Iuwne10 S06 L02

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Iuwne10 S06 L02

  1. 1. WLAN Maintenance and Troubleshooting Design and Site Survey Considerations
  2. 2. Building Materials
  3. 3. Identify Problematic Areas
  4. 4. Signal Attenuation These values are examples, and attenuation may vary depending on the actual material used 3 - 6 dB Wireless device position 12 dB Metal door in brick wall 6 dB Metal door 3 dB Office window 4 dB Cinderblock wall 6 dB Glass wall with metal frame 3 dB Plasterboard wall Signal Attenuation Through Object Object in Signal Path
  5. 5. Non-802.11 Sources of Interference 20 MHz 20 MHz 802.11 a or g OFDM 802.11 b DSSS
  6. 6. Microwave Ovens Loud moving signal seen at max. Duty cycle higher in part of band Drifts in frequency
  7. 7. Bluetooth Speckled pattern in spectrogram Duty cycle spread across band See more hops in max. hold See hops in max.
  8. 8. Wireless Phones Pulses increase in max. Speckled appearance in swept = frequency hopper Duty cycle fairly low and spread across band
  9. 9. Analog Cameras Constant signal seen in avg./max. Duty cycle Is 100% Constant power level stripe
  10. 10. Verifying Coverage with Site Survey <ul><ul><li>In a wireless network creation process, there commonly are two site surveys: </li></ul></ul><ul><ul><ul><li>Pre-deployment site survey to determine AP position and density, along with problematic areas </li></ul></ul></ul><ul><ul><ul><li>Post-deployment site survey, to audit coverage, cell overlap, roaming and RF-related issues </li></ul></ul></ul><ul><ul><li>Pre-deployment site survey is never the first step in a wireless project </li></ul></ul><ul><ul><li>Post-deployment site survey should be for verifying conformity to the design </li></ul></ul>
  11. 11. Which Coverage for Which Usage
  12. 12. WLAN Coverage and Capacity
  13. 13. Recommended Parameters for 2.4-GHz Data Networks Minimum packet performance should be greater than 90 percent successful packet transfer (10 percent lost) 31 22 -62 -72 48 14 4 -84 -94 1 16 6 -81 -91 2 18 8 -79 -89 6/5.5 20 10 -72 -82 12/11 22 12 -67 -77 24 28 18 -63 -73 36 35 25 -61 -71 54 Recommended Minimum SNR Rx SNR Recommended Minimum Rx Threshold Rx Threshold Data Rate
  14. 14. Voice Cell Overlap Guidelines <ul><li>A typical deployment showing a 15-20% overlap from each of the adjoining cells </li></ul><ul><li>Provides almost complete redundancy throughout the cell </li></ul>
  15. 15. AP Placement for Location
  16. 16. Coverage Overlap
  17. 17. Multifloor Coverage
  18. 18. Site Survey Tools
  19. 19. Basic Survey Tools
  20. 20. Summary <ul><ul><li>Walls, doors, and furniture may affect and degrade a wireless signal. </li></ul></ul><ul><ul><li>Many other devices may use the ISM band, and although they would not be directly visible to the wireless infrastructure, they may degrade or completely block the wireless signals. </li></ul></ul><ul><ul><li>The size of the coverage area, the overlap between cells, and the number and position of APs depends on the type of wireless devices expected in the network. </li></ul></ul>

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