Kun-Hsien Lu

Feng Chia University, 臺中市, Taiwan, Taiwan

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Publications (9)2.74 Total impact

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    ABSTRACT: Multicast in MANETs is an important issue, and most of existing multicast schemes are designed for networks with only bidirectional links and thus may become malfunction in networks with unidirectional links. In this work, we exploit unidirectional links and employ the clustering technique to design an efficient multicast scheme with asymmetric link support in MANETs. By detecting and utilising unidirectional links, the performance of multicasting in MANETs with unidirectional links is improved. Simulation results demonstrate that the proposed scheme achieves higher delivery ratio and incurs relatively moderate control overhead with respect to that of ODMRP and ODMRP-ASYM.
    International Journal of Ad Hoc and Ubiquitous Computing 05/2012; 9(3):171-183. · 0.51 Impact Factor
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    ABSTRACT: Data gathering is an essential operation in wireless sensor networks. For periodic data gathering applications, each sensor node has data that must be sent to a distant base station in a round of communication. Due to the limited battery power of sensor nodes, each sensor node transmitting its sensed data to the base station directly significantly consumes its energy. This work presents a hierarchical ring-based data gathering (HRDG) scheme for dense wireless sensor networks. A hierarchical grid structure is constructed, and only some sensor nodes are elected as grid heads for gathering data, subsequently reducing the total energy consumption per round. Grid heads are then organized into hierarchical rings to decrease the transmission delay of a round. The proposed HRDG scheme focuses on reducing the energy × delay cost in a round of data gathering. Moreover, the energy × delay cost of HRDG is analyzed. Simulation results indicate that the proposed HRDG scheme outperforms other data gathering schemes in terms of the number of rounds, the energy × delay cost and coverage ratio.
    Wireless Personal Communications 05/2012; 64(2). · 0.43 Impact Factor
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    ABSTRACT: This study proposes an energy-efficient data reporting scheme that supports sink mobility in Object Tracking Sensor Networks (OTSN). To achieve energy efficiency, the proposed scheme presents an active node selection and scheduling method to save and balance the energy consumption among nodes based on a virtual grid structure. In addition, the proposed scheme develops an elegant weight function associated with active nodes, allowing active nodes to forward data to the mobile sink efficiently. This study also proposes an object tracking method. Simulation results show that the proposed scheme outperforms TNT and SNEM in terms of the energy consumption and average path length.
    International Journal of Ad Hoc and Ubiquitous Computing 01/2012; 10(3). · 0.51 Impact Factor
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    ABSTRACT: In most studies of wireless sensor networks (WSNs), sensor nodes and sinks are typically stationary. However, mobile sinks are required in various applications of real-life environments, and delivering sensed data to mobile sinks using ordinary routing protocols is very inefficient. Multicasting is an important process in the minimization of the number of transmissions in WSNs. Since sensor nodes have limited resources, many studies have focused on how to send data to specific receivers efficiently. This work presents a grid-based hierarchical multicast (HM) routing protocol for WSNs with mobile sinks. Location servers (LSs) are adopted to manage the information about the locations of receivers and then a multicast tree is constructed distributively to reduce the update cost and energy consumed by sink mobility. The multicast tree can be shared by multiple sources, reducing the path construction overhead. Furthermore, effective maintenance mechanisms that make the multicast tree more stable and robust are presented. Finally, the performance of the proposed HM is investigated by simulation. Simulation results demonstrate that the proposed protocol has a lower energy consumption and higher multicast efficiency than distributed multicast routing protocol (DMRP) and hierarchical geographic multicast routing (HGMR), especially when many sources and receivers are involved. Copyright © 2010 John Wiley & Sons, Ltd.
    Wireless Communications and Mobile Computing 01/2012; 12:71-84. · 0.86 Impact Factor
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    ABSTRACT: A mobile ad hoc network (MANET) is a distributed wireless network. The characteristics such as free mobility, self configuration, and fast deployment make MANETs suitable for various tasks. Multicasting can efficiently support a variety of applications and services. Most of existing multicast routing protocols in MANETs consider only one source in a multicast group and become inefficient when the protocol is extended to multi-source multicasting. In this paper, we propose a cluster-based multi-source multicast routing protocol to provide efficient multicasting in the multi-source multicast environment. The proposed shared forwarding cluster and cluster-based routing preserve forwarding efficiency as well as robustness. Simulation results show that the proposed protocol maintains the delivery ratio without losing efficiency in the multi-source multicast environment. KeywordsMobile ad hoc networks–Multicasting–Routing–Multi-source multicasting–Cluster
