• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.141-150
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• 2005

Wireless Sensor Networks have been rapidly developed due to the advances of sensor technology and are expected to be applied to various applications in many fields. In Wireless Sensor Networks, schemes for managing the network energy-efficiently are most important. For this purpose, there have been a variety of researches to suggest routing protocols. However, existing researches have ideal assumption that all sensor nodes have sensing data to transmit. In this paper, we designed and implemented a sensing-aware cluster selection algorithm based on LEACH-C for the sensor network in which part of sensors have sensing data. We also simulated proposed algorithm on several network situation and analyzed which situation is suitable for the algorithm. By the simulation result, selecting cluster head among the sensing nodes is most energy-efficient and the result shows application of sensing-awareness in cluster head selection when not all sensors have sensing data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4738-4753
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• 2018

Efficient rendezvous node selection and routing algorithm (RNSRA) for wireless sensor networks with mobile sink that visits rendezvous node to gather data from sensor nodes is proposed. In order to plan an optimal moving tour for mobile sink and avoid energy hole problem, we develop the RNSRA to find optimal rendezvous nodes (RN) for the mobile sink to visit. The RNSRA can select the set of RNs to act as store points for the mobile sink, and search for the optimal multi-hop path between source nodes and rendezvous node, so that the rendezvous node could gather information from sensor nodes periodically. Fitness function with several factors is calculated to find suitable RNs from sensor nodes, and the artificial bee colony optimization algorithm (ABC) is used to optimize the selection of optimal multi-hop path, in order to forward data to the nearest RN. Therefore the energy consumption of sensor nodes is minimized and balanced. Our method is validated by extensive simulations and illustrates the novel capability for maintaining the network robustness against sink moving problem, the results show that the RNSRA could reduce energy consumption by 6% and increase network lifetime by 5% as comparing with several existing algorithms.

• 전자공학회논문지 IE
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• v.47 no.1
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• pp.41-47
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• 2010

It is very important to prolong the lifetime of wireless sensor networks by using their limited energy efficiently, since it is not possible to change or recharge the battery of sensor nodes after deployment. LEACH protocol is a typical routing protocol based on the clustering scheme for the efficient use of limited energy. It is composed of a few clusters, which consist of head nodes and member nodes. Though LEACH starts from the supposition that all nodes have data transferred to a head, there must be some nodes having useless data in actual state. In this paper we propose a power saving scheme by making a member node dormant if previous sensed data and current data is same. We evaluate the performance of the proposed scheme in comparison with original clustering algorithms. Simulation results validate our scheme has better performance in terms of the number of alive nodes as time evolves.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.561-565
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• 2006

무선 모바일 애드 혹 네트워크에서 에너지 효율을 위한 많은 라우팅 알고리즘이 연구되어 왔다. 이러한 제안된 다른 알고리즘들을 살펴보면, 에너지 효율 뿐 만 아니라 성능의 향상을 위한 노력도 기울여 왔다. 일반적으로 목적지 노드가 전송받은 RREQ의 메트릭을 통하여 에너지 효율적인 경로를 선택 하게 되는데, 이것은 결국 데이터 전송 지연이 발생하게 된다. 그리고 경로가 설정된 이후에 경로를 유지하는데 있어서, 노드의 이동이나 배터리의 소진으로 링크가 끊기게 되면 경로를 다시 찾는 과정에서 제어 패킷을 다시 플러딩 하기 때문에 여러 노드의 에너지 소비를 초래하게 된다. 본 논문에서는 이러한 문제들을 해결하기 위해 기존의 AODV(On-Demand Distance Vector Routing) 프로토콜을 기반으로 다음과 같은 방법을 제안한다. 먼저 RREQ를 받은 노드가 남은 배터리의 양을 고려하여 전송의 여부를 결정하는 방법을 제안하고, 경로를 유지하는데 있어서 전송의 세기를 통해 노드의 이동성을 인지하고 링크가 끊기기 전에 다른 노드로 경로를 대체함으로써 경로 재설정을 통한 에너지 소비를 줄이는 방안을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.625-630
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• 2006

