• 한국멀티미디어학회논문지
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• 제8권12호
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• pp.1613-1622
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• 2005

Broadcasting is fundamental and effective data dissemination mechanism for route discovery, address resolution, and many other network services in mobile ad hoc networks. Although many approaches for broadcasting have been proposed to minimize the number of retransmissions, none of them guarantee the best-suited bounds of retransmissions. Appropriate use of probabilistic method can lower the chance of contention and collision among neighboring nodes, so that it reduces the number of rebroadcasts. In this paper, we propose a probabilistic approach that dynamically adjusts the rebroadcasting probability according to the distance between the sender and the receiver. While the rebroadcast probabilities of a mobile node close to sender will be set lower, the rebroadcast probabilities of a mobile node far away from sender wi1l be set to higher, The rebroadcast probability of a node wi1l be set according to the distance from sender. We evaluate the performance of proposed approach by comparing it with flooding as well as a fixed probabilistic broadcast approach. Simulation results showed that the performance of proposed scheme outperforms by about $70\%$ than flooding scheme and outperforms by about $20\%$ than fixed probabilistic scheme.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2012년도 춘계학술발표대회논문집
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• pp.190-192
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• 2012

Vehicular Ad hoc Networks (VANETs) is the new wireless networking concept of mobile ad hoc networks in research community. Routing in vehicular is a major challenge and research area. The majority of current routing algorithms for VANETs utilize indirect metrics to select the next hop and produce optimal node path. In this paper, we propose a distance and angle based routing algorithm for VANETs, which combines a distance approach with an angle based geographical strategy for selecting the next hop, with the purpose of using direct metrics to build a optimal node route. The proposed algorithm has better performance than the previous scheme.

• 한국컴퓨터정보학회논문지
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• 제21권4호
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• pp.81-88
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• 2016

The optimal solution of quadratic assignment problem (QAP) cannot get done in polynomial time. This problem is called by NP-complete problem. Therefore the meta-heuristic techniques are applied to this problem to get the approximated solution within polynomial time. This paper proposes an algorithm for a random type QAP, in which the instance of two nodes are arbitrary. The proposed algorithm employs what is coined as a max flow-min distance rule by which the maximum flow node is assigned to the minimum distance node. When applied to the random type QAP, the proposed algorithm has been found to obtain optimal solutions superior to those of the genetic algorithm.

• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.142-147
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• 2018

We present a practical design algorithm for quantizers at nodes in distributed systems in which each local measurement is quantized without communication between nodes and transmitted to a fusion node that conducts estimation of the parameter of interest. The benefits of vector quantization (VQ) motivate us to incorporate the VQ strategy into our design and we propose a low-complexity design technique that seeks to assign vector codewords into sets such that each codeword in the sets should be closest to its associated local codeword. In doing so, we introduce new distance metrics to measure the distance between vector codewords and local ones and construct the sets of vector codewords at each node to minimize the average distance, resulting in an efficient and independent encoding of the vector codewords. Through extensive experiments, we show that the proposed algorithm can maintain comparable performance with a substantially reduced design complexity.

• 한국화재소방학회논문지
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• 제23권6호
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• pp.75-81
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• 2009

화재감지 데이터 전송에 있어서 기존의 유선기반의 전송선로보다 설치에 용이하고 다양한 정보수집에 효율성이 높은 무선기반의 USN망이 대안으로 제시되고 있다. 그러나 USN망 구축에 사용되는 센서노드의 무선전송거리 및 정보의 신뢰성에 대해서는 문제점이 대두되고 있다. 본 연구에서는 국제적 표준규격 지그비 프로토콜을 사용하여 센서노드를 구현하였다. 제안한 센서노드 사이에 전송거리 및 수신된 정보의 신뢰성을 검증하고자 테스트 전압 3V와 5V를 센서노드 입력단자에 인가하고, 실내에서 10m씩 거리를 증가시켜 실험한 결과 최대 유효전송거리가 90m 내외임을 확인하였다. 또한, Mesh Routing 중계센서노드를 사용했을 때 전송거리에는 제한이 없었다. 제안한 센서노드로 USN망을 구축하고 실제 화재감지센서를 센서노드 입력단자에 연결하여 전송하였을 때 센서에서 직접측정 한 데이터와 USN망으로 전송하여 수집된 화재감지데이터가 잘 일치하였다. 따라서 제안한 센서노드의 화재감지정보 전송용 USN망 구축에 있어서 전송거리 및 정보의 신뢰성이 확인 되었다.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.333-343
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• 2009

