
pCell, A Bold Scheme For Super-Fast Wireless Data - ghalusa
http://readwrite.com/2014/03/19/pcell-artemis-wireless-dido-steve-perlman
======
politician
Previous discussion on HN (with participation from the inventor):

[https://news.ycombinator.com/item?id=7316606](https://news.ycombinator.com/item?id=7316606)

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cbhl
This looks like it'd work for fixed broadband installations (say, for people
in rural Montana or Ontario), but I'm less convinced it'd work well for cell
phones because the tower would need to predict your movements in advance of
you actually moving there in order for it to know where to build the
constructive interference.

~~~
StandardFuture
Perlman demonstrates [0] some sort of 'adaptive algorithm' that pCell uses to
track real-time a UE's position.

[0] [http://youtu.be/wGAnDQEQJ_s](http://youtu.be/wGAnDQEQJ_s)

~~~
sgrove
I'm surprised at how rough the audience was for the presentation. I wonder
where those emotions came from.

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KaiserPro
_Sigh_

The biggest limiting factor of wireless is the lack of frequency in which to
put you're data. Not interference.

pCell only works for small areas, what it does is essentially beamform a
signal directly to the consumer (basically cupping your hands around your
mouth when you shout at someone) I assume the "magic" comes from some sort of
noise cancelling (yes just like the ear phones)

However in practice I assume they just use more than one beam former to create
more than one beam.

It cannot be used for wide area systems, as the only reason this works is
because its local. it provides bandwidth for one small area using the same
frequency that the wider area is using.

~~~
MrBuddyCasino
Can you elaborate why it wouldn't work in a wide area setting? In a
demonstration, they had a lot of cellphones on a desk, but not a matching
number of pCell antennas, so it seems they can support many devices with a
single (or at least much less) antenna.

Or do you mean to say that the beam forming is not going to work over large
distances, so phones must be in close proximity to the antennas?

~~~
KaiserPro
the system will work over long distances, indeed he claims in the paper (with
nothing to back it up, that paper is extra-ordinarily vague.)

However it wont increase bandwidth. (I should have been more precise) The only
reason why people are interested in this is because it offers the idea of
greater bandwidth.

The way they increase bandwidth is effectively partitioning the local airspace
off from the wider world. Each cell (be it TV, phone or $other) can deliver x
bandwith.

The bigger the area covered by the cell, the less bandwidth per unit of
volume. (conversely the smaller the more bandwidth per volume)

This is before we start doing clever things like spread spectrum or account
for signal loss/noise/shannon's law

This is pretty much snake oil. Its beam forming with a marketing budget. There
is nothing in that paper that suggests otherwise

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tbolse
I have seen some statements of Perlman and persons related to him or his
companies, that this technology is not only applicable to communication
networks. That, and the recent patent applications, make me think that he is
talking about wireless power.

I really wonder if, and I have some doubts that, the underlying technology is
at all feasible for such an application?

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timmclean
Here's the actual white paper, which is fairly readable:
[http://www.rearden.com/DIDO/DIDO_White_Paper_110727.pdf](http://www.rearden.com/DIDO/DIDO_White_Paper_110727.pdf)

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barefootford
I wish he would have taken Apple's lead on having a big launch with a product
that ships in a couple weeks rather than a dribble of presentations with a
shipping: ??? slide.

If pCell works, getting press won't matter. If you can _destroy_ the markets
for mobile data + home internet you won't have to fight Stanford undergrads in
some anonymous lecture hall. So, I am sorta skeptical.

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diafygi
Question: The article mentions that pCells use interference to their
advantage. Would a network of these be able to operate in a public spectrum?

~~~
msandford
With the licensing environment that exists today the answer is a definite
"uhhhh maybe?!"

If you wanted to do it with LTE gear no since it's fixed to non-public
spectrum.

If you did some serious wifi hacking to use the same concepts you might be
able to. But with the area that wifi covers and the generally terrible power
efficiency of the amplifiers I'm not entirely sure you'd want to. I don't
think you'd be able to call it pCell but you could probably use the DIDO ideas
and make it happen if sufficiently motivated.

