Pervasive ComputingPervasive Computing 研究群研究群研究能量與研發成果研究能量與研發成果

Members and Research Members and Research DirectionsDirections

– Sensor networksSensor networks 曾煜棋、王國禎、黃俊龍曾煜棋、王國禎、黃俊龍

– WLANWLAN 曾煜棋、王國禎曾煜棋、王國禎

– Mesh networksMesh networks 曾煜棋、王國禎曾煜棋、王國禎

– Mobile peer-to-peer service gridMobile peer-to-peer service grid 邵家健、彭文志邵家健、彭文志

– Ubiquitous sensor/actuator infrastructureUbiquitous sensor/actuator infrastructure 邵家健邵家健

– Sensor data management and miningSensor data management and mining 彭文志彭文志、、黃俊龍黃俊龍

研發成果研發成果

Step 1. Select one hop neighbor nodes closer to the anchor

Step 2. Choose the node with the maximum energy level from the

selected nodes

Energy consumption vs. number of nodes

Latency per packet vs. number of nodes.

A Cluster-based Energy Efficient Routing A Cluster-based Energy Efficient Routing Algorithm in Mobile Wireless Sensor NetworksAlgorithm in Mobile Wireless Sensor Networks

An illustration of dwDVS

Effect of WCET/BCET ratio onenergy consumption

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Static laEDF DRA dwDVS Bound

Effect of worst-case utilization onenergy consumption

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Worst-case utilization (%)CPU

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Static laEDF DRA dwDVS Bound

A Deferred-Workload-based Dynamic Voltage Scaling Algorithm for Hard Real-Time Systems

Power saving mechanism in PSM-V

VoIP over WLANs system architecture

A Power Saving MAC Mechanism for VoIP over IEEE 802.11e WLANs

Polling scheme comparison

Proposed power-efficient polling scheme

SchemeRound-robin polling (RRP) scheme [8]

On-demand polling (ODP) scheme [4]

Power-Efficient Polling (PEP) scheme

(Proposed)

Characteristics of polling scheme

Static Dynamic Dynamic

Complexity of implementation

Easy Medium Medium

Normalized power consumption

Highest Medium Lowest

Aggregate throughput Higher LowerAlmost the same as

RRP

Average end-to-end delay Lowest Highest Medium

PIFS SIFS SIFS SIFS SIFS PIFS

Beacon QoS CF-Poll QoS

NullData

ACK

TXOP 1

Controlled Access Phase (CAP)

…..

QAP

QSTA

QSTA 2

.... Beacon....

ContentionPeriod (CP)

CAP

....

QSTA 1QSTA 2

QSTA 1

A Power-Efficient MAC Protocol for VoIP Traffic over IEEE 802.11e WLANs

Emergency Guiding System by Wireless Sensor Networks

Physical layer and Data link layer

TreeReconstruction

Deployment GUINetworkinitialization

Guidanceinitialization

Query

Sensor taskGuidance

service

Symmetric linkdetection

Tree maintenance

HELLO Report EMG

Application-level UI

Application layer

Network layer

Sensors partUsers part

Emergency Guiding Scheme

Water toward low spot Hazardous regions Distributed adjust weight to find escape path

Protocol StackMonitoring Guidance Interface

Tree Reconstruction Support reliable reporting scheme, when emergencies occur Dynamically recover the failure links Low cost and quick convergence

The Deployment and Dispatch Issues of Mobile Wireless Sensor Networks

1 234

Indoor Sensor Deployment• Characteristics - Arbitrary-shaped obstacles in the field - Arbitrary relationships of rc and rs - Fewer sensors required for deployment - Sensor dispatch to reduce deployment cost >> Max-weight max-match problem

obstacle

rcrsrs3

rc

rs

k-covered Sensor Deployment• Characteristics - Deployment for multi- level coverage WSN - Arbitrary relationships of rc and rs - Fewer sensors required for deployment - Distributed sensor dispatch algorithms >> greedy-based & pattern-based schees

Multi-type Sensor Dispatch•Problem - How to dispatch sensors so that events can be detected on time & total energy consumption can be minimized

a

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{a, b}

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{b, c}

{a, c}

{a, b}

Event “a” is not detected All events are detected

iMouse System• Characteristics - Implementation of “mobile” sensor - Provide WSN-based surveillance service - Combine adv. of both WSN and traditional surveillance systems

