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Scan during DFS wait time

This capability provides the mechanism to start an environment scan, even if the AP is on a DFS channel and currently in DFS-wait state.

  • Reject the DFS wait time and stop the DFS channel search.

  • Start the environment scan.

  • After finishing the scan, immediately restart the DFS search. Before the implementation of this feature, during DFS wait time, if a scan is initiated, the DFS search will stop and then restart again after the scan is complete. The feature will be enabled only when the following command is given. By default, it is disabled.

  • Enable : cfg80211tool wifiX scan_over_cac_en 1

  • Disable : cfg80211tool wifiX scan_over_cac_en 0 When an AP is in DFS wait state, that is, it is trying to find an appropriate channel to switch, if a scan command is issued, it is not executed. The requirement here is to prioritize scan over DFS. Also, the DFS should start again once the scan is completed.

  • NOTE: When the ‘scan over CAC’ feature is enabled for a dependent repeater scenario make sure that the channel switch option ‘CSwOpts’ 4 is set. This is enabled because when the scan is done over CAC, all the VAPs go down, scan happens and the VAPs are brought up. To ensure that CAC is done in the dependent repeater, the CSwOpts need to be enabled.

  • NOTE: Until “Spoof test”( Host DFS confirmation check) happens, CAC is always done for an AP that needs the Host DFS confirmation check (applicable for FCC domain only and for chipsets that support Host DFS confirmation check, for example: IPQ401x or QCA9984. Consequently, a dependent repeater does CAC before the STA VAP connects to the Root AP

Zero wait for DFS channels

To set and get intermediate CAC channels, enter the following commands: cfg80211tool wifiX interCACChan <non_dfs_chan_num> cfg80211tool wifiX getInterCACChan) Configuration:

  1. Enable/disable precac (preCAC)
  2. Set intermediate channel (interCACChan)
  3. Set preCAC timeout (preCACTimeout)

Sample configuration scenario

AP: IPQ8064+QCA9984, Open Security/Mode:-11ac VHT80/Channel:auto

  1. Configure the AP in VHT80 mode using cfg80211tool athX mode 11ACVHT80 (option htmode HT80) command.
  2. Configure the AP in ETSI domain using cfg80211tool wifiX setCountryID 0x0D0 (option country 0x0D0) command.
  3. Enable/disable preCAC using cfg80211tool wifiX preCACEn 1/0 command.
  4. Configure intermediate channel using cfg80211tool wifiX interCACChan <non-dfs_chan_ num> command.
  5. Display precac-required, precac-done, and precac-nol lists using radartool -i wifiX showPreCACLists command.
  6. Configure Agile bangradar using radartool -I wifiX agilebangradar command