This design document proposes changes in hostapd to include "Power
Constraint IE" in beacon.
Based on the current operation mode (11a) and 80211h flag enabled in
hostapd.conf and if the operating channel is within 5.25-5.35 GHz and
5.47-5.725 GHz band hostapd supports the following:
Including "Power Constraint IE" in beacon with appropriate value for
"Local power constraint" helps the device/AP to be in compliance with
802.11h (part of 11n / wpa2 interop test specification).
1.1 Ability for an AP to generate beacons/probe response with Power
* hostapd generates beacons with "Power constraint IE" with value
for "Local Power Constraint" set to 0dB.
1.2 Reason for setting "Local Power Constraint" as 0db:
* Section (h)(1) of Electronic Code of Federal Regulations (e-CFR)
states that TPC mechanism is not required for systems with an e.i.r.p.
of less than 500 mW. U-NII devices operating in the 5.25-5.35 GHz band
and the 5.47-5.725 GHz band shall employ a TPC mechanism
* As per FCC standard, for country US, the MAX TX power for UNII-2
band is 23dB/200mW.
* As per CRDA, as an example, the Max TX power provided for UNII-2
band for country US is 20dbm/100mW which is below the mimimum
requirement to start TPC.
* As per ETSI standard, the MAX TX power for UNII-2 band is 23dB.
As per CRDA, as an example, the MAX TX power for UNII-2 band for country
SWITZERLAND (CH) is 20dB. * Since CRDA provides a reduced TX power
level, value of 0dB provides an opportunity for the client devices to
operate at Power Limit provided by CRDA (Local MAX TX power = regulatory
max - power constraint).
Looking forward for suggestions & information.
Thanks & regards,