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Now showing 1 - 10 of 16

A robust user authentication scheme with self-certificates for wireless sensor networks
(2011-08-01)
Tseng, Huei-Ru
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Jan, Rong-Hong
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Yang, Wuu
;
資訊工程學系
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Department of Computer Science
User authentication is a critical part of security, along with confidentiality and integrity, for computer systems that allow legitimate users remote access over an open communication network. Recently, user authentication for wireless sensor networks (WSNs) has received considerable attention. We propose a robust user authentication scheme for WSNs. The scheme is based on elliptic-curve cryptosystems with self-certificates. The proposed scheme allows users to change their key pairs without interaction with a key distribution center (KDC). Moreover, the proposed scheme still works well even if the adversary captures t nodes out of n nodes in the WSNs. Security of the proposed scheme is modeled and analyzed with Petri nets. Our analysis shows that the proposed scheme can successfully defend some of the most notorious attacks, including replay attacks, forgery attacks, and node-capture attacks. Copyright (C) 2010 John Wiley & Sons, Ltd.
The Critical Grid Size and Transmission Radius for Local-Minimum-Free Grid Routing in Wireless Ad Hoc and Sensor Networks
(2010-12-01)
Yi, Chih-Wei
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Wan, Peng-Jun
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Su, Chao-Min
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Huang, Chen-Wei
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資訊工程學系
In grid routing, the plane is tessellated into equal-sized square cells. Two cells are called neighbor cells if they share a common edge, and two nodes are called routing neighbors if they are in neighbor cells and within each other's transmission range. If communication parties are in the same cell, packets can be transmitted directly; otherwise, packets are forwarded to routing neighbors that are in cells closer to destination cells. As a greedy strategy, grid routing suffers the existence of local minima at which no neighbor nodes exist for relaying packets. To guarantee deliverability, in this paper, we investigate two vital parameters of grid routing, called the grid size and the transmission radius. Assume that nodes are represented by a Poisson point process with rate n over a unit-area square, and let l denote the grid size and r the transmission radius. First, we show that if l = root beta ln n/n for some constant beta and r = root 5l, then beta = 1 is the threshold for deliverability. In other words, there almost surely do not exist local minima if beta > 1 and there almost surely exist local minima if beta < 1. Next, for any given beta > 1, we give sufficient and necessary conditions to determine the critical transmission radius (CTR) for deliverability. Then, we show that as beta congruent to 1.092, the CTR r congruent to 2.09 root ln n/nis the minimum over all beta > 1. Simulation results are given to validate this theoretical work.
iPCA: an integration information system for patient controlled analgesia using wireless techniques
(2013)
Yang, Shu-Fen
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Ku, Tien-Hsiung
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Jeng, Andy An-Kai
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Jan, Rong-Hong
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Tseng, Yu-Chee
Recently, pain management has become an important aspect of medical care. Patient Controlled Analgesia (PCA) is a particularly effective and flexible treatment that allows patients to adjust the dosages of the analgesics that control their pain after surgery. However, PCA requires manual operation for sustained attention, and should be analysed with other pathology information for synergic usage. In this paper, we propose an integrated information system for pain management, called Integrated Patient Controlled Analgesia (iPCA). The system integrates various PCA-related devices by wireless techniques to provide real-time information for medial staffs, and offer more efficient and convenient pain control for both in-hospital and at-home patients. To evaluate our system, we have developed a prototype and conducted a series of field trails at a large private hospital in southern Taiwan. The results show that the iPCA system indeed works well with patients, and can provide better post-operative pain control by efficiently collecting PCA usage information.
A lightweight, self-adaptive lock gate designation scheme for data collection in long-thin wireless sensor networks
(2013-01-01)
Wang, You-Chiun
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Chuang, Che-Hsi
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Tseng, Yu-Chee
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Shen, Chien-Chung
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資訊工程學系
Constrained by the physical environments, the long-thin topology has recently been promoted for many practical deployments of wireless sensor networks (WSNs). In general, a long-thin topology is composed of a number of long branches of sensor nodes, where along a branch each sensor node has only one potential parent node toward the sink node. Although data aggregation may alleviate excessive packet contention, the maximum payload size of a packet and the dynamically changing traffic loads may severely affect the amount of sensor readings that may be collected along a long branch of sensor nodes. In addition, many practical applications of long-thin WSNs demand the exact sensor readings at each location along the deployment areas for monitoring and analysis purposes, so sensor readings may not be aggregated when they are collected. This paper proposes a lightweight, self-adaptive scheme that designates multiple collection nodes, termed lock gates, along a long-thin network to collect sensor readings sent from their respective upstream sensor nodes. The self-adaptive lock gate designation scheme balances between the responsiveness and the congestion of data collection while mitigating the funneling effect. The scheme also dynamically adapts the designation of lock gates to accommodate the time-varying sensor reading generation rates of different sensor nodes. A testbed of 100 Jennic sensor nodes is developed to demonstrate the effectiveness of the proposed lock gate designation scheme. Copyright (c) 2011 John Wiley & Sons, Ltd.
