I. F. Akyildiz, T. Melodia, and K. R. Chowdhury, "A survey on wireless multimedia sensor networks," Computer Networks, vol. 51, pp. 921-960, 2007.

• Introduction

  WMSN :

  networks of wirelessly interconnected devices that allow retrieving video and audio streams, still images, and scalar sensor data

     

  Possible new applications (existing apps - tracking, home automation, environment monitoring) :

  • Multimedia surveillance sensor networks
  • Storage of potentially relevant activities
  • Traffic avoidance, enforcement and control systems
  • Advanced health care delivery
  • Automated assistance for the elderly and family monitors
  • Environmental monitoring
  • Person locator services
  • Industrial process control

     

  Advantages :

  • Enlarging the view.
    • distributed system of multiple cameras and sensors -> multiple view points
  • Enhancing the view
    • redundancy by multiple -> provide enhanced understanding
    • same area, different views
  • Enabling multi-resolution views
    • can be used recognize people based on facial characteristics

     

  Needs :

  • provide QoS
    • network layer metrics : latency, jitter
  • minimize the energy consumption

     

  Challenging for QoS :

  • Resource constraints : battery, memory, processing, data rate
  • Variable channel capacity
    • depending on interference level
    • power control, routing, rate policies
  • Cross-layer coupling of functionalities
    • due to the shared nature of the wireless communication channel
    • should not be treated separately
  • Multimedia in-network processing
    • the processing and delivery of multimedia content are not independent and their interaction has a major impact on the levels of QoS that can be delivered
    • cross-layer optimization of communication process
    • in-network processing of raw data streams

         

         

• Design Factors

  WMSN :

  convergence of communication and computation

  (signal processing, control theory, embedded computing)

  Factors :

  • Application-specific QoS requirements
    • Snapshot or streaming multimedia
  • High bandwidth demand
    • Crossbow's MICAz or TelosB : 250kbit/s
  • Multimedia source coding techniques
    • QCIF(176x120) : 21Kbytes -> 5Mbit/s at 30 fps
    • considering processing and energy constraints
  • Multimedia in-network processing
    • require new architectures to extract semantically relevant information
      • increase the system scalability by reducing tx of redundant information
      • merging data originated from multiple views, multiple resolutions
    • distributed filtering techniques can create a time-elapsed image
      • H. Stockdon, R. Holman, "Estimation of wave phase speed and nearshore bathymetry from video imagery," J. Geophys. Res. 105 (C9) (2000) 22, 015-22, 033.
  • Power consumption
    • protocols, algorithms and architectures to maximize the network lifetime
      • providing QoS required by application
  • Flexible architecture to support heterogeneous applications
  • Multimedia coverage
    • larger sensing range and directivity
  • Integration with Internet (IP) architecture
    • for the commercial development (anywhere, anytime)
    • approaches
      • use of application level gateways
      • overlay IP networks
  • Integration with other wireless technologies
    • create large-scale sensor network
    • need sacrificing on the efficiency of the operation within individual technology

         

         

• Network Architecture

  Focus :

  • Scalability

     

  
   

     

  Reference Architecture :

  • single-tier network of homogeneous video sensors
    • processing hubs : higher processing capabilities
    • wireless gateway : interconnected to a storage hub and to a sink
    • storage hub : storing multimedia content locally for subsequent retrieval
    • sink : front-end for network querying and tasking
  • single-tiered clustered architecture of heterogeneous sensors
    • cluster head (processing hub)
      • perform intensive multimedia processing
      • relay the gathered content to wireless gateway and storage hub
  • multi-tiered heterogeneous network
    • resource-constrained, low-power scalar sensors : simpler tasks
    • resource-rich, high-power device : complex tasks

     

  Coverage :

  • sensing range -> camera's field of view (FoV)

    S. Soro, W.B. Heinzelman, "On teh coverage problem in video-based wireless sensor networks,"
    in Proc. of the IEEE intel. conf. on Broadband Communications, Networks nd Systems (BroadNets), Boston, MA, USA, October 2005

       

       

• Collaborative In-network Processing

  Objective :

  • to avoid transmitting large amounts of raw streams

       

  Needs :

  • application-specific querying and processing
  • architectures allowing data fusion or other complex processing operations in-network

       

  Data Alignment and Image Registration :

