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Research Challenges in Environmental Observation and Forecasting Systems

Research Challenges in Environmental Observation and Forecasting Systems. 소프트웨어 전문가 학제 전공 고재일. Contents. CORIE pose a number of difficult challenges. 1. Introduction. EOFS CORIE. 2. EOFS. The Key Characteristics of EOFS. 3. CORIE. An EOFS for Columbia River 현재 CORIE 의 구성 필요로 하는 것.

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Research Challenges in Environmental Observation and Forecasting Systems

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  1. Research Challenges in Environmental Observation and Forecasting Systems 소프트웨어 전문가 학제 전공 고재일

  2. Contents • CORIE pose a number of difficult challenges. 1. Introduction • EOFS • CORIE 2. EOFS • The Key Characteristics of EOFS 3. CORIE • An EOFS for Columbia River • 현재 CORIE의 구성 • 필요로 하는 것 4. Research Challenges • The research issues for CORIE • Mobile Computing and Wireless networking 5. Existing Work • Another example of EOFS 6. Conclusion • The solution to these research problems can enable the next generation of EOFS

  3. 1. Introduction • EOFS(Environmental Observation Forecasting System) • real-time in-situ monitoring of physical processes with distributed networks 1. EOFS • 특징 • large-scale, distributed embedded systems in which data primarily flows from remote sensors to over wireless links to collection points, and from these to centralized processing via wired links • 문제들 • The sensor stations • cost, power, size, weight constraints • The environment • variable • Movability • capable of changing locations • QoS • The data may be rate- and time-sensitive

  4. 1. Introduction • EOFS to study the Columbia river estuary and plume • CORIE consists of sensor stations in the Columbia River Estuary that carry various environmental sensors 2. CORIE • CORIE provides the Information • temperature • salinity • water levels • flow velocities • CORIE regeneration Issues (Research 주제) • Wireless networking • Mobile Computing

  5. 2. EOFS • Distributed Systems that span wide geographic areas • 3 components • sensor stations • distribution networks • A centralized processing farm 1. 구성 요소

  6. 2. EOFS • The Key characteristics of EOFS • Centralized Processing • sensor station은 processing power가 약하기 때문에 Processing관련 작업은 central farm에게 이관 • High Data volume • wireless network bandwidth문제로 Sampling Data 중 일부만 전송 • QoS sensitivity • 일정 시간이 지나면 data의 활용성이 떨어질 수 있다. • Backwards data flow • 각 station은 farm의 control signal을 받을 수 있어야 한다. • Extensibility • 다양한 instruments를 장착하여 다양한 기능성을 제공할 수 있으면 좋다. • Autonomous Operation • 사람이 Sensor 문제를 해결하기는 비용문제가 있다. 2. 특징

  7. 3. CORIE Environmental Columbia River Estuary Observation Sensor network Forecasting Eulerian-Lagrangian Finite Volume model System Regular Production of Data Products 1. EOFS

  8. 3. CORIE • CORIE monitoring networks • 13 stations throughout the River estuary and 1 off-shore stations • DGR-115 spread-spectrum wireless network • 115Kbaud radio modem • 1 watt in 902-928 Mhz • 1 centralized farm • from receivers to farm via T1 network 2. 전체 구성

  9. 3. CORIE • Sensor Stations • one or more instruments • conductivity, temperature, depth gauge, doppler profiler (flow field, nautical x-band radar) • a field computer • 133Mhz 586 processor, 32MB RAM, HDD, Radio Modem, all of them are contained in a sealed box. • Power Supply • Near Shore => electric grid • others => Solar panels Master Stations • Each Sensor Station communicates to master station. • time-division multiple access protocol • Some stations need relay for communicate with a master station. • 각 Station은 자신이 통신하는 master station이나 relay station 정보를 수동으로 입력해야 한다. 3. Sensor Station

