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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Cheng Wang Changjun Jiang Yunhao Liu Xiang-Yang Li Shaojie Tang Huadong Ma Key Laboratory of Embedded System and Service Computing Ministry of Education Shanghai China Department of Computer Science University of Tongji Shanghai China Department of Computer Science and Engineering Hong Kong University of Science and Technology Hong Kong China TNLIST School of Software Tsinghua University China Department of Computer Science Illinois Institute of Technology Chicago IL USA Department of Computer Science Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781424499199

A critical function of wireless sensor networks (WSNs) is data gathering. While, one is often only interested in collecting a relevant function of the sensor measurements at a sink node, rather than downloading all the data from all the sensors. This paper studies the capacity of computing and transporting the specific functions of sensor measurements to the sink node, called aggregation capacity, for WSNs. It focuses on random WSNs that can be classified into two types: random extended WSN and random dense WSN. All existing results about aggregation capacity are studied for dense WSNs, including random cases and arbitrary cases, under the protocol model (ProM) or physical model (PhyM). In this paper, we propose the first aggregation capacity scaling laws for random extended WSNs. We point out that unlike random dense WSNs, for random extended WSNs, the assumption made in ProM and PhyM that each successful transmission can sustain a constant rate is over-optimistic and unpractical due to transmit power *** derive the first result on aggregation capacity for random extended WSNs under the generalized physical model. Particularly, we prove that, for the type-sensitive perfectly compressible functions and type-threshold perfectly compressible functions, the aggregation capacities for random extended WSNs with n nodes are of order Θ ((log n) -β/2-1 ) and Θ (((log n) -β/2 )/(log log n)), respectively, where β >; 2 denotes the power attenuation exponent in the generalized physical model.

关键词： Wireless sensor networks Signal to noise ratio Interference Throughput Lattices Routing PROM

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General capacity scaling of wireless networks

General capacity scaling of wireless networks

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Cheng Wang Changjun Jiang Xiang-Yang Li Shaojie Tang Panlong Yang Key Laboratory of Embedded System and Service Computing Ministry of Education Shanghai China Department of Computer Science University of Tongji Shanghai China Department of Computer Science Illinois Institute of Technology Chicago IL USA TNLIST School of Software Tsinghua University China People''s Liberation Army University of Science and Technology China

We study the general scaling laws of the capacity for random wireless networks under the generalized physical model. The generality of this work is embodied in three dimensions denoted by (λ ∈ [1, n], n d ∈ [1, n], n s ∈ (1, n]). It means that: (1) We study the random network of a general node density λ ∈ [1, n], rather than only study either random dense network (RDN, λ = n) or random extended network (REN, λ = 1) as in the literature. (2) We focus on the multicast capacity to unify unicast and broadcast capacities by setting the number of destinations for each session as a general value n d ∈ [1, n]. (3)We allow the number of sessions changing in the range n s ∈ (1, n], rather than assume that n s = Θ(n) as in the *** derive the general lower bounds on the capacity for the arbitrary case of (λ, n d , n s ). Particularly, we show that for the special cases (λ = 1, n d ∈ [1, n], n s = n) and (λ = n, n d ∈ [1, n], n s = n), our schemes achieve the highest multicast throughputs proposed in the existing works.

关键词： Roads Routing Throughput Lattices Schedules Mathematical model

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SelectCast: Scalable data aggregation scheme in wireless sensor networks

SelectCast: Scalable data aggregation scheme in wireless sen...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Cheng Wang Shaojie Tang Xiang-Yang Li Changjun Jiang Key Laboratory of Embedded System and Service Computing Ministry of Education Shanghai China Department of Computer Science University of Tongji Shanghai China Department of Computer Science Illinois Institute of Technology Chicago IL USA TNLIST School of Software Tsinghua University China

In this work, for a wireless sensor network (WSN) of n randomly placed sensors with node density λ ∈ [1, n], we study the tradeoffs between the aggregation throughput and gathering efficiency. The gathering efficiency refers to the ratio of the number of the sensors whose data have been gathered to the total number of sensors. Specifically, we design two efficient aggregation schemes, called single-hop-length (SLH) scheme and multiple-hop-length (MLH) scheme. By novelly integrating these two schemes, we theoretically prove that our protocol achieves the optimal tradeoffs, and derive the optimal aggregation throughput depending on a given threshold value (lower bound) on gathering efficiency. Particularly, we show that under the MLH scheme, for a practically important set of symmetric functions called perfectly compressible functions, including the mean, max, or various kinds of indicator functions, etc., the data from Θ(n) sensors can be aggregated to the sink at the throughput of a constant order Θ(1), implying that our MLH scheme is indeed scalable.

