Gigafast AV2 and beamforming...

[stevech]

This sales sheet

http://www.gigafast.com/?projects=psg959-eb6-bcm60500

says the IP over power wiring device includes beam-forming technology. Since the product does not have any 802.11 wireless, how could beam-forming, a technology for wireless antenna spatial directionality, apply?

 

[paranoised]

Yes beam-forming is indeed being used in the new homeplug av2 adapters. It has been mentioned in the article written by Higgins:

According to this diagram from the HomePlug Alliance, AV2 expands the spectrum even more, out to 86 MHz. Note also that there are two forms of AV2—SISO (Single Input Single Output) and MIMO (Multiple Input Multiple Output). Homeplug AV2 uses a lot of the technology used in 802.11n and ac wireless, including OFDM, MIMO and even beamforming!

http://www.smallnetbuilder.com/lanwan/lanwan-reviews/32164-homeplug-av2-head-to-head?start=1

Not sure how it's accomplished though..

 

[stevech]

but beamforming is about steered-beam antennas in a spatial sense. Not about spectrum and frequencies.
Beamforming is about electronically "aiming" a directional antenna. Very rapidly.
I don't see how that applies to a wired medium.

 

[JoesRevenge]

See my comment on beam-forming in thread: http://forums.smallnetbuilder.com/showthread.php?t=18738

 

[stevech]

See my comment on beam-forming in thread: http://forums.smallnetbuilder.com/showthread.php?t=18738

Ah, I'm an old broadband guy in an antenna world. So what you're saying is that they direct RF to one of the two phases to try to get concurrent streams? And they call this beamforming. How would this work in countries that don't have two phase power?

 

[thiggins]

Ah, I'm an old broadband guy in an antenna world. So what you're saying is that they direct RF to one of the two phases to try to get concurrent streams? And they call this beamforming. How would this work in countries that don't have two phase power?

Line and neutral are not separate phases

 

[JoesRevenge]

I'm not at all an expert on the math involved here. But, from my understanding, the transmitter sends out a signal on each of the LN and LG paths. Each signal encodes different data. As these two signals travel from the transmitter to the receiver they encounter different "stuff" - different length wires, different loads, etc. Because the wires generally are bundled together, they also couple together so some of the LN signal transfers to the LG wire and vice versa. The different devices on your power line also act as filters for different frequencies which further mix up the entire signal path. The net result is that the signals that arrive at the receiver are a mixed version of the two transmitted signal with a lot of attenuation and filtering thrown in. Beam forming attempts to reverse this process.

When two devices first communicate, they sound the channel to determine how the channels mix and what frequencies have noise and which don't. From this they compute a beam forming matrix that will reverse this mixing and distortion. This is then applied to all received signals an the original signals can be recovered (or enough of them that the error correction can take care of it from there).

Joe