Chapter 1-3: Wireless Network Architecture & Potential Research Directions

1. Chapter 1-3: Wireless Network Architecture&Potential Research Directions Yu-Chee Tseng Dept of Computer Science National Chiao-Tung University

3. With Infrastructure: Without Infrastructure (ad hoc networks): Wireless Network Models

4. Cellular: Infrared:

5. As relaying link Packet Radio Network

6. 無線隨意網路（Multi-hop Ad Hoc Network）

7. 感測網路（Sensor Network）

8. Nokia Rooftop Product

11. Bluetooth Technology bluetooth headset bluetooth dongle bluetooth remote car control bluetooth MP3 watch

12. Research Directions:Mobile Computing, Communications, and MEMS Technologies

13. 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

14. 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

15. 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

16. 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. segway digital propulsion Microthruster optical switch

17. 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

18. 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.

19. 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”