What does Massive MIMO really do?

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Below are some FAQs that I get asked. But first, let’s talk about what massive MIMO can really do.

Just imagine that someday we have over a hundred radio heads and antennas all working together in one unit. Imagine that we have 3D beamforming and can pass massive broadband to multiple devices at the same time. Imagine that one antenna can do 4G LTE and 5G NR simultaneously. Now, imagine massive MIMO. The active antenna has all of these features. In fact, it’s a reality now.

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Nokia, Samsung, and Ericsson are deploying massive MIMO with Sprint in the 2.5GHz band. This is a game-changer for mobile broadband. (I worked on this offer for deployment.)

This new technology will allow the antennas to pass large amounts of data to multiple units at the same time. How? They have 3D beamforming that allows the radio head and technology to use target RF focus and hit specific users, or a user while doing the same with other devices, at the same time. It is very exciting to see this technology hit the real world.Small Cell Cover 4

How can one unit do all of this? It is a very smart active antenna. A group of individual radio heads and radiating elements in the antenna unit are all working together so that they can focus on one particular device. They also have the brains to help them dimension the RF signal to focus on one specific area, with the azimuth and elevation both condensing into one beam of RF, which you would call 3D beamforming. Focusing on one specific geographical area in that sectors coverage area. Now, imagine that many groups of elements are doing this simultaneously in that same antenna unit. How cool is that?

It takes a team, in this case, a large group of tiny radio heads and radiating elements in each active antenna. The technology is amazing.

Massive MIMO can pass more data, but not necessarily to an individual device, the magic is that the new beamforming technology will allow it to pass more data to more devices simultaneously.official logo

The key to all of this is that you still need spectrum. Lots of it if possible. It takes more spectrum to do this and to do 5G. There’s the issue for some of the larger carriers. Some carriers will need more spectrum to see the benefits of massive MIMO. That’s why they are looking forward to grabbing the 24GHz spectrum as well as the 3.5GHz.

Massive MIMO is going to be a game changer for LTE and 5G moving ahead. It’s going to improve efficiencies for the carriers exponentially. We just have to get there.

FAQ Massive MIMO Questions:

