Proxim ORiNOCO AP-4000M User Manual page 57

Advanced Configuration
Interfaces
The beacon frame contains information on the country code, the maximum allowable transmit power, and the channels to
be used for the regulatory domain.
The same information is transmitted in probe response frames in response to a client's probe requests. Once the client
has acquired the information required to meet the transmit requirements of the regulatory domain, it configures itself for
operation in the regulatory domain.
On some AP models, the regulatory domain and associated parameters are automatically configured when a country is
selected on the System tab. On APs in which country selection is not available on the system tab, the regulatory domain
is pre-programmed into the AP prior to shipment. Depending on the regulatory domain, a default country code is chosen
that is transmitted in the beacon and probe response frames.
Configuring 802.11d Support
Perform the following procedure to enable 802.11d support and select the country code:
1. Click Configure > Interfaces > Operational Mode.
2. Select Enable 802.11d.
3. Select the Country Code from the ISO/IEC 3166-1 CountryCode drop-down menu.
NOTE: On APs with model numbers ending in -WD, this object is not configurable.
4. Click OK.
5. Configure Transmit Power Control and Transmit Power Level if required.
Transmit Power Control/Transmit Power Level
Transmit Power Control uses standard 802.11d frames to control transmit power within an infrastructure BSS (Basic
Service Set, or combination of AP and associated clients that can communicate to each other and/or to the backhaul
connection via the AP). This method of power control is considered to be an interim way of controlling the transmit power
of 802.11d enabled clients in lieu of implementation of 802.11h.
When an AP comes online, it automatically uses the maximum TX power allowed in the regulatory domain. The Transmit
Power Control feature lets the user manually lower the transmit power level by setting a "back-off" value between 0 and
35 dBm.
When Transmit Power Control is enabled, the transmit power level of the card in the AP is set to the maximum transmit
power level minus the back-off value. This power level is advertised in Beacon and Probe Response frames as the
802.11d maximum transmit power level.
When an 802.11d-enabled client learns the regulatory domain related information from Beacon and Probe Response
frames, it learns the power level advertised in Beacon and Probe response frames as the maximum transmit power of the
regulatory domain and configures itself to operate with that power level.
As a result, the transmit power level of the BSS is configured to the power level set in the AP (assuming that the BSS has
only 802.11d enabled clients and an 802.11d enabled AP).
NOTE: In FCC DFS-enabled bands, power control is adjusted from beacon information only.
In addition, ATPC (Automatic Transmit Power Control) is a feature to automatically adapt transmit power when the quality
of the link is more than sufficient to maintain a good communication with reduced transmit power. This feature is required
for FCC DFS. It works by monitoring the quality of the link and reducing the output power of the radio by up to 6 dB when
good link quality can still be achieved. When link quality reduces, the output power is automatically increased up to the
original power level to maintain a good link. For a full discussion of DFS, see
Detection (DFS/RD).
Configuring TX Power Control
1. Click Configure > Interfaces > Operational Mode.
2. Select Enable Transmit Power Control.
AP-4000/4000M/4900M User Guide
Dynamic Frequency Selection/Radar
57