• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.181-184
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• 2008

근래에 센서 네트워크 내의 싱크 노드 이동에 대한 많은 연구가 이루어지고 있다. 이들 연구의 대부분은 싱크 노드의 이동으로 인한 데이터 손실을 최소화하거나 싱크 노드가 소스 노드의 위치를 인식하는 것에 초점을 맞추고 있다. 그러나 센서 네트워크는 그 특성 상 노드의 에너지 공급이 매우 어렵기 때문에 에너지 절약이 데이터 손실 방지 못지 않게 중요하다. 본 논문에서는 모바일 싱크 노드를 가진 센서 네트워크에서 에너지 소모량을 최소화할 수 있는 라우팅 기법을 제안하고, NS2를 이용하여 이 기법을 구현한다. 또한, 이 시뮬레이션을 통해 센서 네트워크의 에너지 소모량을 측정한다. 그 결과, 기존의 에너지 효율적인 라우팅 프로토콜인 Pulse 프로토콜과 에너지 효율 면에서 유사함을 보인다.

• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.395-402
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• 2007

Wireless sensor networks have many sensor nodes which response sudden events in a sensor fields. Some efficient routing protocol is required in a sensor networks with mobile sink node. A data-path template is offered for the data announcement and data request from source node and sink node respectively. Sensed data are transferred from source node to sink node using short-distance calculation. Typical protocols for the wireless networks with mobile sink are TTDD(Two-Tier Data Dissemination) and CBPER(Cluster-Based Power-Efficient Routing). The porposed SPDR(Short-Path Data Routing) protocol in this paper shows more improved energy efficiencies from the result of simulations than the typical protocols.

• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.169-180
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• 2009

With fixed sinks, the network stability could be improved while the network life time could be decreased by the rapid energy dissipation around the fixed sink because of the concentrated network traffic from sensor nodes to the fixed sink in wireless sensor network. To address this problem, mobile sinks, which decentralize the network traffic, has received a lot of attention from many researchers recently. Since a mobile sink has a limited period to communicate with each sensor nodes, it is necessary for a scheduling algorithm to provide the fairness of data collection from each sensor nodes. In the paper, we propose the new scheduling algorithm, ASF(Availability based Scheduling scheme for Fair data collection), for the fair data collection by a mobile in the sensor networks. The ASF takes account of the distance between each sensor nodes and the mobile sink as scheduling metric, as well as the amount of collected data from each sensor nodes. Experiment results shows that the ASF improves the fairness of data collection among the sensor nodes, comparing to existing algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.104-105
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• 2016

무선 센서 네트워크에서 위치 서비스는 싱크의 이동성을 지원하기 위한 효율적인 솔루션으로 주목 받았으며 이에 대한 연구가 진행되어왔다. 연구된 방안은 싱크의 속도, 궤도와 같은 이동성 정책을 이용하여 위치 서비스의 성능을 향상시켰다. 그러나 기존의 방안은 싱크가 이동할 것으로 예상된 지점에서 데이터 전달을 위해 플러딩을 사용한다. 이러한 플러딩의 결과로 기존 방안은 센서 노드들의 많은 에너지 소비를 야기하며 센서 네트워크에서 노드들의 에너지 소모량은 중요한 이슈가 된다. 그러므로, 본 논문은 기존 방안과는 달리 싱크의 지속적인 업데이트를 통해 유니캐스트를 사용하여 센서 노드들의 에너지 소비를 줄이면서 소스로부터 이동 싱크로 데이터를 전달하는 방안을 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.719-722
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• 2006

무선 센서 네트워크는 센서 노드가 센싱한 정보를 무선 네트워크를 통해서 싱크 노드에게 전달한다. 지금까지의 센서 네트워크는 에너지 소모를 최소화하기 위한 연구가 주로 진행되어 왔다. 그러나 데이터를 수집하는 싱크 노드의 이동성이 보장된다면 더욱 다양한 서비스를 제공할 수 있다. PULSE 프로토콜은 센서 네트워크상에서 에너지 효율적으로 경로를 설정하는 프로토콜이다. 본 논문에서는 기존의 PULSE 프로토콜의 펄스 플러딩 사이에 네트워크 일정 범위 내의 플러딩이 가능하도록 수정한 인터 펄스 플러딩을 추가하여 싱크 노드의 이동성을 지원하고 에너지 효율성도 높인 M-PULSE 프로토콜을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1068-1077
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• 2014