关键词： TV Wireless sensor networks Power capacitors Blogs Lattices

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Node localization in wireless Ad-Hoc networks using elastic force

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Ruan Jian Xue Bao/Journal of software 2011年第SUPPL. 1期22卷 23-31页

作者： Guan, Lu-Bin Wu, Xiao-Bing Chen, Gui-Hai Department of Computer Science and Technology Nanjing University Nanjing 210093 China State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210093 China

In wireless ad-hoc and sensor networks, localization is often viewed as one of the most significant problems. This study has designed a localization system that abstracts the distance of every neighbor nodes pair as the length of a spring between them and then attains the final position information through spring updating. Compared with other spring-based localization methods, this system converges faster because it uses a displacement vector that has proven to be more efficient in updating coordinates. The system performs better than range-free localization methods even under high ranging error. © Copyright 2011, Editorial department of Journal of software. All rights reserved.

关键词： Elasticity

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Polynomial-time hierarchy of computable reals

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Journal of Computational Information Systems 2011年第4期7卷 1108-1115页

作者： Chen, Qingliang Su, Kaile Wu, Lijun Department of Computer Science Jinan University Guangzhou 510632 China Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai China Key Laboratory of High Confidence Software Technologies Ministry of Education Peking University Beijing China Institute for Integrated and Intelligent Systems Griffith University Brisbane Australia School of Computer Science and Engineering University of Electronic Science and Technology Chengdu 610054 China

In mathematics, various representations of real numbers have been investigated and all these representations are proved to be mathematically equivalent. Furthermore, it is known that all effective versions of these representations lead to the same class of "computable real numbers". However, when subrecursive (such as primitive recursive) is taken into account, these representations can lead to different notions of "computable real numbers". This paper will look into the polynomial-time version of the problem for computable real numbers under different representations. We will summarize the known results to exhibit the comprehensive hierarchy they form. Our goal is to clarify systematically how the polynomial-time computability depends on the representations of the real numbers. Copyright © 2011 Binary Information Press.

关键词： Polynomial approximation

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Directional diagnosis for wireless sensor networks

Directional diagnosis for wireless sensor networks

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International Conference on Distributed Computing in Sensor Systems (DCOSS)

作者： Wei Gong Kebin Liu Yunhao Liu Xibin Zhao Ming Gu Tsinghua University Beijing Beijing CN Department of Computer Science Hong Kong University of Science and Technology Hong Kong China Key Laboratory of Information System Security of Ministry of Education TNLIST School of Software Tsinghua University China

Network diagnosis is crucial in managing a wireless sensor network (WSN) since many network-related faults, such as node and link failures, can easily happen. Diagnosis tools usually consist of two key components, information collection and root-cause deduction, while in most cases information collection process is independent with root-cause deduction. This results in either redundant information which might pose high communication burden on WSNs, or incomplete information for root-cause inference that leads false judgments. To address the issue, we propose DID, a directional diagnosis approach, in which the diagnosis information acquirement is guided by the fault inference process. Through several rounds of incremental information probing and fault reasoning, root causes of the network abnormalities with high credibility are deduced. We employ a node tracing scheme to reconstruct the topical topology of faulty regions and build the inference model accordingly. We implement the DID approach in our forest monitoring sensor network system, GreenOrbs. Experimental results validate the scalability and effectiveness of this design.

关键词： Network topology Probes Topology Wireless sensor networks Sensors Relays Probabilistic logic

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RASS: A real-time, accurate and scalable system for tracking transceiver-free objects

RASS: A real-time, accurate and scalable system for tracking...

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IEEE International Conference on Pervasive Computing and Communications (PerCom)

作者： Dian Zhang Yunhuai Liu Lionel M. Ni College of Software Shenzhen University China Department of Computer Science and Engineering Hong Kong University of Science and Technology Hong Kong China Shenzhen Institutes of Advanced Technology Chinese Academy and Sciences China Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiaotong University China

Transceiver-free object tracking is to trace a moving object without carrying any communication device in an environment where the environment is pre-deployed with some monitoring nodes. Among all the tracking technologies, RF-based technology is an emerging research field facing many challenges. Although we proposed the original idea, until now there is no method achieving scalability without sacrificing latency and accuracy. In this paper, we put forward a real-time tracking system RASS, which can achieve this goal and is promising in the applications like the safeguard system. Our basic idea is to divide the tracking field into different areas, with adjacent areas using different communication channels. So the interference among different areas can be prevented. For each area, three communicating nodes are deployed on the ceiling as a regular triangle to monitor this area. In each triangle area, we use a Support Vector Regression (SVR) model to locate the object. This model simulates the relationship between the signal dynamics caused by the object and the object position. It not only considers the ideal case of signal dynamics caused by the object, but also utilizes their irregular information. As a result it can reach the tracking accuracy to around 1m by just using three nodes in a triangle area with 4m in each side. The experiments show that the tracking latency of the proposed RASS system is bounded by only about 0.26s. Our system scales well to a large deployment field without sacrificing the latency and accuracy.

