• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.116-121
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• 2017

In wireless sensor networks, the multipath prefers energy efficient routing method due to the characteristic of low-power sensor which uses geographic method to transmit data packet through information of the neighbor nodes. However, when multipath meets the routing fail area called hole area, path overlap problem can occur, resulting in failed maintenance of disjoint multipath. To solve this problem, multipath research studies have been performed to exploit the modeling and detouring method in routing fail area by keeping the disjoint multipath. However, in an energy point of view, additional method like modeling can lead to a lot of energy consumption of sensor node. Moreover, lots of energy consumption of sensor node can shorten the life span of sensor network. In this study, we proposed an energy efficient geographic routing by keeping the disjoint multipath in routing fail area. The proposed scheme exploited the face routing using the geographic recovery method without additional method like modeling.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.316-320
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• 2008

Data dissemination schemes for wireless sensor networks, where sinks and event targets might be mobile, has been one of the active research fields. For doing that, stationary nodes gathered data on behalf of mobile sinks and the relayed data in previous studies. their schemes, however, lead to frequent query flooding and report congestion problems over sink moving. We propose a data dissemination protocol to solve both the query flooding and the report congestion problem. Our scheme improves the two shortcomings through sink location management. Finally, we prove effectiveness of our protocol through computer simulations.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.505-510
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• 2009

Sensor networks are composed of a great number of sensor nodes. Since all sensor nodes are energy-restricted and hard to recharge, it is very important.However, the energy consumption may significantly increase if mobile sources or sinks exist in sensor networks. The reason is that the routing information for mobile sources and sinks needs to be update frequently for efficientdata delivery. The routing algorithm supporting mobile sinks should consider not only continuous data delivery but also the energy consumption of sensor nodes. However, most of the existing research focuses on even energy consumption while the mobility of sinks and sources is rarely consider. In this paper, we propose an efficient routing protocol with multiple virtual grids to reduce energy consumption and improve packets delivery efficiency. Then this paper considers the mobility. Simulation results show that our algorithm can guarantee high data delivery ratio and lower average delivery delay, while consuming lower energy than existing routing protocols in sensor networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.72-78
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• 2011

Localization information of an object can be a very useful element for many application areas. Presently, GPS is typically used for it, but many researches on the wireless localization technology are going on recently actively using mobile communication network, wireless sensor network, and ad hoc network in order to overcome the limitations of the GPS such as indoor, cost, power consumption, and etc. Therefore, this article surveys the most representative wireless localization techniques, which can be deployed in the wireless networks, and their principles and performances are analyzed based on the researched papers. In a conclusion, selection of a localization technique should consider the key design elements to a given application from the design elements such as localization environment, accuracy, time to fix, computation amount, implementation ease, and etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1133-1141
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• 2009

In this paper, we present a distributed fault-tolerant topology control protocol that configure a wireless sensor network to achieve k-connectivity and (k+1)-coverage. One fundamental issue in sensor networks is to maintain both sensing coverage and network connectivity in order to support different applications and environments, while some least active nodes are on duty. Topology control algorithms have been proposed to maintain network connectivity while improving energy efficiency and increasing network capacity. However, by reducing the number of links in the network, topology control algorithms actually decrease the degree of routing redundancy. Although the protocols for resolving such a problem while maintaining sensing coverage were proposed, they requires accurate location information to check the coverage, and most of active sensors in the constructed topology maintain 2k-connectivity when they keep k-coverage. We propose the fault-tolerant topology control protocol that is based on the theorem that k-connectivity implies (k+1)-coverage when the sensing range is at two times the transmission range. The proposed distributed algorithm does not need accurate location information, the complexity is O(1). We demonstrate the capability of the proposed protocol to provide guaranteed connectivity and coverage, through both geometric analysis and extensive simulation.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.185-190
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• 2007