Lego car

WebCam

StargateWLAN card

Mobile sensor

Static sensor

Coverage of a Wireless Sensor Network Coverage of a Wireless Sensor Network without Location Informationwithout Location Information

• Goal– Determine whether the sensing region of each sensor is sufficiently

covered by k other nodes without location information– Provide comparable results to the location-based algorithm

S0

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Real Network

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Location Management for Object Tracking Location Management for Object Tracking in Wireless Sensor Networksin Wireless Sensor Networks

Two Location Management Schemes

Tree-based location management scheme that consists of(1) The update and query mechanisms(2) The tree construction algorithms

The Beacon Movement Detection Problem in Wireless Sensor Networks for

Localization Applications

•System model:

If beacon sensors are moved by accident, the localization error will be increased seriously.

A Noise-Tolerant Indoor Positioning Method by Signal Scrambling

Design Guidelines:Design Guidelines:• Propose a tracking scheme to improve accuracy of various localization algorithmsPropose a tracking scheme to improve accuracy of various localization algorithms• Temporal dependency is used to enlarge real-time sample spaceTemporal dependency is used to enlarge real-time sample space• Spatial dependency is used to select a better locationSpatial dependency is used to select a better location

System Flow Viterbi-like Location Selection Module

Quick Convergecast in ZigBee/IEEE 802.15.4 Tree-Based Wireless Sensor Networks

Problem formulation• Convergecast is a fundamental operation i

n wireless sensor networks• This paper defines a minimum delay beac

on scheduling problem for quick convergecast in ZigBee/IEEE 802.15.4 tree-based wireless sensor networks

• We prove that this problem is NP-complete.

Current results• Our formulation is compliant with the low-

power design of IEEE 802.15.4.• We propose

– Optimal solutions for special cases

– Heuristic algorithms for general cases

• Simulation results show that the proposed algorithms can indeed achieve quick convergecast

Energy Efficient Algorithms for Mobile Sensors

• Impact of load balancing

• Sensor dispatching problem in collaborative network

100 100 100

85 45 95

Total :225Usage:75

70 70 70

Total :210Usage:90

ROUND 1

70 0 85 20 0 40

Total :155Usage:70

50 40 40

Total :130Usage:80

Total :60Usage:95

40 20 30

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ROUND 2 ROUND 3

Total:300

1. Always minimize the total cost

2. Consider load balancing issue

This sensor is dead!

Remaining sensors bear heavier load

Static sensors detect the event

Mobile sensors achieve advanced

detection

Exploiting Data Coverage for Approximate Query Processing in Wireless Sensor

Networks• Data Coverage

useruser

sinksink

SELECT AVG(S.Temperature)FROM Sensor SWHERE S.Location IN region

query

approximate answer

approximate answer

• Sensors with correlated readings are clustered together.

• We pick a representative out from each cluster.

• The representatives will answer queries; the other sensors only sense the environment and do not respond.

• Data-Covering Problem

Input: set of sensors S, clustering criteria ε

Output: set of representatives R

Constraint: minimize the size of R while keeping every sensor is clustered.

Filtering Faulty Readings to Improve Data Accuracy in Sensor Networks

StableNo cheat

x

x

o

o

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v.s.

Traitor

Traitor

PatriotUnstablecheated

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• Byzantine Problem (trust degree is equal)

Hybrid Program Verification for AFSM Based Sensory-Motor Control

Cleaning Crew Interacting AFSM Modules

Transform Experiment from continuous domain to discrete domain

•Use Binary Decision Diagram (BDD) verification technique (for program) to check automatic robot behaviors

•Based on Rodney Brooks’ Augmented FSM(AFSM) model

•Described by UNITY specification language

•Can be verified by BDD-based model checker

•Verify obstacle avoidance behaviors of roving robot

Resilient Application Layer Multicast Tailored for dynamic Peers with Asymmetric

Connectivity•Application Layer Multicast (ALM)

•Minimize and equalize transport latency to all peers

•Dynamic Peer Behaviors

•Unpredictable join/leave

•Asymmetric connectivity

•Limited upstream bandwidth

Application layer Multicast System

Multiple Multicast Trees

Demand of Helper

Major ProjectsMajor Projects

ZyXEL Inc.: “802.11eZyXEL Inc.: “802.11e 無線網路下的傳輸品質與快速換手之研究 無線網路下的傳輸品質與快速換手之研究 (QoS and Fast Ha(QoS and Fast Handover in 802.11e WLAN)”, 2005.03-2006.02.ndover in 802.11e WLAN)”, 2005.03-2006.02.