In this paper, we propose a novel method for path setup that optimizes energy consumptions for wireless sensor network. Existing studies usually generate paths according to Random way point approach so that it requires unnecessary energy consumptions for estimating location of the mobile sink node and transmission paths of packets. To address this problem, we propose a method that creates paths for mobile sink node using the Hilbert curve. Moreover, our method adjusts the path of the mobile sink node according to the density of sensor nodes to minimize data transmission delay. In our experiments, the proposed method outperforms existing work such as TTDD and CBPER by up to 50 times in terms of energy efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1208-1214
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• 2009

Sensor networks are vulnerable to data congestion and hot-spot compared with wireless networks. Mobile sink supporting route protocol has such problems as hot-spot and data congestion because agent of cluster node transmits all data packet. Therefore, mobile sink supporting route protocol needs to reduce the number of packets and keep the packets from concentrating on a single node. To solve these problems, we propose mobile sink supporting routing Protocol using agent of cluster node. Cutting down on the number of packets compared with the existing mobile sink supporting routing Protocol, our proposed protocol has reduced both communication overhead and energy consumption.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.216-220
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• 2008

Sensor nodes in wireless network have several limitations such as lack of energy resource and network bandwidth. There are many researches to extend lifetime of sensor network and enhance availability. However, most of the previous researches didn't consider the mobile sink node. Those researches aren't suitable in the environment having mobile sinks. In this paper. we propose a scheme that reduces communication overheads and energy consumptions and improves reliability in routing path setup. Proposed scheme has excellent scalability without degrading performance in environment where many sink nodes exist and/or the network size is huge. Proposed scheme saves the energy consumption up to 70% in comparison with the previous grid-based and cluster-based protocol. As a result, proposed scheme increases the lifetime of sensor network and enhances availability of wireless sensor network.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.51-58
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• 2010

In data collection using a mobile sink, the time that sensor nodes are included in its communication radius is not uniform. The data collection schedule in non-uniform time is needed between a mobile sink and sensor nodes for efficient data collection. The existing data collection schemes using a mobile sink considered staying time in its communication range and data collected by the mobile sink. However, they did not consider the characteristics of data collected in sensor networks. In this paper, we propose a TDMA based schedule scheme that consists of the data collection period by each sensor nodes and the data collection period between a mobile sink and sensor nodes. Moreover, we propose a data collection scheme considering the variability of data in sensor networks. The proposed data collection scheme collects only data that changed larger than the threshold set by the user. In order to show the superiority of the proposed scheme, we compare it with DWEDF that aims to collect data uniformly. As a result, our experimental results show that the proposed scheme reduces about 23% energy consumption and the data collection failure of sensor nodes over the DWEDF.

• Journal of KIISE:Information Networking
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• v.36 no.3
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• pp.222-230
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• 2009

A sensor network is an important element of the ubiquitous and it consists of sensor fields that contain sensor nodes and sink nodes that collect data from sensor nodes. Since each sensor node has limited resources, one of the important issues covered in the past sensor network studies has been maximizing the usage of limited energy to extend network lifetime. However, most studies have only considered fixed sink nodes, which created various problems for cases with multiple mobile sink nodes. Accordingly, while maintaining routes to mobile sink nodes, this study aims to deploy the hybrid communication mode that combines single and multi-hop modes for intra-cluster and inter-cluster transmission to resolve the problem of failed data transmission to mobile sink nodes caused by disconnected routes. Furthermore, a 2-level hierarchical routing protocol was used to reduce the number of sensor nodes participating in data transmission, and cross-shape trajectory forwarding was employed in packet transmission to provide an efficient data dissemination method.