  • Different Viewpoints (Multi-view Analysis)
    • larger 2D view or a 3D representation : in remote sensing, computer vision and 3D shape recovery
  • Different times (multi-temporal analysis)
    • find and evaluate changes in time in the scene
  • Different sensors (multi-modal analysis)
    • acquired by different sensors

     

  Registration methods :

  • feature detection
    • detect distinctive objects (closed-boundary regions, edges, contours, line intersections, corners...)
  • feature matching
    • establish correspondence between detected features and those detected in the reference images
  • transform model estimation
    • estimate the types and parameters of mapping functions
  • image re-sampling and transformation
    • transform sensed image using the mapping functions

         

         

• Application Layer

  Service :

  • traffic management and admission control functionalities
  • source coding
  • flexible and efficient system software
  • primitives for applications to leverage collaborative, advanced in-network multimedia processing techniques

     

  Traffic classes :

  
   
  
  

  Multimedia encoding techniques :

  • Design Objectives
    • High compression efficiency
    • Low complexity
    • Error resiliency
  • Distributed Source Coding
    • B. Girod, A. Aaron, S. Rane, D. Rebollo-Monedero, "Distributed video coding," Proc. IEEE 93 (1) (2005) 71–83.

      Z. Xiong, A.D. Liveris, S. Cheng, "Distributed source coding for sensor networks," IEEE Signal Process. Mag. 21 (September) (2004) 80–94.

  • JPEG with differential encoding
  • distributed coding of images taken by cameras having overlapping FoV
  • multi-layer coding with wavelet compression

    S. Misra, M. Reisslein, G. Xue, A survey of multimedia streaming in wireless sensor networks, submitted for publication.

  • Wyner-Ziv video coder
    • Pixel-domain Wyner–Ziv encoder
    • Transform-domain Wyner-Ziv encoder

     

  System Software and middleware :

  • Main desired characteristics of a system software
    • provide a high-level interface
    • application-specific algorithm for in-network processing on multimedia content
    • long-lived
    • shared among multiple heterogeneous applications
    • shared among heterogeneous sensors and platforms
    • scalable
  • trade-off between degrees of flexibility and network performance
    • flexibility, inter-operability, reprogrammability

     

  Open research issues :

  • trade-offs between fidelity and energy consumption
  • high layer abstraction for fast development (controlling efficiency of low-level operations)
  • high-level primitives for applications to leverage collaborative, in-network multimedia processing

       

       

• Transport Layer
  
   

     

  Consideration :

  • Congestion control need to :
    • be tuned for immediate response
    • avoid oscillations of data rate along the affected path
  • Packet re-ordering due to multi-path
    • large burst data, but limited buffers at the intermediate sensor nodes
    • channel conditions not permitting high data rate for the entire duration

         

  Open research issues :

  • Trade-offs between reliability and congestion control
  • Real-time communication support
  • Relation between multimedia coding rate and reliability

       

       

• Network Layer
  
   

  Tasks :

  • providing variable QoS guarantees
  • supporting multimedia applications with lack of global knowledge, reduced energy end computational ability of node

     

  Open research issues :

  • Identification of the optimal routing metrics
  • End-to-end QoS guarantees

       

     

• Cross-layer Design

  Why not layered Design?

  • Redundancy for service interface
  • Functions handled at different layers are highly coupled
    • scheduling with rate allocation (MAC & Routing)
    • congestion and power control (capacity based on transmission power)

     

  Advantages of layered design : modularity

  • Simplicity
  • Easy debugging
  • Easy to standardize
  • Flexibility to deploy new protocols (easy upgradeable)

     

  Cross-layer design advantages :

  • Exploits the interactions between layers
  • Promotes adaptability at all layers based on information exchange between layers
  • In wireless networks: tight interdependence between layers

     

  Cross-layer design disadvantages :

  • Hard to characterize the interactions between protocols at different layers
  • Joint optimization across layers may lead to complex algorithms
  • Potential to destroy modularity

     

     

• Other Research Issues

  Convergence of Sensing and Actuation

  • Wireless Sensor and Actor Networks : WSANs

  Network Synchronization

  • to aggregate according to packet generation times

  Inter-media synchronization

  • sound vs. image from RoI

  Localization

  • to allocate resources to events, decide sensing precision and ensure complete monitoring

     

총명님 연구도 하고/레퍼런스 WSN, 서베이, 센서네트워크, 참고논문

센서 네트워크를 연구하는 외국 대학의 연구실들을 대충 막~~! 찾아봤습니다.
다른 참고할 만한 좋은 사이트 있으면 트랙백이나 댓글로 부탁드립니다.

