As
reported by IEEE Spectrum:
A new San Francisco-based start-up,
Artemis Networks,
announced today that it plans to commercialize its “pCell” technology, a
novel wireless transmission scheme that could eliminate network
congestion and provide faster, more reliable data connections. And the
best part? It could work on your existing 4G LTE phone.
If it proves capable of scaling, pCell could radically change the way
wireless networks operate, essentially replacing today’s congested
cellular systems with an entirely new architecture that combines signals
from multiple distributed antennas to create a tiny pocket of reception
around every wireless device. Each pocket could use the full bandwidth
of spectrum available to the network, making the capacity of the system
“effectively unlimited,” says Steve Perlman, Artemis’s CEO.
First introduced in 2011 under the name
DIDO (for
distributed input, distributed output),
pCell seems almost too fantastic to believe. And no doubt Artemis will
have plenty of critics to pacify and kinks to smooth out before
operators like Verizon or AT&T pay serious attention. But there are
at least a couple reasons why the idea might have some real legs.
First, it’s an elegant solution to a persistent global problem. Wireless traffic is
more than doubling each year and
cellular operators are struggling to keep up with that growth.
“Demand for spectrum has outpaced our ability to innovate,” says
Perlman, whose past entrepreneurial ventures include the cloud-based
gaming service
OnLive and WebTV (now
MSN TV), which he sold to Microsoft in 1997.
The reason isn’t for a lack of ideas. The wireless industry is pursuing plenty of them, including
small cells,
millimeter-wave spectrum, fancy
interference coordination, and multiple antenna schemes such as MIMO.
But Perlman thinks many of these fixes are just clever kludges for an
outdated system. The real bottleneck, he argues, is the fundamental
design of the cellular network. “There is no solution if you stick with
cells,” he says.
What’s wrong with cells? In a word: interference. Base stations and
wireless devices must carefully coordinate their transmission power and
spectrum use so that they don’t jam one another’s signals. This ability
to divide spectrum resources among many users has been at the heart of
mobile systems pretty much since they emerged in the 1980s. It’s also
the reason why data rates tend to plummet when many users try to use the
same cells, such as in New York City’s Times Square.
Artemis is approaching wireless transmission in a completely new way.
Basically, its pCell technology could allow each wireless device to use
the full bandwidth of the network regardless of how many users join and
how tightly they’re packed together. It’s as if your phone were
continuously the sole user of its own personal cell. Hence the name
pCell.
To understand how such a system would work, let’s start with the basic
set-up. To deploy the technology, an operator would first need a
cloud-based data center—a rack or many racks of connected servers that
would do all the heavy computation for the system. The operator would
then need to install radio antennas where its customers are located,
such as in homes, businesses, and city streets. Although these access
points might
look like
small cells
(Artemis’s, pictured below, are about the size of a hat box), they’re
unlike ordinary base stations. “They’re dumb devices,” Perlman says,
serving merely as waypoints for relaying and deciphering signals. Each
one could be placed anywhere that’s convenient and would link back to
the data center through a fiber or wireless line-of-site Internet
connection.
Now suppose that your phone wants to connect with this pCell network.
It would simply send out an access request as it normally does. And all
of the “dumb” antennas in your vicinity—let’s say there are 10 of
them—would pick up those signals and relay them to the data center.
That’s where things get interesting. Say, for example, you play a
YouTube video. The pCell data center would request the video from
Google’s servers, and then stream it to your phone through those 10
antennas. But here’s the key innovation: No one antenna would send the
complete stream or even part of the stream.
Instead, the data center
would use the positions of the antennas and the channel characteristics
of the system, such as multipath and fading, to calculate 10 unique
waveforms, each transmitted by a different antenna.
Although illegible
when they leave the antennas, these waveforms would add up to the
desired signal at your phone, exploiting interference rather than trying
to avoid it.
And as you move about, and as other devices connect to and drop off the
network, the data center would continuously recalculate new waveforms
so that each device receives the correct aggregate signal. “There’s no
handoffs and one has to take turns,” Perlman says. “You could literally
light up a whole city using all the same spectrum.”
If pCell technology does take off in the next few years, it will likely
be because it’s compatible with 4G LTE phones. It does this by
simulating LTE base stations in software. The data center would use
these virtual radios to inform its waveform calculations, essentially
tricking an LTE phone into believing it’s connected to a physical base
station. “Your phone thinks its the only phone in the cell and is
sitting right next to the tower,” Perlman says. The same technique could
also work for other wireless standards, such as 3G and Wi-Fi, he says.
So will operators adopt pCell? It’s unlikely that LTE carriers would
replace their networks any time soon, even if Artemis’s technology
proves to be the “seed change” Perelman believes it is. But its
compatibility with LTE changes the game. For instance, operators could
deploy pCell antennas in congested hot spots such as airports, sports
stadiums, and city centers—places where they’re already investing in new
infrastructure.
Users could roam seamlessly between the two networks
without having to buy new phones or switch service plans.
Artemis says it plans to license pCell to wireless carriers and
Internet service providers. The company is now beginning large-scale
trials in San Francisco and expects the technology will be ready for
commercial rollouts by the end of 2014. It will be fascinating to see
how its ambitions pan out.