Massive MIMO gains ground in 5G, but it's creator argues it is still not reaching its full potential

Tom Marzetta developed the principles of Massive MIMO at a time when having 100 active antennas, each with its own electronics, seemed like science fiction. Now the director of the research center at NYU Wireless, Marzetta spent many years at Bell Labs, where he was given the freedom to pursue the concepts that led to his advancements in Massive MIMO, which at the time was considered rather radical thinking.

Time division duplex (TDD) is particularly conducive for Massive MIMO, Marzetta explains: “This is just a beautifully simple scheme for the most efficient known way for the base station to get the information it needs to do its work.”

Is Massive MIMO going to see its full potential in 5G? “No,” he said. “I don’t think Massive MIMO is going to reach its full potential in 5G.”

That’s for two reasons. For one, huge segments of the spectrum in the U.S. are still FDD (frequency division duplex). Over the years, he has recommended that the FCC change policy and mandate the replacement of all FDD spectrum with TDD. However, “that’s a very contentious issue,” he added.

Another reason Massive MIMO is unlikely to reach its full potential in 5G: Unlike previous generations of wireless, 5G was designed with a considerable amount of backward compatibility. In previous generations of wireless, each one made the earlier generation obsolete. For example, with the old 4G user equipment, you can get Massive MIMO service under 5G, but it’s not as good as it could otherwise be. In fact, “we could do 10 times better if we jettisoned FDD” and if didn’t require these new measures to work with old 4G terminals, he said.