What impact would it have if wireless carriers could support the same number of users at the same or higher data rates using 12 MHz (two TV channels, not counting guard bands) that would require 180 MHz (30 TV channels) at the highest average spectral efficiency targeted by LTE-A? San Francisco start-up Artemis Networks claims that not only is it possible, but that the FCC should establish minimum spectrum efficiency requirements for licensees in the 600 MHz spectrum to meet what the FCC has repeated said is a looming spectrum crisis.
In its Petition for Reconsideration of the FCC's incentive auction Report and Order, Artemis says “that the 600 MHz band will be utterly congested soon after it is deployed, and will remain congested for a 'generation'. Given the unique propagation characteristics of 600 MHz, it is strongly contrary to public interest to make a technical ruling which will relegate 600 MHz to a generation of congestion when a practical technical alternative exists that will eliminate congestion and still remain LTE device compatible.”
Artemis claims it its “pCell” technology is able to increase the spectrum efficiency (SE) of LTE to greater than 50 bps/Hz consistent throughout the coverage area compared to less than the 3 bps/Hz average for LTE-A while remaining compatible with off-the-shelf devices. Users would not have to replace their smartphones to take advantage of the improved coverage and higher data rates. Artemis states “pCell has been extensively tested indoors and outdoors with unmodified commercial LTE devices in bands 38, 39, 40 and 41 and with custom LTE UEs [user equipment] at 400 and 900 MHz.”
Artemis doesn't have to break the Shannon limit to achieve these efficiencies. It uses many base stations that transmit precise RF waveforms that only combine to create a coherent signal at one location. In effect, the base stations are able to create many hot-spots each providing full bandwidth only to their small area. Frequencies can be reused to create similar hot-spots wherever needed. See my article Artemis Networks Claims 'Reinvention' of Wireless Technology for more details on how pCell technology works and a link to an earlier paper published by Dr. Antonio Forenza, the principal researcher at Artemis founder Steve Perlman's Rearden lab in San Francisco.
Why wouldn't the FCC be interested in pCell technology? One cynical reason could be that an improvement in spectrum efficiency of over 15x could reduce the value of the spectrum it is offering. Since it would lower the cost of spectrum, why wouldn't the major wireless carriers be interested? One reason might be that a scarcity of spectrum leads to higher prices and higher profits. A surplus of data capacity, even on a short-term basis, should drive down costs. Of course, all it would take would be for one wireless company, even one with a limited amount of spectrum, to roll out the technology (assuming it can actually scale to cover a huge number of users) and offer double the speed at half the cost to force other carriers to compete.
Could pCell technology be used in broadcasting? Probably not because it is designed to track individual devices and this would require a two-way connection, although it is possible that it could be an option in ATSC 3.0 or, more likely, ATSC 3.1. Could it impact broadcasting? Definitely, if the cost of streaming video to wireless devices drops and the bandwidth to devices increases.
Artemis said large-scale pCell trials will be commencing later this year for commercial deployment in 2015. Because pCell's over-the-air waveforms fit precisely within standard LTE power and spectral envelopes, they may not need FCC approval to test the technology under a carrier's existing licenses. This is certainly something to monitor!
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Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.
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