Why dont I get full EIRP from AP?

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  • Updated 6 months ago
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I try to do a test with creating a 5GHz link outdoor.

The link works but to know the maximum distance I can do with this AP/antenna combination I want to get the AP to use the maximum allowed EIRP.

But I only get half (500mW = 27dBm) instead of 30dBm.

this is my setting and status of radio.

ap6562-690AB4#sh wireless regulatory device-type ap6562 se
----------------------------------------------------------------------------------------------------
  #   Channel Set Power(mW) Power (dBm)    Placement          DFS       CAC(mins)        TPC
----------------------------------------------------------------------------------------------------
  1    1-13        100       20          Indoor/Outdoor   NA             NA        NA
  2    36-48       200       23          Indoor           Not Required   0         Not Required
  3    52-64       100       20          Indoor           Required       1         Not Required
  4    52-64       200       23          Indoor           Required       1         Required
  5    100-116     500       27          Indoor/Outdoor   Required       1         Not Required
  6    100-116     1000      30          Indoor/Outdoor   Required       1         Required
  7    120-128     500       27          Indoor/Outdoor   Required       10        Not Required
  8    120-128     1000      30          Indoor/Outdoor   Required       10        Required
  9    132-140     500       27          Indoor/Outdoor   Required       1         Not Required
  10   132-140     1000      30          Indoor/Outdoor   Required       1         Required
----------------------------------------------------------------------------------------------------
ap6562-690AB4#
Radio: 84-24-8D-69-0A-B4:R2, alias ap6562-690AB4:R2
 STATE                : On
 PHY INFO             : Bssid: 84-24-8D-69-0E-20 RF-Mode: 5GHz-wlan
 ACCESS POINT         : Name: ap6562-690AB4  Location: Test  Placement: Outdoor
 CHANNEL              : Current: 100 Configured: 100 Width: 20MHz
 TRANSMIT POWER       : 17 dBm
 ANTENNA USAGE        : 2x2
 MAXIMUM DATA RATES   : Phy: 144 Mbps User: 108 Mbps
 PHY SETTINGS         : Short Preamble: N Dual Channel: N Spectrum Mgmt: Y
 RATE SELECTION       : Standard
 ANTENNA DOWNTILT     : Not-Supported
 RADIO SHARE MODE     : Off
 TRANSMIT BEAMFORMING : -
 MU-MIMO              : Not-Supported
 SCAN_AHEAD CHANNEL   : -
 ERP COEXISTENCE      : ERP Protection: N Non-ERP detected: N Non-ERP associated: N
 HT COEXISTENCE       : HT Protection: no-protection, Non-HT detected: N
 Current Channel Width: 20Mhz, reason: per configuration
 Num of Mcast Streams : 0 (max:25)
 Multicast streams    :
 # MP Mcast Streams   : 0
 WLAN MAP             :
     BSS-1            : Test* (*=primary)
     Shutdown WLANs   :
 MESHPOINT map        :
 BSS MAP              :
     BSS-1            : basic-rates    = 6 12 24
                      : supported-rates= 6 9 12 18 24 36 48 54 mcs-1s mcs-2s
 Last error           :

ap6562 84-24-8D-69-0A-B4
 use profile default-ap6562
 use rf-domain Test
 hostname ap6562-690AB4
 interface radio2
  channel 100
  power 30
  wlan Test bss 1 primary
  antenna-gain 10.0
  no dynamic-chain-selection
ap6562-690AB4(config-device-84-24-8D-69-0A-B4)#end


AP is powered by a 802.3at capable switch.

If I fool the AP that I have a 7dBi antenna instead it amplifies the IR to 20dBm so its something I cant see.

Kind regards

Paul




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Paul Holmgren

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Posted 6 months ago

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Andy Holden, Employee

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Hi Paul


A word of caution, configuration of a wireless access point to fool it to exceed the FCC defined limits is a violation of the FCC regulations and could leave you open to fines if detected.


Rather than try to push a single AP to provide coverage over a large area, please do a proper Rf- Survey to determine the number of APs required to support you site

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Paul Holmgren

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I know,

the problem is its not exceeding regulations limits inside the AP list.

see this.

