Transcript 感測網路（Sensor Network）

Chapter 0: Overview
Wireless Network Architecture
&
Potential Research Directions
Yu-Chee Tseng
Dept of Computer Science
National Chiao-Tung University
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Wireless Network Models
 With Infrastructure:
 Without Infrastructure (ad hoc
networks):
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 Cellular:
 Infrared:
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 As relaying link
 Packet Radio Network
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無線隨意網路
（Multi-hop Ad Hoc Network）
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感測網路（Sensor Network）
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Nokia Rooftop Product
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The Ricochet Network Overview
Modem
Internet and
Corporate
Networks
900 MHz
Poletop
Radio
2.3 GHz
2.4 GHz
Wired
Access
Point
High-speed
dedicated
wired
connections
Network Interface
Facility Ch0:9
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Easy Installation
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Bluetooth Technology
bluetooth headset
bluetooth dongle
bluetooth MP3 watch
bluetooth remote Ch0:11
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car control
Research Directions:
Mobile Computing, Communications,
and MEMS Technologies
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Three Directions Together
 Wireless Communication Technology
 Portable Computer Technology
 appearance of light-weight computing devices
 MEMS Technology
 微機電系統(Micro Electro Mechanical Systems，MEMS)，其定義
為一個智慧型微小化的系統，包含感測、處理或致動的功能，包含
兩個或多個電子、機械、光學、化學、生物、磁學或其他性質整合
到一個單一或多晶片上。其應用領域極為廣泛，包括製造業、自動
化、資訊與通訊、航太工業、交通運輸、土木營建、環境保護、農
林漁牧等。
 Vision: Ubiquitous/ Nomadic Computing, communication, and control
 computers everywhere;
 information anywhere anytime
 control
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Features of Wireless Communication
 one global bandwidth shared by all users
 fortunately channels, such as (frequency, time-slot) pairs,
can be reused
 Radio-based
 low bandwidth
 high latency radio communication links
 higher bit error rate (BER)
 fading
 short-term multipath fading (Rayleigh effect)
 due to same signal taking different paths and arriving at the
receiver shifted in phase
 long-term fading (radio shadow)
 topology of the terrain (like mountains) can cause signal
dropouts
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Features of Portable Computers
 Limited resources:
 limited energy (battery life)
 limited CPU speed
 limited memory
 limited display
 Mobile Applications/Services
 Pico-service: local parking lot availability, layout of a building
 Micro-service: train and bus station information
 Macro-service: weather information, news service, stock market
information
 Real-time multimedia applications
 tele-medicine
 collaborative working environment
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Features of MEMS
 MEMS (Micro Electro Mechanical Systems) are the
integration of electrical devices and mechanical structures
at the micrometer (10-6 m = 0.000001 m) scale.
 The essence of MEMS is their ability to perform and
enhance tasks, in ways and in the micro world, impossible
using conventional technologies.
digital propulsion
Microthruster
optical switch
segway
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Research: Hardware Aspects
 power saving
 display, LCD
 low-voltage CPUs
 Example: AT&T's Hobbit chip: 5,000 times less power
consumption in doze mode than active mode
 radio: an example of IEEE 802.11 power consumption
 transmit: 1400 mW
 receive: 1000 mW
 idle: 830 mW
 sleep: 130 mW
 “transmitting 1 bit is equal to executing > 1000 instructions
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Research: Software Aspects
 mobile communication protocols
 WAP
 wireless TCP
 Mobile IP
 MAC protocols
 Energy-efficient protocol
 related to the above send/receive/idle/sleep model
 Mobile Operating Systems:
 Windows Mobile, Android, etc.
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Research: Application Aspects
 Compute, communicate, and micro-control
 Context-aware computing
 context includes
 user's location
 environment (e.g., noise level, communication b/w,
communication cost etc.)
 social situation (e.g., with boss, with co-worker etc.)
 context-aware applications
 context-sensitive information access (e.g. where are the
bookstores in the vicinity)
 context-sensitive commands: in active badge system
 command format: <badge> <location> <event-type> <action>
 Ex: Coffee Kitchen arriving “play -v 50 ~/sound/rooster.au”
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