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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.... 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