SAN FRANCISCO—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 Broadband Plan.
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 Networks, 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 computer--the Mac.”
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 by Steve 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 on his StevenCrowley.com website.
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.
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