• 한국멀티미디어학회논문지
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• 제19권5호
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• pp.910-917
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• 2016

Sensors have limited resources in sensor networks, so efficient use of energy is important. Representative clustering methods, LEACH, LEACHC, TEEN generally use direct transmission methods from cluster headers to the sink node to pass collected data. However, the communication distance of the sensor nodes at low cost and at low power is not long, it requires a data transfer through the multi-hop to transmit data to the sink node. In the existing cluster-based sensor network studies, cluster process and route selection process are performed separately in order to configure the routing path to the sink node. In this paper, in order to use the energy of the sensor nodes that have limited resources efficiently, a cluster-based multi-hop routing protocol which merges the clustering process and routing process is proposed. And the proposed method complements the problem of uneven cluster creation that may occur in probabilistic cluster methods and increases the energy efficiency of whole sensor nodes.

• 한국통신학회논문지
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• 제35권3A호
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• pp.287-295
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• 2010

무선 센서 네트워크에서, 위치정보 없이 이동 싱크를 지원하는 연구들은 노드로 클러스터를 이루고 이들의 연결을 통해서 싱크로 데이터를 전달하는 가상의 인프라구조를 형성한다. 소스 노드가 위치한 클러스터와 싱크가 위치한 클러스터 간에는 이 구조를 통해서 연결되지만, 모든 클러스터 헤드와의 연결을 만들기 위해 플러딩을 하기 때문에 높은 라우팅 비용을 야기한다. 비록 다계층의 클러스터를 통해서 클러스터의 수를 줄일 수는 있지만, 싱크와 소스가 가깝더라도 다른 최상위 클러스터에 속한다면, 데이터는 우회될 수밖에 없다. 그래서 우리는 데이터 우회를 해결하고 클러스터의 수를 줄일 수 있는 멀티 홉 클러스터 기반의 프로토콜을 제안한다. 싱크의 위치 정보서비스와 싱크로의 데이터의 전달을 위해 랑데부 클러스터 헤드를 선정하지만, 소스와 싱크가 속한 클러스터 간의홉 수를 이용해서 효과적으로 데이터의 우회를 줄인다. 시뮬레이션은 기존 방안보다 효과적으로 데이터가 전달되는 것을 보인다.

• 한국멀티미디어학회논문지
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• 제17권8호
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• pp.977-987
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• 2014

Many of the recent performance evaluation of clustering schemes in wireless sensor networks considered one sink node operation and fixed sink node location without mentioning about any network application requirements. However, application environments have variable requirements about their networks. In addition, network performance is sufficiently influenced by different sink node location scenarios in multi-hop based network. We also know that sink location can influence to the sensor network performance evaluation because of changed multipath of sensor nodes and changed overload spots in multipath based wireless sensor network environment. Thus, the performance evaluation results are hard to trust because sensor network is easily changed their network connection through their routing algorithms. Therefore, we suggest that these schemes need to evaluate with different sink node location scenarios to show fair evaluation result. Under the results of that, network performance evaluation results are acknowledged by researchers. In this paper, we measured several clustering scheme's performance variations in accordance with various types of sink node location scenarios. As a result, in the case of the clustering scheme that did not consider various types of sink location scenarios, fair evaluation cannot be expected.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2052-2067
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• 2011

Complementary trees are two spanning trees rooted at the sink node satisfying that any source node's two paths to the sink node on the two trees are node-disjoint. Complementary trees routing strategy is a special node-disjoint multi-path routing approach. Several complementary trees routing algorithms have been proposed, in which path discovery methods based on depth first search (DFS) or Dijkstra's algorithm are used to find a path for augmentation in each round of path augmentation step. In this paper, a novel path discovery method based on multi-tree-growing (MTG) is presented for the first time to our knowledge. Based on this path discovery method, a complementary trees routing algorithm is developed with objectives of low average path length on both spanning trees and low complexity. Measures are employed in our complementary trees routing algorithm to add a path with nodes near to the sink node in each round of path augmentation step. The simulation results demonstrate that our complementary trees routing algorithm can achieve low average path length on both spanning trees with low running time, suitable for wireless sensor networks in industrial scenarios.

