topic The simplest way to in Wireless

Transmit Power Control (TPC) - when no clients are available

dot1x — Mon, 05 Jul 2021 14:33:57 GMT

Hi All,

Does WLC reduce the AP Transmit power when there are no active clients available?

Does WLC increase the AP Transmit power when the clients start connecting to the network?

No for both questions.

Flavio Miranda — Fri, 18 Aug 2017 00:51:35 GMT

No for both questions.

Transmit Power Control has not to see with Clients. TPC is related with APs only.

From Cisco docs:

"TPC uses the TX neighbor and RF Neighbor lists generated by the NDP process. RSSI organized lists built on how we hear other AP's (RX Neighbor) and how other AP's hear us (TX Neighbor), to form a picture of how every AP is heard by every other AP within the RF Neighborhood and RF Group. Based on this information TPC sets the transmit power of each AP to maximize the coverage and minimize co-channel interference. TPC will adjust the Tx power up or down to meet the required coverage level indicated by the TPC Threshold."

I encourage you to read this:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_RRM_White_Paper/b_RRM_White_Paper_chapter_0101.html

Enjoy!

Thanks Flavio.

dot1x — Fri, 18 Aug 2017 01:03:36 GMT

Thanks Flavio.

Reason I had this question in my mind is:

I have performed post install site survey and could see that most of the areas have RSSI ranging between -70 to -80 where the AP is located not more than 20 to 25 meters away with low density area.
Tx power showing 5, 6, 7, 8 on different APs.

Shouldn't the Tx power be increased in such scenario?

Note: RRM is set to default and no active client present on site when the survey was performed.

The simplest way to

Flavio Miranda — Fri, 18 Aug 2017 01:20:49 GMT

The simplest way to troubleshooting this is run the command "show ap auto-rf {802.11a|802.11b}" on WLC and see how many AP hear each other and at which RSSI level.

If RRM is lowing down Power, it is because AP is receiving strong signal from neighbors. But, keep in mind that if this area gets crowded, RRM will increase the power. Human bodies absorb RF signal decreasing RSSI among APs thus making RRM to adjust.