Among the many elements carrying us toward the high-speed, low-latency world of 5G is an approach called Massive MIMO.

The “massive” tag is less about physical size – a good thing in our ever-shrinking-hardware world – and more about capability. Massive MIMO (multiple input/multiple output) is all about maximizing antenna arrays on wireless radios in order to boost signals, capacity, and reach and enable providers to deliver the 5G performance that enterprises are hungering for.

A good way to picture this is to think of your home Wi-Fi router. A router with a single antenna can only do so much, but with additional antennas, you can achieve better control over the signals and direct them appropriately to different user positions.

MIMO is far from a new technology, but the advancements are in the ability to add so many antennas to radios on cell towers – and mix in the all-important ingredient of beamforming technology – to accomplish the objective of high data rates and low latency.

Typically, cell towers provide line-of-sight communication, enabling strong signals without eating up too much battery energy in your handset. But the laws of physics do tend to get in the way of trying to deliver higher capacity and low latency. It takes more power to do that, both at the tower and in your handset. That means higher costs for service providers and faster battery discharge for you.

Shifting the signal

Massive MIMO offers a way to get around some of these limitations. The secret is in the combination of beamforming technology with up to 128 antennas, an amazing concentration in a small piece of radio equipment. Although it’s called beamforming technology, it’s really more like beam-shifting. What happens is the antennas can target a signal beam toward a user who may not be right on the center axis of the fixed beam.

Through focused energy and some complicated math, the beam can be redirected and make it possible to reach more users with improved signal strength and in essence create more capacity.

Dynamic and adaptive beamforming with massive MIMO enables constant targeting of mobile users regardless of their speeds and horizontal or vertical movement. The capability of using massive MIMO-based beamforming is independent of user application or direction of data.

The importance of 2.5 GHz

It happens that 2.5 GHz is a “sweet spot” for Massive MIMO deployment, which is why you are seeing so much commentary from Sprint. We own the bulk of the 2.5 GHz spectrum, and we own it in a contiguous block that maximizes channel flexibility.

With 2.5 GHz, it is possible to put so many small – about 1.5-by-1.5-inch – antennas in a radio set that has a total footprint of about two by two feet, or the size of an extra-large pizza box. If you tried to do that with 600 MHz transmission, the antenna array would be the size of a small automobile. Compactness maximizes space efficiency not only on traditional cell towers, but also on the microsites that will be added to boost coverage in hard-to-reach areas.

At frequencies other than 2.5 GHz, Massive MIMO can be achieved through the use of millimeter wave technology, which is a fine technology but one that doesn’t propagate very far. 2.5 GHz, especially when the available spectrum is contiguous, offers an optimal convergence of capacity and coverage in order to deliver the best 5G results.

Beginning in April, Sprint will start to deploy Massive MIMO in three markets – Chicago, Dallas, and Los Angeles – with Atlanta, Houston, and Washington, D.C., following later this year, and scores more after that.

The bottom line is that Massive MIMO offers maximum flexibility outdoors, better coverage indoors, and the ability to leverage the spectrum to allow for greater volumes of data. All the promises of 5G, delivered. Frankly, 4G LTE is already fast, but 5G will take that up a notch. A big notch. Thank you, Massive MIMO.