MR36 - Transmit Power

[PJ51182]

Hi,

I have recently been supplied with MR36 APs rather than the MR33 we ordered due to supply issues. I installed my first batch of MR36 and found that the transmit power maximum setting is only 12 where as the MR33 is 16.

"1 radio is incompatible with a max power of 16 and will be set to its highest compatible power."

As we have planned the install for the dBm being higher it has had an affect on the coverage.

I have checked the datasheet for the MR36 and there is no mention of the dBm at all.

Please see screen grab below:

I'm not sure why the transmit power is lower? Any thoughts?

[NolanHerring]

You have your 'Target Power' range set from 5 - 30dBm

Your 'Transmit Power' is the value the AP is actually using.

Since you have default settings, the AP will determine (using magic) which power level it will use. 

For whatever reason, it settled on 12dBm

You can manually change this to a different value, or, you can tweak your 'Target Power' range settings to not go below 16 for example.

Your power level will vary per frequency, and also depend on what country you are operating in, as far as 'max' goes.

[cmr]

If this is a 5GHz radio then some of the frequencies have different maximum power ratings, what jurisdiction are you in and what channel are they on?

[PJ51182]

The maximum Target power for the MR36 is 12.  If you go to the Target power for the MR33 it's up to 16 (when you try to set manually).

I have logged a support ticket and this is being investigated.  I have been asked to try Beta firmware (27.4) to see if the power can then be increased and they are also going to be speaking with the developer's team.

From what I understand the MR36 should be able to have the same maximum transmit power as the MR33.

"I am going to reach the developer's team about this for any suggestions.

For the time being, it would be interesting to check if it is something Firmware related, for that you can temporarily install Firmware 27.4, which is at the moment in Beta, but it is very stable and solid from my experience; we can always roll back to the previous firmware if desired, it also contains new features that you may be interested in too.

It will be helpful to know if it is capable to setting the transmit power to 16 in the new firmware or not.

I will let you know with anything that the developer's team reaches me with.

Let me know the outcome of the firmware upgrade. I am going to reach the developer's team about this for any suggestions."

[PJ51182]

I'm in the UK.  Please see further details below:

[cmr]

@PJ51182 we are running a couple of MR36s in the UK with 27.4 and indeed get the same issue as you, both were running on 12 with 5-30 set on the 2.4GHz band.  I tried overriding one of them and and if you pick 13 upwards then the same warning about the radio being incompatible comes up.

[PJ51182]

@cmr thankyou for your comment.   I've upgraded this morning and hasn't made any difference.  I've fed this back to Meraki so will see what they come back with. If the reply is useful, I'll post it on this thread.

[NolanHerring]

I have some on 26.8.1 (United States) and I just set the power manual to max, and it went to 23dBm. So I suspect its due to domain regulation issue.

[PJ51182]

@NolanHerring Thankyou for the information. I understand that regulations play a part but can't understand why a newer model (i.e. the MR36) has a lower maximum setting than the model it's replacing. 🤔

See what Meraki support come back with.

[cmr]

For the 5GHz band I know they need to get each model certified to be able to go to higher power levels and perhaps the same applies to the 2.4GHz band

[AnythingHosted]

I have a case open with support. Our MR52s are capped at 14dBm on the 2.4Ghz band, no matter what override or other settings we choose. 

In fact, if I override the profile to 30dBm, after saving it sets the target to 14dBm. 

[PJ51182]

Been busy so haven't had a chance to post the reply from support:

"the developers team has acknowledged the issue, they have categorized it, and add it to their backlog.

I will let you know when it gets fixed using an email response.

Sorry for the inconvenience."

Not sure if this will have to wait until the next release or will be done in the background.  If I get any further updates I'll post them.

[paddyboy]

We are looking into MR36.  Is the OP referring to 2.4Ghz band with max of 12 dB, or 5Ghz channel (band)? 

in the case of 2.4Ghz, this doesn't hurt us too much in our dorms, as we tune at around that level already.

Is your screen shot showing Tx power for your 2.4Ghz or 5Ghz radios?

Thanks.

Paddy

[cmr]

@paddyboy it is the 2.4GHz that we are talking about in this thread.

[paddyboy]

@cmr  thanks very much.  Appreciate the fast reply.

[GreenMan]

I'm not sure of your in-country regulatory rules, but note the difference in peak antenna gain between the two models.

From the datasheets:

MR33:   Integrated omni-directional antennas (3.8 dBi gain at 2.4 GHz, 3.9 dBi gain at 5 GHz)

MR36:   Internal Antenna (5.4 dBi gain at 2.4 GHz, 6 dBi gain at 5 GHz)

With a higher peak gain, you usually need lower Tx power, to avoid exceeding max EIRP for the system

[GIdenJoe]

I have also noticed some possible discrepancies in the allowed EIRP on Meraki W6 AP's vs the actual regulatory allowed EIRP.

In Europe you have following rules.
All 2.4 GHz channels - max 20 dBm EIRP.
So the MR 33 should be max 16 dBm Tx Power and the MR36 should be max 14 dBm.

In case of 5 GHz it depends on the channel.

36 - 48 and 52 - 64 = max 23 dBm EIRP

In this case you should have max 19 dBm Tx power on MR33 and max 17 dBm on MR36.

100 - 140 = max 30 dBm EIRP

In this case you should have max 26 dBm on MR33 and max 24 dBm on MR36

However the MR33 also has a total max Tx power of 17 to 21 dBm depending on the channel used.
And the MR36 is even a bit lower I've found the datasheet in the library section of the site (it's not linked on the product page itself 😕 )  the max power is 18 dBm in 2.4 GHz and 17 on 5 GHw