~~~
azdle
I don't see any legal reason why you couldn't do something like this today.
There are already WiFI routers that do beamforming and this just seems like an
application of beam forming where your antennas are much further apart.

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rasz_pl
secong gen 802.11ac will do this too, MU-MIMO will use beam forming to send up
to 4 streams to up to four clients simultanously.

[http://chimera.labs.oreilly.com/books/1234000001739/ch04.htm...](http://chimera.labs.oreilly.com/books/1234000001739/ch04.html)

~~~
kristoffer
It is not the same thing. 11ac does normal beam forming not
network/distributed MIMO.

~~~
rasz_pl
secong gen will be distributed

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StandardFuture
For all interested, here is a link to a recent talk Perlman gave at Stanford:
[https://www.youtube.com/watch?v=wGAnDQEQJ_s](https://www.youtube.com/watch?v=wGAnDQEQJ_s)

Since many will not watch through the whole thing here is a basic synopsis.

If you are looking for pCell's strength to be in any sort of physical layer
innovation, stop. It's not the actual antenna 'box' that you see in photos
that is doing the heavy work. That is just a basic RF frontend that Artemis
could care less if you broke it open and reverse engineered every component
inside.

Perlman's talk confirms my suspicions that this is not an RF advancement at
all. It's a software advancement. The real work is being done by the
"datacenter". The overall RAN architecture is a CRAN (Cloud RAN) architecture,
which means that it fails miserably to be innovative without it's special
software.

We are not talking about protocol stack software (as found in LTE eNodeB's and
LTE capable UEs). We are talking about Artemis's proprietary software (which
must be some killer highly optimized, low-level, kick-ass mathematics and
networking algorithms).

Artemis's datacenter seems to create a virtual enodeB for every device
accessing the CRAN (the access points being the 'Cloud' of those antenna boxes
you see in the photos/videos which work together).

Each device then communicates physically through the boxes but virtually with
an enodeB "server" in the datacenter. Thus, it reads the environment AS IF it
has an ENTIRE basestation (tower) all to itself. :P

Now if you know every device's information via uplink information provided by
the protocol stack and every access points information provided by the already
in-house data then you could theoretically play around heavily with wave-front
mathematics.

But I think pCell's potential is being a bit overestimated. I remember Perlman
saying something like pCell offering a 10x advantage or something. (Sorry
don't remember every detail I watched the video late last night).

That advantage level is cool, but it seems Artemis is pushing (and for good
reason) not some sort of instant HUGE advantage with pCell, but a long-term
scalable advantage.

According to their claims, it seems that you should just be able to add more
access points (as well as extend the processing capability of the datacenter)
to increase the overall capability of the CRAN.

It would be neat to know what algorithms they are using, but they really seem
to not want to say anything that might even come close to giving it away.

I am not sure what aspects of the channel quality and UE feedback they use
from the protocol stacks (LTE, wi-fi, etc.) but they seem to have something
working.

We shall see what happens.

EDIT: It's a funny way to think about it, but it seems that the 'innovation'
exists outside of the protocol stack. It's like a "sub-physical layer" that
"transports" the actual link between the device and the virtual enodeB by
placing the wave-front 1cm around the antenna(s) of the device? (Open to
critiques on anything I said) :)

~~~
3rd3
Typo or
[http://www.youtube.com/watch?feature=player_detailpage&v=om7...](http://www.youtube.com/watch?feature=player_detailpage&v=om7O0MFkmpw#t=50)
?

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zw123456
Whenever I see something that claims to overcome a long tested theory like
Shannon's law, it always makes me very suspicious. The explanations I have
seen so far are long on claims and short on proof and remind me very much of
"perpetual motion machines". So far nothing I have seen shows how they are
"side stepping" Shannon. I smell a rat.

~~~
foobarqux
This doesn't violate the Shannon capacity theorem: Different channels, like
MIMO channels, have different capacities.

pCell is basically a proprietary version of network MIMO. (Though maybe still
valuable if it can get to market faster).

