Cable TV Industry Opposes LTE-U, Cites Interference Risk

Disputes over spectrum rights are routine. So it comes as no surprise that many stakeholders are concerned about Long Term Evolution-Unlicensed protocols that would allow LTE networks to bond new Wi-Fi channels in the 5 GHz band.

“Although some wireless carriers developing these LTE-based technologies have acknowledged the need to share spectrum fairly with unlicensed technologies like Wi-Fi, nothing in the current design of LTE-U provides confidence in that result,” the National Cable and Telecommunications Association NCTA argues. “Unlike Wi-Fi, which uses politeness protocols to effectively share spectrum with other unlicensed users, the current formulations of LTE-U do not require providers to build in adequate sharing protocols.”

The NCTA has notified the Federal Communications Commission of its concerns about interference.

Wi-Fi protocol includes listen-before-talk and back-off mechanisms. Listen-before-talk, as it sounds, means devices do not transmit data while there is another active signal in the band.

And back-off is a second protocol in the event of that two Wi-Fi signals transmit at the exact same time.

When such a collision happens, Wi-Fi transmission will wait a period of time before trying again.

Proponents of LTE-U are “threatening to deviate from the careful and collaborative stewardship of shared frequency bands,” NCTA argues.

As always, public policy concerns also have private interest corollaries. Mobile operators would gain if allowed to bond 5-GHz Wi-Fi channels.

Cable TV operators also plan to build mobile networks substantially based on use of Wi-Fi capacity. So keeping one important class of potential users off 5 GHz channels would help cable operators.

The NCTA also wants “non-standard” versions of any such protocols to be barred, in the interim, a move that would prevent mobile operators from deploying the protocol soon, even if they incorporate “listen before talk” protocols.

That isn’t to say legitimate interference issues exist. They do, and must be addressed. That said, more users and devices sharing any specific set of resources will increase congestion. That always is true, for existing or new spectrum available to any shared network.

source: NCTA