  • Is massive MIMO only for 5G?
    • No, it is for 4G LTE and 5G NR. In fact, the beauty of massive MIMO is that is can be used on both technologies simultaneously. WOW!
  • Does massive MIMO need the radio heads and antennas or an active an active antenna?
    • It needs the active antenna, massive MIMO is generally much more than the 8 transmit and 8 receive that today’s MIMO has, we are talking 16×16 or 32×32 or 64×64, which is 64 transmit and 64 receive all in the same active antenna. An 8×8 system could have the radio heads connected to an antenna with 8 ports.
  • Does massive MIMO need coax?
    • No, the active antenna will have fiber and power run directly to it. The active antenna will have all the mini radio heads and radiating elements all in one box. Sweet!
  • Will massive MIMO need more power?
    • In most cases, yes, but it should be comparable to having the radio heads up there, but now it is being asked to do more.
  • Is massive MIMO harder to engineer and deploy?
    • Yes, it takes more time, a good RF engineering plan will be needed. If you’re deploying new, then you need to understand where the coverage is happening. If you’re replacing a system, then you need to understand that the coverage will change. Your customers may notice the change, and you want to know what the improvements are for each cluster.
  • Is massive MIMO only for TDD? FDD? Or both?
    • It’s for both. The only difference is that for TDD the same element on the antenna will transmit and receive, but in the FDD there will be a set of elements for transmitting and a set of elements for receiving. This means that the FDD units will be bigger and heavier because they will have more elements and separate internal radio heads. That is why, in this case, TDD will offer some great value. The uplink-downlink ratio is going to be tailored to the need of the end user whereas FDD is pretty much set.Tower Safety for all your safety training!
  • Is it for mobile or fixed?
    • It’s for both, and it will be used differently for each application. While we see that Sprint and T-Mobile are going to use for Mobile, they expect to be able to push the 5G data through it for anyone who wants broadband, mobile or fixed. Whereas Verizon will be using it mostly for fixed wireless because that is their 5G play. They will be competing with the cable companies, along with AT&T, for a piece of that Internet Service Provider, ISP, market share. The realization that Fiber to the Home, FTTH, is not cost-effective has them hoping that from one pole using wireless they can connect many homes with extreme broadband connections. Massive MIMO will play a roll in this point to multipoint use case.
  • Will it pass more throughput than traditional MIMO?
    • Yes, it can talk to so many units simultaneously! While the device will not get a lot more of throughput, maybe 20% more on LTE, but the # of devices the active antenna can talk to simultaneously will greatly improve allowing many devices to get that data at the same time! With that said, the macro site has to be engineered with a better backhaul to handle all of that data.
  • Does the UE device need a special antenna?
    • No, that’s the beauty of having 3D beamforming. It should be able to focus in on the device and talk to it with the whatever antennas are in the device. You can use a smartphone with MIMO, most of them have 2×2 or 2×4, and it will work great.
  • Will beamforming be improved in massive MIMO?
    • Yes, because the active antenna will treat the radio heads and elements like a conductor would conduct his orchestra. Each group will be able to form the radiating pattern into a focused beam, 3D beamforming so that it is focused on a specific user or a small group of users and pass as much data to and from them at the same time other 3D beams are talking to their UE devices.
  • Is the antenna pattern just like my older 8×8 or 4×4 MIMO?
    • No, you have greatly improved the beamforming and null fill, but you have a different radiation pattern. Remember that you’re going from a 4×4 or 8×8 to 16×16 or higher. You have variables that will not match up with the existing radiating patterns. This is not a normal antenna; it is an active antenna that is going to change patterns as users move around. It’s no longer a set radiation pattern as we have always known! It’s actively changing for improvement if it’s set up
  • If the pattern changes, won’t that affect my existing customers?
    • Yes, you need to do a proper RF design and test and look at the correct KPIs when bringing the system up. Don’t expect this to mock what you have, it will change, and you may not get coverage everywhere you want it, although you may have more null fill than ever before if you design the system properly.
  • What bands are primed for massive MIMO in the USA?
    • I think that Sprint’s 2.5GHz spectrum is ideal. It is TDD, and they have around 120MHz to play within most of the USA. That means they can have the smaller units and turn up 5G quickly.

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  • How can they run 4G and 5G on the same unit?
    • Simple, there is a mode called split mode where they can run both formats from the same antenna. They could also have concurrent mode which will allow the same, but split mode allows the full spectrum of both to happen efficiently.
  • Who is rolling out massive MIMO in the USA?
    • Sprint, they are rolling it out now for mobility in their 2.5GHz spectrum with all three OEMs, Samsung, Ericsson, and Nokia. T-Mobile is planning to roll it out in the 600MHz spectrum. AT&T is adding massive MIMO as it adds the FirstNet spectrum on its towers. Verizon has tested it, tried it in fixed, but I am not sure where they will deploy it, if anywhere.
  • Does it work today?
    • Well, it is being deployed and tested. Each band has its challenges. Remember when working for a carrier that the technology is generally tailored for their specific needs. While it’s a new technology, the new product will have challenges. One is that people expect to see it match their existing coverage if replacing existing, but it should not be looked at like that. It is going to be different. If rolling out new, then you have the option to test and fine tune. It’s going to improve, just like standard LTE did. Only now, it will be expected to do 5G and LTE.


  • Where will we see it deployed first?
    • Urban areas make the most sense. They are going to see the biggest gain, especially for the macro sites there. If massive MIMO works the way it’s supposed to, then there will be fewer small cells needed for fill and offloading in the macro umbrella coverage. Small cells will be used more for extended coverage and indoor. Massive MIMO macro sites will start to do even more. The payback has to be there.
  • Does the macro site need to be upgraded to do massive MIMO?
    • Obviously, the radio equipment needs to be upgraded or replaced. Then the router and backhaul need to be upgraded to pass 10 times the traffic. If adding 5G then maybe, even more, 100 times maybe. Remember that we are going to expect great improvements to the macro site, broadband will be on steroids compared to traditional 4G!
  • Where can I learn more?


Thank you for your support and your time. And good job on learning all you can in the wireless industry, you are amazing! Now, go out and impress people!

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