工研院工研院 // 學研計畫學研計畫 : "Communication Protocols for Wireless Access Networks". (2: "Communication Protocols for Wireless Access Networks". (2005.01~2005.12)005.01~2005.12)

後卓越計劃後卓越計劃 (Program for Promoting Academic Excellence of Universities II), NSC: (Program for Promoting Academic Excellence of Universities II), NSC: "Advanced Technologies and Applications for Next Generation Information Net"Advanced Technologies and Applications for Next Generation Information Networks" works" 下一世代資訊通訊網路尖端技術與應用下一世代資訊通訊網路尖端技術與應用 (2004.04~2008.03).(2004.04~2008.03).– 分項計畫三分項計畫三 : B3G All-IP Wireless Network Technologies, : B3G All-IP Wireless Network Technologies, 後三代全後三代全 IPIP 無線網路無線網路

技術技術– 分項計畫四分項計畫四 : Wireless Ad Hoc and Sensor Networks Technologies, : Wireless Ad Hoc and Sensor Networks Technologies, 無線隨意無線隨意

及感測網路技術及感測網路技術

國科會國科會 : “: “ 藍芽個人無線區域網路上通訊議題之設計實作與分析”藍芽個人無線區域網路上通訊議題之設計實作與分析” (2003.08~2006.0(2003.08~2006.07)7)

無線感測網路之動態定位技術無線感測網路之動態定位技術 , National Science Council, August 1, 2004 - July 31, , National Science Council, August 1, 2004 - July 31, 20072007

Prof. Kuochen Wang Prof. Kuochen Wang (( 王國禎王國禎教授教授 ))

Areas of research interestsAreas of research interests– Wireless networks and mobile Wireless networks and mobile

ComputingComputing Sensor networks, ad-hoc networks, Sensor networks, ad-hoc networks,

and mesh networksand mesh networks– Power-aware computing and Power-aware computing and

communicationscommunications– Network reliability and securityNetwork reliability and security

PublicationsPublications– Journal papers: 22Journal papers: 22– Conference papers: 47Conference papers: 47– Book Chapters: 1Book Chapters: 1

B.S., NCTU-Control Eng., 1978B.S., NCTU-Control Eng., 1978 M.S., Univ. of Arizona-ECE, 1986M.S., Univ. of Arizona-ECE, 1986 Ph.D., Univ. of Arizona-ECE, 1991Ph.D., Univ. of Arizona-ECE, 1991 Senior Engineers, Directorate GeneSenior Engineers, Directorate Gene

ral of Telecommunications, 1980-1ral of Telecommunications, 1980-1984984

Professor, NCTU-CS, 1999 ~Professor, NCTU-CS, 1999 ~ Research projectsResearch projects

– NCTU-MediaTek Project: NCTU-MediaTek Project: Low power,Low power, handover and QoS schemes in het handover and QoS schemes in heterogeneous wireless networkserogeneous wireless networks

– NSC Project: Dynamic localization in NSC Project: Dynamic localization in wireless sensor networkswireless sensor networks

Prof. Yu-Chee Tseng Prof. Yu-Chee Tseng (( 曾煜棋教授曾煜棋教授 ))

Areas of research interestsAreas of research interests– Wireless Network Wireless Network – Communication ProtocolCommunication Protocol– Mobile ComputingMobile Computing– Network SecurityNetwork Security– Wireless Sensor NetworkWireless Sensor Network– Wireless Mesh NetworkWireless Mesh Network– Wireless VoIPWireless VoIP– Distributed SystemDistributed System– Parallel Processing PublicationsParallel Processing Publications

International journal: 91International journal: 91 International conference: 99International conference: 99 Book Chapters: 12Book Chapters: 12 Patents: 2 granted, 5 pending Patents: 2 granted, 5 pending

B.S., NTU-CSIE, 1985B.S., NTU-CSIE, 1985 M.S., NTHU-CSIE, 1987M.S., NTHU-CSIE, 1987 Ph.D., Ohio State University-CIS, Ph.D., Ohio State University-CIS,

19941994 Professor, NCTU-CS, 2000~Professor, NCTU-CS, 2000~ Chief Executive Officer, ITRI-NCTU Chief Executive Officer, ITRI-NCTU

