I believe they are referring to a beam-forming antenna when they say active phased array. Basically, timing of the RF signal to various portions of the antenna is altered such that it restricts and focuses the beam towards an intended target. The technology has only recently come to the point that it is practical for consumer level applications. I don't see it helping with reflections, with endpoints all over, you'll have a bunch of very strong beams scattering everywhere, but it can help push the signal further than a simple omni-directional or even sector antenna. I don't believe it helps much with the received signal.

A real engineer will be able to answer the signal processing question much better than I, but to my knowledge, multipath can only be effectively dealt with when all versions of the signal originated from the same device. When you have effectively a stray signal, it's difficult to tell even where the carrier is. There is some mitigation possible with timing of transmit/receive signals(usually with GPS), but this also requires some control over the propagation of the signal.

As far as weather, for most areas, 39ghz would probably be practical out to 2 miles, with some brief interruptions for very heavy rain. But with the bandwidth limitations, this isn't in line with the stated goal of gigabit level service to high-density urban environments.

This would certainly be a last-mile tech, but the described target is high-density urban areas, where population densities far exceed 1000/sq mile. I can't see this technology ever being able to function at gigabit speeds with those densities.

Mesh networking has it's own issues. If you're going to run it on the same frequency as your endpoints, then you are sharing spectrum with them and your overall bandwidth is significantly reduced. You can backhaul it on a different frequency, but now you have more equipment and expense, licensing, etc... I have to be careful saying it because I haven't kept up with the lastest in mesh developments, but over the last 10 years, I have never seen a mesh network system work reliably with any sort of appreciable speed. Most have failed miserably. The idea looks great on paper, but rarely works out in the real world.

There are tons of last-mile tech available that work very well. FSO(free space optics)[1] is one of them. It has nearly unlimited bandwidth. It's limitation is, it is, as the name implies, optical in nature, so line of sight is an absolute must. Currently available equipment is overpriced as well, but a newcomer could change that.

The FCC just opened up about 150mhz of spectrum in the 3.5ghz area also for last-mile delivery of wireless broadband - Citizens Broadband Radio Service[2]
This band is aimed at rural deployments, and isn't concerned with pushing 1gb to everyone, but will go a long ways towards getting a lot of people on the internet at decent(20mb/s+) speeds.

The 5ghz unlicensed band is also very effective at distances under 2 miles, and can be pushed up to 100 miles in certain situations. There is about 600mhz of spectrum available here, some of it ideal for urban situations as it shares frequencies with weather radar and is under strict power restrictions that make it difficult to use for longer and rural connections.

On a tangent, I deal with people nearly every day that can't even get 3mb/s DSL service. The only high-speed that's available to them is satellite, with data caps and horrendous latency, or 3g/4g with spotty speeds and availability, data caps, and impractical per GB billing. When they are able to get even 10mb/s of real internet, they are happier than a 5 year old on Christmas morning. It's by far the most rewarding thing I get to do. It would be nice to see more money flowing towards things like this. But not like FRBA [3] -- Essentially $24 million wasted.

[1] https://en.wikipedia.org/wiki/Free-space_optical_communicati...

[2] https://www.fcc.gov/rulemaking/12-354

[3] http://blog.tmcnet.com/on-rads-radar/2013/04/florida-broadba...

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fix footnotes