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Wireless Topology

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A detailed presentation about Wireless Topology

A detailed presentation about Wireless Topology

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  • This is just a pictorial description of the SKY wave communication ….
  • This is just a pictorial description of the Ground wave communication ….
  • Transcript

    • 1. Wireless topology
    • 2. By. P. Victer Paul Dear, We planned to share our eBooks and project/seminar contents for free to all needed friends like u.. To get to know about more free computerscience ebooks and technology advancements in computer science. Please visit.... http://free-computerscience-ebooks.blogspot.com/ http://recent-computer-technology.blogspot.com/ http://computertechnologiesebooks.blogspot.com/ Please to keep provide many eBooks and technology news for FREE. Encourage us by Clicking on the advertisement in these Blog.
    • 3. Topologies Relevant for Wireless Networking • Star  Yes, standard wireless topology • Tree Yes (a combination of star and line) • Line Yes, with two or more elements (PtP) • Mesh  Yes, mainly partial mesh • Ring  Possible, but rarely found • Bus  Not applicable. Why?
    • 4.
      • Basic Network Topologies
      • Most wireless implementations are based on
      • – Star, tree or line topology
      • Real life wireless networks are very often
      • combinations of more than one topology
    • 5. Wireless transmission
    • 6. Overview
      • Characteristics and quality determined by:
        • Medium
        • Signal
      • Medium
        • Guided - wire
        • Unguided - wireless
      • For Guided Medium
        • The medium is more important
      • For Unguided
        • The bandwidth produced by the antenna is more important
      • Key concerns are data rate and distance
    • 7. Design Factors
      • Bandwidth
        • Higher bandwidth gives higher data rate
      • Transmission impairments
        • Attenuation
      • Interference
        • Issue especially in case of unguided medium
      • Number of receivers
        • Unicast (one sender, one receiver)
        • Multicast (multiple receivers can introduce more errors)
    • 8. Electromagnetic Spectrum
    • 9. Wireless Transmission Frequencies
      • 2GHz to 40GHz (Microwave Frequency)
        • Highly directional
        • Point to point devices
        • Microwave communications
      • 30MHz to 1GHz (Radio Frequency)
        • Omnidirectional
        • Broadcast radio
      • 300GHz – 400THz( Infrared )
        • Short-range communication in a closed area using line-of-sight propagation (ex, wireless keyboard)
    • 10. Antennas
      • By definition
        • Is a electrical device
      • Transmission
        • Radio frequency energy from transmitter
        • Converted to electromagnetic energy
        • By antenna
        • Radiated into surrounding environment
      • Reception
        • Electromagnetic energy impinging on antenna
        • Converted to radio frequency electrical energy
        • Fed to receiver
      • Same antenna often used for both
    • 11.
      • An isotropic antenna radiates power in all directions.
      • Parabolic reflective antenna are used to focus received signals and to transmit a parallel beam without dispersion
    • 12. Terrestrial Microwave (TMW)
      • Parabolic antenna
      • Small beam
      • Line of sight
      • Use especially for P2P applications
      • Usually use for long distance communication
      • Loss = 10 log 10 (4d/)² dB.
      • Rain attenuates the signal .
    • 13. Satellite Microwave (SM)
      • Satellite is relay station
      • Satellite
        • receives on one frequency
        • amplifies or repeats signal
        • transmits on another frequency
      • Requires geo-stationary orbit
        • Height of 35,784km
      • Applications
        • Television
        • Long distance telephone
        • Private business networks
    • 14.
      • Used to link two or more ground stations.
        • A single satellite might have several transponders.
        • Optimal transmission frequencies are 1-10 G Hz but saturation is causing higher frequencies to be used.
    • 15. Satellite Point to Point Link ground based microwave transmitter ground based microwave receiver
    • 16. Satellite Broadcast Link
    • 17. Broadcast Radio
      • Omnidirectional ( travel in all directions )
      • Line of sight is not required
      • Doesn’t need parabolic antenna
      • Example FM radio
      • Typical frequencies range from 30 MHz to 1GHz.
      • Less sensitive to rain than microwave radio.
      • Multipath interference is a prime source of impairment.
    • 18.
      • Infrared
        • Transceivers modulate noncoherent infrared light.
        • Transceivers must be within line-of-sight or each other or must be able to receive reflections of the signal.
        • Infrared does not penetrate walls, and hence has a security advantage over radio waves.
    • 19. Wireless Propagation
      • Signal travels along three routes
        • Ground wave
          • Follows contour of earth
          • Up to 2MHz
          • AM radio
        • Sky wave
          • Signal reflected from ionize layer of upper atmosphere
          • BBC world service, Voice of America
        • Line of sight
          • Above 30Mhz
          • Antennas must be physically aligned
          • Atmosphere can reflect the microwave signal
    • 20.
      • LOS Impairments
        • Free Space Loss--the signal disperses with distance
        • Atmospheric Absorption
        • Multipath Reflection
        • Refraction (bending of waves through the atmosphere.)
    • 21. Sky Wave Propagation
    • 22. Ground Wave Propagation
    • 23. Line of Sight Propagation
    • 24. Multipath Interference
    • 25. Transmission Impairments in Wireless Transmission
      • Free Space Loss
        • Signal dispersion is a function of distance
        • Ratio between power-radiated to power-received
        • Greater for lower wavelength
        • Antenna gain can be used to compensate the losses
        • Also known as near far problem
      • Refraction
        • Each wireless medium has its own density
        • Propagation speed is a function of density of the medium
        • When medium changes, the result is refraction
        • Refraction means change of direction