The efficient node energy utilization is one of important performance factors in wireless sensor networks because sensor nodes operate with limited battery power. To extend the lifetime of the wireless sensor networks, maintaining balanced power consumption between sensor nodes is more important than reducing each energy consumption of the sensor node in the network. In this paper, we proposed a cluster formation algorithm to extend the lifetime of the networks and to maintain a balanced energy consumption of nodes. To obtain it, we add a tiny slot in a round frame, which enables to exchange the residual energy messages between the base station (BS). cluster heads, and nodes. The performance of the proposed protocol has been examined and evaluated with the NS 2 simulator. As a result of simulation, we have confirmed that our proposed algorithm show the better performance in terms of lifetime than LEACH. Consequently, our proposed protocol can effectively extend the network lifetime without other critical overhead and performance degradation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3C
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• pp.233-240
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• 2012

Unlike traditional factory environment, in an industrial factory network applied wireless sensor network technologies, all procedures of discovery, identification and verification of devices should be performed in an automatic fashion. To address these challenges, we design a management system using the device registry server that we propose in this paper. In the phase of device discovery, the proposed system utilizes properties of routing protocol running in factories. Also, in the phase of identification and verification, the system uses unique and general information of a device stored within the device registration server. Such a way allows management system to reduce implementation complexity and to easily manage devices in a factory applied with a wireless network consisting of heterogeneous devices.

• Journal of Internet Computing and Services
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• v.15 no.5
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• pp.1-7
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• 2014

WireWireless sensor networks(WSNs) are generally comprised of densely deployed sensor nodes, which causes highly redundant sensor data transmission and energy waste. Many studies have focused on energy saving in WSNs. However, delay problem also should be taken into consideration for mission-critical applications. In this paper, we propose a BISA (Bio-Inspired Scheduling Algorithm) to reduce the energy consumption and delay for WSNs inspired by biological systems. BISA investigates energy-efficient routing path and minimizes the energy consumption and delay using multi-channel for data transmission. Through simulations, we observe that the BISA archives energy efficiency and delay guarantees.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.225-229
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• 2007

센서 망에서 비어 있는 공간(홀)은 현실의 다양한 지리적인 환경 때문에 회피하는 것이 쉽지 않다. 일반적으로 데이터 패킷이 홀 경계에 마주쳤을 경우, 목적지까지의 다른 길을 찾기 위해 라이트 핸드 법칙(right hand rule) 또는 푸쉬드 백(pushed back)을 이용하여 홀 경계를 따라 패킷을 전달한다. 한편, 라이트 핸드 룰은 홀 경계에 있는 노드들의 에너지를 더 많이 소모하므로 홀이 확장될 것이다. 또한 동시에 여러 통신 세션이 같은 홀의 경계를 공유한다면 데이터 충돌을 초래할 것이다. 이 논문에서 우리는 무선센서 망에서의 홀 문제를 해결하기 위해 라우팅 홀 우회 방안을 제안한다. 우리의 라우팅 홀 우회 방안은 두 가지 목표를 갖는다: 하나는 데이터 패킷이 홀의 경계를 따라 이동하는 것을 방지하는 것이고, 다른 하나는 로컬 미니멈(local minimum) 문제를 피하는 것이다. 시뮬레이션 결과는 우리의 방안이 다른 프로토콜들에 비해 제어 부하와 에너지 소비 면에서 우수하다는 것을 보여준다.

• Information and Communications Magazine
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• v.24 no.7
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• pp.69-78
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• 2007

본고에서는 광대역 무선 멀티미디어 재난통신 기술의 기술개발 동향 및 표준화 동향을 알아본다. 기술 개발동향의 경우는 정보시스템, 센서망, 통신 인프라 측면에서 개발하고 있는 프로젝트 내용을 분석하고 필요한 기술들을 알아본다. 표준의 경우는 MESA, ETSI (EMTEL, TETRA, SES) 등 주요 표준 단체의 표준 추진현황을 살펴보고 내용을 설명한다.