OnQ

The 4G LTE network we have will get us the 5G network we need

2016年2月24日

Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.

Ted Rappaport is a 5G pioneer and the founding director of NYU WIRELESS, the world’s first academic research center to combine engineering, computer science, and medicine. Earlier, he founded two of the world’s largest academic wireless research centers: The Wireless Networking and Communications Group (WNCG) at the University of Texas at Austin, and Wireless @ Virginia Tech. The views expressed are the author’s own, and do not necessarily represent the views of Qualcomm.

Last fall, the Federal Communications Commission set the stage for our 5G future. In a historic proposal, the FCC tripled the amount of available licensed radio spectrum for today’s cellular industry by suggesting that high-frequency bands (specifically, 28, 37, 39, and 64-71 GHz) be opened up for mobile use.

Already in the U.S., Verizon and AT&T have been vocal about their interest in deploying 5G trials that will use these new, higher frequencies (sometimes referred to as millimeter-wave bands), and other governments are quickly lining up with similar proposals. In December, the World Radiocommunication Conferences (WRC) approved the planning and ratification of the global use of these wavelengths for cellular by 2019. And in recent weeks, Japan and South Korea both announced plans to have multi-gigabit-per-second 5G cellular systems in place for the Olympic Games each country will be hosting—summer 2020 in Tokyo and winter 2018 in PyeongChang.

Despite this broad international support, the evolution from 4G to 5G will be much more gradual and deliberate than these recent events might imply. Over the next four years, both networks will continue to develop in parallel, allowing time for 5G networks to revolutionize wireless while also incorporating the improved, mature, and tested features and capabilities of 4G.

This type of careful stage-setting will allow the transition to happen smoothly and more deliberately than in the past. Take the move from 3G networks to 4G as an example. The U.S. was first in building out 4G, with Verizon and AT&T announcing LTE deployments before 2010. Yet many U.S. towns still don’t have 4G service today. Meanwhile, most carriers and the global wireless industry took a more conservative approach, rolling out the less mature HSPA (which extended 3G) ahead of LTE. As a result, the transition to 4G is still in full swing throughout the world—and in some places, it’s just beginning.

Fourth-generation LTE introduced a revolutionary network hierarchy for the cellular world. From a user standpoint, it provided major speed gains and the ability to simultaneously deliver voice calls and data. All this requires wholesale changes to a provider’s network—including a rollout of new beam-forming antenna technologies like MIMO. As LTE evolves and new features come online, download speeds will continue to rise from today’s 20 megabits per second to hundreds of megabits per second. This evolution means that a move to 5G will need to be made in a graceful manner, and will surely come to high-density urban centers before reaching the entire population.

The good news, though, is that we’re quickly settling on what 5G standards will look like. In fact, our demand for mobile data leaves the cellular-standards-making body, 3GPP, little choice but to move forward. Case in point: On average, mobile users are consuming 57 percent more mobile data each year, a trend that shows no signs of slowing down. Part of this effort centers around unifying many spectrum bands on a single network, while another large part centers on demonstrating the benefits millimeter-wave bands might bring to bear.

The idea of using millimeter-wave bands is still relatively new. It was scarcely two-and-a-half years ago that New York University first published research showing that higher frequencies offer great potential for mobile use in urban environments. Up until then, a prevailing myth in the industry was that as a person moved away from a cell tower, higher frequencies would drop off quickly in signal strength, and frequencies below 3.5 GHz would prevail. NYU’s research demonstrated that millimeter waves (i.e., those found in the high-frequency bands the FCC is opening up for mobile use) can actually extend multi-gigabit-per-second coverage to over 200 meters in New York City.

Now, companies around the world are conducting their own experiments to learn about the potential and unique engineering challenges of millimeter-wave frequencies. The 3GPP officially added frequencies above 6 GHz to its purview a few months ago, so the first steps to building 5G standards are now underway.

The technical challenges of making millimeter-wave frequencies work for mobile use are daunting. But they’re quickly being solved through advances that are now coming to market in WiGig and IEEE 802.11ad, the superfast Wi-Fi standard at 60 GHz.

As LTE continues to develop in parallel with 5G, the advances it brings will easily “upband’ into the new cellular and unlicensed frequencies. The new millimeter-wave spectrum bands for 5G will open up even more “pipes” to deliver content and capacity to the masses, while beamforming will extend the net of coverage farther than ever. This makes for exciting technological challenges—how will we adapt our devices to receive more radio bands?—and unthinkable data access and speed for future mobile phone users, connected-car drivers, and smart-home adopters.