Joint Research Center, 2005~Joint Research Center, 2005~ Chairman, NCTU-CS, 2005~Chairman, NCTU-CS, 2005~

““Distinguished Alumnus Award”, Distinguished Alumnus Award”,

2005, The Ohio State University2005, The Ohio State University

Distinguished Research Award Distinguished Research Award

(two times)(two times)

Distinguished EE Professor Award, Distinguished EE Professor Award,

The Chinese EE Institute, 2005The Chinese EE Institute, 2005

Prof. Wen-Chih PengProf. Wen-Chih Peng(( 彭文志教授彭文志教授 ))

B.S., NCTU-CSIE, 1995B.S., NCTU-CSIE, 1995 M.S., NTHU-CSIE, 1997M.S., NTHU-CSIE, 1997 Ph.D., NTU-EE, 2001Ph.D., NTU-EE, 2001 Assistant Professor, NCTU-CS, 2003/8~Assistant Professor, NCTU-CS, 2003/8~ A member of the IEEE A member of the IEEE Research interestsResearch interests

– Data management and mining in sensor networksData management and mining in sensor networks– Mobile data managementMobile data management– Data mining/databasesData mining/databases

PublicationsPublications– International journal: 8International journal: 8– International conference: 14International conference: 14

Email: Email: wcpeng@cs.nctu.edu.twwcpeng@cs.nctu.edu.tw

Prof. Jiun-Long Huang Prof. Jiun-Long Huang (( 黃俊龍教授黃俊龍教授 ))

Associate Professor, NCTU, 20Associate Professor, NCTU, 2005– 05–

Ph.D., NTU EE, 2003Ph.D., NTU EE, 2003 M.S., NCTU CSIE, 1999M.S., NCTU CSIE, 1999 B.S., NCTU CSIE, 1993B.S., NCTU CSIE, 1993 Research interestsResearch interests

– Mobile data managementMobile data management Dependent data broadcastDependent data broadcast On-demand data broadcastOn-demand data broadcast

– Mobile InternetMobile Internet Cache relocationCache relocation Transcoding proxyTranscoding proxy

– Sensor networkSensor network

PublicationsPublications– Journal papers: 5Journal papers: 5– Conference papers: 17Conference papers: 17

EmailEmail: : jlhuang@cs.nctu.edu.twjlhuang@cs.nctu.edu.tw

Prof. John K. Zao Prof. John K. Zao (( 邵家健教授邵家健教授 ))

Research interestsResearch interests– Pervasive Sensor-Actuator SystemPervasive Sensor-Actuator System

ss Autonomous Sensor/Actuator AsseAutonomous Sensor/Actuator Asse

mblymbly Model-based Software SpecificatioModel-based Software Specificatio

n & Implementationn & Implementation Operational/Functional ComponeOperational/Functional Compone

nt Coordinationnt Coordination– Infrastructure-less (P2P) Service SInfrastructure-less (P2P) Service S

ecurityecurity P2P Security Policy ManagementP2P Security Policy Management P2P Service Security EnforcementP2P Service Security Enforcement

PublicationsPublications Journal Papers : 2Journal Papers : 2 Conference Papers : 7Conference Papers : 7 Internet Draft : 3Internet Draft : 3 Patents : 2Patents : 2

EmailEmail: jkzao@cs.nctu.edu.tw: jkzao@cs.nctu.edu.tw

Associate Professor (NCTU), 2Associate Professor (NCTU), 2004 – 004 –

Ph.D. (Harvard), 1995Ph.D. (Harvard), 1995 Senior Member, IEEE, 2001Senior Member, IEEE, 2001 Senior MTS (BBN), 1994–2002Senior MTS (BBN), 1994–2002 Principal MTS (BBN), 2002–20Principal MTS (BBN), 2002–20

0303 Chairman, Security Policy TasChairman, Security Policy Tas

k Force, DARPA Information Ask Force, DARPA Information Assurance (IA) Program, 1999–20surance (IA) Program, 1999–200000

Member, US Army Task Force Member, US Army Task Force XXI Tactical Internet Gray-bearXXI Tactical Internet Gray-beard Panel, 1996–1997d Panel, 1996–1997

Co-founder, SecurKey Inc. (CaCo-founder, SecurKey Inc. (Canada), 1987–1990nada), 1987–1990