ISSCC sees 5G on the horizon as Alcatel-Lucent, Intel collaborate on air interface
5G is expected to include a suite of radios and other network technologies aiming to deliver by 2020 a variety of advances for a wide array of applications. Alcatel-Lucent is working with Intel on the Universal Filtered OFDM air interface, which had its origins in WiMax, as just one small piece of the puzzle.
“We have a prototype air interface we showed last year and another [version to be shown] at the Mobile World Congress handing streaming video…[that] we expect to bring to standards efforts which we expect to start early next year,” said Theodore Sizer, a domain leader at Alcatel-Lucent’s Bell Laboratories.
UF-OFDM could be one of at least three air interfaces companies such as Intel propose for 5G, said Asha Keddy, a vice president of Intel’s platform engineering group. Separate air interfaces may be needed to support Internet of Things nodes in the 100 MHz to GHz bands and high-bandwidth applications in the 10-100 GHz range, she said.
NTT DoCoMo is still investigating which of at least two air interfaces it is likely to support in standards discussions, said Yoshihisa Kishiyama, a senior research engineer in the company’s 5G lab.
The World Radio Congress may not decide until as late as 2019 how to allocate spectrum above 6 GHz for 5G services, geared for short range, high data rate links. That creates a heady challenge for engineers “designing new air interfaces ahead of when spectrum is released,” said Intel’s Keddy.
To speed connections, new air interfaces and protocols need to reduce the amount of interactivity such as message acknowledgments used today, said Sizer of Alcatel-Lucent. He noted short bursts of less than 300 bytes represent half of today’s LTE traffic. “This will get worse with more IoT traffic,” he said.
Engineers will need to make multiple radios cooperate so that with 5G services “users don’t even have to spell WiFi and LTE, they just work in concert,” he said.
One of the many technical challenges of 5G is developing base stations that support hundreds of antennas in massive MIMO arrays.
“We have been near Shannon’s Limit for the past decade in the cellular system, and we will not do much better except by using multiple antennas…we really need a breakthrough to get to cost performance you need,” said Sizer of Alcatel Lucent.
Sweden’s Lund University created and tested a prototype 5G base station (described above and shown below) that supports 100 coherent RF chains using OFDM transmission. It uses an array antenna printed at the university and generated 10 Gbytes/second of data in operation.
In tests so far with 10 users working in 20 MHz of spectrum at 3.7 GHz, the prototype supported adequate coherency with signals well aligned in time, said Fredrik Tufvesson, a professor at Lund. “We got it working, now we need to squeeze it,” he said.
National Instruments supplied some components of the prototype 5G base station in Sweden.
In a sign of the work ahead, Kishiyama of NTT DoCoMo noted 5G services at 20 GHz may require as many as 676 antennas on a base station.
As many as a dozen 5G forums around the world are working on concept for the technology, Kishiyama said. Europe’s 3GPP group is expected to lead the way with a working group on LTE Release 13 that could be formed by the end of the year, he said.
If all goes well, the Tokyo Olympics in 2020 could be one of the first big demonstrations of 5G services. Kishiyama showed an animation of attendees in a large stadium using 5G techniques to deliver enough bandwidth to support 4K video downloads.
Lund University printed the antenna array used in its 5G base station.
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