    Wireless Personal Communications 03/2011; 57(2):255-275. · 0.43 Impact Factor
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    ABSTRACT: Object tracking is an important application in wireless sensor networks (WSNs). However, most of researches focus on how to track mobile objects accurately and do not consider data reporting, especially when sinks move arbitrarily in the sensor field. In this paper, we propose an efficient data reporting method for object tracking in WSNs with mobile sinks. In our network environment, the sensor field is divided into several grids. Only some nodes are elected as active nodes for tracking the object and reporting data, the others are in sleep mode for saving energy. Moreover, a simple scheduling is given to balance the energy consumption of nodes. To guide the current position of the sink and reduce the update cost as the sink moves, we design an elegant weight function for active nodes. By the weight function, the tracking data can be forwarded to the mobile sink efficiently. In addition, we also propose a simple object tracking method in which an object can be detected by two or more active nodes with tracking flags. Simulation results show that our proposed method outperforms than TNT and SNEM in terms of the energy consumption and average hop counts.
    Communications, 2008. APCC 2008. 14th Asia-Pacific Conference on; 11/2008
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    ABSTRACT: Purpose – This paper aims to balance the total energy consumption and the transmission delay for data gathering application in wireless sensor networks. Design/methodology/approach – This paper adopts a hierarchical grid structure to reduce the total energy consumption, and utilizes a tree architecture to decrease the transmission delay. Findings – In the results, the proposed method performs better, in terms of the number of rounds and the energy?×?delay cost, than other data gathering protocols with different network sizes and node densities. Moreover, the proposed method also provides good coverage preservation in different environments. Research limitations/implications – In this paper, sensor nodes are assumed to be uniformly distributed, homogenous, energy-constrained. Each sensor node also has ability to adjust its transmission power. For practice, the proposed method needs location information of sensor nodes and the radio interference between sensor nodes during data transmissions should be considered. Practical implications – The proposed method can significantly reduce the delay time and may be suitable for real-time data gathering applications. Originality/value – This paper combines hierarchical grid structure with tree architecture to minimize the energy?×?delay cost for data gathering application.
    International Journal of Pervasive Computing and Communications 01/2008; 4:299-321.
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    ABSTRACT: Data gathering is an important operation in wireless sensor networks. Due to the limited battery power, sensor nodes consume significant energy and drain out of it quickly if each node transmits its sensed data directly to a distant base station, even though the delay time is minimized in a round of communication. Hence, there is a trade-off between minimizing both of the energy consumed by sensor nodes and the delay time, then the overall cost is defined as the energy × delay cost. In this paper, we propose an Efficient Grid-based Data Gathering (EGDG) scheme which adopts a hierarchical grid structure and constructs cycles by connecting heads in each order of the hierarchy. Data transmissions move toward a leader from two starter nodes simultaneously in each cycle. The objective of EGDG is to achieve a better result for the energy × delay cost comparing to other schemes, and also to accomplish significant coverage-preserving at the same time. Simulation results show that EGDG outperforms than LEACH and PEGASIS in terms of rounds, the energy × delay cost and coverage-preserving.
    Ubiquitous Intelligence and Computing, 4th International Conference, UIC 2007, Hong Kong, China, July 11-13, 2007, Proceedings; 01/2007
  • Shiow-Fen Hwang, Kun-Hsien Lu, Chyi-Ren Dow
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    ABSTRACT: Services providing between clients and servers is an important issue in mobile ad hoc networks. Since services become complex and various increasingly, current group communication mechanisms like multicast or anycast do not completely support some kind of services such as NTP (Network Time Protocol) or threshold cryptography, etc. Manycast is a novel group communication paradigm in which a client communicates simultaneously with a number k of m equivalent servers in a group and can support these kinds of services. In this paper, we present a grid-based manycast scheme that employs manycast level calculation algorithm to predict a manycast region and uses an efficient grid broadcast method to support manycast delivery for large ad hoc networks. Simulation results show that our scheme not only reduces significantly more manycast overhead and the average number of replied servers but also keeps high manycast successful rate.
    Information Networking, Advances in Data Communications and Wireless Networks, International Conference, ICOIN 2006, Sendai, Japan, January 16-19, 2006, Revised Selected Papers; 01/2006