Ch0:1 Tseng:WirelessNet Chapter 0: Chances of Wireless Communications Yu-Chee Tseng Dept of Computer Science and Information Engr. National Chiao-Tung University

Ch0:2 Tseng:WirelessNet Wireless Network Architectures

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Ch0:4 Tseng:WirelessNet Wireless Network Models  With Infrastructure:  Without Infrastructure (ad hoc networks):

Ch0:5 Tseng:WirelessNet  Cellular:  Infrared:

Ch0:6 Tseng:WirelessNet  As relaying link  Packet Radio Network

Ch0:7 Tseng:WirelessNet 無線隨意網路 （ Multi-hop Ad Hoc Network ）

Ch0:8 Tseng:WirelessNet 感測網路（ Sensor Network ）

Ch0:9 Tseng:WirelessNet Nokia Rooftop Product

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Ch0:12 Tseng:WirelessNet Bluetooth Technology

Ch0:13 Tseng:WirelessNet Applications of Wireless Communications

Ch0:14 Tseng:WirelessNet When You Are Mobile Today  Desperately looking for a computer to check your s  Need to access Internet, or other information  Contacting other people using pay phone, cellular phone, airphone, BB call  Someone may be paging you, faxing you, …  Using a laptop to do work while traveling

Ch0:15 Tseng:WirelessNet Who Needs Wireless Communications  Law Makers in the Congress  One who needs to work with customers face-to-face doctor/nurse clerk/salespersons adv.: paperless, less error-prone  Retail: order, pricing, sell, inventory  Warehousing: the most paper-intensive industry can incorporate with barcodes

Ch0:16 Tseng:WirelessNet  Health Care: personal health history blood-drawing request X-ray taking request  Hospitality: 服務業, 餐廳入座, 代客泊車  Utility: 水公司, 電力公司 Kansas City: wireless metering system, serving 150,000 customers.  Field work, Field services: always on the road  Vending Machines: need to check stocks …

Ch0:17 Tseng:WirelessNet Advantages  Easy to Install: hard-to-networking environment: river, highway, historic cites fast installation: festival, assembly, Q-&-A in congress reliability: (wired cables might be cut, get rusty, …) in a company: re-organization, change office, etc.

Ch0:18 Tseng:WirelessNet Mobile Computing  Wireless Communication Technology  Portable Computer Technology appearance of light-weight computing devices  Vision: Ubiquitous Computing / Nomadic Computing computers everywhere; information anywhere anytime

Ch0:19 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  solution: deploying multiple antenna sites

Ch0:20 Tseng:WirelessNet Features of Portable Computers  Limited resources: limited energy (battery life) limited CPU speed limited memory  Less reliable, less secure

Ch0:21 Tseng:WirelessNet Mobile System Architecture  Cellular-based  Ad hoc  Relaying link  Wireless ATM  Packet Radio Network  Sensor Networks

Ch0:22 Tseng:WirelessNet Mobile Computing Applications/Services  Wireless information services: Pico-service: local parking lot availability, layout of a building Micro-service: train and bus station information, local traffic information Macro-service: weather information, local news service Wide Area Service: stock market information  Real-time multimedia applications tele-medicine tele-computing collaborative environments

Ch0:23 Tseng:WirelessNet New Dimensions in Mobile Computing  wide variations of available resources  heterogeneity  how to adapt to changes in the environment  multiple administrative domains  scalability

Ch0:24 Tseng:WirelessNet Research: Hardware Aspects  power saving display, LCD low-voltage CPUs  AT&T's Hobbit chip: 5,000 times less power consumption in doze mode than active mode radio:  IEEE power consumption example: transmit: 1400 mW receive: 1000 mW idle: 830 mW sleep: 130 mW  size, user interface (wearable computers)

Ch0:25 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 ... and many others

Ch0:26 Tseng:WirelessNet Research: Algorithmic Aspects  Bandwidth saving  Data caching for broadcast  channel allocation  communication scheduling  math. analysis

Ch0:27 Tseng:WirelessNet Research: Application Aspects  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: Ex: Coffee Kitchen arriving “play -v 50 ~/sound/rooster.au”