Re: [Madwifi-devel] invalid packets received (latest HAL)

[Alfred A. <al...@cc...>]

Hi,

>You mean it is not permitted to use active scanning in the 5GHz range ?

Correct, if DFS is required by local regulations.  With DFS, a WLAN device
has to assure it doesn't interfere with radar systems before it starts to
transmit anything, and that also includes a probe request.  Typically only
the AP has to the capability to detect radar interference, so a client has
no other chance than stepping through the channels and listening for
beacons.  Which implicitly means that stuff like disabled SSID broadcast
doesn't work anymore either...

The lack of radar detection code in the client is by the way also a reason
why many vendors of client adapters disallow Adhoc network operation at 5
GHz.

At least here in Germany, there is a small exception from DFS: If a 5 GHz
WLAN only operates in the 5.15...5.25 GHz range, and devices are limited 
to 60mW EIRP, and all devices are indoor, then it is allowed to operate
without DFS.  The reason is that radar systems WLAN might interfere with
operate at frequencies above 5.25 GHz.

Best Regards

Alfred Arnold

-- 
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