6    100-116     1000      30          Indoor/Outdoor   Required       1         Required


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Timo

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Hi,

you need to configure the radio for outdoor. Max. 30dBm is EIRP or TX power in your country?

30dBm EIRP with 2x2 radio, TX power is 27dBm, based on the MIMO. For 1x1 you can do 30dBm.
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Paul Holmgren

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Hi,

Are you shure?

Is it possible that you mixing up that you can calculate +3dBm from a MIMO signal if you whant it to reach further instead of deliver more data when designing, but the regulation is on EIRP an that will not get any higher from a dual antenna? 

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Timo

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Yes, I'm sure.

max. 30dBm EIRP with 5dBi antenna gain the max. TX power:
25dBm for legacy data rates with 1 antenna chain
22dBm for 802.11n/ac data rates with 2 antenna chains

If you configure now antenna gain of 5dBi and TX power for 30dBm, AP will do 25dBm or 22dBm -> dynamic chain selection is enabled by default and responsible for this automatically power changes.
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Paul Holmgren

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I have now lowered the radio to 1x1.

and that does not change any behaviour on the AP.

CHANNEL              : Current: 100 Configured: 100 Width: 20MHz
 TRANSMIT POWER       : 17 dBm
 ANTENNA USAGE        : 1x1

transmit power is what AP is selecting it self.

I have configured it for 30dBm EIRP.


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Timo

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For this case, open a GTAC. I had some problems last year with AP6522. Mostly the same, but if I can remember with 14dBm max TX power.

After some mails looks like, radio problem. I think AP6522 and AP6562 use the same radio.
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Alona, Employee

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AP 6562 doesn't support TPC so it won't be able to go to 30dbm. 
When AP is not able to support TPC - it uses regulatory for non-TPC case:
100-116     500       27          Indoor/Outdoor   Required       1         Not Required
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Paul Holmgren

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Hi,

Strange that that a Outdoor AP with built in heat does NOT support TPC.

Can you give me some documentation that supports that?

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Timo

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Really? Datasheet says:

Maximum Available Transmit Power:

2.4GHz: 21dBm Per Chain

5GHz: 20dBm Per Chain 

You already do more power as the AP can ;D


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Paul Holmgren

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But I have a 10dBi antenna and the AP backs down to 17dBm.

And when I test to set the antenna to 7dBi it rises the radio to 20dBm so I don't do more than the AP can do.

So that's not the answer.

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Timo

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I think it's the answer?

Max EIRP based on regulatory is 30dBm EIRP. Max TX power based on hardware (see data sheet) is 20dBm.

If you configure 10 dBi for antenna gain, use 802.11n/ac rates, max TX power for this is 17dBm:
30 dBm EIRP - 10dBi antenna - 3 dBi (using 2 chains for 802.11n/ac rates)
For legacy data rates it can use 20dBm, but not show it!

If you configure 7 dBi for antenna gain, use 802.11n/ac rates, max TX power for this is 20dBm:
30 dBm EIRP - 7dBi antenna - 3 dBi (using 2 chains for 802.11n/ac rates)
For legacy data rates it can do 23dBm, but not show it and AP don't support more than 20dBm TX power for single chain!

If you configure 5 dBi for antenna gain, use 802.11n/ac rates, max TX power for this is 22dBm:
30 dBm EIRP - 5dBi antenna - 3 dBi (using 2 chains for 802.11n/ac rates)
For legacy data rates it can do 25dBm, but not show it and AP don't support more than 20dBm TX power for single chain! But in this case it should show 22dBm, because 23dBm for dual antenna composite transmit power is possible.
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Ondrej Lepa, Employee

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Hi,

as discussed with Paul in the background, below table shows a regulatory limitations based on region.

It might get misleading in the way you specify particular device and then it shows TPC required / not required.
However, it does not say if the device supports the feature.

In other words, as AP-6562 does not support TPC, you may operate only within TPC - Not Required boundaries.

Regards,
Ondrej
(Edited)