关键词： Accuracy Wireless communication Wireless sensor networks Interference Lead Synchronization Predictive models

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Strong Barrier Coverage Using Directional Sensors with Arbitrarily Tunable Orientations

Strong Barrier Coverage Using Directional Sensors with Arbit...

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International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Dan Tao Xu-Fei Mao Shao-Jie Tang Hai-Tao Zhang Hua-Dong Ma Hai-Jiang Xie School of Electronic and Information Engineering Beijing Jiaotong University Beijing China Beijing Key Laboratory of Intelligent Telecommunication Software and Multimedia Beijing University슠of Posts and슠Telecommunications Beijing China Department of Computer Science Illinois Institute of Technology Chicago IL USA Department of Computer Science and Technology XiAn JiaoTong University XiAn China

Barrier coverage is an important problem for sensor networks to fulfill some given sensing tasks. Barrier coverage guarantees the detection of events happened crossing a barrier of sensors. In majority study of barrier coverage using sensor networks, sensors are assumed to have an isotropic sensing model. However, in many applications such as monitoring an area using video camera, the sensors have directional sensing model. In this paper, we investigate strong barrier coverage using directional sensors, where sensors have arbitrarily tunable orientations to provide good coverage. We investigate the problem of finding appropriate orientations of directional sensors such that they can provide strong barrier coverage. By exploiting geographical relations among directional sensors and deployment region boundaries, we first introduce the concept of virtual node to reduce the solution space from continuous domain to discrete domain. We then construct a directional barrier graph (DBG) to model this barrier coverage question such that we can quickly answer whether there are directional sensors' orientations that can provide strong barrier coverage over a given belt region. If the belt region is strong barrier covered, we then develop energy-efficient solutions to find strong barrier path(s) that will approximately minimize the total or the maximum rotation angles of all directional sensors. Extensive simulations are conducted to verify the effectiveness of our solution.

关键词： Sensors Belts Clocks Numerical models Educational institutions Cameras Complexity theory

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Extracting Semantic Subgraphs to Capture the Real Meanings of Ontology Elements

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Tsinghua science and technology 2010年第6期15卷 724-733页

作者：汪鹏徐宝文周毓明 School of Computer Science and Engineering Southeast University State Key Laboratory for Novel Software Technology Nanjing University Department of Computer Science and Technology Nanjing University

An element may have heterogeneous semantic interpretations in different ontologies. Therefore, understanding the real local meanings of elements is very useful for ontology operations such as querying and reasoning, which are the foundations for many applications including semantic searching, ontology matching, and linked data analysis. However, since different ontologies have different preferences to describe their elements, obtaining the semantic context of an element is an open problem. A semantic subgraph was proposed to capture the real meanings of ontology elements. To extract the semantic subgraphs, a hybrid ontology graph is used to represent the semantic relations between elements. An extracting algorithm based on an electrical circuit model is then used with new conductivity calculation rules to improve the quality of the semantic subgraphs. The evaluation results show that the semantic subgraphs properly capture the local meanings of elements. Ontology matching based on semantic subgraphs also demonstrates that the semantic subgraph is a promising technique for ontology applications.

关键词： ontology ontology graph semantic subgraph ontology matching

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The integration of skin color segmentation and self-adapted template matching for the robust face detection

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International Review on computers and software 2011年第5期6卷 795-805页

作者： Zhiwen, Wang Shao-Zi, Li Ying, Dai Cognitive Science Department Xiamen University Xiamen 361005 China Department of Computer and Engineering Guangxi University of Technology Liuzhou 545006 China Fujian Key Laboratory of the Brain-like Intelligent Systems Xiamen University Xiamen 361005 China Faculty of Software and Info. Science Iwate Pref. University Iwate Japan

In this paper, an approach of integrating skin color segmentation and self-adapted template matching for the robust face detection is proposed. According to the clustering properties of the skin color of human faces in the YCbCr color space, the regions which close to the skin color are separated from the image by using Gaussian mixture model in order to achieve the purpose of rapidly detecting the external face. The influence of the brightness on the detection of the human faces is eliminated by using the illumination compensation technology, and also the confusion of the regions with the closed skin color with the human face is overcome by the adaptive template matching. Computation in the matching process is reduced by using the second matching algorithm. Experimental results show that proposed method can rapidly detect the human faces from a variety of images, while those detected faces include several of facial images with the different sizes, poses, races under the different illumination conditions. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.

关键词： Template matching

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