Cable Industry Pushing for 'Listen Before Talk' Protocol for LTE-U
LTE-U must have a "listen before talk" (LBT) protocol to ensure no interference with Wi-Fi, the cable industry said in the form of a NCTA blog post Wednesday in response to a separate CableLabs blog post Tuesday. The way LTE-U…
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currently is being configured lacks any requirement "to share fairly in time, to avoid interrupting Wi-Fi transmissions mid-stream, or to adapt to different levels of Wi-Fi usage and traffic," CableLabs said. "In the ‘off’ state, LTE-U may still send discovery signals that can also interfere with Wi-Fi. LTE-U 'listens and talks anyway' regardless of whether somebody else is talking or not." Meanwhile, the general consensus in the rest of the world is that LBT "is a fundamental coexistence requirement," CableLabs said, pointing to EU and Japanese regulations and 3GPP rejecting non-LBT approaches to the license assisted access standard. The LTE-U Forum should follow 3GPP, CableLabs said. NCTA echoed CableLabs as it said LTE-U "should follow the lead of international standards" and come up with sharing protocols and other fixes. Such politeness protocols "are not merely clever features -- they’re fundamental to fair coexistence in unlicensed bands," NCTA said. Wireless carriers and Wi-Fi advocates such as the cable industry have been sparring over concerns of LTE-U interference with Wi-Fi, with Qualcomm and Verizon last week demonstrating interoperability testing that showed the throughput of numerous Wi-Fi access points unaffected when an LTE-U access point was turned on (see 1509160039). In an email Wednesday, CTIA Chief Technology Officer Tom Sawanobori said CableLabs "did not actually conduct a test of LTE-U. As extensive testing has shown, LTE in the unlicensed band makes consumers’ wireless experience better. Given that 57 percent of current mobile traffic is offloaded on Wi-Fi networks today, wireless companies are invested in making LTE in the unlicensed band work for all users. We are confident policymakers will overlook the attempts by the cable companies to try to limit what they always supported, which is ‘permission-less innovation.'"