Energy-Aware Set-Covering Approaches for Approximate Data Collection in Wireless Sensor Networks
(2012-11-01)
Hung, Chih-Chieh
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Peng, Wen-Chih
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Lee, Wang-Chien
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資訊工程學系
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Department of Computer Science
To conserve energy, sensor nodes with similar readings can be grouped such that readings from only the representative nodes within the groups need to be reported. However, efficiently identifying sensor groups and their representative nodes is a very challenging task. In this paper, we propose a centralized algorithm to determine a set of representative nodes with high energy levels and wide data coverage ranges. Here, the data coverage range of a sensor node is considered to be the set of sensor nodes that have reading behaviors very close to the particular sensor node. To further reduce the extra cost incurred in messages for selection of representative nodes, a distributed algorithm is developed. Furthermore, maintenance mechanisms are proposed to dynamically select alternative representative nodes when the original representative nodes run low on energy, or cannot capture spatial correlation within their respective data coverage ranges. Using experimental studies on both synthesis and real data sets, our proposed algorithms are shown to effectively and efficiently provide approximate data collection while prolonging the network lifetime.
Mobility management algorithms and applications for mobile sensor networks
(2012-01-01)
Wang, You-Chiun
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Wu, Fang-Jing
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Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Wireless sensor networks (WSNs) offer a convenient way to monitor physical environments. In the past, WSNs are all considered static to continuously collect information from the environment. Today, by introducing intentional mobility to WSNs, we can further improve the network capability on many aspects, such as automatic node deployment, flexible topology adjustment, and rapid event reaction. In this paper, we survey recent progress in mobile WSNs and compare works in this field in terms of their models and mobility management methodologies. The discussion includes three aspects. Firstly, we discuss mobility management of mobile sensors for the purposes of forming a better WSN, enhancing network coverage and connectivity, and relocating some sensors. Secondly, we introduce path-planning methods for data ferries to relay data between isolated sensors and to extend a WSN's lifetime. Finally, we review some existing platforms and discuss several interesting applications of mobile WSNs. Copyright (C) 2010 John Wiley & Sons, Ltd.
Optimal Number of Clusters in Dense Wireless Sensor Networks: A Cross-Layer Approach
(2009-02-01)
Wang, Li-Chun
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Wang, Chung-Wei
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Liu, Chuan-Ming
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電信工程研究所
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Institute of Communications Engineering
Cluster-based sensor networks have the advantages of reducing energy consumption and link-maintenance cost. One fundamental issue in cluster-based sensor networks is determining the optimal number of clusters. In this paper, we suggest a physical (PRY)/medium access control (MAC)/network (NET) cross-layer analytical approach for determining the optimal number of clusters, with the objective of minimizing energy consumption in a high-density sensor network. Our cross-layer design can incorporate many effects, including lognormal shadowing and a two-slope path loss model in the PRY layer, various MAC scheduling, and multihop routing schemes. Compared with the base-line case with one cluster per observation area (OA), a sensor network with the proposed optimal number of clusters can reduce the energy consumption by more than 80% in some cases. We also verify by simulations that the analytical optimal cluster number can still effectively function, regardless of the different densities of sensors in various OAs.
Distributed clustering algorithms for data-gathering in wireless mobile sensor networks
(2007-11-01)
Liu, Chuan-Ming
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Lee, Chuan-Hsiu
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Wang, Li-Chun
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交大名義發表
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National Chiao Tung University
One critical issue in wireless sensor networks is how to gather sensed information in an energy-efficient way since the energy is a scarce resource in a sensor node. Cluster-based architecture is an effective architecture for data-gathering in wireless sensor networks. However, in a mobile environment, the dynamic topology poses the challenge to design an energy-efficient data-gathering protocol. In this paper, we consider the cluster-based architecture and provide distributed clustering algorithms for mobile sensor nodes which minimize the energy dissipation for data-gathering in a wireless mobile sensor network. There are two steps in the clustering algorithm: cluster-head election step and cluster formation step. We first propose two distributed algorithms for cluster-head election. Then, by considering the impact of node mobility, we provide a mechanism to have a sensor node select a proper cluster-head to join for cluster formation. Our clustering algorithms will achieve the following three objectives: (1) there is at least one cluster-head elected, (2) the number of cluster-heads generated is uniform, and (3) all the generated clusters have the same cluster size. Last, we validate our algorithms through an extensive experimental analysis with Random Walk Mobility (RWM) model, Random Direction Mobility (RDM) model, and a Simple Mobility (SM) model as well as present our findings. (C) 2007 Elsevier Inc. All rights reserved.
Processing k nearest neighbor queries in location-aware sensor networks
(2007-12-01)
Xu, Yingqi
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Fu, Tao-Yang
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Lee, Wang-Chien
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Winter, Julian
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交大名義發表
Efficient search for k nearest neighbors to a given location point (called a KNN query) is an important problem arising in a variety of sensor network applications. In this paper, we investigate in-network query processing strategies under a KNN query processing framework in location-aware wireless sensor networks. A set of algorithms, namely the geo-routing tree, the KNN boundary tree and the itinerary-based KNN algorithms, are designed in accordance with the global infrastructure-based, local infrastructure-based and infrastructure-free strategies, respectively. They have distinctive performance characteristics and are desirable under different contexts. We evaluate the performance of these algorithms under several sensor network scenarios and application requirements, and identify the conditions under which the various approaches are preferable. (C) 2007 Elsevier B.V. All rights reserved.
Hybrid address configuration for tree-based wireless sensor networks
(2008-06-01)
Wong, Yung-Chang
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Wang, Jui-Tang
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Chang, Nai-Hsin
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Liu, Ho-Han
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Tseng, Chien-Chao
This letter proposes a new scheme to alleviate the issue on address acquisition failure in wireless sensor networks (WSNs). The basic idea is to use a hierarchical address structure to make the proposed scheme less susceptible to physical distribution of WSN devices. Simulation results show that the new scheme significantly reduces the failure probability.

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