1

Part 4 Wireless Network

Wireless Technologies

Wireless Networks

Wireless Computer Networks

Personal Mobile Networks

Industry Use Wireless Networks

2

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

3

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.

4

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

5

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.

6

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…

7

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

8

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

9

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

10

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.

11

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

12

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

13

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?

14

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

15

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”

16

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

17

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

18

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.