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WIRELESS LAN

WIRELESS LAN. Presented by Ching-Man Chong Tracy Tien Johnny Wong Zhong Wei Yu. WIRELESS LAN. WIRLESS LOCAL AREA NETWORK. WIRELESS LAN. Introduction Wireless Technology Wireless LAN Configuration Differences between wired LAN vs wireless LAN Cost-Benefit Study

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WIRELESS LAN

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  1. WIRELESS LAN Presented by Ching-Man Chong Tracy Tien Johnny Wong Zhong Wei Yu

  2. WIRELESS LAN WIRLESS LOCAL AREA NETWORK

  3. WIRELESS LAN • Introduction • Wireless Technology • Wireless LAN • Configuration • Differences between wired LAN vs wireless LAN • Cost-Benefit Study • Customer Considerations

  4. 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

  5. WHY WIRELESS? Advantages: • MOBILITY • INSTALLATION • COST • SCALABILITY

  6. MOBILITY • Real-time information access from anywhere at any time • Increases productivity and flexibility

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

  8. 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

  9. SCALABILITY • Can be configured in different topologies to meet the specification of applications and installations • Can be easily changed from peer-to-peer networks (small # of users) to full infrastructure networks (thousands of users)

  10. 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

  11. 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.

  12. WIRELESS TECHNOLOGY

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

  14. 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

  15. LEO SATELLITES • Orbit no higher than 500 miles above the earth • Travel the earth in a couple of hours • Multiple satellites needed • Allow access to very low-power devices

  16. WIRELESS WAN • Provide nationwide or citywide coverage • Example: Ricochet Micro-Cell Coverage in Washington D.C., San Francisco, and Seattle Source: http://dcs.umd.edu

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

  18. ACCESS POINTS • Connects to the wired network • single access point can support a small group of users within a range of several hundred feet Wireless Clients Connected to LAN via Access Point Source: http://dcs.umd.edu

  19. 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

  20. ROAMING • Each access point can provide between 50,000 to 250,000 square feet of coverage • Example: Hospital Environment Source: http://dcs.umd.edu

  21. WIRELESS LAN TECHNOLOGY • Narrowband Technology • Spread Spectrum Technology • Frequency-Hopping Spread Spectrum Technology • Direct-Sequence Spread Spectrum Technology • Infrared Technology

  22. NARROWBAND TECHNOLOGY • Transmits and receives user information on a specific radio frequency • keeps the radio signal frequency as narrow as possible • Radio receiver filters out all radio signals except the ones on its designated frequency • Example: private telephone lines

  23. SPREAD SPECTRUM TECHNOLOGY • Mostly used in wireless LAN system • Trades of bandwidth efficiency for reliability, integrity, and security • Signal looks like background noise if not turned to the right frequency

  24. FREQUENCY-HOPPING SPREAD SPECTRUM TECHNOLOGY • Uses a narrowband carrier that changes frequency in a pattern known to both transmitter and receiver • Maintain a single logical channel

  25. FREQUENCY-HOPPING SPREAD SPRECTRUM TECHNOLOGY (con’t) Source: www.wlana.com

  26. DIRECT-SEQUENCE SPREAD SPECTRUM TECHNOLOGY • Generates a redundant bit (chip) pattern for each bit to be transmitted • The longer the chip, the greater the probability that the original data can be recovered • To unintended receivers: • Viewed as low-power wideband noise • Rejected by most narrowband receivers

  27. DIRECT-SEQUENCE SPREAD SPECTRUM TECHNOLOGY (con’t) Source: www.wlana.com

  28. INFRARED (IR) TECHNOLOGY • Little used in commercial wireless LANs • Use very high frequencies • Inexpensive, but provide very limited range (3ft) • Typically used for personal area networks • Used only to implement fixed subnetworks

  29. WIRELESS STANDARD • IEEE 802.11 • represent the 1st standard for wireless LAN • standardize radio equipment and networks operating system for wireless LAN • Addresses for: • Physical (PHY) layer • Media Access Control (MAC)

  30. CONFIGURATION • Peer-to-peer network • Client and Access point • Multiple access points and roaming • Using an extension point • Using directional antennas

  31. PEER-TO-PEER NETWORK • Wireless adapter cards • Connect 2 PCs • Client access only to each other, not with a central server Source: http://www.proxim.com

  32. CLIENT & ACCESS POINT (AP) • Access point • Must be wired to the network • Extend the range of the network • Allow access from client-to-server and among each workstation • Real-world: each Access Point can accommodate from 15-50 client devices Source: http://www.proxim.com

  33. MULPTIPLE AP & ROAMING • In large facility, more than one AP might be needed to coverage the whole area • Access Point range: • Indoor = 500 ft; Outdoor = 1,000 ft Source: http://www.proxim.com

  34. EXTENTION POINT (EP) • EP can be connected to the network without wiring. • EP extend the range of the network by relaying signals from a client to an AP or another EP. Source: http://www.proxim.com

  35. DIRECTIONAL ANTENNAS • Extend the wireless networks between buildings • Antenna must be connected to an AP of the network Source: http://www.proxim.com

  36. PHYSICAL LAYER

  37. MEDIUM ACCESS CONTROL • A collision may occur when 2 stations transmit data simultaneously • Detects the collision and ignores the message • Each station that wants to transmit waits a random amount of time and then attempts to transmit again • The random transmission delays reduce the probability that the stations will transmit simultaneously again.

  38. DIFFERENCES BETWEEN WIRED LAN AND WIRELESS LAN

  39. WIRED vs. WIRELESS LAN WIRED • Wired • Link clients, printers, and network equipment using cables • Wireless • Basic building block is the Cell WIRELESS Source: www.breezecom.com

  40. WIRE vs. WIRELESS (con’t) • Bridging • Wired • Access point connects to the backbone of a wired Ethernet LAN via a simple cable • Wireless • can be mounted back-to-back with an access point • Able to link buildings that are miles apart Source: www.breezecom.com

  41. WIRED vs. WIRELESS (con’t) • Cells • Linked Cells (Wired) • user can walk from Cell A to overlap Cell B without interrupting a work session • Multi-cells (Wireless) • Position Access Points at different locations in the coverage areas with their directional antennas Source: www.breezecom.com

  42. WHEN DO YOU NEED WIRELESS LAN TECHNOLOGY?

  43. WHEN? • When you truly need mobility • When you plan to move or remodel soon • When set up a portable buildings for temporary use • When you don’t have time to configure and maintain a wiring scheme • When running cable is too expensive

  44. Cost-Benefit Study

  45. COST-BENEFIT STUDY • 89% successful implementation • 92% of respondents believe the definite economic and business benefit after installation • 92% continue to deploy wireless technology in their network • Payback was less than 1 year across all industries surveyed. Source: www.wlana.com

  46. COST/BENEFIT STUDY (con’t) • Economic Benefits • Payback Source: www.wlana.com

  47. COST/BENEFIT STUDY (con’t) • Broad cross-section of the representative industries with successful implementation of wireless LAN • Education: 23% • Healthcare: 23% • Manufacturing/Warehouse: 21% • Retail: 15% • Financial/Office Automation: 18% Source: www.wlana.com

  48. Wireless LAN Market

  49. WIRELESS LAN MARKET • Customer considerations • Range and coverage • Throughput • Compatibility • Interoperability • Interference and Coexistence • Licensing issues • Simplicity • Security • Cost • Major vendors • Scalability

  50. Customer Considerations

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