[ View Lists ]

총명님 연구도 하고/레퍼런스 Research Lab, topic, WSN

• Energy harvesting
  • J. Paradiso, T. Starner, "Energy scavenging for mobile and wireless electronics," IEEE Perv. Comput. 4 (1) (2005) 18–27.
• Deploying hardware and software
  • P. Kulkarni, D. Ganesan, P. Shenoy, Q. Lu, "SensEye: a multi-tier camera sensor network," in: Proc. of ACM Multimedia, Singapore, November 2005.
  • S. Nath, Y. Ke, P.B. Gibbons, B. Karp, S. Seshan, "A distributed filtering architecture for multimedia sensors," Intel Research Technical Report IRP-TR-04-16, August 2004.
• In-network Processing
  • B. Zitova´, J. Flusser, "Image registration methods: a survey," Image Vis. Comput. 21 (11) (2003) 977–1000.
• Localization techniques for WMSNs
  • A. Savvides, L. Girod, M. Srivastava, D. Estrin, "Localization in sensor networks", in: T.Z.C.S. Raghavendra, K.M. Sivalingam (Eds.), Wireless Sensor Networks, Springer, New York, 2005.
• Comprehensive surveys of the major routing schemes in WSN
  • K. Akkaya, M. Younis, "A survey of routing protocols in wireless sensor networks," Ad Hoc Network (Elsevier) 3 (3) (2005) 325–349.
• Crosslayer Design
  • M.V.D. Schaar, S. Shankar, "Cross-layer wireless multimedia transmission: Challenges, principles and new paradigms," IEEE Wireless Commun. 12 (4) (2005) 50–58.

     

총명님 연구도 하고/레퍼런스 Research, topic, WSN, 읽을거리

Title : Reference Interpolation Protocol for Time Synchronization in Wireless Sensor Networks
Author : Chongmyung Park, Joahyoung Lee, and Inbum Jung
Pub : Lecture Notes in Computer Science, Vol. 4611, pp.684-695, August 2007

Abstract :
Advance in processor, memory and wireless communication technique have led to an increase of economical and small wireless sensor nodes. To provide the right responses quickly for the diverse events, wireless sensor nodes have cooperation with together. For successful cooperation, the time synchronization among sensor nodes is an important requirement for application execution. In wireless sensor networks, message packets are used for the time synchronization. However, the transmission of message packets dissipates the battery energy of wireless sensor nodes. Since wireless sensor nodes works on the limited battery capacity, the excessive use of message packets has a negative impact upon their lifetime. In this paper, reference interpolation protocol is proposed for reducing the number of message packets for the time synchronization. The proposed method performs time interpolation between the time of reference packets and the global time of the base station. The proposed method completes the synchronization operation with only two message packets. Due to the simple synchronization procedure, our method greatly reduces the number of synchronization messages. From the decrease in the transmission of message packets, the convergence time among wireless sensor nodes is shortened and the lifetime of wireless sensor nodes is also prolonged as much as the amount of saved battery energy.

총명님 연구도 하고/논문 LNCS, UIC2007, 논문, 센서네트워크

Title : 유전자 알고리즘 기반의 센서 네트워크 토폴로지 제어
        (Topology Control based on Genetic Algorithm in Sensor Network)
Author : 박총명, 김동국, 이좌형, 김윤, 정인범
Pub : 정보과학회 2006년 추계 학술발표논문집 제 33권 제2호 666 ~ 670 페이지
Date :  2006년 10월 21일

Abstract :
많은 센서 노드가 환경정보를 수집하는 이벤트 기반의 센서 네트워크는 국부적인 이벤트 발생에 따라 혼잡이 발생할 수 있다. 네트워크의 혼잡으로 인해 중요한 정보의 손실이 일어날 수 있으며, 과다한 RF 모듈의 사용으로 네트워크의 수명이 단축될 수 있다. 본 논문에서는 이벤트가 발생하여 네트워크 트래픽이 증가할 때, 트래픽이 집중된 노드에서 주변 노드들의 데이터 전송률을 고려하여 자식 노드들의 트래픽을 분산 시키는 유전자 알고리즘 기반의 트래픽 분산 기법을 제안한다.

