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Do I need an RF Survey and how to use Wireless ACS and ATPC with RF Survey?

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TitleDo I need an RF Survey and how to use Wireless ACS and ATPC with RF Survey?
Question
Do I need an RF Survey and how to use Wireless ACS and ATPC with RF Survey?
Environment
  • ExtremeWireless
  • Automatic Channel Selection (ACS)
  • Automatic Tune Power Control (ATPC)
  • Firmware All
  • Radio Frequency (RF) Survey
 
 
Answer
  • An RF survey determines AP placements and power in order to obtain desired signal strength.  Deployments based on an RF survey provide stable and predictable Wi-Fi performance. Extreme recommends an RF survey be done prior to AP installation for any Wi-Fi deployment or a predictive plan can be done with a post install RF survey.
  • NOTE: Because voice services require signals that are consistent, stronger than Wi-Fi data-only networks and special attention is required for call density planning, Voice deployment should have mandatory RF surveys.
  • ACS/ATPC can be used with the RF Survey in order to facilitate initial channel planning and Tx power. Channel plan and power settings for each AP should be fine-tuned afterwards based on the RF Survey data.
Below are the typical steps for installation with an RF Survey: 
  1. Calculate the expected number of users in each area of the deployment. Allocate enough AP’s in the area with big user density (auditoriums), taking in account application traffic requirement, available channels (2.4 vs 5GHz), and the number of users. 
  2. Perform the RF survey to determine the AP placements in order to achieve the required signal strength (RSSI). RSSI value would depend on the noise level in the environment but for most office deployments an RSSI of -60dBm is sufficient to achieve high data rates (Stadium and other high-density areas would need/require stronger signals than -60dBm). 
  3. Determine the noise level during the normal operating hours.
  4. If external antennas are used, do the site survey taking in account the antenna radiation pattern.
  5. In general avoid placing AP’s behind RF obstacles, metal structures, near an elevator, or up high in the ceiling. 
  6. If the AP needs to be concealed, place it suspended from the ceiling with external antenna protruding
  7. Configure the ExtremeWireless Appliance and deploy the AP with Auto Channel Selection (define the channel plan) and Auto Transmit Power Control and let the algorithm distribute the AP’s across the channels and adjust the power for sufficient cell overlap and controller interference.
  8. Verify the Auto selected power and channel by inspecting the deployment with wireless clients (running test application like voice or video streaming) for coverage and quality (use the typical client for the installation). If the area of insufficient coverage (bad voice/video quality) or roaming delays (interruption) is identified, be prepared for manual tuning of the auto selected powers and channels.
  9. Record the channels and power setting for each of the AP (export the channel plan and powers using the GUI).
  10. Disable ATPC to prevent dynamic changes to manually tuned powers due to transient changes in the RF environment. 
 


 

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