Thank you for the detailed scan! Indeed, there are a lot of radios there, and some of them pretty powerful.
I'm assuming the antennas used are jirous, right?
Which model? It would be interesting and useful to see how different antennas (especially mikrotik's and rocketdishes) work under same conditions.
Here is a place where isolation is more important than on other installations.
Thank you!
Yes - we're using the JIrous JRC-29 Duplex on both sides - it has 53 dBi of port to port isolation.
http://en.jirous.com/antenna-5ghz/jrc-29-duplex
There's been some discussion about how higher cross polarity isolation may improve SNR between each of the spatial streams.
This book has a great break down of the differences between 802.11N & AC and why that may be the case:
http://chimera.labs.oreilly.com/books/1 ... ng_set_mcs
As with many other aspects of the protocol, 802.11ac kicks up the existing technology a notch by using 256-QAM. Rather than a constellation that is 8 by 8, the 256-QAM constellation has 16 phase shifts and 16 amplitude levels. Figure 2-4 compares the 64-QAM constellation to the 256-QAM constellation. At first glance, they’re quite similar, though there are many more constellation points in the latter. One analogy that is often helpful is to compare QAM to a game of darts. The transmitter picks a target point and encodes an amplitude and phase shift. This amplitude and phase shift starts off at the ideal constellation point, and the receiver pulls the transmission out of the air and maps it onto what was received. As the constellation points get closer and closer together, the transmitter must be able to throw its darts much more accurately to hit the target point.
easg_0204.png
With twice as many phase shifts and amplitude levels, higher SNR between each of the constellation points becomes important. Better cross-polarity isolation is a step in that direction.
Our initial upgrades were to links that already had the DuplEX's. We haven't had a chance to compare the other dishes with less cross-pol isolation.
We do know that upgrading the boards alone with everything else held equal dramatically improved performance.
Hope that helps!
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as this link isn't in production on the channel you mentioned. We certainly do not condone or encourage operators to exceed FCC EIRP limitations. In situations where EIRP becomes a factor, MikroTik provides the ability to decrease the TX power output accordingly.