Zigbee 센서 네트워크에서는 multihop 전송을 위하여 tree topology와 beacon-enabled 네트워크 구성을 갖는다. 이러한 multihop beaconing 네트워크의 목적은 routing 노드들에게 Sleep할 기회를 주어 파워의 소모를 줄이고자 하는 데 있다. 파워의 소모를 줄이고 beacon 전송시의 충돌을 방지하기 위하여 beacon 전송 스케줄링이 필요한데 본 논문은 multihop을 지원하고 에너지 효율에 효과적인 beacon 전송 스케줄링 알고리즘과 이를 바탕으로 에너지 효율적인 라우팅 기법을 제안한다. 본 제안은 Zigbee coordinator의 beacon interval(BI)이 결정되면 네트워크 내의 beacon을 전송하는 모든 노드들은 Zigbee coordinator의 BI를 알고 모든 노드의 superframe duration(SD)은 동일하다고 가정한다. 이러한 가정하에서 beacon을 전송하는 노드들이 Zigbee coordinator의 BI 구간 중 항상 정해진 시간에 자신의 beacon을 전송한다면 beacon의 충돌을 막을 수 있음을 보여 준다. 또한 노드들이 서로의 beacon 전송 시간을 알 수 있기 때문에 목적지 노드의 beacon을 tracking하지 않고도 목적지 노드가 active 되는 시점에 패킷을 전송하면 에너지 측면에서 좀 더 효율적인 라우팅 기반을 제공한다는 것을 보여 준다.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.351-352
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• 2007

The sensor networking technique as the radio network which does not have the base infrastructure network. The sensor nodes oneself automatic compose the network and simultaneously accomplish two roles of the router and data source. The sensor network is kind of Ad-hoc network is a possibility of seeing from point. sensor networking technique is restricted that limit of the memory and the battery back with the resources of the node. The sensor nodes overcomes the restriction of the resources it is in the process of researching the multi-hop routing technique which the sensor network divided cluster routing techniques which are researched. this paper proposed using beamforming antenna which has the directivity of the electric wave. the beamforming antenna from the Ad-hoc network using technique. the proposal is that raises the efficient of data trans mission from the sensor network and extends the lift time of the sensor network.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.252-258
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• 2013

As WSN is energy constraint so energy efficiency of nodes is important. Because avoiding long distance communication, clustering operating in rounds is an efficient algorithm for prolonging the lifetime of WSN and its performance depends on duration of a round. A short round time leads to frequent re-clustering while a long round time increases energy consume of cluster heads more. So existing clustering schemes determine proper round time, based on the parameters of initial WSN. But it is not appropriate to apply the round time according to initial value throughout the whole network time because WSN is very dynamic networks nodes can be added or vanished. In this paper we propose a new algorithm which calculates the round time relying on the alive node number to adapt the dynamic WSN. Simulation results validate the proposed algorithm has better performance in terms of energy consumption of nodes and loss rate of data.

• Journal of Internet Computing and Services
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• v.4 no.4
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• pp.15-25
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• 2003

Wireless ad-hoc networks are only composed with mobile devices. Unlike the traditional wired networks, those devices are mostly operated with battery power. Since the battery-operated power is limited, the efficient energy resource managements becomes an important issue in wireless ad-hoc networks and various studies that considered these characteristics are progressed. One of those studies is an energy efficient routing using coordinators. In this method. only devices elected as coordinator participate in data transmissions in ad-hoc networks, while other devices remain in sleep node. The overall energy consumption of a system can be reduced. In order to minimize energy consumption of a total network, previous results try to maximize the number of nodes in sleep mode. However, minimizing the number of coordinators does not ensure to increase the system lifetime. In this thesis, we propose an algorithm that can elect coordinators with considering the amount of necessary energy to transmit assigned data and a connectivity of nodes in the networks. The result of proposed coordinator election algorithm can increase the system lifetime of an Ad-hoc network from the results of existing coordinator election algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.4
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• pp.665-683
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• 2011

Wireless sensor networks (WSN) consist of a large amount of sensor nodes distributed in a certain region. Due to the limited battery power of a sensor node, lots of energy-efficient schemes have been studied. Clustering is primarily used for energy efficiency purpose. However, clustering in WSNs faces several unattained issues, such as ensuring connectivity and scheduling inter-cluster transmissions. In this paper, we propose a location-based spiral clustering (LBSC) algorithm for improving connectivity and avoiding inter-cluster collisions. It also provides reliable location aware routing paths from all cluster heads to a sink node during cluster formation. Proposed algorithm can simultaneously make clusters in four spiral directions from the center of sensor field by using the location information and residual energy level of neighbor sensor nodes. Three logical addresses are used for categorizing the clusters into four global groups and scheduling the intra- and inter-cluster transmission time for each cluster. We evaluated the performance with simulations and compared it with other algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.762-770
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• 2010

The researches about energy efficieny of wireless sensor MAC protocol is an issue in present days. Therefore, MAC and routing protocols for reducing energy consumption at sensor nodes is needed. In this study, a low-power MAC protocol for sensor network is proposed, which in based on X-MAC by exploiting virtual synchronization. The virtual synchronization technique lets senders postpone packet transmission until receivers' wake-up time, so that senders transmit only one or two short preambles. Using NS-2, a proposed MAC protocol improve the energy efficiency by 10% compared with the X-MAC protocol.