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LTE-U vs. Wi-Fi Battle Edges Toward a Peaceful Settlement

LTE-U vs. Wi-Fi Battle Edges Toward a Peaceful Settlement
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The day that your cellphone provider can offer massive data by using an unlicensed spectrum is coming.

Credit: ShutterstockCredit: ShutterstockThere are at least two sides to every story, but when it comes to LTE-U and Wi-Fi and the quest to decongest today's overloaded mobile data networks, there are enough sides and stories to fill a library.

Wouldn't it be amazing if your cellphone provider could provide massive amounts of extra mobile data by pushing some of the traffic over the wide open, unlicensed spectrum now used for Wi-Fi? The technology is called LTE for Unlicensed (LTE-U) and many cellphone providers see it as a godsend.

But wouldn't a flood of new LTE-U devices interfere with existing Wi-Fi routers, resulting in slow and unreliable home and office Wi-Fi connections? That's the question the Wi-Fi Alliance and others would like answered before LTE-U technology is deployed.

But the answers aren't as simple as getting a ruling from the Federal Communications Commission. Since the 2.4-GHz and 5-GHz spectrums are not subject to regulation like the proprietary LTE data networks used by cellphone providers, the task of getting LTE-U to work alongside Wi-Fi lies not with the FCC, but with the companies and trade organizations involved.

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From initial chaos, however, has evolved a consensus that cooperation is better than the worst-case scenario: An FCC takeover of the now-unlicensed spectrum.

The LTE-U Forum, founded by Verizon with aid from Alcatel-Lucent, Ericsson and Qualcomm, maintains that LTE-U devices, when configured correctly, can safely work alongside Wi-Fi. The group maintains that LTE-U uses the unlicensed spectrum more efficiently than Wi-Fi, which means more and faster data for all.

"The main advantages for LTE-U over Wi-Fi as an access technology stem from better link performance, medium access control, mobility management, and excellent coverage," said the LTE-U Forum in its "Coexistence Study for LTE-U."

The Wi-Fi Alliance, which features top-level sponsors such as Apple, Cisco, Comcast, Dell, Microsoft, Qualcomm and T-Mobile, has developed a Coexistence Test Plan and has conducted LTE-U/Wi-Fi coexistence workshops. The Alliance maintains that new LTE-U networks must not interfere with existing Wi-Fi networks any more than adding new Wi-Fi routers would.

So, which side is winning? Hard to say since some participants are part of both sides. However, LTE-U supporters gained ground in February when the Federal Communications Commission approved LTE-U hardware so Qualcomm could perform LTE-U tests with Verizon in Oklahoma City and Raleigh, NC. FCC Chairman Ajit Pai wrote that "…voluntary industry testing has demonstrated that both these [LTE-U] devices and Wi-Fi operations can co-exist in the 5-GHz band."

T-Mobile is rolling out LTE-U today, which uses unlicensed spectrum in the 5GHz band to improve capacity and boost speeds. It's now live in select locations in Washington, Brooklyn, Michiga, Las Vegas and other locations. You'll need a compatible device to take advantage, such as the Samsung Galaxy S8. The carrier has also started testing License Assistated Access (LAA) on its network in Los Angeles. Through this technology, T-Mobile can combine unlicensed and licensed spectrum to offer more bandwidth and faster speeds. 

There are many technologies LTE-U providers could deploy to minimize interference with Wi-Fi. One would provide for pauses in the LTE-U signal so Wi-Fi traffic could flow freely. A step beyond LTE-U is Licensed Assisted Access (LAA), a communications specification developed by the 3rd Generation Partnership Project (3GPP).

LAA offers similar features as LTE-U, but adds a listen-before-talk (LBT) feature which causes LTE cells to wait their turns before transmitting in an area already congested with Wi-Fi traffic. Since LTE-U requires no license, however, cell phone companies can deploy it much earlier than LAA since there is no wait for 3GPP's standards to solidify or for FCC approval.

For the now the rollout of LTE-U technology simmers in a test phase which will continue at least into the fall. So what do consumers need to do for now? Nothing. Until LTE-U hardware is available and compatible cell phones are developed and sold, consumers and cell phone providers can only stay tuned.