• Journal of Information Processing Systems
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• 제20권2호
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• pp.252-262
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• 2024

The multi-hop wireless sensor network (WSN) suffers from energy limitation and eavesdropping attacks. We propose a simple and energy-efficient convergecast mechanism using inter-flow random linear network coding that can provide confidentiality to the multi-hop WSN. Our scheme consists of two steps, constructing a logical tree of sensor nodes rooted at the sink node, with using the Bloom filter, and transmitting sensory data encoded by sensor nodes along the logical tree upward to the sink where the encoded data are decoded according to our proposed multi-hop network coding (MHNC) mechanism. We conducted simulations using OMNET++ CASTALIA-3.3 framework and validated that MHNC outperforms the conventional mechanism in terms of packet delivery ratio, data delivery time and energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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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.

• 융합보안논문지
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• 제13권6호
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• pp.69-76
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• 2013

무선 센서 네트워크에서 에너지 효율성을 높이려는 연구가 많이 진행되어 왔다. 그러나 현재 이루어지고 있는 대부분의 연구는 클러스터 헤드와 싱크 노드들 사이의 직접적인 통신에 바탕을 두고 있다. 앞에서 이루어진 연구들은 노드들 사이의 거리에 따라 에너지를 계산하는 방식에 기초를 두고 있다. 거리에 따라 에너지를 계산하여 알고리즘을 구현하는 것은 어려운 문제가 된다. 이 논문에서는 싱크 노드에서 다른 모든 노드들까지 고정된 전파 파장의 반경을 갖는 다단계 라우팅 알고리즘을 제안한다. 이 논문에서는 시뮬레이션을 이용하여 WSN이 에너지를 효율적으로 줄이는 것과 WSNdp 활용 방안을 제시한다.

• 한국통신학회논문지
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• 제40권12호
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• pp.2450-2460
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• 2015

최근 IoT(Internet of Things)에 대한 관심이 증가함에 따라, IoT의 특징을 고려한 새로운 프로토콜에 대한 연구 및 표준화가 진행되고 있다. 그 중 RPL(IPv6 for Low-Power Lossy Network)는 IoT를 위해 표준화된 라우팅 프로토콜이다. RPL은 싱크 노드로부터 네트워크 전체로 플러딩 되는 DIO(DODAG Information Object) 메시지를 사용하여 라우팅 경로를 생성 및 관리한다. 그러나, 대규모 네트워크에서는 네트워크 전체에 DIO 메시지를 전파하는 데 많은 시간이 소모될 뿐만 아니라 싱크 노드 주변에서 데이터 패킷의 병목 현상이 발생하게 된다. 이러한 문제를 해결하기 위해서 라우팅 오버헤드 및 병목 현상을 감소시킬 수 있는 멀티 싱크 기반 접근법이 널리 활용된다. 이 논문에서는 멀티 싱크 기반 IoT 네트워크에 RPL 프로토콜을 적용 시 발생할 수 있는 '불필요한 경로 업데이트 문제'를 정의하고, 선택적인 경로 업데이트를 위한 2가지 기법인 Routing Metric based Path Update Decision 기법과 Immediate Successor based Path Update Decision 기법을 제안한다.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1778-1786
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• 2009

Many sensor network applications have been developed for smart home, disaster management, and a wide range of other applications. These applications, however, generally assume a fixed base station as well as fixed sensor nodes. Previous research on sensor networks mainly focused on efficient transmission of data from sensors to fixed sink nodes. Recently there has been active research on mobile sink nodes, sink mobility is one of the most comprehensive trends for information gathering in sensor networks, but the research of an environment where both fixed sink nodes and mobile sinks are present at the same time is rather scarce. This paper proposes a scheme for context-aware by ubiquitous devices with the sink functionality added through fixed sinks under a previously-built, cluster-based multi-hop sensor network environment. To this end, clustering of mobile devices were done based on the fixed sinks of a previously-built sensor network, and by using appropriate fixed sinks, context gathering was made possible. By mathematical comparison with TTDD routing protocol, which was proposed for mobile sinks, it was confirmed that performance increases by average 50% in energy with the number of mobile sinks, and with the number of movements by mobile devices.

• 한국컴퓨터정보학회논문지
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• 제21권6호
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• pp.77-81
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• 2016

This paper deals with the optimization problem that decides the routing of connection between multi-source and multi-sink. For this problem, there is only in used the mathematical approach as linear programming (LP) software package and has been unknown the polynomial time algorithm. In this paper we suggest the heuristic algorithm with $O(mn)^2$ time complexity to solve the optimal solution for this problem. This paper suggests the simple method that assigns the possible call flow quantity to augmenting path of ($s_i,t_i$) city pair satisfied with demand of ($s_i,t_i$). The proposed algorithm can be get the same optimal solution as LP for experimental data.