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Part 4 Wireless Network
Wireless Technologies
Wireless Networks
Wireless Computer Networks
Personal Mobile Networks
Industry Use Wireless Networks
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Wireless Technology Basics
Medium: -- Air
Types of Waves used for wireless communicationsInfrared
Radio Wave
Microwave
Satellite
Wired communication, directions fixed between sender and receiver
Wireless communication, goes to all directions as long as there is an receiver configured with the right frequency
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Comparison of wired and wireless comm.
Wired Wireless
Bandwidth Depending on the media used, can be large
Narrow in general, regulated by FCC (Federal Communication Commission, US government agency.)
Signal reception Reliable due to dedicated link Unreliable, signal can be blocked, reflected
Security High, difficult to tap in Everyone within the range can intercept the message
Interference Very little Significant because all share the same medium: air
Mobility No Yes
Cost Changes dramatically in recent years.
Depending on the technology. Keep tracking.
Expansion Add wires Adding relays, etc.
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Comparison of Different Wireless Wave
Bandwidth: a measure of frequency range and is typically measured in hertz. Central concept in data communication. Larger bandwidth = more channel to communicate simultaneously faster
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Multiplexing – Share communication channel
TDMA – Time Division Multiple Access
CDMA -- Code division multiple access
Each can only talk in his assignedtime slots. Have to agree upon when to talk.
Both can talk together, using assigned codes, which insure that the two signals are orthogonal. So two can talk together.Complicated, but can be more efficient.
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Wireless Computer Networks – Radio Frequencies
Wireless Personal Area Networks (WPANs)
Wireless Local Area Networks (WLANs)
Extension: Wireless Mesh Network
Wireless Metropolitan Area Networks (WMANs)
Wireless Wide Area Networks (WWANs)
Just Proposed. Wider…
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Wireless Personal Networks
Connecting Personal Devices
Use Bluetooth Technologies
Bluetooth = IEEE 802.15
Can connect up to 8 devices within
10-meter area (~30 feet, 10.95
yard)
Transmission rate: ~1Mbps
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Wireless LAN
Wireless Local Area Network
Mainly used for devices to communicate to Internet using “hotspots” – access points (APs)
Technology: Wi-Fi = IEEE 802.11 familyWireless-Fidelity: Industry standards for WLANs
~ 100 meters, 300 feet, 110 yards
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Wi-Fi Family
IEEE 802.11 standards have a set of standards, use 2.4 GHz and 5 GHz frequency channel
Faster due to multi-channelingWatch Microsoft video
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Problems with Wi-Fi
Roaming: currently hotspots are owned by a variety of vendors. Users cannot roam from hotspot to hotspot if use different Wi-Fi network
Security: radio waves, easy to intercept, difficult to protect
Survivability: currently intense competition. No viable and profitable business model yet.
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Wireless MAN
Wireless Metropolitan Area Networks
Technology: Wi-Max = IEEE 802.16~ 31 miles, 75 Mbps
$349 per receiver
Good for city-wide wireless deployment
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Summary of RF Wireless Standards
IEEE Standard A.K.A Range Speed
WPAN IEEE802.15 Bluetooth ~30 feet 1Mbps
WLAN IEEE 802.11 Wi-Fi ~ 300 ft 11~54Mbps
WMAN IEEE 802.16 Wi-Max ~ 30 miles 75Mbps
WWAN IEEE802.20 N/A >>30miles N/A
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Computation:
Company A is designing a new service used for travelers to download music
to their handheld devices. They have the following choices of technologies to
communicate between the music server and the personal handheld device.
A) 10mbps Ethernet B) Bluetooth technology C) IEEE 802.11b
D) IEEE 802.11g
1) Assume that the effective communication rate is 40% for all the above
communication technologies. Also assume that the average size of a music file is
4MB per song. Estimate the time needed to download 15 songs.
2) Except for communication speed, discuss other pros and cons of implementing
those technologies. Based on your discussion, give your choice.
3) Why Wimax is not being considered in this application?
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Extension: Using Wi-Fi to Build WMAN
Use Wi-Fi to create a Mesh NetworkWhat is mesh network? – discuss how to form a mesh using cables.
Compare to the current WLAN with wireless-mesh
Less number of access points
Economical solution for rural area
and developing countries
Wired Network
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Mobile Wireless Devices
Use telephone network, satellite network, and other channels
Wireless Application Protocols (WAP)
Application level (5th layer) protocol for small devices,
Tiny screen
Low bandwidth
Minimal memory
The new age of “M-Commerce”
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Industry Wireless Applications
Telemetry: sensor + antenna, measure remotely
Used in dangerous, remote, inconvenient areas.
Mesh: Wireless Sensor Networks
RFID: Radio Frequency Identification Tags
http://www.youtube.com/watch?v=4Zj7txoDxbE
Future Fantasy: mote/dust
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Business: Telemetry Services
Information Right Where You Need Information Right Where You Need ItIt
WAN Coverage Radio Mo. Fee Data
Plain Old Telephone
Anywhere w/wires
$5-25
$.05/min
Wide variety
Voice Cellular
You’re breaking up
$500-1,000
$15-50 +airtime
Wide variety
Control Channel
Western hemisphere
$75-100 $2-25 Just a few bytes
Two-way Pager
Metro areas
$75-100 $1-50 Small to medium
Satellite (GEO/LEO)
Almost everywhere
$1,000-2,500
$10-100 Usually lots of data
CDPD Few metro areas
$75-100 $15 + airtime
Small to medium
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After class reading
A) The Road to WiMaxTo get more business information about WiMax development
(Optional) blog your knowledge of WiMax and your opinions on the future of this technology.
B) Network ApplicationsHow many major categories of network applications have been discussed in this material?
Pick one category you are the most familiar with or the most interested in (based on your reading) and write a paragraph to discuss your understanding. Post your writing on the blog site.