ch0.ppt

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ch0.ppt

  1. 1. Chapter 0: Overview Wireless Network Architecture & Potential Research Directions <ul><ul><li>Yu-Chee Tseng </li></ul></ul><ul><ul><li>Dept of Computer Science </li></ul></ul><ul><ul><li>National Chiao-Tung University </li></ul></ul>
  2. 3. Wireless Network Models <ul><li>With Infrastructure: </li></ul><ul><li>Without Infrastructure (ad hoc networks): </li></ul>
  3. 4. <ul><li>Cellular: </li></ul><ul><li>Infrared: </li></ul>
  4. 5. <ul><li>As relaying link </li></ul><ul><li>Packet Radio Network </li></ul>
  5. 6. 無線隨意網路 ( Multi-hop Ad Hoc Network )
  6. 7. 感測網路( Sensor Network )
  7. 8. Nokia Rooftop Product
  8. 11. Bluetooth Technology bluetooth headset bluetooth dongle bluetooth MP3 watch bluetooth remote car control
  9. 12. Research Directions: Mobile Computing, Communications, and MEMS Technologies
  10. 13. Three Directions Together <ul><li>Wireless Communication Technology </li></ul><ul><li>Portable Computer Technology </li></ul><ul><ul><li>appearance of light-weight computing devices </li></ul></ul><ul><li>MEMS Technology </li></ul><ul><ul><li>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。 </li></ul></ul><ul><li>Vision: Ubiquitous/ Nomadic Computing, communication, and control </li></ul><ul><ul><li>computers everywhere; </li></ul></ul><ul><ul><li>information anywhere anytime </li></ul></ul><ul><ul><li>control </li></ul></ul>
  11. 14. Features of Wireless Communication <ul><li>one global bandwidth shared by all users </li></ul><ul><ul><li>fortunately channels, such as (frequency, time-slot) pairs, can be reused </li></ul></ul><ul><li>Radio-based </li></ul><ul><ul><li>low bandwidth </li></ul></ul><ul><ul><li>high latency radio communication links </li></ul></ul><ul><ul><li>higher bit error rate (BER) </li></ul></ul><ul><li>fading </li></ul><ul><ul><li>short-term multipath fading (Rayleigh effect) </li></ul></ul><ul><ul><ul><li>due to same signal taking different paths and arriving at the receiver shifted in phase </li></ul></ul></ul><ul><ul><li>long-term fading (radio shadow) </li></ul></ul><ul><ul><ul><li>topology of the terrain (like mountains) can cause signal dropouts </li></ul></ul></ul>
  12. 15. Features of Portable Computers <ul><li>Limited resources: </li></ul><ul><ul><li>limited energy (battery life) </li></ul></ul><ul><ul><li>limited CPU speed </li></ul></ul><ul><ul><li>limited memory </li></ul></ul><ul><ul><li>limited display </li></ul></ul><ul><li>Mobile Applications/Services </li></ul><ul><ul><li>Pico-service: local parking lot availability, layout of a building </li></ul></ul><ul><ul><li>Micro-service: train and bus station information </li></ul></ul><ul><ul><li>Macro-service: weather information, news service, stock market information </li></ul></ul><ul><li>Real-time multimedia applications </li></ul><ul><ul><li>tele-medicine </li></ul></ul><ul><ul><li>collaborative working environment </li></ul></ul>
  13. 16. Features of MEMS <ul><li>MEMS (Micro Electro Mechanical Systems) are the integration of electrical devices and mechanical structures at the micrometer (10 -6 m = 0.000001 m) scale. </li></ul><ul><ul><li>The essence of MEMS is their ability to perform and enhance tasks, in ways and in the micro world , impossible using conventional technologies. </li></ul></ul>digital propulsion Microthruster optical switch segway
  14. 17. Research: Hardware Aspects <ul><li>power saving </li></ul><ul><ul><li>display, LCD </li></ul></ul><ul><ul><li>low-voltage CPUs </li></ul></ul><ul><ul><ul><li>Example: AT&T's Hobbit chip: 5,000 times less power consumption in doze mode than active mode </li></ul></ul></ul><ul><ul><li>radio: an example of IEEE 802.11 power consumption </li></ul></ul><ul><ul><ul><li>transmit: 1400 mW </li></ul></ul></ul><ul><ul><ul><li>receive: 1000 mW </li></ul></ul></ul><ul><ul><ul><li>idle: 830 mW </li></ul></ul></ul><ul><ul><ul><li>sleep: 130 mW </li></ul></ul></ul><ul><ul><li>“ transmitting 1 bit is equal to executing > 1000 instructions </li></ul></ul>
  15. 18. Research: Software Aspects <ul><li>mobile communication protocols </li></ul><ul><ul><li>WAP </li></ul></ul><ul><ul><li>wireless TCP </li></ul></ul><ul><ul><li>Mobile IP </li></ul></ul><ul><ul><li>MAC protocols </li></ul></ul><ul><li>Energy-efficient protocol </li></ul><ul><ul><li>related to the above send/receive/idle/sleep model </li></ul></ul><ul><li>Mobile Operating Systems: </li></ul><ul><ul><li>Windows Mobile, Android, etc. </li></ul></ul>
  16. 19. Research: Application Aspects <ul><li>Compute, communicate, and micro-control </li></ul><ul><li>Context-aware computing </li></ul><ul><ul><li>context includes </li></ul></ul><ul><ul><ul><li>user's location </li></ul></ul></ul><ul><ul><ul><li>environment (e.g., noise level, communication b/w, communication cost etc.) </li></ul></ul></ul><ul><ul><ul><li>social situation (e.g., with boss, with co-worker etc.) </li></ul></ul></ul><ul><ul><li>context-aware applications </li></ul></ul><ul><ul><ul><li>context-sensitive information access (e.g. where are the bookstores in the vicinity) </li></ul></ul></ul><ul><ul><ul><li>context-sensitive commands : in active badge system </li></ul></ul></ul><ul><ul><ul><ul><li>command format: <badge> <location> <event-type> <action> </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ex: Coffee Kitchen arriving “play -v 50 ~/sound/rooster.au” </li></ul></ul></ul></ul>

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