Download Overview of Computer Networks

CPET 355
2. The Physical Layer Wireless Transmission
Paul I-Hai Lin, Professor
Electrical and Computer Engineering Technology
Purdue University, Fort Wayne Campus
Feb. 2, 2004
Prof. Paul Lin
1
The Electromagnetic Spectrum

NASA
• http://imagine.gsfc.nasa.gov/docs/science/kno
w_l1/emspectrum.htm
• http://imagers.gsfc.nasa.gov/ems/waves3.htm
l


Berkeley Lab: Electromagnetic
Spectrumhttp://www.lbl.gov/MicroWorlds/
ALSTool/EMSpec/EMSpec2.html
Naval Spectrum Management Supporthttp://www.navemscen.navy.mil/index.ht
m
Feb. 2, 2004
Prof. Paul Lin
2
Frequency Allocation
• Radio wave- < 3 x109 Hz
• Microwave – 3.0x109 – 3x1012 Hz
• Infrared
- 3.0x1012 – 4.3x1014 Hz
• Visible
- 4.3x1014 – 7.5x1014 Hz
• Ultraviolet - 7.5x1014 – 3.0x1017 Hz
• X-Rays
- 3.0x1017 – 3.0x1019 Hz
• Gamma Rays - > 3.0x1019 Hz
f = c
Wavelength*Frequency = speed of light
Feb. 2, 2004
Prof. Paul Lin
3
Wavelength

f = c
Wavelength*Frequency = speed of light

Electromagnetic Wave
• http://www.geo.mtu.edu/rs/back/spectr
um/

An Applet Example http://lectureonline.cl.msu.edu/~mm
p/applist/Spectrum/s.htm
Feb. 2, 2004
Prof. Paul Lin
4
Spectrum for Wireless
Transmission


Usable spectrum: Radio wave,
Microwave, Infrared, and Visible light
f = c
f = c/ 
df/d = c/ 2
f = c  / 2
Narrow frequency band
f/f << 1, best reception (watts/Hz)

Frequency hopping spread spectrum
• Military application, 802.11, Bluetooth,
Feb. 2, 2004
Prof. Paul Lin
5
Wireless Transmission

Federal Regulations
• Wireless Telecommunication Bureau,
http://wireless.fcc.gov/

Emerging Wireless Technologies,
http://www.fcc.gov/initiatives.html






Feb. 2, 2004
3G Wireless
Broadband
Digital TV
Lower Power FM
Rural Wireless ISP
Voice Over IP
Prof. Paul Lin
6
Wireless Transmission




Radio Transmission
Microwave Transmission
Lightwave Transmission
Satellite Communications
Feb. 2, 2004
Prof. Paul Lin
7
Radio Transmission

Omnidirectional systems
•
•
•
•

For indoor and outdoor
No need for physical alignment
Can penetrate buildings easily
Low bandwidth
Examples
• Paging – short message, 10s of k meters
• Cordless telephone – analog/digital, 10s of
meters
• Cellular phone – analog/digital/data, k meters
• Personal communication services – digital
voice and data, 100s
of meters
Feb. 2, 2004
Prof. Paul Lin
8
Microwave Transmission




Wave > 100 MHz can penetrate haze, light
rain and snow, clouds, and smoke
Do not passing through building well, and
has multipath fading effect (some delay
waves that may cancel the signals)
Wave can travel in nearly straight line and
can be narrowly focused for transmitting
information (data & voice)
100 meter tower, repeaters can be spaced
by 80 km apart
Feb. 2, 2004
Prof. Paul Lin
9
Microwave Transmission

Microwave Spectrum
• http://imagers.gsfc.nasa.gov/ems/micro.html

ISM bands – Industrial, Scientific and
Medical for unlicensed usage
• International Telecommunication Union
http://en.wikipedia.org/wiki/ITU-T
• 900 MHz – crowded, not available world wide
• 2.4 GHz – available worldwide; 802.11 wireless
LAN
• 5.7 GHz – new; 802.11a use it
Feb. 2, 2004
Prof. Paul Lin
10
Microwave Transmission

Applications
• Microwave cooking (about foot
wavelength)
• Transmitting information: data and
phone (can penetrate haze, light rain
and snow, clouds, and smoke)
• Remote sensing – weather forecasting
• Wireless LAN
Feb. 2, 2004
Prof. Paul Lin
11
Lightwave Transmission



IrDA Association http://www.irda.org/
Wavelength range – 850 nm to 900
nm
IrDA-C
• 75 kbps, up to 8 meters

IrDA-D
• 115 kbps to 4Mbps, up to 1 meter
Feb. 2, 2004
Prof. Paul Lin
12
Satellite Communications

GOES (Geostationary Satellite)
Systems
• 36,000 km above the equator
• Transponder data rate – 50 Mbps, at
4/6. 11/14, and 20/30 GHz bands


LEOS (Low-Earth Orbit Satellite)
Systems
MEOS (Multiple-mission Earth
Observatory Satellite) Systems
Feb. 2, 2004
Prof. Paul Lin
13
GOES Satellite
Communications
Significant satellite operators & Industries
http://www.3g-generation.com/satellite.htm
 GOES Satellites
http://ww2010.atmos.uiuc.edu/(Gh)/guide
s/rs/sat/goes/home.rxml
 GOES Science Projects
http://rsd.gsfc.nasa.gov/goes/
 GOES Servers

• http://www.goes.noaa.gov/
• http://www.goes.noaa.gov/g8hu.html
Feb. 2, 2004
Prof. Paul Lin
14
Satellite Communications

Overview of LEO Satellite Systems
• http://www.its.bldrdoc.gov/meetings/art/art99
/slides99/red/red_s.pdf

LEOS (Low-Earth Orbit Satellite)
• Technologies and Trends http://www.mindbranch.com/listing/product/R
201-084.html

Routing and Multicasting in LEO Satellite
IP Networks
• http://users.ece.gatech.edu/~cchen/routing/dr
p.html
Feb. 2, 2004
Prof. Paul Lin
15
MEOS Satellite

Multiple-mission Earth Observatory
Satellite
• http://www.eumetsat.de/en/area2/proc
eedings/eump33/pdf/session_5/softwar
e/oynes.pdf
Feb. 2, 2004
Prof. Paul Lin
16
Web References






Hughes Network Systems, www.hns.com
• http://research.mwjournal.com/data/detail?id
=988922143_314&type=ORG
NEC Optical Network Division
http://www.necpng.com/press/
Panduit Network Connectivity Solutions
http://www.panduit.com/
www.commscope.com
Errcsson Microwave Systems AB
http://www.ericsson.com/microwave/
Northrop Grumman – California Microwave
Systemshttp://sensor1.northgrum.com/calmw/
Feb. 2, 2004
Prof. Paul Lin
17