Wi-Fi Alliance has released a finalized test plan for coexistence between Wi-Fi and LTE in unlicensed spectrum, the technology backed by Verizon and Qualcomm for leveraging LTE at 5 gigahertz. The test plan was a result of industry collaboration born out of fears that LTE-U, which was developed outside of established standards bodies and relies on proprietary technology for coexistence, would disrupt Wi-Fi networks in the 5 GHz band. Despite calling the plan a compromise for all sides, WFA said that “consensus was unachievable” on some aspects of the test plan.
“The test plan will help ensure LTE-U devices can demonstrate they share unlicensed spectrum fairly and will serve as a valuable tool for vendors and service providers seeking to improve how their deployments coexist with Wi-Fi networks,” Wi-Fi Alliance said in a statement. “The Coexistence Test Plan is the only available mechanism that includes a comprehensive set of test scenarios agreed upon by industry as adequate to determine proper sharing, and Wi-Fi Alliance encourages all LTE-U vendors and operators to use the test plan to ensure their LTE-U devices and network deployments coexist fairly with Wi-Fi.”
Kevin Robinson, VP of marketing for Wi-Fi Alliance, told RCR Wireless that particularly challenging areas for the test plan were those of what Wi-Fi signal levels as well as how much complexity in test scenarios would be demanded to ensure fair coexistence. Those two issues have been brought up repeatedly as areas of concern, with Wi-Fi companies worried that LTE-U did not have a low enough threshold for detecting and accommodating Wi-Fi signals at which users can still have decent Wi-Fi connectivity. Robinson said that the final test plan requires tests at three different signal levels: a strong Wi-Fi signal, a middle signal level and one at -82 dbm. The complexity of testing, he added, was addressed through a multi-company proposal from companies including Qualcomm, Ericsson, HP Enterprise and Cisco that focused on multi-vendor benchmarking and was adopted as part of the test plan.
Wi-Fi Alliance said that the plan (downloadable from WFA) is meant to be used as an “unedited whole” and that alternative test approaches such as omitting or modifying elements of the plan ” will not provide assurances of fair coexistence.
“In developing the test plan, LTE-U vendors agreed to use the full Coexistence Test Plan to demonstrate that LTE-U products share spectrum fairly,” WFA said. “It is expected that LTE-U vendors will test every LTE-U device against the entire Coexistence Test Plan.”
However, WFA added that it is not asking for a regulatory mandate to force vendors to use the coexistence test plan.
Wi-Fi Alliance said that the test plan was developed under agreement to “[maintain] the typical connectivity experience for Wi-Fi users” as well as a clear definition of “fairness”. It said that “consensus was unachievable” on some parts of the plan, so it finalized those aspects based on those two principles “augmented by robust technical data.”
The release of the test plan delivers on Wi-Fi Alliance’s timeline announced earlier this month, when it said it would deliver the plan by today. While the test plan had originally been planned for release in August, lingering disagreements delayed its finalization. Qualcomm criticized a draft plan last month, saying it was “unacceptable” and “fundamentally biased against LTE-U” while calling on the Federal Communications Commission to ignore the plan. Evolve, the group formed to promote LTE-U by companies which back the technology, complained that “Wi-Fi Alliance has buckled under political pressure from the cable lobby and proposed a one-sided plan that is fundamentally unfair to new technologies.”
Shawn Chang, spokesman for Evolve, told RCR Wireless in an emailed statement that “Evolve Coalition members look forward to reviewing the details of the Wi-Fi Alliance coexistence test plan. It’s important that the details support a fair coexistence baseline and a clear path forward for LTE-U devices, and that [License Assisted Access] not be subject to this process at all. ”
Test group AT4 Wireless has been working with Wi-Fi Alliance to provide testing services based on the new coexistence test plan. Robinson said that WFA is in the process of test lab qualification so that testing can start immediately and is working with both AT4 and Cetecom.
Industry group WifiForward responded to the test plan release with support for what it called “a consensus-driven test plan that will ensure new LTE-U devices coexist fairly with the existing Wi-Fi networks and devices hundreds of millions of consumers already use and enjoy” as well as protecting existing enterprise and governmental investments in Wi-Fi.
“This has necessarily been a thorough, compromise-driven process, but we are pleased that at the end of the day, parties have come together to implement the finalized test plan and move forward,” WifiForward said, adding that, “given the FCC’s support for the Wi-Fi Alliance process, we expect that moving forward, device authorizations will be based on successful completion of the testing protocols.”
Editor’s Note: This story has been updated with comments from WifiForward, Evolve and Wi-Fi Alliance.
