The city of New York today expressed “grave concern” that any interference from the deployment of LTE-U technology will cause harmful interference to Wi-Fi in the city. In a letter to 3GPP leaders that was copied to FCC officials and others, Maya Wiley, counsel to New York City Mayor Bill de Blasio (D.), said “the City has embarked on an aggressive effort to achieve universal broadband for all New Yorkers, including affordable high-speed residential service and free service in public areas. Wi-Fi is a central part of this effort and any technological interference with our ability to deliver free and affordable wireless access to our residents is of grave concern.”

The letter outlined efforts to deploy Wi-Fi in the city through the LinkNYC, Harlem Free Wi-Fi, Queensbridge Wi-Fi, and Red Hook Wi-Fi initiatives, as well as through Wi-Fi deployed in schools, libraries, parks, and subway stations.

“Clearly, any threat to Wi-Fi is a threat to the very fabric of the city,” it said. “Even a modest loss of coverage area for a Wi-Fi hotspot, 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 [LBT], exponential backoff, and sensitivity to lower level Wi-Fi signals (e.g., below -72 dBm),” the letter added. “We are heartened that LAA, the variant of LTE-Unlicensed being standardized by 3GPP, incorporates some of the coexistence mechanisms above, but remain concerned about the lack of coexistence mechanisms for lower level Wi-Fi signals.”

3GPP should ensure that specifications for LTE-U protect Wi-Fi, the letter added.

“I understand that the Wi-Fi Alliance is developing a Coexistence Test Plan for proprietary LTE-U. I hope that such a plan will account for all of the use cases cited above,” Ms. Wiley said. “I strongly encourage that a similar test plan be created for 3GPP versions of LTE-Unlicensed to ensure coexistence with Wi-Fi to any widespread deployment.

Ms. Wiley added, “The City will remain vigilant for any technological or regulatory developments that would undermine our ambitious efforts to use Wi-Fi to connect all New Yorkers to the benefits of broadband.”

Proponents of LTE-U technology say that it will not interfere with Wi-Fi and that LBT capability, which will be in a standards-based version of LTE-U deployed in Europe and Japan to comply with regulatory mandates, is not necessary to ensure coexistence of LTE-U and Wi-Fi technologies in the U.S. LTE-U proponents stress that they have worked with the Wi-Fi Alliance on a test plan to measure LTE-U/Wi-Fi coexistence. – Paul Kirby, paul.kirby@wolterskluwer.com

Courtesy TRDaily