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총명님 연구도 하고/논문 논문, 센서네트워크, 정보과학회

해외 컨퍼런스나 저널에 논문을 제출하기 위해서는 해당 기관에서 요구하는 LaTex 형식에 맞추어 논문을 작성해서 pdf 로 변환해야한다. 따라서 LaTex 라는거에 대해 좀 알아야 한다.
대략적인 소개만 하고.. 자세한내용은 Tex사용자그룹에가서 배우자~ (아래 FAQ링크 참고)
ps. LaTex 는 "레이텍", "라텍" 등으로 읽히지만, "레이텍" 이라고 읽자.. ^^

LaTex 란 ?

LaTex 의 설치 (for WinXP)

LaTex 사용의 대략적 흐름

LaTex FAQ 링크

LaTex 예제 (for LNCS)

총명님 연구도 하고/기타 latex, 레이택

TinyOS의 Tython 스크립트를 이용한 Tossim 시뮬레이션에서 노드들의 전력 소모량을 측정하기 위한 방법을 소개한다.

<tos>/tools/java/net/tinyos/sim/plugins/ 에 다음 파일을 복사하고, make 한다. (기존 파일은 백업)


tossim 실행시 -p 옵션을 주면 노드가 소비하는 모든 전력(tx,rx,adc,cpu,eeprom, led)이 측정된다.
하지만, 자신이 원하는 부분에서의 전력소모만을 측정하기 위해 -p 옵션을 주지 않고 실행한다.
그리고 측정을 원하는 부분에 dbg(POWER, "...")를 추가한다. 예를 들어 메시지 전송에 따른
전력 소모를 측정하기 위해 전송 코드에 다음과 같은 dbg 를 추가하면 된다.

위와 같이 해서, 모트 프로그램에서 전력 소모를 측정하기 위한 부분을 설정하였다.
다음은 tython 스크립트에서 전력 소모량을 측정하는 방법이다.
위에서 컴파일한 PowerProfilePlugin 을 이용하여 전력 소모량을 측정한다.

tossim 실행시 발생하는 dbg 메시지를 분석해서 전력 소모량을 나타내게 되어있다.
위 코드는 tython에서 시뮬레이션 플러그인 클래스를 인스턴스화하고 핸들러를 등록하는 부분이다.
그리고 Periodic()을 이용하여 주기적으로 함수를 실행하게 한후 그 함수 안에서 전력 소모량을 측정하여 화면에 출력하거나 파일에 기록하면 되겠다.
전력소모량을 읽어오는 부분은 다음과 같다. (nodeID 노드의 현재까지 전력 소모량 출력)

※ 스크립트 실행시 dbg mode 에 power 포함시켜야 함 (EX> export DBG=usr1,power)
※ 자신이 원하는 부분의 전력만 측정하기 위해서는 tossim 실행시 -p 옵션을 주지 않음.
※ 참고 파일
  <tos>/tos/platform/pc/PowerStateM.nc
  <tos>/tos/platform/pc/packet/TossimPacketM.nc

총명님 연구도 하고/레퍼런스 TinyOS, TOSSIM, Tython, 센서 네트워크, 시뮬레이션

It's my work to do in this month...
writing paper to participate Pervasive 2007, International Conference...

Let's start...

http://www.dgp.toronto.edu/conferences/pervasive2007

Welcome to Pervasive 2007

Pervasive 2007, the Fifth International Conference on Pervasive Computing, will be held May 13-16, 2007 in Toronto, Ontario, Canada. The annual conference provides a premier forum in which to present research results in all areas related to the design, implementation, application and evaluation of pervasive computing as it integrates into our lives.

Building on the success of previous conferences in this series held in Zurich (August 2002), in Linz/Vienna (April 2004), in Munich (May 2005) and in Dublin (May 2006), Pervasive 2007 will include a highly selective single-track program for technical papers, accompanied by posters, videos, demonstrations, workshops, a doctoral colloquium, invited tutorials, and an invited plenary speaker.

We welcome submissions that report on innovations in mobile and pervasive computing, including but not limited to the following topics:

• New technologies and devices for pervasive computing
• New applications of pervasive computing technologies
• New interfaces and modes of interactions between people and pervasive computing devices, applications or environments
• New tools, infrastructures, architectures and techniques for designing, implementing & deploying pervasive computing applications
• Evaluations and evaluation methods, for assessing the impact of pervasive computing devices, applications or environments
• Privacy, security, trust & social issues and implications of pervasive computing

Technical Papers will be included in the Conference Proceedings published by Springer-Verlag in the series Lecture Notes in Computer Science (LNCS). The proceedings will also be made available through the digital library.

