• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.578-580
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• 2009

Wireless Sensor Networks(WSNs) has been used for various applications. It is optimized to low power operation than various function and transmission reliability because of limited power by batteries. but it is necessary to guarantee of reliability for using exact data for more diversity purpose. In WSNs environment composed by multi-hop, it is guarantee to end-to-end transmission reliability based hop-by-hop reliability. however, IEEE 802.15.4 standard is not consider link-layer reliability. in this paper, we propose energy efficient Reliable Link-layer Protocol for Wireless Sensor Networks.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1196-1203
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• 2013

In general, the cost of transceiver for wireless network configuration is more expensive than that for wired network. However, in case of environmental management system in a tunnel, the cost can be minimized by adopting low rate tranceiver because the amount of the exchanged data for tunnel monitoring is very small. When the obtained data from sensor node is sent directly to the corresponding command node, there is no need to consider routing problem of the data transfer. However in this case, sensor nodes are required to be implemented with high power transmitter and experience high energy consumption. To tackle this problem, relay nodes can be used to transfer the data of tunnel monitoring, and suitable routing protocols for selecting optimum path are needed. Therefore, in this paper, we propose a routing algorithm and a self-configuration protocol for environment management system in tunnel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.763-770
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• 2014

In traditional routing protocols including LEACH for wireless sensor networks, nodes suffer from unbalanced energy consumption because the nodes require large transmission energy as the distance to the sink node increase. Multi-hop based routing protocols have been studied to address this problem. In existing protocols, each cluster head usually chooses the closest head as a relay node. We propose LEACH-CHT, in which cluster heads choose the path with least energy consumption to send data to the sink node. In our research, each hop, a cluster head selects the least cost path to the sink node. This method solves the looping problem efficiently as well as make it possible that a cluster head excludes other cluster heads placed farther than its location from the path, without additional energy consumption. By balancing the energy consumption among the nodes, our proposed scheme outperforms existing multi-hop schemes by up to 36% in terms of average network lifetime.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.139-145
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• 2015

This paper proposes to increase the node energy effienciecy, which rapidly drops during the transmission of LEACH (Low Energy Adaptive Clustering Hierachy), using the method of DL-LEACH (Dual-hop Layered LEACH). By introducing dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission was introduce. By introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was introduces. In the proposed DL-LEACH, the energy consumption of cluster head for remote transmission reduces and increases the energy efficiency of sensor node by reducing the transmission distance and simplifying the transmission routine for short-range transmission. As compared the general LEACH, it was adapted to a wider sensor field.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.517-520
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• 2005

지금까지의 주변 환경 정보를 감지 및 분석하는 구조물 감시 시스템은 유선으로 구성되었다. 이러한 유선 시스템이 가지는 단점들을 해결하기 위해 무선 센서 네트워크를 이용한 연구들이 활발히 이루어지고 있다. 무선 센서 네트워크란 지역적으로 배치된 많은 수의 센싱 노드들 사이에서 데이터를 수집, 가공 및 무선으로 전송하는 하나의 네트워크이다. 본 연구에서는 센서 네트워크를 이용한 구조물 감시 시스템을 구현하고 성능을 측정하였다. 제안된 시스템에서의 가속도 측정 소프트웨어인 MultiHopAccel은 많은 센서 노드들 사이에서의 데이터 전송을 위한 멀티 홉 라우팅 기능과, 네트워크 내의 모든 노드들이 동일한 시간을 유지하기 위한 시간 동기화 기능을 제공한다. 본 연구에서는 MultiHopAccel을 통하여 센서 노드에 저장된 데이터들을 분석하고, 인터넷을 통하여 센서 노드들의 동작을 원격 감시 할 수 있음을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.706-714
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• 2010

In wireless sensor networks, real-time data delivery schemes typically achieve a desired delivery speed by performing one-hop lookahead. Recently, to reduce the deadline miss ratio against the desired delivery speed, a study has proposed a real-time routing protocol based on proactively performing two-hop lookahead. However, the study might cause heavy message exchange overhead and high computing complexity to carry out obtainment of two-hop neighborhood speed information in the entire sensor nodes whether data are delivered or not. Moreover, although multi-hop lookahead provides the least deadline miss ratio, due to the restriction from the overhead and the complexity, the recent study merely adopts the two-hop lookahead manner. In this paper, we propose a novel real-time routing protocol that adopts on-demand neighborhood multi-hop information obtainments only around data forwarding paths. Simulation results prove that the proposed routing protocol offers better performances with respect to deadline miss ratio, total communication costs, energy efficiency, and network lifetime.

• Journal of Internet Computing and Services
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• v.10 no.1
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• pp.159-173
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• 2009

Locations of positioned 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. And this research verifies this technology is excellent in terms of performance, accuracy, and scalability through simulation.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.3
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• pp.37-42
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• 2007

This paper reconsiders established power conservation models for ubiquitous sensor networks that use relay nodes instead of direct communication and proposes novel network power consumption model with consideration of the channel level and radio chip level simultaneously. We estimate the effect of minimum hop-count policy in terms of network power consumption through simulation of various situations for low power RF module CC2420. It is observed that maximum RF power and minimum hop-count results in lower energy consumption relatively. Also, in total network energy consumption, which is included re-transmission, minimum hop count policy presents decrease by 33.1% of energy consumption in compare with the conventional model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.123-134
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• 2008

In this paper, a routing algorithm for wireless sensor networks is proposed to improve the efficiency of energy consumption in sensor nodes. Each sensor node has the value called ‘Flooding Level’ obtained through the initial flooding from a sink node instead of sending beacon messages in multi-hop sensor field. This value can be used for guaranteeing the sensor nodes to connect with a sink node and determining the roles of cluster-head and cluster-gateway node efficiently and simply during the clustering. If different algorithms are added to our protocol, it will work better in the side of energyefficiency. This algorithm is evaluated through analysis and extensive simulations.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.331-333
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• 2005

유비쿼터스 컴퓨팅을 가능하게 해주는 기반기술의 하나인 유비쿼터스 센서 네트워크(Ubiquitous Sensor Networks)란, 주변 사물과 환경을 인식하고 네트워크를 통해 실시간 정보를 구축, 활용토록 하는 초소형, 저전력 센서들로 구성된 무선 통신망이라 할 수 있다. 유비쿼터스 센서 네트워크에서의 MAC 프로토콜은 그 특성상 기존의 MAC 프로토콜과는 달리 에너지 사용량을 최소화하여 네트워크 수명을 오랫동안 유지하도록 하는 것이 요구된다. 따라서 본 논문에서는 센서 네트워크의 수명의 최대화를 고려한 DT (Dynmic-Threshold) MAC프로토콜을 제안한다. DTMAC프로토콜은 각 노드의 버퍼에 임계값을 적용하여 전송 주기를 지연시켜 에너지 절감성을 극대화하게 되며 멀티 홉 환경에서 에너지 절감성의 효과론 더욱 높이기 위해 각 노드의 버퍼에 싱크와의 홉 수에 따른 차등적 임계값을 적용하며, 또한 이로 인해 야기되는 데이터 전송지연 문제를 해결키 위하여 긴급 데이터에 대한 빠른 전송을 보장하는 알고리즘을 포함한다.