Wireless Topology


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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 ….
  • Wireless Topology

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