 재난 감지 이벤트를 잘못 해석하여, 방향을 오판할 수 있고, 이를 통한 대응은 큰 재난으로 나타날 수도 있다. 배터리의 제약과 컴퓨팅 파워의 제약 등으로 인해 센서 노드에 들어가는 시각동기화 알고리즘은 복잡한 계산을 요구하지 않고, 많은 메시지를 발생시키지 않으면서 정확하게 동기화할 수 있어야 한다. 동기화의 오차를 줄이기 위해서는 동기화 할 센서노드와 동기화 정보를 제공하는 참조노드(reference node)와의 홉 수가 적어야 한다. 이를 위해 망 내에 하나의 참조노드만 사용하는 것이 아니라, 여러 개의 참조노드를 사용하게 되는데, 이는 참조노드들 사이의 동기화를 맞추어야 하는 문제를 낳는다. 지금까지 망동기화를 위한 여러 알고리즘들이 제안되어 왔지만, 참조노드들끼리의 동기화 문제가 잘 고려되지 못하였다. 본 논문에서는 다수의 참조노드를 갖는 Sensor network에서 센서 노드 자체의 동기 뿐 아니라, 참조노드들의 동기를 향상시켜 전체적인 망동기화를 개선시킬 수 있는 방안을 제시하였고, 이를 시뮬레이션을 통해 확인하였다.

• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.459-465
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• 2008

Locations of nodes as well as gathered data from nodes are very important because generally multiple nodes are deployed randomly and data are gathered in wireless sensor network. Since the nodes composing wireless sensor network are low cost and low performance devices, it is very difficult to add specially designed devices for positioning into the nodes. Therefore in wireless sensor network, technology positioning nodes precisely using low cost is very important and valuable. This research proposes Cooperative Positioning System, which raises accuracy of location positioning and also can find positions on multiple sensors within limited times.