Ch0:2Tseng:WirelessNet國立交通大學國立交通大學國立交通大學國立交通大學資訊工程系資訊工程系資訊工程系資訊工程系曾煜棋曾煜棋曾煜棋曾煜棋教授教授教授教授國立交通大學國立交通大學國立交通大學國立交通大學資訊工程系資訊工程系資訊工程系資訊工程系曾煜棋曾煜棋曾煜棋曾煜棋教授教授教授教授

Ch0:3Tseng:WirelessNet國立交通大學國立交通大學國立交通大學國立交通大學資訊工程系資訊工程系資訊工程系資訊工程系曾煜棋曾煜棋曾煜棋曾煜棋教授教授教授教授

Wireless Network Models

� With Infrastructure: � Without Infrastructure (ad hoc

networks):


� Cellular: � Infrared:


� As relaying link � Packet Radio Network


無線隨意網路無線隨意網路無線隨意網路無線隨意網路

（（（（Multi-hop Ad Hoc Network））））

Laptop

PDA

LaptopLaptop

Laptop

A

B

C

D

E

PDA

Laptop

Laptop

Laptop

PDA

PDA

C'


感測網路感測網路感測網路感測網路（（（（Sensor NetworkSensor NetworkSensor NetworkSensor Network））））


Nokia Rooftop Product


2.3 GHz

900 MHz

Modem

Wired

Access

Point

Poletop

Radio

2.4 GHz

High-speed dedicated

wired connections

Internet and

Corporate

Networks

Network Interface

Facility

The Ricochet Network Overview


Easy Installation


Bluetooth Technology

bluetooth headset bluetooth dongle

bluetooth MP3 watch bluetooth remote

car control

Ch0:12Tseng:WirelessNet

Research Directions:

Mobile Computing, Communications,

and MEMS Technologies


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


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


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


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

Microthrusteroptical switch

segway


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


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.


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”

Chapter 0: Overview Wireless Network Architecture...

Documents

Transcript of Chapter 0: Overview Wireless Network Architecture...