• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1207-1210
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• 2005

본 논문에서는 센서 네트워크에서 수명을 연장하기 위해 이동하는 모바일 싱크를 사용할 때 싱크가 이동함에 따라 늘어난 전체 네트워크 트래픽 량을 줄여 더욱더 수명을 연장하기 위해서 클러스터를 도입한다. 고정된 위치에서 싱크가 데이터를 수집할 경우 싱크 한 홉 내에 있는 노드들이 에너지를 빨리 소모하여 네트워크 파티션이 일어나기 쉽기 때문에 모바일 싱크를 사용하여 네트워크 수명을 연장하는 방법이 연구되었다. 이에 우리는 모바일 싱크가 이동하는 패턴이 주어지고 센서들로부터 매 T 마다 데이터를 받는다고 할 때 모바일 싱크와 클러스터를 함께 사용하였을 경우 네트워크 성능을 분석하고 에너지 효율적인 클러스터 형성 방법에 대해서 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.108-109
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• 2016

무선 센서 네트워크에서의 모바일 싱크를 지원하기 위한 다양한 방법이 연구되어져왔다. 이러한 연구 중에서 에너지 효율과 링크효율을 최 우선시 하는 멀티패스 라우팅 방안은 가장 중요시되는 연구 분야중 하나이며 여러 연구방안이 진행되어져왔다. 그런 기존방안은 이동하는 싱크에 따라 효율적으로 노드선택을 진행함에 있어 에너지와 링크효율 정보 기반에 따른 최선의 선택을 이루지 못하고 있음에 따라 본 논문은 기존 방안과는 달리 쓰래쉬 홀드 설정을 통하여 최적의 노드 선택을 이루며 멀티패스를 생성하는 방안을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1077-1080
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• 2007

센서 네트워크는 어떠한 현상을 인식하고 측정하여 수집된 데이터를 싱크(sink)노드에 전송하는 역할을 한다. 이러한 센서네트워크에서 고려해야 하는 중요한 사항 중 하나는 제한된 자원을 가진 센서 네트워크에서 주어진 에너지 소모를 최소화 하여 네트워크 수명을 연장하는 것이다. 그러나 기존에 제안된 프로토콜은 다중 모바일 싱크가 존재할 경우에 싱크 노드의 잦은 위치 업데이트와 다수의 컨트롤 패킷으로 인하여 많은 베터리 소모를 야기 하게 되었다. 그러므로 본 논문에서는 그리드와 클러스터 개념을 이용하여 다수의 모바일 싱크 존재 시 발생하는 문제점을 해결하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1431-1439
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• 2016

In this paper, we propose a new location service and location-based routing for data dissemination from a source to a mobile group sink in less energy consumption of the sensor node. Unlike the existing protocols, the proposed protocol uses a leader sink instead of a group area as the location information to represent a mobile sink group. The proposed protocol also uses grid leaders on virtual grid structure to support sink mobility in location service. By using a leader sink as a representative and grid leaders for mobility supporting, the proposed protocol can exploit an efficient hierarchical location service and data dissemination method without using flooding. Accordingly, the proposed protocol carries out upper layer location services and data dissemination between a leader sink and a source and lower layer location services and data dissemination between the leader sink and member sinks. Simulation results demonstrate that the proposed protocol achieves energy-efficiency.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.4
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• pp.77-82
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• 2020

Wireless sensor networks (WSNs) suffer from not only a short lifetime due to limited energy but also an energy imbalance between nodes close to the sink and others. In order to fundamentally solve the short lifetime, recent studies utilize the environmental energy such as solar power. Additionally, WSNs using mobile sinks are being studied to address the energy imbalance problem. This paper proposes an improved CTP (Collection Tree Protocol) scheme which uses these two approaches simultaneously. Basically, it is based on a CTP scheme which is a very popular data collection strategy designed for the typical battery-based WSNs with a fixed sink. Therefore, we tailored it for solar-powered WSNs with a mobile sink. Performance verification confirms that our scheme reduces the number of blackout nodes significantly compared to the typical CTP, thus increases the amount of data collected by the sink.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.76-90
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• 2006

Sensor network consists of a large number of sensor nodes that are densely deployed either inside the phenomenon or very close to it. The life time of each node in the sensor network significantly affects the life time of whole sensor network. A node which drained out its battery may incur the partition of whole network in some network topology The life time of each node depends on the battery capacity of each node. Therefore if all sensor nodes in the network live evenly long, the life time of the network will be longer. In this paper, we propose Cluster-Based Power-Efficient Routing (CBPER) Protocol which provides scalable and efficient data delivery to multiple mobile sinks. Previous r(luting protocols, such as Directed Diffusion and TTDD, need to flood many control packets to support multiple mobile sinks and many sources, causing nodes to consume their battery. In CBPER, we use the fact that sensor nodes are stationary and location-aware to construct and maintain the permanent grid structure, which makes nodes live longer by reducing the number of the flooding control packets. We have evaluated CBPER performance with TTDD. Our results show that CBPER is more power-efficient routing protocol than TTDD.

• KIISE Transactions on Computing Practices
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• v.24 no.2
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• pp.77-81
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• 2018

Many studies that improve the efficiency of data collection and a network's lifetime by using a mobile sink have been conducted using wireless sensor networks. If a drone is used as a mobile sink, the drone can collect data more efficiently than can existing mobile sinks operating on the ground because the drone can minimize the effects of obstacles and the terrain. In this paper, we propose a rendezvous node selection scheme which considers estimated drone's trajectory and data collection latency of sensor networks for reliable data collection, when a drone whose trajectory is not predetermined works with terrestrial wireless sensor networks. A selected rendezvous node on the ground collects data from the entire network and it sends then collected data to the drone via direct communication. We also verify that the proposed scheme is more reliable than previous schemes without considering the drone's trajectory and data collection latency.

• 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 Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.617-625
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• 2011

In wireless sensor networks, data dissemination protocols have been proposed for mobile sink groups that are characterized by geographically staying closely and collective movement. They usually exploit flooding technology for mobility supporting and data delivery guarantee. However, it causes the excessive energy consumption of all sensor nodes in the group region due to data delivery participation. Moreover, the costs of the flooding would become higher in proportional to the group region. In this paper, we propose an energy efficient data dissemination scheme that resolves these problems. The virtual infrastructure called a 'pipe' is used as a rendezvous area. A source delivers data to the pipe, from which member sinks in the group retrieve it directly. Simulation results showed that this solution has better performance than existing protocols in terms of energy consumption as it reduces the number of regional flooding and eliminates unnecessary data flooding.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.5
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• pp.239-246
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• 2017

Communications for mobile sink groups such as rescue teams or platoons bring about a new challenging issue for handling group mobility in wireless sensor networks. Recently, a group region-based approach has been proposed to send data to a mobile sink group. However, it uses excessive flooding for 3 steps (group region discovery, region information notification, and data dissemination) to support mobile sink group. Thus, it causes high energy consumption and data delivery failure. Moreover, its per-sink mobility supporting scheme makes energy consumption and data delivery failure more serious. Thus, this paper proposes an Energy-efficient and Reliable Mobile Group communication protocol (ERMG) to support a mobile sink group, which exploits a virtual grid structure. For the group region discover and notification and the data dissemination, ERMG uses communications with only cell heads of grid cells that manages group sinks. ERMG also uses a per-grid based scheme to support sink mobility. Simulation results show that ERMG has 30% less energy consumption and 6% more desired delivery deadline success ratio than the existing protocols.