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Ch0:1Tseng:WirelessNet
Chapter 0: OverviewWireless Network Architecture
&Potential Research Directions
Yu-Chee Tseng
Dept of Computer Science
National Chiao-Tung University
Ch0:2Tseng:WirelessNet
Ch0:3Tseng:WirelessNet
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 )
Laptop
PDA
LaptopLaptop
Laptop
A
B
C
D
E
PDA
Laptop
Laptop
Laptop
PDA
PDA
C'
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感測網路( Sensor Network )
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Nokia Rooftop Product
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2.3 GHz
900 MHz
Modem
Wired Access Point
PoletopRadio
2.4 GHz
High-speed dedicated wired
connections
Internet and Corporate Networks
Network InterfaceFacility
The Ricochet Network Overview
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Easy Installation
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Bluetooth Technology
bluetooth headset bluetooth dongle
bluetooth MP3 watch bluetooth remote car control
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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 bandwidthhigh latency radio communication linkshigher 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/ServicesPico-service: local parking lot availability, layout of a building Micro-service: train and bus station informationMacro-service: weather information, news service, stock market in
formation 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 enhanc
e tasks, in ways and in the micro world, impossible using conventional technologies.
digital propulsion Microthruster
optical switchsegway
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Research: Hardware Aspects
power saving display, LCDlow-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 mWsleep: 130 mW
“transmitting 1 bit is equal to executing > 1000 instructions
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Research: Software Aspects
mobile communication protocolsWAPwireless TCPMobile IPMAC protocols
Energy-efficient protocolrelated 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 applicationscontext-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”