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What is Massive MIMO Beamforming?

Let’s put them together, beamforming and massive MIMO, and we get massive MIMO beamforming. This combination of great ideas and technology allow us to go beyond what has been done in the past. It takes all the antenna elements to work together and separately to create 3D beamforming and with over 32 elements to push data and coverage to the outer limits. Read on to learn more.

Coming soon, the “Road to 5G” book with reports on Massive MIMO, Beamforming, and more about the trend of the tech industry.

To recap:

Massive MIMO is where the elements in the antenna each have an individual radio head feeding them, could transmit or receive or both (TDD).
Beamforming is where the beam focuses the “transmit” and/or “receive” in one specific area to avoid interference from outside sources and to increase gain and throughput.

In Massive MIMO they use 3D beamforming. This focuses the beam both vertically and horizontally. It is going to allow the element to talk to specific users if they need to. It allows the RF to focus on one area while the other elements can focus on other areas. It increases coverage and densification without moving an antenna or dropping in a small cell. WOW!

Learn more in a blog about Massive MIMO, found here, https://wade4wireless.com/2017/11/27/what-is-massive-mimo/. Then, read the blog about beamforming, found here, https://wade4wireless.com/2018/01/08/what-is-beamforming/.

How is it done?

How can they do that? With a control beam that can track where a user is located. This was brought to light with MU-MIMO, Multi-User MIMO. It allows the elements to talk to more than one user at a time. Mainly because you have so many elements that are readily available to focus on users.

Can you imagine where you have more carriers and spectrum to communicate to the UE device? Not only that, but each element can talk to a device while the next element can talk to another simultaneously. All at the same time, using different chunks of the same spectrum along with 64 or 256 QAM. It’s really amazing, so much so there is no way I can explain how it works in detail. Sorry, look at the resources below to learn more technical details.

Here we’ll learn the high-level overview. The RF will be able to be utilized more efficiently than ever because it will be focused in a very concentrated area while other elements can concentrate on their specific users.

Please note, there is SU-MIMO, Single User MIMO, I don’t talk about that here because I think the key is to talk to as many users as possible at the same time.

While Massive MIMO Beamforming is thought of like a 5G technology, it can be and will be used in LTE. They will call it LTE Advanced, LTE-A, but really it’s LTE evolution to get more throughput. It is a critical factor in getting to 5G, so it is going to be part of the NR, New Radio. (New Radio, not a creative name at all!) I think it’s important to remember that all of these advances in LTE will be a foundation of what’s to come for 5G, but I digress, let’s get back to massive MIMO Beamforming.

Massive MIMO paves the way for 3D beamforming for several reasons. First, it’s an active antenna that has a radio head dedicate do each element. This makes it exceptionally smart. Second, it has fiber and power to the antenna which has embedded antennas, so the electronics of the element allow it to focus energy the way the radio head sees fit. That means this can pick a user, focus all of its energy on that user, and slice out RF for that user, and communicate directly with that user.

Why is the last statement so important? I am glad you asked! It’s because the UE Device doesn’t need to match the MIMO of the transmit antenna. I don’t see SAMSUNG and APPLE putting in 32 or 64 antennas on their smartphones, do you? I know they’re getting bigger, but we’re lucky they put 4 in each one. Not only that, but they have to put a crapload of RF chips in each device to handle any carrier. It’s a lot to ask of a smartphone, yet we expect it today, don’t we? Don’t deny it! You would be pissed if you couldn’t take your device and use it on another carrier or maybe even in another country. Now, pile that on top of all the formats they need to communicate, like GSM, CDMA, LTE, TDD. To make it simpler for you, 3G, 4G, Wi-Fi, and soon 5G. Yowsa that is a lot to ask of that device that used to fit in your hand. Now we want them bigger, but not too big!

What made all of this possible? The OFDM format, it helped us build to what we have today. The other thing that helps is beam tracking. The beam can track where the user is and where they are going to keep the RF concentrated on that user, beam steering.

Why does it matter?

Why does massive MIMO beamforming matter? You ask some great questions! It matters because where we once thought that the antenna would just point to where we thought we needed the coverage. Then we had MIMO to allow us to pass more data simultaneously to a user, but it was really SU-MIMO passing more than twice the data to an individual user. We also had beamforming, used heavily in TDD, like Wi-Fi, to reduce interference and concentrate that low power signal to where the users were. Lower interference and increase gain to the user.

Now, on the road to 5G, we have mutated all of this to something extreme. You know, like the X-Men, we have LTE and RF superpowers! The superpower to increase coverage and densification using the antenna and the radio and the electronics to make one antenna do the job of 32 or 64 or even 128 at this time. Who knows what the future will hold.

With beamforming you can concentrate the signal to one user, increasing the gain of that element and talk to one user while the elements are talking to another user.

Does this save money for the carrier?

Trick question! I wanted to see if you were paying attention here, so I threw in a trick question to make sure your on your toes and wearing your thinking cap.

It will cost money up front. The carriers have to replace the antennas and the radio heads. They now have to install the massive MIMO antennas. They have to run fiber and power to the antenna because it no longer has the radio head broken out. It is all one unit. They have to upgrade their BBUs, I would think, and upgrade the backhaul, (fiber) so that they can deliver 10Gbps to every macro site, maybe 100Gbps. Because now you could have 64 users all crying for 1Gbps to each device.

