Q:
How is the Transmit EIRP calculated for IAPs post 6.5.2.x?
A: Article applicable for AP 2xx and 3xx series APs.
On the older version transmit EIRP was calculated = user configured EIRP+Antenna gain
Post 6.5.2.x Transmit EIRP is calculated = user configured EIRP + Antenna gain + MIMO Gain
power gain = 10*log (#txchains) --> ( TX chain is varied across different models of the APs).
Example:
AP 103,207,205,203H203R,205H & 303H - 2 Tx Chains
AP 215,225 - 3 TX Chains
AP 315 - 2 TX chains in 2.4Ghz and 3 TX chains in 5Ghz
AP 325,335 - 4 TX chains
In general, radio will not support per chain conducted power say <0 dBm (1 mW)
Example:
Pre 6.5.2.
If a user configured EIRP is 5 dBm then the transmit EIRP will be displayed as 5 dBm.
However, actual EIRP calculated = 5 dBm-4dBi+10*log(4)+3dBi = 10 dBm
Post 6.5.2.
In post 6.5.2. the AP will display the actual Transmit EIRP which includes the MIMO gain.
Following command will help to check the min transmit EIRP,
# show ap debug power-table. --> can be specified with radio 0 &1 respectively.
Example:
00:0b:86:ed:c5:20# show ap debug power-table
Home Channel: 36
Channel Width: 20MHz
User Configured: 6.0 dBm (EIRP) User Input
7.2 dBm (EIRP) Effective
0.0 dBm (Conducted)
Min Power: 7.2 dBm (EIRP)
0.0 dBm (Conducted)
Max Power: 22.7 dBm (EIRP)
Actual Power: 7.2 dBm (EIRP)
Antenna Gain: 4.3 dB
4.25 dB (Rounded to quarter-dB)
Antenna Polarization: Co-Polarized
Number of Active Chains: 2
Muli-Chains Power Gain: 3.0 dBm
TXBF Max Correlation Gain: 3.0 dBm
Power Limit Under 802.3af: No
OLPC: On
Regulatory Limits (Conducted, dBm):
20MHz:
Nss Ntx
CCK/DSSS 1 1 * * * *
OFDM 1 1 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5
HT/VHT 1 1 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5
CCK/DSSS 1 2 * * * *
OFDM CDD 1 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
HT/VHT CDD 1 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
HT/VHT STBC 1 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
HT/VHT SDM 2 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
HT/VHT TXBF 1 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
HT/VHT TXBF 2 2 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 -0.25 -0.25
Board Limits (Conducted, dBm):
20MHz:
Nss Ntx
CCK/DSSS 1 1 * 0.0 0.0 0.0
OFDM 1 1 16.0 16.0 16.0 16.0 16.0 15.5 15.0 14.5
HT/VHT 1 1 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 14.0 14.0
CCK/DSSS 1 2 0.0 0.0 * 0.0
OFDM CDD 1 2 16.0 16.0 16.0 16.0 16.0 15.5 15.0 14.5
HT/VHT CDD 1 2 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 14.0 14.0
HT/VHT STBC 1 2 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 14.0 14.0
HT/VHT SDM 2 2 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 14.0 14.0
HT/VHT TXBF 1 2 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 14.0 14.0
HT/VHT TXBF 2 2 16.0 16.0 16.0 16.0 15.5 15.0 14.5 14.0 * *
Combined Target Powers (Conducted, dBm):
20MHz:
Nss Ntx
CCK/DSSS 1 1 * * * *
OFDM 1 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT 1 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
CCK/DSSS 1 2 * * * *
OFDM CDD 1 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT CDD 1 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT STBC 1 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT SDM 2 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT TXBF 1 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
HT/VHT TXBF 2 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 * *
Actual Transmit Powers (EIRP, dBm):
20MHz:
Nss Ntx
CCK/DSSS 1 1 * * * *
OFDM 1 1 4.25 4.25 4.25 4.25 4.25 4.25 4.25 4.25
HT/VHT 1 1 4.25 4.25 4.25 4.25 4.25 4.25 4.25 4.25 4.25 4.25
CCK/DSSS 1 2 * * * *
OFDM CDD 1 2 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25
HT/VHT CDD 1 2 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25
HT/VHT STBC 1 2 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25
HT/VHT SDM 2 2 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25
HT/VHT TXBF 1 2 10.25 10.25 10.25 10.25 10.25 10.25 10.25 10.25 10.25 10.25
HT/VHT TXBF 2 2 7.25 7.25 7.25 7.25 7.25 7.25 7.25 7.25 * *
Note:
Nss: Number of Spatial Streams
Ntx: Number of Transmit Chains
TXBF: Transmit Beamforming
OLPC: Open Loop Power Control
Effective User Configured (EIRP) = MAX(User Input (EIRP), Min Power (EIRP))
User Configured (Conducted) Power is maxed at 31.75 dBm
Board Limits = the original Board Limits - Transmit Power Back-off
Combined Target Powers = MIN(Regulatory Limits, Board Limits, User Configured (Conducted),
Power Limit Under 802.3af)
Actual Transmit Powers = Combined Target Powers + Muli-Chains Power Gain + Antenna Gain
+ TXBF Correlation Gain