Discrepancies in max EIRP numbers

Hello there,

Been slowly rolling out CBRS on 450m and 450i's.

I am kind of confused about the EIRP limits and subsequent CBSD power settings, and am seeing different numbers in different places;

CBRS spec says max EIRP is 47 dBm for cat B CBSD.

Cambium CBRS import tool will allow me to request 51 EIRP at 40MHZ wide on a 450m CBSD, and gives a grant to the 450M CBSD, but the 450M actual configuration indicates it's EIRP is a range of 22 ~42, and is set at 42dBm.

Cambium's link planner also references 51 eirp as the max for a 450M in CBRS.

How can I get my 450m to transmit at its maximum legal alowed power, as 42 seems below what I should be able to push it at.

Or am I totally misunderstanding something here?


You are correct, you should be able to get a 51 dBm total EIRP grant from the SAS at 40MHz and push that down to your 450m, and the 450m will operate at 51 EIRP (for 40MHz). 

You can request to  bump this up at AP itself by navigating to HOME --> Session status,  selecting the Relinquish button for this AP, clicking on the Relinquish action button below that, then quickly navigating to the Configuration --> Radio page and bumping up the EIRP to the desired level and SAVE.  In ~1 minute or so you will see the AP send out a new grant request automatically at the higher power level.  It's important to note though that this action should be done in a maintenance window just prior to the CPAS time, as it's quite possible the AP will be in suspended state after you reliquiksh, and  until the SAS's CPAS event.

I am interested in why this happened.  Let me reach out to you via a private channel for additional discussion as to what might have gone wrong.  

1 Like

Sounds good!

For what it's worth attached is a screen grab of cnMaestro CBRS tool showing MAX and Requested EIRP as 51 for an AP, and another screen grab from the AP itself showing 42.

By the way, you can email me directly at; jrl@infowest.com

James Lockwood450m-CBRS-Status.jpgcnMaestro-CBRS-tool.jpg

We're just getting our first 450m running (on CBRS - but we're new to the platform in general). I also received a max EIRP of 48, not 51. I tried relinquishing as outlined above, but the radio tab only shows 48 as a maximum - it would let me type 51, but hit "save" and it's back to 48.


@thebracket wrote:

We're just getting our first 450m running (on CBRS - but we're new to the platform in general). I also received a max EIRP of 48, not 51. I tried relinquishing as outlined above, but the radio tab only shows 48 as a maximum - it would let me type 51, but hit "save" and it's back to 48.


Are you using a 20 or 40MHz channel width? If you're using 20MHz, the max EIRP is 48dBm.

That explains it, thank you! So use 40 Mhz for 51 EIRP? I'll give that a go before we get many SMs setup (upside of being in the testing phase)