  10. 3. CORIE • Studying phenomena requires extensions to CORIE • Autonomous Mobility • 현재 vessel의 location => manually controlled (비싸고 비효율적) • physical process를 따라 자동으로 위치를 잡도록 한다면 좋을 것이다. • Reactive behavior • 사건에 따라 reprogrammed된다면 좋을 듯(특정 사건에 대해, Sampling rate를 증가하는 등.) • Time and Location dependence • The integrated management of the mobile observation network • sampling 정책 같은 것을 주변의 다른 station의 정보를 바탕으로 설정할 수 있으면 좋을 듯. 4. Required Extension

  11. 4. Research Challenges • Demand for resources is higher than the supply • Computation, Battery, Bandwidth • Optimal trade-offs depends on the use of sensor. • The ultimate use of the sensor data에 따라 computation, battery, bandwidth중에 적절히 선택 • Low level mechanism (media, link, transport) 최적화 • TCP와 같은 General purpose protocol은 너무 load가 크다. AdaptabilityChallenge

  12. 4. Research Challenges • Surface wave의 높이가 sensor 안테나의 높이를 넘어서는 경우가 있다. • Surface wave의 높이가 다시 낮아지면 Communication bandwidth는 바로 회복되야 한다. • Power 소모량을 고려해야 한다. • Probing이나 rebroadcasting은 power소모가 너무 크다. • Shore에서 멀리 떨어진 station은 더 큰 power를 소모한다.(base station으로부터 거리가 더 멀다.) • ad hoc routing에 대해 고려해야 할 것이다. • Periodic disruption시에 routing한다면 • GPS같은 것을 통해 shore에 가까운 station으로만 route하도록 • Deploy special flagships with the fleet that are always available for communication Disruptions In Line of sight

  13. 4. Research Challenges • Control message to all sensors는 excess traffic • Knowledge of network topology를 통해 traffic ↓ • Shortest path 설정 가능 • Network 속성 • Periodic disruption 있다. • Intermittent power failure 있다. • Limited broadcast (range에 있는 것만 받는다.) • Range 벗어나 있는 것들이 있다. • Network 좋은 것들을 통해 Hierarchy를 구성 • That station can be repeaters for those farther out • Time to convergence와 energy conservation중 한 정책을 실행시간에 선택할 수 있도록 • 전체 node에 message도착을 보장 하려면 power 소모가 많아진다. Distribution Of Control Message

  14. 4. Research Challenges • The sensor station is the weakest link. • sensor station -> central server에 data를 보내는 형태로 일반적인 distributed system (server -> client)과 다르다. • Power and cost consideration • The need to deploy sensors near the location of the physical phenomena to be studied • The variability of the operating environment. • Station을 hazard 발생하는 곳에 둘 수도 있는 데, 이런 곳은 noise 수준이 높은 곳이다. Low Power Low Cost

  15. 4. Research Challenges • 지진 연구 • Communication between ocean-floor sensors and surface stations => 수 km나 떨어져 있으므로 cable로 연결하기는 비현실적이다. • 1200 baud on uplink and 80 baud on downlink • Max uplink : 300~600 bps • Error loss < 25% • Max downlink : 40bps • 1200 baud가지고는 sufficient data collection이 힘들다. High Bit-rate Acoustic Modems

  16. 5. Existing Work • Pacific Marine Environmental Lab • 지진 연구 • Ocean floor bottom pressure recorders (BPR) • Relay data through acoustic modem • If unreachable, using satellite • The need for better communication tech. PMEL

  17. 5. Existing Work • Physical Oceanography RealTime System • Safe and cost-efficient navigation for ship • Operation without centralized control • The chief processing in EOFS must be centralized. • Microscopic sensor, large density. • EOFS sensor is large, sparsely distributed • Networking for smart dust are not appropriate for EOFS. PORTS MOBICOM MEMSbased sensor

  18. 5. Conclusion • A new class of distributed sensor networks • Collect streams of instrument data from in-situ sensor stations over multi-hop wireless networks • Feed this data to computationally intensive physical models to produce nowcast/forecasts of the physical processes • Differences to traditional Distributed Systems • Several Research Problems in EOFS • Adaptability • Line-of-sight • Efficient distribution of control • Low-power, low-cost sensor • High bit-rate acoustic modems EOFS

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