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Trying to calculate link budget for bridges with 802.11ac link

We've got some 2702Es in autonomous mode to be deployed as wireless PTP bridges and I'm trying to document the link power budget for the PTP link.  I have all the power data in dB for the hardware, I have the free space path loss calculated, and know the attenuation loss of antenna cables used, but for life of me can't make sense of what I should use for the txpower from the transmitter.

 

The radio controller is configured for the hardware maximum of 23 dBm, but since it's channel 165 it's less than that, isn't it?  I can't find a specific reference to what it would be, though.

 

And let's say the link is a steady a5.2b2, which translates to MCS 5, 2 spatial streams, 20Mhz bw, and beamforming.  Does that affect the txpower?

 

Help, I'm confused.

 

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Re: Trying to calculate link budget for bridges with 802.11ac link

Not a fan of using indoor AP’s for PTP bridges as there are various other units and vendor products that are true bridges. 

That being said, you are using this as autonomous so there is no beamforming.  So don’t get confused with what is supported with a controller as you need to treat this just like what you are calculating. Depending on your distance and also channel utilization on the path, you would always start with the highest TX power and work your way down. Antenna type, alignment are important. So once you do your generic calculations and that ensures a link and provides you with data that meets your requirements, then you just need to bring the link up and make final adjustments. 

-Scott
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