Understanding Wireless LAN: Technology, Topology, Cost, and Customer Considerations, Slides of Computer Networks

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WIRELESS LAN

WIRELESS LAN

WIRLESS LOCAL AREA NETWORK

INTRODUCTION

• Data communications system
• Alternates wired LAN
• Transmits and receives data over the air
• Minimize the need for wired connections
• Become more popular in general-purpose

alternative of business customers.

• Benefited several industries in productivity and

mobility

WHY WIRELESS?

Advantages:

• MOBILITY
• INSTALLATION
• COST
• SCALABILITY

INSTALLATION

• Fast and easy
• No cable needed
• No frustration with wiring
• Go where wires cannot go

COST

• Short run
  • Initial investment is higher than wired LAN
• Long run
  • Long-term costs is essentially lower than wired LAN
  • Long-term cost and benefits are very important in dynamic and ever- changing business environments

IN THE REAL WORLD

• Not a replacement for the wired infrastructure
• Great complement to what currently exists
• Examples
  • Doctors and nurses
    • more productive in delivering patients’ information and status instantly
  • Student
    • access the Internet to consult the catalog of the Library of Congress
  • Network managers
    • provide backup for mission-critical applications

HOW IT WORKS

• Use electromagnetic airwaves to communicate

information

• Data imposed on radio carrier (radio wave)
• RF electromagnetic wave can easily pass through ordinary wall, it needs to implement with heavy concrete or metal screening.

WIRELESS TECHNOLOGY

• Satellite-Based System
  • Geosynchronous Earth Orbiting (GEO)
  • Low Earth Orbiting (LEO)
• Land-Based Network Access System
  • Wireless WAN
  • Wireless LAN

GEO SATELLITES

• Circle the earth from a height of 22,300 miles
• 3 satellites can be used to provide worldwide coverage
• used for:
  • television broadcasts, long distance telecommunications, and various science and military applications

WIRELESS WAN

• Provide nationwide or citywide coverage
• Example: Ricochet Micro-Cell

Source: http://dcs.umd.edu

Coverage in Washington

D.C., San Francisco, and

Seattle

WIRELESS LAN

• Wireless LAN Topology
  • 2 main components
    • Access Points
    • Adapters
  • Roaming
• Wireless LAN Technology
  • Types
  • Standard
  • Configuration

ADAPTERS

• Users used wireless-LAN adapters to connect to access points
• Implemented as :
  • PC cards in notebook computers
  • ISA or PCI cards in desktop computers
  • Integrated within hand-held computers

ROAMING

• Each access point can provide between 50,000 to 250,000 square feet of coverage
• Example: Hospital Environment

Source: http://dcs.umd.edu