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What is Dynamic Frequency Selection (DFS)?

  • WiFi
  • DFS
DFS is the process of detecting radar signals that must be protected against interference from 5.0 GHz (802.11a/h) radios, and upon detection switching the operating frequency of the 5.0 GHz (802.11a/h) radio to one that is not interfering with the radar systems. The trransmit power control is used to adapt the transmission power of a radio based on regulatory requirements and range information.

DFS Actions
DFS-enabled radios monitor the operating frequency for radar signals. If radar signals are detected on the channel, the wireless device takes these steps:
  • Blocks new transmissions on the channel.
  • Flushes the power-save client queues.
  • Broadcasts an 802.11h channel-switch announcement.
  • Disassociates remaining client devices.
  • Randomly selects a different channel:
    •     If the wireless device does not select a DFS-required channel, it enables beacons and accepts client associations.
    •     If the wireless device selects a DFS-required channel, it scans the new channel for radar signals for 60 seconds.
      •         If there are no radar signals on the new channel, the wireless device enables beacons and accepts client associations.
      •         If a radar signal is detected, the wireless device selects a different channel.
      •         If a preferred channel is configurable and available, it is selected first.

To configure and run DFS tests on Spirent TestCenter Application, please look at the KB articles below:
  • FAQ19636 - Spirent TestCenter: How to test Dynamic Frequency Selection (DFS) on STC?
  • FAQ19649 - Spirent TestCenter: How can I run different trials on a DFS test?

Product : WiFi,Spirent TestCenter