• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.287-293
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• 2013

Cognitive radio has been recently proposed to dynamically access unused-spectrum. The CR users can share the same frequency band with the primary user without interference to each other. Usually each CR user needs to determine spectrum availability by itself depending only on its local observations. But uncertainty communication environment effects can be mitigated so that the detection probability is improved in a heavily shadowed environment. Soft detection is a primary user detection method of cooperative cognitive radio networks. In our research, we will improve system detection probability by using optimal cooperative node selection algorithm. New algorithm can find optimal number of cooperative sensing nodes for cooperative soft detection by using maximum ratio combining (MRC) method. Through analysis, proposed cooperative node selection algorithm can select optimal node for cooperative sensing according to the system requirement and improve the system detection probability.

• Journal of KIISE
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• v.43 no.1
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• pp.119-125
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• 2016

Cognitive radio technology can allow secondary users (SUs) to access unused licensed spectrums in an opportunistic manner without interfering with primary users (PUs). Spectrum sensing is a key technology for cognitive radio (CR). However, few studies have examined energy-efficient spectrum sensing in cognitive radio sensor networks (CRSNs). In this paper, we propose an energy-efficient cooperative spectrum sensing nodes selection scheme for cluster-based cognitive radio sensor networks. In our proposed scheme, false alarm probability and energy consumption are considered to minimize the number of spectrum sensing nodes in a cluster. Simulation results show that by applying the proposed scheme, spectrum sensing efficiency is improved with a decreased number of spectrum sensing nodes. Furthermore, network energy efficiency is guaranteed and network lifetime is substantially prolonged.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.391-394
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• 2006

무선 센서 네트워크에서 각 센서 노드는 에너지의 한계를 가지기 때문에, 에너지 소비문제는 매우 중요한 이슈이다. 조밀한 환경의 센서 네트워크에서 모든 노드들이 센싱에 참여한다면, 센싱영역의 중복영역이 커지게 되고, 이로 인해 불필요한 에너지를 소비하게 된다. 본 논문에서는 connectivity 와 coverage 를 보장할 수 있고, 효율적으로 활성화 노드를 선택할 수 있는 기법을 제안하여, 불필요한 센서 노드들의 에너지소비를 막아 전체적인 네트워크의 lifetime 을 연장시키고자 한다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.157-158
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• 2006

무선 센서 네트워크에서 각 센서 노드는 에너지의 한계를 가지기 때문에, 에너지 소비문제는 매우 중요한 이슈이다. 조밀한 환경의 센서 네트워크에서 모든 노드들이 센싱에 참여한다면, 센싱영역의 중복영역이 커지게 되고, 이로 인해 불필요한 에너지를 소비하게 된다. 본 논문에서는 WSN 에서 connectivity 와 coverage 를 보장할 수 있는 효율적인 활성화 노드를 선택하는 기법을 제안하여, 불필요한 센서노드들의 에너지소비를 막고 전체적인 네트워크의 lifetime 을 연장시키고자 한다

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.107-116
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• 2006

In this paper, we propose a Sensing Resolution-based Grouping(SRG) protocol for wireless sensor networks. SRG is intended for meeting the application's sensing objectives, where sensor nodes are densely deployed and have the determinate accuracy requirement. The primary contribution of this paper is active group header node selection and round-robin procedure, which increase the sensing accuracy and evenly distribute the node energy consumption. The second contribution is use of energy efficient intermediate node selection by considering group size and energy consumption. We present the design principle of SRG and provide simulation results.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.66-70
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• 2013

In this paper, Threshold setting method is proposed to improve detection probability for cooperative sensing. Even if cooperative users have all same false alarm rate, each user has different threshold due to pass ad-hoc channel. threshold level is related to detection probability. So, we select the highest threshold among cooperative users and then share threshold information for getting the high detection probability.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.366-369
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• 2006

기존 single sink 센서 네트워크에서의 모든 센서 노드들은 sink로부터 flooding된 질의(query)를 전송 받은 후 센싱 data를 sink로 보냄에 있어서 목적지인 sink 주변 노드의 traffic 집중에 따른 에너지 소비로 인해 전체 네트워크 수명에 영향을 끼쳤다. 이러한 single sink 방식에서의 주변 노드의overhead와 센싱 데이터를 sink로 전달 할 때의 특정 경로상의 노드들의 잔여 에너지량을 고려하여 데이터를 전송하게 함으로써 전체 네트워크 수명을 연장 할 수 있다.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.37-46
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• 2007

In wireless sensor networks, one of the most important goals of designing protocols is to extend the network lifetime. A node has lots of duplication in sensing and communication range with surrounding nodes after many of nodes are randomly scattered. Such a heavy duplication overhead affects on the network lifetime seriously so usually all nodes need not activated constantly to carry out sensing and communication operation. One of the optimal methods of prolonging the network lifetime is finding the number of surrounding nodes necessary to maintain the network coverage and connectivity. It has been studied till the current date in wireless networks. If the neighbor necessary can be acquired to satisfy the probability using the ideal number of neighbors necessary and the acquired number of neighbors m to guarantee network coverage and connectivity. We use the result that F. Xue et al and S. Song et al derive previously in finding the neighbor necessary to guarantee the network connectivity and cany out the computer simulation to verify the necessary number. We present that our scheme satisfy the network coverage and connectivity. We present the simulation results compared with constant probability scheme through computer simulation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.5
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• pp.116-124
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• 2016

This paper proposes a medium access control protocol for collision detection and resolution when a large number of sensor nodes transmits data in vehicle. The proposed protocol selects a random collision detection (CD) slot after data transmission, suspends its transmission and senses the channel to check whether a collision occurs by the detection of both energy level and jam signal. The proposed scheme uses multiple CD phases and in each CD phase, colliding stations are filtered and only surviving stations compete again in the next CD phase; thus, the collision resolution probability significantly increases. Simulation results show that the proposed protocol using the multiple CD phases has significantly better throughput than the conventional protocol. In addition, according to the number of CD phases and the number of CD slots per phase, the throughput aspect of the proposed scheme is investigated and the optimal parameters are derived.