LTE-U Allies Dismiss NYC Fears of Threat to Muni Wi-Fi

“We are quite concerned about the potential disruption to [Wi-Fi],” said Dmytro Pokhylko, vice president of New York City Economic Development Corp., on the panel. “When I first learned about the technology, LTE-U, I couldn’t help but make analogies to many shows that you see on [National Geographic] and elsewhere about invasive species, where something gets introduced into an existing ecosystem” and it changes that environment, he said. LTE-U isn’t designed to protect weaker signals and could “drown out about 90 percent” of a Wi-Fi hot spot’s coverage area, said Chris Szymanski, Broadcom director-government affairs. It could also interfere with home Wi-Fi, he said. LTE-U could reduce the range and speed of Wi-Fi devices outside and indoors, agreed CTC Technology & Energy CEO Andrew Afflerbach. For a city building a Wi-Fi network, it would mean having to install many more wireless hotspots to get the same coverage, driving up costs, he said.

New York City has multiple projects to spread free Wi-Fi throughout the city, including LinkNYC, a public-private partnership to convert payphones into a citywide system of about 7,500 high-speed hot spots for an estimated $200 million. The network generates revenue from advertising installed on the sides of the hot spot locations. The network will provide 1 Gbps speeds and is critical to the city, said mayor’s counsel Maya Wiley in a keynote. She said 20 percent of New Yorkers, and 36 percent of New Yorkers with an annual salary of $30,000 or less, don't have broadband at home.

“Clearly, any threat to Wi-Fi is a threat to the very fabric of the city,” Wiley wrote in the letter to 3GPP. “Even a modest loss of coverage area for a Wi-Fi hot spot, when multiplied and magnified over the scale of New York City, could impact millions of users daily and decrease the value of hundreds of millions of dollars of public and private investment. Likewise, any increase in latency could undermine the utility of the city’s investments for innovative voice and video applications.”

“As a general principle, any wireless technology deployed in a band that provides broadband access to millions must incorporate the basic protocols for fair sharing of the unlicensed bands, including listen-before-talk, exponential backoff, and sensitivity to lower level Wi-Fi signals,” Wiley wrote. She defined the latter as signals below -72 dBm. FCC testing of LTE-U should be comprehensive and conducted with neutral equipment, and should “not be done purely on the terms of the manufacturers of LTE-U and the carriers,” Afflerbach said on the panel. In the tests, LTE equipment should be set at the same power levels and settings as it would be in the real world, and with a wide range of Wi-Fi equipment and use cases, he said.

Some who watched the New America event disagreed that LTE-U is a problem. “The claim that LTE-U is an invasive species in unlicensed spectrum is hyperbole that's intended to mislead,” emailed Brent Skorup, research fellow at the Mercatus Center at George Mason University. “Unlicensed spectrum was created to serve as a managed commons with very few rules in order to encourage experimentation among competing low-power technologies. Every Part 15 device maker therefore knows that the FCC provides them with no interference protection from other licensed and unlicensed users.” Skorup said the agency should have rejected complaints like this long ago: “If the FCC cannot credibly administer its Part 15 rules, it is back in the business of picking technology winners and losers via beauty contests. If the agency continues to delay new unlicensed technologies via opaque and politicized processes, it will be time to revisit the wisdom of giving away free unlicensed spectrum.”

A mobile industry coalition including AT&T, CTIA, Qualcomm, T-Mobile and Verizon also rejected the interference concerns. "New technologies in unlicensed spectrum like LTE Unlicensed will not crowd out or degrade Wi-Fi in New York City or anywhere for that matter,” said a spokesman for the coalition, Evolve, in a statement. “Multiple tests have shown that LTE-U can share the unlicensed platform with Wi-Fi and other unlicensed technologies. In fact, LTE Unlicensed actually improves Wi-Fi performance as it works better alongside Wi-Fi than Wi-Fi does with itself.”

Wi-Fi came out of an unregulated environment and the panelists said they aren’t asking to radically change its treatment. “On one level, we want to keep that going, but on another level we have to recognize that LTE could essentially be the takeback of all that was there,” said Afflerbach. “Regulation would be appropriate to basically intervene.” Broadcom isn’t “a huge fan of heavy regulation,” said Szymanski. “We like the opportunity for innovation in the unlicensed bands. But oversight is incredibly important … We’re not saying that [LTE-U and Wi-Fi] can’t coexist. We’re saying that there needs to be some work.”