Are LTE-Unlicensed and Wi-Fi really pitted against one another from a technological perspective, or has the debate been hijacked by parties protecting business interests? Depending on who you ask, LTE-U is either a new system leveraging unlicensed spectrum that will work in conjunction with Wi-Fi to make life better for the billions of people now using wireless devices, or LTE-U is a huge mistake that will jam Wi-Fi networks and degrade the end user quality of experience.
CableLabs, a consortium funded by various cable and Wi-Fi companies, is of the opinion LTE-U and Wi-Fi don’t play nice. In a recent blog post, the group said its latest round of testing highlights “the need for the open and collaborative [research and development] that we have long been urging, so that we can find solutions that actually work for everyone. … Hopefully LTE-U proponents will move toward actual collaboration.”
CableLabs went on to note they tested LTE-U and Wi-Fi coexistence in its offices and, more recently, in a residential test house it uses to examine Wi-Fi functionality in an actual home environment. Using off-the-shelf Wi-Fi access points and an LTE signal generator programmed for duty-cycling, CableLabs said it found “Wi-Fi performance suffered disproportionately in the presence of LTE-U.”
CableLabs data seems to be validated by an admission from LTE-U’s own research consortium, LTE-U Forum, which found “there are scenarios where all available channels are occupied by Wi-Fi devices. Without proper coexistence mechanisms, LTE-U transmissions could cause considerable interference on [the] Wi-Fi network relative to Wi-Fi.”
So while it is technically possible for LTE-U and Wi-Fi to interfere with each other, everyone is starting to admit in most cases the interference is a result of bad network architecture and not caused by inherently incompatible technologies.
At the recent unveiling of Qualcomm’s 820 Snapdragon processor in New York City, RCR Wireless News asked Sherif Hanna, Qualcomm’s senior technical marketing manager, his opinion on LTE-U/Wi-Fi debate.
“There is no LTE-U versus Wi-Fi,” Hanna said. “There is only LTE-U and Wi-Fi together.”
This echoed statements Hanna had made earlier in the event when unveiling the Snapdragon 820’s ability to seamlessly transition between Wi-Fi, LTE-U and traditional LTE based on signal strength. “Qualcomm is as much a Wi-Fi company as it is an LTE company.”
Even Wi-Fi’s staunchest proponents are coming to accept the future will, most likely, see a universe in which Wi-Fi and LTE-U coexist. The Wi-Fi Alliance recently unveiled its initial coexistence guidelines.
As a reminder, there are two flavors of LTE-U that are being debated — the most controversial of which is the proprietary form being driven by a group of vendors and operators in the LTE-U Forum, which relies on duty-cycling in order to reduce interfere with Wi-Fi; and the standardized license-assisted access, which relies on a listen-before-talk approach. The final spec for LAA is still working its way through the standards process. Qualcomm has an infographic that breaks down the differences (see below) and also mentions its MuLTEfire technology designed for standalone LTE-over-unlicensed deployments.
Tim McDonough, VP of marketing at Qualcomm, told RCR Wireless News that at this point everyone is already planning to use both the technologies and the debate has become, “like an argument over politics or religion.”
McDonough’s colleague Neville Meijers, SVP of business development for Qualcomm, during the recent CTIA Super Mobility event, pointed to numerous tests conducted by Qualcomm and others that suggest Wi-Fi and LTE-U can share spectrum. So what’s the holdup?
“I think it has gone beyond a technical discussion,” Meijers said. “I think it’s a business issue. Now it’s really a discussion around the opportunity for wireless carriers to utilize unlicensed spectrum. They’re already utilizing the unlicensed spectrum for purposes of data offload and giving consumers a better experience. If that experience can be enhanced through LTE-U … why not leverage that?”
