Power gain or loss?

[fjcardenas-1]

I am reading a section that says that when you change a power level from 1 to 2 for a specific AP, the power decreases by 50% ans so on. My question is: If FCC says that transmit power should not exceed 30 dBm (I guess that is power level 1 in the AP), then setting the power level to 2 would mean the power is reduced to 15 dBm

[Kayle Miller]

That is incorrect Below is a table showing the power levels in dbm along with a link to the document and a conversion chart for the dbm to mw.

Table 3-5 Example of Output Power Levels

Controller Tx Power Settings1	Radio Output Power
	802.11b/g (dBm)	802.11a (dBm)
1 (maximum)	202	173
2	17	14
3	14	11
4	11	8
5	8	5
6	5	2
7	2	-1
8	-1	-

http://www.cisco.com/en/US/docs/wireless/access_point/channels/lwapp/reference/guide/1130_chp.html

20dBm = 100mw

17dBm = 50mw

14dBm = 25mw

11dBm = 12.5mw

each 3dbm of change results in either a Halving or Doubling of of the power.

Does this help? If so please feel free to rate it.

Thanks,

Kayle

[fjcardenas-1]

So, the power that is cut in half by going from power level 1 to 2 is in mw and not in dBm. The statement that each 3dbm of change results in either a Halving or Doubling of of the power, and the example made it very clear . Thank you.

[Johannes Luther]

The WLC power levels always confuses me a little bit.

From my  understanding it depends on the regulatory domain.

For the -E regulatory domain, the setting "1" would represent 17dBm (50mW) not 20dBm.

Check out "http://www.cisco.com/en/US/docs/wireless/access_point/channels/lwapp/reference/guide/lw_chp2.html"

Example for a 1240AG:

At the bottom of the page is the table "Table 6-7     Example of Output Power Levels"

The note "2" sais: ^"The maximum output power levels obtained from Table 6-2 and Table 6-3"

If you check out the mentioned tables, you'll see, that the maximum power levels differs between each regulatory domain.

So again, from my understanding the power level 1 means:

- 20dBm in the US (-A)

- 17dBm in the ETSI (EUROPE) (-E)

Can someone confirm my theory?

EDIT:

I just checked some live systems. The above statements are correct