Mobile telephone service providers are trying to block a plan to create a free, nationwide wireless broadband network by insisting on protections from interference that would make it impossible to deliver wireless broadband, according to the company proposing the network.
Mobile carriers, led by T-Mobile, are insisting on interference protections for their existing spectrum that goes beyond any current protections and would disqualify several widely used products that currently emit low levels of energy in the radio spectrum, including microwave ovens and Wi-Fi equipment, said officials with M2Z Networks, a startup that proposed building a free wireless network on unused spectrum.
The two sides are now arguing about the interference questions before the U.S. Federal Communications Commission, which has released its own proposal to auction spectrum for a free, nationwide network. Mobile carriers don’t want a free broadband network that would compete with their own services, John Muleta, M2Z’s CEO, said at a Monday press briefing previewing an M2Z filing to the FCC.
Some of the devices that would essentially be prohibited under the interference rules that T-Mobile and other mobile carriers want are devices the carriers themselves sell, Muleta said. If a T-Mobile handset operates at -105 dBm (the ratio of power in decibels to one milliwatt) signal strength, then Wi-Fi equipment and Bluetooth headsets sold by the carriers themselves would interfere, Muleta said. But that’s the level of protection T-Mobile wants.
“If you do -105 [dBm], then all these devices are going to start interfering,” said Muleta, a former chief of the FCC’s wireless telecommunications bureau. “How does that make sense? It doesn’t.”
The interference protections T-Mobile and other carriers have proposed go beyond the operating capabilities of T-Mobile’s mobile phones, added Paul Kolodzy, senior tech advisor to M2Z and a former senior spectrum policy advisor at the FCC. At a -100 dBm signal strength, a T-Mobile handset would drop calls, he said.
A representative of T-Mobile, which provides mobile service in the nearby spectrum, called M2Z’s conclusions inaccurate. Microwave ovens and Bluetooth receivers operate on spectrum 100 to 200 MHz away from T-Mobile’s spectrum, while the proposed broadband network would operate in adjacent spectrum, said Patrick Welsh, senior corporate counsel for regulatory affairs at T-Mobile.
“It’s complete apples to oranges,” he said. “It demonstrates a complete lack of technical knowledge and expertise in this.”
In addition, more than five percent of T-Mobile’s traffic operates at or below a -105 dBm signal strength, Welsh said. And a T-Mobile proposal to the FCC that would pair the so-called AWS-3 spectrum in the FCC’s proposal with another block of spectrum would allow the winning bidder to offer broadband service, he said.
Test results in Seattle earlier this month “clearly showed that there would be significant harmful interference … under the FCC’s proposed rules,” Welsh added. “M2Z’s wildly inaccurate conclusions can only reflect that either they do not understand the test results or they are being disingenuous.”
M2Z’s reading of the Seattle tests is that they showed no technical or interference problems, said Kolodzy, who observed the tests. T-Mobile’s service and the proposed free network “can coexist … using the technical rules similar to those that M2Z has been advocating for over two years,” he said.
The wrangling over interference goes back to May 2006, when M2Z proposed building a nationwide wireless network, with service available for free, on 20 MHz of unused wireless spectrum referred to as AWS-3 spectrum. The FCC sat on the proposal until a year ago, when it proposed to auction about 20 MHz of spectrum in the 2155 MHz band, with the winner required to use part of it for a free nationwide network.
T-Mobile operates a network that uses nearby AWS-1 spectrum, for which it paid about US$4 billion in a 2006 auction.
In June, the FCC asked for comments on a specific proposal that would require the auction winner to use 25 percent of the spectrum’s capacity to provide a free broadband network with downstream speeds of at least 768K bps (bits per second). The FCC also proposed that the operator of the free network filter out pornography and other material that might harm children.
The network filtering proposal has drawn criticism from some civil rights and tech trade groups, who say the filtering mandate is “extraordinarily” broad and would amount to government censorship.
In addition to the other criticisms of T-Mobile, Kolodzy and Muleta noted that T-Mobile handsets are dual-mode, meaning they are able to receive both AWS-1 and PCS (Personal Communications Service). If there was interference with AWS-1 spectrum, a handset would switch to PCS, they said.
Welsh said dual-mode phones can receive both signals, but it’s difficult to make the switch in the middle of a call. A phone experiencing interference from a AWS-3 device would likely drop the call instead of switching on the fly from an AWS-1 to PCS signal, he said.
“M2Z wants us to have a network that works sometimes in some places,” Welsh said. “T-Mobile wants to design a network that works all the time in all places.”