Up front, they have to replace hardware, install new units, and replace most everything at the cell site. Up front, it’s more money.

OpEx will increase for the backhaul. They will need more fiber, more bandwidth, more monthly cost on the backhaul

Now, it will save money in the long run. Here is what I see and it’s not as clear as I would like to make it. Please, use your imagination, will you?

The savings will be that the macro site can now supply well over 10 times the users it could before. In urban areas, this is a game changer! What does this mean? Fewer small cells to be deployed for offloading! If you have a kick-ass macro site throwing data out to many users simultaneously, who needs those pesky small cells in the same coverage area as the macro site? If you don’t think this is a thing, look at any carrier in NYC or LA, they have to offload everywhere. This can start to decline.

Coverage improves as the elements offer higher gain to individual use. This is a small gain, but the edge of the macro should see better coverage as well as throughput. Again, better handoffs and fewer small cells on the edge.

The equipment is smaller than before, and you eliminate the need for the radio head and all that annoying coax between the radio head and the antenna. You heard me! One unit, an active antenna that eliminates the need for coax at the site. This means no more Passive Modulation Interference from all those coax connections. Don’t you hate doing all the PMI testing at the site? I do, and it costs a lot of money, and there is no guarantee that it won’t happen 3 days after you leave the site. Yes, PMI sucks!

Smaller equipment at the site means that it could save the carrier money on-site rental. However, I have to tell you, ATC and CCI have ironclad leases. This is more of a pipe dream. One thing I learned is that the tower owners will NOT lower rent, they only increase rent, and they have leases so tight that Houdini could not get out of one. The thing it may hurt is the small cell leases. If the macro is kicking ass in coverage and loading, maybe a carrier could eliminate some of its small cell sites. That is a considerable cost saving when you look at the backhaul and rent. The equipment and installation are cheap, but the fiber costs are still pretty high.

Who will roll this out?

I have to tell you, the best way that I see massive MIMO beamforming rolling out is by using TDD. It’s cost effective and eliminates the need for separate transmit and receive elements. That means that if you use FDD, you would need 64 transmit and 64 receive elements in one antenna. Ouch, that just got really expensive. But wait, if you have TDD, then you could use 64 elements because the transmit and receive are shared in the same element.

Now, who has TDD in the USA? Can you guess? Go on. I’ll give you another minute. That’s right; Sprint has a crapload of 3.5GHz spectrum that is all TDD that is no longer Wi-MAX. In fact, they are migrating to LTE everywhere. They have a prime opportunity to roll out an incredible system. Will they do it? I hope so, but only time will tell.

That is why the other carriers are clamoring for mmwave and cmwave so that they can also have this technology. Does that make sense?

For this reason, I see Sprint winning this race, if they can get out of their own way. they have not made the best tech decisions in the past decade, in my opinion. Keep the deployment simple, get the teams on the same page, and for GOD’s sake, align with your vendors.

What spectrum will use this technology?

Another good question. It appears that 2GHz and up will work well for this. That means Sprint has prime 2.5GHz spectrum that aligns well with this technology.

The CBRS, 3.5GHz is well suited for this technology. While it is low power, this offers great control to allow the carriers to get the biggest bang for their buck. The lightly licensed users may not use the technology because of price and payback. Usually, private LTE networks won’t invest in anything this impressive, (code work for expensive).

It looks like the 4.4 to 4.9GHz spectrum is also ideal, good news for Japan!

Above 20GHz, where the mmwaves live, it looks to be ideal. So, when AT&T and Verizon start pushing this envelope, they will rely on this technology to deploy. Why, because the massive MIMO will allow them to cram a lot of elements into one antenna. You see, at that spectrum, the antenna elements are tiny, so they could see antennas with a high count of elements. I would think they would see 128 by 128 for almost everything. It would be a game changer, especially for fixed wireless.

Summary:

This new technology takes what the OEMs learned form MIMO and beamforming and put it together to create a new type of macro site. This makes the antenna a team player getting the signal to the end-user in the most efficient way possible. The elements of the antenna each have their own radio head and control. Using this technology to create parallel RF streams of data to the user increases throughput and loading all at the same time. That is what I call smart technology.

We have an active antenna that can do massive MIMO and 3D beamforming all controlled by a base station with even more features in it like carrier aggregation, higher throughput, more carriers, and advance interference rejection. All that and coverage improves, better densification from one BTS. WOW! We’ve come a long way, baby.

All of this so that the throughput and use loading goes way up.

I have it listed in the resources section, but a good paper on this has been put out by Nokia at https://onestore.nokia.com/asset/201377/Nokia_5G_Beamforming_mMIMO_White_Paper_EN.pdf if you have time to read it.

What can you do?

Prepare for this new technology! Come on, all the cool kids are learning it. The OEMs are relying on this as a precursor to 5G for whatever the carrier plans to use it for. What services will be needed for this? Let me count the ways:

RF Design – to deploy, it needs to be planned out properly to avoid self-interference.
Installation of new material.
Site engineering.
Commissioning, Integration, Testing, Optimization all done for the new sites.
Drive testing to verify it works the way we all hope it works.
Then, self-optimization should start cleaning up the services.
Then the end users will have to evaluate how awesome it is.
Then the carrier can start re-evaluating the use of small cells.

Resources:

Be smart, be safe, and pay attention!

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