Tactical Information Communication Network(TICN) is a concept-type integrated Military Communication system that enables precise command control and decision making by unifying the diversified military communication network and conveying diverse range of battle field information on real-time, at right place at right time. TICN is designed to advance into high speed, large capacity, long distance wireless relay transmission. To support mobility in battlefield environments, the application of Ad-hoc networking technology to its wireless communication has been examined. Ad-hoc network is consist of mobile nodes and nodes in the network depends on the cooperation of other nodes for forwarding of packets. In this context, some non-cooperating nodes may delay forwarding of packets or drop the packets. This may hamper the network as a whole and disrupt communication between the cooperating nodes. To solve this problem, we present a solution with a Node Weight Management Server(NWMS), which manages each node's weight according to its behavior in local area. When the NWMS detects misbehaving node, it increases the node's weight. If the node's weight exceeds a predefined threshold then the NWMS broadcasts the node's information into network to isolate the misbehaving node from the network. These mechanisms show that they are highly effective and can reliably detect a multitude of misbehaving node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권6호
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• pp.612-627
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• 2009

The high-level contribution of this paper is to illustrate the effectiveness of using graph theory tree traversal algorithms (pre-order, in-order and post-order traversals) to generate the chain of sensor nodes in the classical Power Efficient-Gathering in Sensor Information Systems (PEGASIS) data aggregation protocol for wireless sensor networks. We first construct an undirected minimum-weight spanning tree (ud-MST) on a complete sensor network graph, wherein the weight of each edge is the Euclidean distance between the constituent nodes of the edge. A Breadth-First-Search of the ud-MST, starting with the node located closest to the center of the network, is now conducted to iteratively construct a rooted directed minimum-weight spanning tree (rd-MST). The three tree traversal algorithms are then executed on the rd-MST and the node sequence resulting from each of the traversals is used as the chain of nodes for the PEGASIS protocol. Simulation studies on PEGASIS conducted for both TDMA and CDMA systems illustrate that using the chain of nodes generated from the tree traversal algorithms, the node lifetime can improve as large as by 19%-30% and at the same time, the energy loss per node can be 19%-35% lower than that obtained with the currently used distance-based greedy heuristic.

• 한국군사과학기술학회지
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• 제24권1호
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• pp.115-122
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• 2021

In this paper, we propose a dynamic slot allocation scheme to improve the slot utilization rate in tactical multi-hop networks in which the channel condition varies due to node movements. The proposed scheme takes advantage of the fact that nodes that are more than three hops apart can use the same slot simultaneously. The frame is divided into two parts: the control period and the data period. To know the available slot information within two-hop distance, the node exchanges a slot allocation information with one-hop neighbors during the control period. The node can get the information on idle slots that are not used within two-hop distance but assigned already to other nodes that are more than three-hop away. The identified idle slot can be used by the node, which increases the slot utilization rate. The performance analysis results of the proposed scheme show that it increases the slot utilization rate sufficiently despite the overhead of the control period in the multi-hop networks of the future soldier system.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.39-45
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• 2014

This paper proposes an architecture of a sensor network for gathering data under a powerful beam cluster tree architecture. This architecture is used when there is a need to gather data from sensor node where there is no sink node connected to an existing network, or it is required to get a series of data specific to an event or time. The transmit distance of the beam signal is longer than that of the usual sensor node. The nodes of the network make a tree network when receiving a beam message transmitting from the powerful root node. All sensor nodes in a sink tree network synchronize to the superframe and know exactly the sequence value of the current superframe. When there is data to send to the sink node, the sensor node sends data at the corresponding allocated channel. Data sending schemes under the guaranteed time slot are tested and the delay and jitter performance is explained.

• 한국통신학회논문지
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• 제34권10A호
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• pp.784-795
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• 2009

주변 상황을 인지하여 사용자가 이를 적절히 사용할 수 있도록 하는 무선 센서 네트워크에서 각 센서 노드의 정확한 위치 추정은 매우 중요하다. 멀티홉 기반 위치 추정기법은 다수의 저전력 노드로 구성된 센서네트워크에 적합한 방법 중의 하나로 고려되고 있다. 하지만 일부 지역에서 노드들이 위치하지 않는 홀이 형성되는 경우에는 위치추정 오차가 허용한계 이상으로 크게 증가할 수 있다. 네트워크는 이러한 홀을 감지하고 그 영향을 최소화함으로써 오차를 가급적 억제할 수 있어야 한다. 본 논문에서는 비거리기반 알고리즘의 하나인 DV(Distance Vector)-hop이 갖고 있는 홀에서의 큰 위치 추정오류를 해결할 수 있는 새로운 위치 추정기법을 제안한다. 제안된 기법은 이웃노드와의 관계를 통해 홀을 탐지하는 방법, 전파반경을 가상으로 홉을 나누어 예상위치의 정확도를 높이는 방법, 그리고 노드가 예상위치를 추정할 때 신뢰도가 적은 기준노드(anchor)를 배제하는 방법으로 나눌 수 있다. 시뮬레이션을 통해 본 논문에서 제안된 방법이 흘 검출을 통해 정밀한 위치 추정이 기존의 DV-hop에 비해 향상된 성능을 나타냄을 보인다.