US telco Sprint put out a press release in mid January touting its preparations to cater for the massive demand on its cellular network during the Super Bowl game to be held in Atlanta on February 3. It was headed: “Massive MIMO in Atlanta: Sprint’s MVP for the Big Game and Beyond.”
(For sports ignoramuses like myself MVP means ‘most valuable player’, not minimum viable product)
Sprint said: “Along with numerous upgrades to existing sites and the installation of hundreds of small cells across the city, we’ve also been rolling out our own MVP – Massive MIMO (Multiple Input, Multiple Output) technology. For the more than one million football fans expected to be in the city, Massive MIMO will significantly increase capacity and provide faster speeds for more people.”
While we’ve been bombarded with hype about 5G for months, massive MIMO is something that hasn’t had much exposure outside the technical community. It is a key feature of the 5G air interface standard and will be essential to delivering the performance promised for 5G.
64 x 64 massiveness
And Sprint is not backward about coming forward on the benefits of massive MIMO and its own achievements. “We are deploying 64T64R (64 transmit, 64 receive) Massive MIMO radios that use 128 antennas,” it says.
“That’s a ‘massive’ increase from our earlier 8T8R MIMO units. In fact, our initial tests of Massive MIMO sites show we’re already seeing a 4X average speed and capacity increase and up to 10X peak increase.
“In the world’s first independent benchmark study on Massive MIMO, Signals Research Group recently found the benefits of our Dallas-area 64T64R commercial deployment ‘real and meaningful, generating significant increases in downlink and uplink throughput’.”
Sprint adds: “All of the upgrades we’ve made to our network in Atlanta are here to stay. What’s more, the innovative massive MIMO units we’ve deployed are capable of simultaneously supporting both 4G LTE and Sprint 5G with a simple software upgrade when we launch our blazing-fast new service in Atlanta in a few months!”
So massive MIMO marketing has well and truly arrived, and as is usually the case when marketeers get hold of something, exaggeration is the order of the day.
This was all anticipated, back in November 2017, on the Massive MIMO blog run by y Erik G Larsson, IEEE Fellow and professor at Linköping University, Sweden, and Emil Björnson, associate professor at linköping university.
Who wants a MIMO tablet?
In that post Björnson wrote: “I have been wondering for years if ‘MIMO’ will always be a term exclusively used by engineers and a few well-informed consumers, or if it eventually becomes a word that most people are using. Will you ever hear kids saying: ‘I want a MIMO tablet for Christmas’?”
He noted that Sprint was marketing its planned 2018 deployment of new LTE technology by talking publicly about ‘Massive MIMO’.
Sprint had already boasted in a press release of its ‘massive MIMO’ with 64 transmit and 64 receive antennas, but Björnson was not impressed. “It is fair to call this massive MIMO, although 64 antennas is in the lower end of the interval that I would call ‘massive’?,” he asked.
Less learned observers put the limit of massive much lower. PCMag’s encyclopaedia says: “Massive MIMO generally refers to 4×4 and 8×8 antennas in an access point. However, there are multiuser-MIMO projects that envision the use of hundreds of antennas.”
What about beamforming?
In short there’s plenty of scope for fairly meaningless marketing claims. And I have not even mentioned beamforming, which is a key component of 5G New Radio that will accompany massive MIMO to achieve the promised performance.
As the IEEE says: “Beamforming can help massive MIMO arrays make more efficient use of the spectrum around them. … By choreographing the packets’ movements and arrival time, beamforming allows many users and antennas on a massive MIMO array to exchange much more information at once.”
But that’s far too complicated for a marketing message.