National Instruments (NI) has been heavily involved in 5G prototyping, including the world’s first MIMO Application Framework that it announced this week, and friends from the University of Bristol in the U.K. were on hand at its annual NIWeek conference to share their breakthroughs.
As participants in NI’s RF/Communications Lead User program, researchers at Bristol University have used NI’s prototyping platform for 5G research and recently announced, in conjunction with Lund University, a world-record 22-fold increase in spectral efficiency over 4G networks.
But to hear the Bristol professors describe it, it was a bit of a surprise when they broke the record. It was the day after they realized that it was a record in spectral efficiency, according to Professors Mark Beach and Andy Nix, who spoke with FierceWirelessTech earlier this week from the NI event in Austin.
Interestingly, the engineers from the Universities of Bristol and Lund set the record less than two months after setting an earlier record. In their May experiment, they used 128 base station antennas, serving 22 users, each modulated with 256-QAM, on the same time-frequency resource. Emulating the frame structure they used in their previous research, they set up a system that equates to a rate of 145.6 bits/s/Hz on a single 20 MHz radio channel.
Their earlier record, set in March, was 79.4 (bits/s)/Hz for 12 users set, which compares to a rate of 71 bits/s/Hz that Facebook achieved for 24 users with its 96-antenna ARIES array. They weren’t satisfied with that, however.
“We did a little bit of work on the hardware platform and extended it to 22 clients, and in doing so, we smashed through the 100 bits/s/Hz barrier and achieved a headline rate of 145.6 bits/s/Hz. Not bad, for a 20 MHz channel,” Nix told the audience at NIWeek.
The project is part of a bigger effort where they’ve deployed 75 kilometers of fiber around the city of Bristol. Bristol has four city-wide wireless networks: Wi-Fi, LTE, IoT and millimeter wave. The system works at 3.5 GHz and supports 22 clients simultaneously.
Given that the industry has said it will require a 1,000-fold increase in capacity in order for 5G to function as anticipated, Massive MIMO technology has an important role to play. Nix points out that unlike millimeter wave spectrum, very little spectrum below 6 GHz is expected to be available for 5G.
While conventional technologies use time or frequency domains to share the resource, Massive MIMO takes a step into the spatial domain, using a massive number of antennas at the base station and coherent processing across them. “By doing so, we can achieve orders of magnitude gains, both in spectral efficiency and energy efficiency at the same time,” explained Ove Edfors, engineering professor of Lund University, during one of this week’s NI keynotes.
Massive MIMO was introduced in 2010 and was met with some skepticism, but is now considered one of the key tenets for achieving 5G goals.
The FCC's decision on July 14 to free vast amounts of millimeter wave spectrum bands established the U.S. as a leader in the space, noted James Kimery, NI’s director of marketing for RF, communications and software defined radio (SDR). While U.S. operators have emphasized that their first objectives involve fixed wireless applications, millimeter wave is not limited to that.
“There are mobile access experiments going on and the technology does look promising,” Kimery told FierceWirelessTech, adding that one of the challenging parts will involve getting the base stations spaced closer together.
NI said the LabVIEW Communications MIMO Application Framework it just announced will enable wireless designers to develop algorithms and evaluate custom IP to solve practical challenges associated with real-world multi-user MIMO deployments.
- see this press release