The download on LTE-U

By: David Young

Permissionless innovation” has given us some remarkable products and services that we now take for granted. Wi-Fi and Bluetooth, both of which operate on unlicensed spectrum, are two examples and have changed the way we live. Now, a new technology is poised to jumpstart a new wave of innovation using unlicensed spectrum. It’s called LTE for Unlicensed, or LTE-U.

LTE-U features what consumers like about 4G LTE mobile broadband: fast speeds, improved downloading and streaming, smooth hand-offs and secure, reliable connections. And it was designed to work using unlicensed spectrum and to be a good neighbor to other technologies sharing the unlicensed bands.

Partnering with engineers from some of the leading equipment makers – Qualcomm, Ericsson, Alcatel-Lucent and Samsung – Verizon helped develop a new technology that would use LTE to make more efficient use of unlicensed spectrum, enable strong security mechanisms, and provide seamless mobility for customers. A key point: this isn’t old-school LTE technology, the kind mobile devices currently use. This is a technology specifically designed for the unique environment used in unlicensed bandwidth.

One of our top priorities is to make sure LTE-U plays nicely with WiFi. The reason is obvious: our customers use their mobile devices with Wi-Fi, either connecting to home and public hotspots, or using their phones and “jet packs” to create their own hotspots. So LTE-U was designed with special “etiquette protocols” to ensure that adding an LTE-U small cell has no more impact on existing Wi-Fi hotspots than adding a new Wi-Fi hotspot would cause.

So, what are these etiquette protocols and how do they work? First, LTE-U is only turned on if things start to get congested on the licensed spectrum. This acts like an “on/off” switch that ensures unlicensed spectrum is fully available for all other uses. Second, LTE-U “listens” before “talking” and will prefer to use channels that don’t have any Wi-Fi or other unlicensed devices on them. Finally, if all channels have unlicensed devices using them already, LTE-U takes turns to ensure that it uses only its fair share of the spectrum to meet LTE-U devices’ needs, while, leaving other unlicensed devices their fair share of the spectrum.

Although LTE-U and Wi-Fi use different etiquette protocols, test results show that they coexist well together. Testing done in Qualcomm’s labs created a worst-case scenario with eight Wi-Fi hotspots operating close to one another, all set to use the same channel. One by one, half of the Wi-Fi base stations were replaced with LTE-U nodes. As expected, LTE-U was able to carry more traffic than the Wi-Fi nodes that it replaced AND the performance of the remaining Wi-Fi hotspots actually improved.

We are excited to see that LTE-U is working exactly as expected in the lab and we will begin field trials this Fall. If all goes well, consumers could begin seeing the benefits of this technology innovation as early as Spring 2016. But as exciting as all of this is, it’s only the beginning of a new wave of innovation in the mobile broadband marketplace.

About the author(s): 

David Young has an engineering background, which enables him to develop positions on emerging public policy issues and asses key technology and communications industry trends. Prior to 2000, he spent six years working in Verizon’s Research and Development (R&D) group on many advanced technologies including VoIP, data network architectures, and audio, video and image compression. He has been awarded ten U.S. government patents for his R&D work. David is a member of the IEEE and IEEE Communications Society.