—Steve Perlman, founder of Artemis Networks
LLC, has unveiled what he calls “pCell” technology which he claims “is a complete
reinvention of wireless [technology]. Perlman went on to describe pCell as “mobile
fiber” and noted that it could provide “the long-sought dream of ubiquitous,
fast Internet, with the reliability and consistency previously only achievable
through a wired connection.”
The new technology could put an end to the spectrum availability crisis and
destroy “spectrum scarcity” assumptions being used to justify reallocating more
television broadcast spectrum to wireless carriers in the FCC’s National
Artemis’s plan involves the use of many simple, discreet “pCell” base
stations, called pWave radios, which transmit RF waveforms designed to add
constructively in one spot to create a “personal cell” around a device which
would allow each such device to take advantage of the full bandwidth of the
channel. Unlike MIMO (multiple input multiple output) technology, multiple
antennas are not required on the devices communicating with the pWave radios
and the technology is supposed to work with standard, unmodified out-of-the-box
LTE devices, including smartphones and Mi-Fi devices. When a mobile device
moves outside the area covered by the pWave radios, it can connect with
conventional wireless networks.
From the descriptions I’ve seen of the technology, a large number of the pWave
radio base stations are needed to get this huge increase in capacity.
Fortunately, pWave radios can be placed anywhere that’s
convenient--indoors, outdoors, visible or hidden, where backhaul is available.
The technology works in all mobile bands, including unlicensed spectrum. User
devices exchange brief test signals with the pWave radios, allow the data
center controlling the radios to analyze the propagation between radios and the
user device. Once this is accomplished, precise waveforms can be simultaneously
transmitted from the pWave radios that will sum together at each user device.
As an example, with 10 pWave radios and 10 users all within range of each
other, the 10 radio signals will sum together at each antenna of each user’s
device producing an independent waveform for each of the users’ devices with
only that device’s data.
The claims sound fantastic, but according to Artemis
, the company that Perlman and a team of engineers formed to
commercialize the technology, is said to be “currently in trials” with partners
in San Francisco and should be ready for commercial deployment in at least one
market by the end of 2014. Expansion to major markets in the United States,
Asia, and Europe is expected to start in 2015.
John Sculley, former Apple CEO, noted that: “pCell is an authentic
‘moon shot’ disruptive invention, one of those rare but
extraordinary moments when what previously seemed improbable in science becomes
possible. The first time I saw a ‘moon shot’ was in 1982
when Steve Jobs showed me a prototype of the original consumer media
Searching for more information on the technology, I found some papers by Dr.
Antonio Forenza, the principal scientist at Perlman’s Rearden lab in San
Francisco. In 2006 Forenza published Antenna and Algorithm Design in MIMO Communication Systems
Exploiting the Spatial Selectivity of Wireless Channels
. In his
paper, Forenza states: “The benefits of MIMO technology are obtained through a
combination of antenna arrays that can provide spatial diversity and algorithms
that can adapt to the propagation channel.”
He noted that antenna arrays needed to be designed for robustness in varying
propagation conditions and to provide “the degrees of spatial diversity
expected by the algorithms.”
Forenza explained that the algorithms “can adaptively reconfigure the
transmission methods by tracking the changing channel conditions” and stated
that that this was all based on the premise that “antenna arrays and algorithms
at the physical layer can be designed, based on performance metrics from
different layers, to exploit the channel spatial selectivity, resulting in
improved system performance.”
More details on the how the current system works are provided in the Rearden
white paper Distributed-Input-Distributed-Output (DIDO) Wireless
Technology – A New Approach to Multiuser Wireless
Perlman and Antonio Forenza, Ph.D.
This paper offers the following explanation of DIDO:
“Distributed Input-Distributed-Output (DIDO) wireless technology is a new
approach to multiuser wireless that allows the number and density of users in
the same area to be steadily increased without additional users reducing the
data rate of others.
“In other words, the shared spectrum capacity is not subject to Shannon’s
law: as more users in a given area share the same wireless spectrum, the data
rate per user does not decline. As a result, regardless of how many users are
in a given area, each user is able to use the entire Shannon Limit of the
channel, despite sharing the same spectrum.”
The white paper says the demonstrated spectral capacity of DIDO today is 10
times the Shannon Limit, but they expect to reach 100 times and are optimistic
that 1,000 times the capacity is achievable. The paper added: “But, until we
start to see some degradation in performance as we add more users, we will not
be able to predict how far it can go.” It also provides some examples that
explain how the technology works.
The technology is not limited to UHF frequencies. The white paper outlined a
demonstration using HF spectrum and near-vertical incidence skywave (NVIS)
propagation. Three transmitting antennas, as far as 32.9 miles away (beyond the
curvature of the Earth) were used to simultaneously send three independent
signals to three user antennas as close to each other as typical rural homes.
Another advantage to the Artemis system is that as each device has its own
channel, complex sharing protocols are not required, thus providing latencies
of typically less than 1 millisecond as compared to more than 100 milliseconds
for conventional LTE links
Steven Crowley, P.E. describes the experimental license application Rearden
filed for testing the technology in his posting Rearden discloses more experimental details at
FCC’s request, plans to use Clearwire spectrum
Cade Metz, in his article "This Man Says He Can Speed Cell Data 1,000-Fold. Will Carriers Listen?" at WIRED.com discusses the implications of this
technology for wireless carriers whose business model is based on maximizing
the value of a scarce resource--spectrum (and bandwidth)--and questioned how
interested they might be in promoting such a revolutionary technology.
If wireless carriers aren’t interested, this pWave could be the breakthrough
technology the cable TV industry needs to compete in the wireless arena with
AT&T and Verizon. Cable companies already have an extensive
distribution system that could provide the ideal backhaul backbone for
thousands of pWave radios. With that many radios, they wouldn’t really need
much spectrum to blow a hole in the wireless carriers’ business models.