Wireless Local Area Network

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iWing Lab CPE - Kasetsart University 1

Wireless Local Area Network

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Anan Phonphoem, Ph.D. [email protected] http://www.cpe.ku.ac.th/~anan Computer Engineering Department Kasetsart University, Bangkok, Thailand

Outline

• Wireless World (2G, 3G, … ) • Basic Wireless Knowledge

• Wireless Local Area Network (WLAN) • WLAN Standards

• Where are we heading to ? Wireless World (2G, 3G, … )

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iWing Lab CPE - Kasetsart University 3

Wireless World

• Mobile (telephony)

• On the move • GSM

• 9.6 kbps – 40 kbps

• Nomadic

• Within a building (low mobility) • Wireless LAN

• 2 mbps – 25 mbps

• Satellite

1G (First Generation)

• Analog

• Circuit-switched Network

• Low voice quality

• No security

• Low capacity

• AMPS

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2G (Second Generation)

• Digital encoding

• High bit rate voice

• Limited data communications (tens Kbps)

• GSM, D-AMPS (TDMA) and CDMA

• Auxiliary services (data, fax and SMS)

• Some levels of encryption

2.5G

• Extend 2G systems (GSM)

• Packet-switched connection (GPRS)

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3G (Third Generation)

• Higher data rates (Mbps) • More than voice...

• Support bandwidth-hungry applications

• Full-motion video

• Video-conferencing

• Full Internet access (IP)

• 3G & WLAN: complementary relationship • IMT-2000

• W-CDMA

4G

• NTT DoCoMo of Japan

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Evolution of the system

Source: Mobile Communications International

Wireless System Path

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Outline

• Where are we heading to ? Basic Wireless Knowledge

Communication Principle

• How can the information be transmitted?

InformationÆSignals (Electromagnetic Energy)

Power, Voice

Radio communication Radio, microwave, satellite

Infrared Light Ultra-Violet Light X, gamma, Cosmic rays Visible light 430-750 THz

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Wireless Applications

• Mobility needs (Inventory)

• Physical media is not feasible (Factory) • Eliminate paperwork (Car Rental)

• Decrease errors (Health care)

• Reduce process cost (Automatic Reading) • Improve efficiency (Mobile Office)

Wireless Network Concerns

• Radio signal interference (Noise) • Power management (Battery)

• System interoperability (Standards)

• Network security and Privacy (Encryption) • Connection problems (Loss, Timeout) • Installation issues (Barrier)

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Wireless Network

Configurations

• Wireless LANs (WLAN)

• Radio Waves • Infrared Light

• Carrier currents (“no new wire”)

• Wireless Point-to-Point Networks • Wireless WANs

Radio Based WLAN

Radio Based Wireless LANs

• Advantages

• No line of sights • Propagate through

obstacles • Disadvantages • Interference • Security ACT ACT

10M100M 1 2 3 4 13 14 15 16 5 67 8 17 18 19 20 9 10 11 12 21 22 23 24 UPLINK 1 23456 78 9101112 131415161718192021222324

COL COL PWR SWITCH

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Point-to-point Infrared LAN Diffused Infrared LAN

Infrared Light LAN Categories

Ceiling

Infrared Light Based WLAN

• Invisible to the naked eye

• Advantages over Radio Waves:

• More Secure

• Less susceptible to common noises (e.g.oven) • Better performance ÆHigh data rate

• Disadvantage:

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• Powerline network • Phoneline network • “No new wire” LAN

• Home networks

Office

Living Room Bed Room 2

Bed Room 1 Kitchen

Residential Gateway

Carrier Current LANs

Wireless Point-to-point

• Similar to WLAN technologies:

• Radio waves • Laser beam

• Applications

• Building links

• Links for traffic control lights • Leased line backup

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Wireless WANs

• Packet Radio WAN • Analog cellular WAN

• Cellular Digital Packet Data WAN • Satellite

• Meteor burst (Ionosphere) • GPS & Wireless WANs

Outline

• Where are we heading to ?

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WLAN

• Topology

• Architecture

Topology

WLAN Topologies

• Physical (Single & Multiple Cells)

• Logical (Ad-hoc & Infrastructure)

• Connectivity(Standalone & Wired Network Interface)

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Single Cell VS. Multiple Cells

Single Cell

AP AP AP

Multiple Cells

Ad-hoc VS. Infrastructure

Infrastructure

AP

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Standalone VS. Wired Network

Interface

Standalone

AP

Wired Network Interface

Distributed VS. Centralized

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WLAN

• Topology

• Architecture

Architecture

Outline

• Where are we heading to ? WLAN Standards

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Why Wireless LAN not so

popular in last ten years?

• Low data rate • High price

• Lack of standard

• Proprietary products

• Active Standards / Organizations

• IEEE 802.11 • Bluetooth • HIPERLAN