RF transmission power control

tetsuo-kawakami · ‎04-19-2005

Hi,

One of our customer is using two 7920 phones through two AP1200 access points with IOS 12.3(2)JA, in a room.

The customer experienced reset of 7920 frequently from the beginning.

However, after we changed RF transmission power settings for AP1200, the resetting problem was decreased very much.

We added the following configuration into the AP.

interface dot11radio0

power local 20

power client 20

Could anyone advise me about the reason why decreasing the TX power is effective for the problem?

Are you supposed to control the TX RF power generally for wireless LAN system or wireless VoIP system?

Best regards,

Kawakami

michaelgillespie · ‎04-19-2005

So with 1.08 firmware or higher the 7920 can adjust it's transmit power dynamically via the "power client X" command. For transmit power settings, this all depends on the site survey for that environment which is required to deploy the 7920 successfully. Need to ensure the noise is kept ot a minimal and that SNR of 25db is met in all areas. Refer to http://www.cisco.com/en/US/products/hw/phones/ps379/products_implementation_design_guide_book09186a00802a029a.html for more info.

Also we don't recommend 12.3(2)JA as there is a bug related to QBSS, where the CU is falsely advertised. Use 12.3(2)JA2 or higher. For 7920, 1.09 was just released and can download from http://www.cisco.com/cgi-bin/tablebuild.pl/ip-7900ser-crypto.