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Chapter 0: Overview Wireless Network Architecture & Potential Research Directions Yu-Chee Tseng Dept of Computer Science National Chiao-Tung University Ch0:1 Tseng:WirelessNet Ch0:2 Tseng:WirelessNet Wireless Network Models With Infrastructure: Without Infrastructure (ad hoc networks): Ch0:3 Tseng:WirelessNet Cellular: Infrared: Ch0:4 Tseng:WirelessNet As relaying link Packet Radio Network Ch0:5 Tseng:WirelessNet 無線隨意網路 (Multi-hop Ad Hoc Network) Ch0:6 Tseng:WirelessNet 感測網路(Sensor Network) Ch0:7 Tseng:WirelessNet Nokia Rooftop Product Ch0:8 Tseng:WirelessNet 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 Tseng:WirelessNet Easy Installation Ch0:10 Tseng:WirelessNet Bluetooth Technology bluetooth headset bluetooth dongle bluetooth MP3 watch bluetooth remote Ch0:11 Tseng:WirelessNet car control Research Directions: Mobile Computing, Communications, and MEMS Technologies Ch0:12 Tseng:WirelessNet 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 Ch0:13 Tseng:WirelessNet 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 Ch0:14 Tseng:WirelessNet 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 Ch0:15 Tseng:WirelessNet 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 Ch0:16 Tseng:WirelessNet 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 Ch0:17 Tseng:WirelessNet 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. Ch0:18 Tseng:WirelessNet 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” Ch0:19 Tseng:WirelessNet