Late Breaking Result, Demonstration, Video and Doctoral Colloquium contributions will be peer reviewed and accepted as short papers to be published in the Adjunct Proceedings of Pervasive 2007, with ISBN. The Adjunct Proceedings will also be published electronically on the conference Web server.

For more information, contact:

Conference Chair Khai N. Truong University of Toronto, Canada
Program Co-Chairs Anthony LaMarca Intel Research, Seattle, USA	Marc Langheinrich ETH Zurich, Switzerland

CRITICAL DATES

October 13, 2006	:	Deadline for Technical Paper submissions
October 27, 2006	:	Deadline for Workshop Proposals
November 17, 2006	:	Notification of accepted Workshop Proposals
December 15, 2006	:	Notification of accepted Technical Paper submissions
January 26, 2007	:	Deadline for Late Breaking Result, Demonstration, Video, Doctoral Colloquium and Workshop Position Paper submissions
March 2, 2007	:	Notification of accepted Late Breaking Result, Demonstration, Video, Doctoral Colloquium and Workshop Position Paper submissions
May 13, 2007	:	Pervasive 2007 conference begins

총명님 연구도 하고/기타 Paper, pervasive

TinyOS에서 재전송 기능을 사용하기 위한 설정을 알아본다.

우선 재전송 기능이 일어나는 경우를 보면 아래와 같다.
A에서 B로 패킷을 전송하고 B는 수신한 패킷에 비트에러가 없을 경우에 ack를 돌려보낸다. 이때 A노드가 ack를 일정 시간내에 받지 못하면 재전송을 수행한다.





TinyOS 에서 설정해야 할 내용은 다음과 같다.

기본으로 아래와 같이 설정되어 있으므로 bAckEnable과 retransmit 변수를 고치면 된다.

TinyOS 애플리케이션에 필요한 내용을 살펴보면,

Configuration 파일에 CC2420RadioC 사용을 명시하고, Module 파일의 MacControl 을 CC2420RadioC 에 wiring 한다.

애플리케이션의 모듈 파일에 MacControl 인터페이스를 추가한 후
StdControl.start() 에서 MacControl.enableAck()를 호출한다.



다음으로, 멀티 홉 과 재전송 기능을 사용할 경우에 발생하는 문제에 대해 설명하고,
해결 방법을 알아본다.

<tos>/lib/Queue/QueuedSendM.nc 는 TinyOS의 메시지 전송 큐를 관리한다.
재전송 기능도 QueuedSendM 에서 수행된다. 관련 부분 소스를 보면...

테스트 프로그램은 멀티홉 라우팅 기능을 사용하며, 라우팅 경로를 빨리 설정하기 위해 라우팅 메시지 전송 주기를 짧게 설정하였다. 그리고 MICAz 모트 3개 정도에 프로그램을 올리고 테스트 한 결과 재전송이 계속 발생하지만 Basestation 노드에 패킷이 수신되지 않는 현상이 발생하였다. 문제의 원인을 파악한 결과,

라우팅 메시지는 Broadcast 를 사용하며 Broadcast도 이 QueuedSend 의 큐를 통해 전송이 일어나고, Broadcast에 대해서도 재전송을 수행하기 때문이었다.

따라서 위 소스를 그대로 사용하여 재전송 기능을 사용할 경우,
Broadcast 하는 패킷에 대한 Ack 가 없을 경우에도 계속 재전송을 하게 되어
Breadcast가 많을 경우 Queue Overflow가 발생할 수 있으며, 쓸데 없이 계속 재전송을 수행하게 된다.
(※ 수신 노드에서는 unicast 일 경우에만 ack 메시지를 전송한다)

이 문제를 해결하기 위해서 위 소스의 if 문 조건을 다음과 같이 변경하여야 한다.

총명님 연구도 하고/레퍼런스 TinyOS, 센서 네트워크, 재전송

유전 알고리즘 맵.. (너비 : 1000px)
현재 진행중인 연구에 적용할 유전 알고리즘을 간단히 정리해 봤다..
이 알고리즘을 적용해서 사용할 수 있을지 의문이다..
아무튼 이번달내로 대략적이나마 알고리즘이 나와야 한다 T_T

총명님 연구도 하고/레퍼런스 Genetic Algorithm, 마인드맵, 유전 알고리즘