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Q'comm CTO ponders on promises and challenges of 5G, LTE-U

Posted: 05 Mar 2015 ?? ?Print Version ?Bookmark and Share

Keywords:5G? LTE-U? spectrum? Wi-Fi?

At the Mobile World Congress, Qualcomm shared insights on LTE-Unlicensed (LTE-U), designed to extend LTE Advanced to unlicensed 5GHz spectrum for higher capacity and coverage.

The very concept of LTE-U is getting buzz at the Mobile World Congress. Yet, it worries some users who fear it will enable carriers to hog unlicensed spectrum and charge more, leaving little precious unlicensed band for Wi-Fi users.

Qualcomm disagrees.

Matt Grob

Grob: It turns out that the unlicensed band is a very good area.

EE Times caught up with Matt Grob, Qualcomm CTO. We asked the why's and wherefore's of LTE-U. Further, we asked what challenges he sees for the yet to be defined 5G standard. Going beyond speed, 5G is expected not only to connect billions of devices but also to cater to myriad use cases, serving very different requirements in disparate industriesautomotive, medical, gaming, entertainment and others.

As the telecommunication industry ponders a number of new ideas, features and technological advances for the embryonic 5G standard, "spectrum sharing," now added to LTE-U, could be considered a harbinger of the promises and challenges faced by operators moving into the new generation.

What was the motivation behind LTE-U development?

Matt Grob: Fundamentally, what we are trying to always do is improve the performance and cost of wireless networks, as data demand continues to explode... We look for better radios/modems, better spectral efficiency and find more radio spectrum. It turns out that the unlicensed band is a very good area. So far, we are talking about 5GHz bands in particularand there will be othersthat has been used by the 802.11 family for 20 years.

... "Wi-Fi spectrum"... is not actually a Wi-Fi spectrum. It is an unlicensed spectrum and Wi-Fi complies with the regulation. It's not licensed to any one family. So, we started to look at fundamental differences between the two families and compare the performance.

Qualcomm is a supplier of 802.11 products, we continue to evolve the state of the art 802.11 technology, and we contribute to the standard, develop products and ship them.

But when we look at the performance and value of the two technologies, and the fact that many operators are already using Wi-Fi for offload, we found that... with the LTE family, we can make the use of the unlicensed spectrum three times more efficiently than with 802.11.

Now, people have said, "Well, you can't do this because this is going to harm Wi-Fi and cause interferences." We take it very seriously.

So, what you are seeing [in LTE-U] is not an unmodified LTE system. We've gone in and added co-existence mechanisms. And we've worked on them extensively for over a year and a lot of testing.

Even a single Wi-Fi user surrounded by LTE-U users will actually perform better than surrounded by other Wi-Fi users.


The crowd gathers around at LTE-U

I understand LTE-U won't harm Wi-Fi users in terms of interference. But wouldn't this shrink the available bandwidth for Wi-Fi users in a hot spot?

Grob: Operators are already using Wi-Fi for offload. What if we convert those users from Wi-Fi to LTE-U? Everyone's performance would just get better. Think of it like upgrading from 802.11a, b, g, to 802.11n. If I put 802.11n, would that make less spectrum for 802.11a, b, g? Well, not really.

It's really a performance enhancement for everyone.

Major operators like Verizon, AT&T and T-Mobile are already using those unlicensed bands, but [currently] in a less efficient way.

I understand that LTE-U is designed not to interfere with Wi-Fi. But isn't this giving operators more spectrum to play with, empowering them to charge more? Today, suppose I'm at Starbucks, watching video for free on their Wi-Fi network. Now, if I must get connected to my cellular operator network to do the same, I'd have to pay my operator. It feels like LTE-U is giving operators an opportunity to make more money off us.

Grob: We're vendors. We can only speculate on operators' pricing policies in the future. But I can tell you what they're doing today. Wi-Fi is often perceived to be free, but someone is paying. It may not be the end user. It could be either the venue or the restaurant chain, or whatever... But since we're offering them more efficiency with LTE-U, we're lowering their cost for whoever is paying.

Now today, at least one major U.S. operator supports Wi-Fi offload. But when you're in Wi-Fi operating modes, it doesn't count against your plan. So it may be like that, again. It's up to the operator, but it's not a foregone conclusion that it will be any different from today.

So, you're saying that they are driven to make better use of spectrum and give subscribers better [connectivity] experience, rather than being in it for the money?

- Junko Yoshida
??EE Times

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