Will CBRS PLTE be an iDAS Killer?

Newsflash, no. However, DAS systems have already evolved. It’s not like the DAS of old. 

First, we need to define the DAS models because this often confuses people. There are different DAS systems out there and they all have a unique use in buildings and stadiums. 

For the sake of this article, I am only talking about the carrier’s spectrum. 

I was talking about the CBRS spectrum and how it serves as a great solution for mid to large size Enterprises to have a secure wireless system inside their offices and campuses. This is the ideal market to fund and build these systems.

In case you’re wondering why I am bringing up funding, it’s because the carriers are reluctant to fund any of this unless they have to. They are looking for financial alternatives. 

What about Wi-Fi?

As we move ahead, I found that the enterprises are concerned with security and would like more control of their network. They like the Wi-Fi but there are still issues with it because more and more indoor equipment is using the Wi-Fi spectrum.

Look at what they have to share it with. 

  • Lighting systems
  • Temperature control systems
  • Security systems
  • Sensors
  • Every laptop, computer, and device inside the office
  • Any IOT systems you can imagine indoors

So the thing is, the spectrum has issues being utilized efficiently. The 2.4GHz is used by so much o this that now it’s spreading into the 5.8GHz range. This is making the Wi-Fi spectrum more and more crowded. Especially now that they want everything to connect wirelessly.

The enterprise is realizing that for security and a guarantee of bandwidth that they need to keep the CAT5 cables at secure locations. 

So here’s the thing, the beauty of wireless was to eliminate running CAT5 everywhere, yet, due to security and loading, they have to hold on the running CAT5 everywhere. 

This sucks. The fact that Wi-Fi capacity has already been maxed out in offices is scary.

It makes sense if you start to realistically look at the loading. 

You not only have all the IOT riding on it, but every smartphone, laptop, and possibly desktops.

Now, carrier systems in these offices were normally DAS or small cells. That made sense because the carriers were only concerned with voice. Today, a completely different story.

Today, we want data to be the primary solution no matter if it’s a smartphone, iPad, or laptop.

The systems that the carriers are putting in today still rely heavily on Wi-Fi as a means to offload data. While the cloud is taking care of that on the carrier side, they still expect Wi-Fi to be the solution.

We all love Wi-Fi because it’s free and usually works great. But indoors someone has to install it and maintain it. It’s not free. It also needs backhaul, maintenance, and upgrades which all adds up in the OpEx models. 

Will PLTE replace Wi-Fi?

No, there is no way. We have Wi-Fi in every device we have and it’s become more than a necessity. It’s really an expectation like electricity and indoor plumbing. At least for businesses. 

What are we, animals? No, we’re civilized workers in the cut-throat enterprise business that expect to have the tools to complete the job. One of the primary tools, or utility depending on your perspective, it Wi-Fi.

However, we can improve upon what’s there now. The one thing there. If loading and security are concerns, then we need to look at how PLTE can fit into the new enterprise network. It’s going to be an addition that would allow many devices to offload from the Wi-Fi to an LTE network that is more secure and a carrier-grade network. This is what the attraction is all about. Then we can roam from this network to a real carrier’s network seamlessly if the agreements are in place. 

Will PLTE replace carrier iDAS?

I don’t think that it’s going to be looked at the replacement but maybe as an enhancement. I have a few reasons for this.

Show me the money!

The money to install and manage these systems all across the USA is insane. The carriers are just tired of funding the installation, upgrades, and maintenance. It’s not a viable business for them to go forward. 

They can offload the costs to the enterprise and allow the enterprise to have a private network with a roaming agreement. An agreement that would be invisible to people on that carrier’s system. Then they would be able to offload from the other systems onto the enterprise system.

The carrier offloads the installation costs along with all the OpEx that goes along with it. 

Now, the enterprise will pick this up but they should see more than just a PLTE network for their devices. They could add CBRS to their iPads and laptops that would make them viable everywhere. 

They have that opportunity to roam on the devices they allow, not all devices. 

Meanwhile, carriers can scale back and just build agreements with these PLTE owners instead of maintaining and upgrading systems.

They still need a support group, like they already have for MVNO customers. They would need to scale it down to meet the needs of very small enterprise and MVNO operators. 

PLTE systems are not easy.

When looking at PLTE, it’s not like putting in Wi-Fi, it’s very different. muLTEfire was supposed to come out with the LTE protocol without a core, but the reality is the PLTE needs some core to point to. 

This is why the enterprise likes it because it has control over the data that is passing. They can create something that is unique to them.

This is a carrier-grade network that manages traffic differently than just a Wi-Fi plug and play does. It has more complexity and management. 

It’s not cheap either. If you want VoLTE, it costs money to add and license it.

Why now?

CBRS is opening up new doors. The SAS model will allow new players. This is an opportunity for enterprise as well and very small carriers to pop up and fill in the gaps where the carriers will not. 

This spectrum is being added to all new devices moving forward. Most smartphones coming out in 2020 should have this spectrum as part of their base models. 

The fact that CBRS has become a standard and that devices have it makes PLTE more commonplace than ever before. 

Carriers no longer will be obligated to build where the business model doesn’t make sense. They can let small carriers, WISPs, and Enterprise fill the holes and then simply create a mini MVNO roaming agreement that benefits both sides. 

What would the system look like, small cells or radio heads?

The thing is, most people don’t understand the difference between a real small cell or a radio head anymore. 

It’s going to be a radio head and possibly an integrated antenna in most locations. However, I see more and more companies that want to install their own antenna. 

The core, probably something simple, will reside in the data center just like all the other routers and servers. 

Most enterprises have their own backhaul, so this would not be any different.

They may have BBUs there that connect to all the radio heads. This also would be in the data center.

It would be connected to CAT6 from the BBU to the radio head. I expected fiber because that’s what they use at the tower sites, but the loading at a tower site is much heavier than in a building. 

They could convert to mmwave at some point, but again, mmwave is licensed by the carrier, so there is a slim chance they would allow that to be used by anyone else. 

What about 5G?

CBRS is already working on 5G solutions. It is part of the roadmap and should be available in 2021. Then 5G could be available to anyone who would want to invest in deploying CBRS.


The way that DAS systems are being deployed in buildings is changing. The fact that CBRS is being released opens up new doors for private LTE will be a game-changer. 

While iDAS will remain in place, it can get another upgrade which is good for the DAS installers. They continue to have business from carriers and now they can add enterprise businesses to their portfolios. 

It makes sense that more and more wiring will be taking place to upgrade and install new systems. 

The CBRS spectrum should add a host of new small MNOs and MVNOs that want to build out systems. Like Wytech in Columbus, Ohio, where I received my first call on CBRS PLTE system, https://wade4wireless.com/2020/01/21/my-first-cbrs-volte-call/, and it works.

My big worry is that smaller OEMs deliver solutions. This is a solution because most smaller companies can’t put it all together. Especially if they only did Wi-Fi, they need to understand how the LTE system works form the core out to the eNodeB. 

Then, they need to understand the licensing of services, like VoLTE and IOT services. 

Finally, they should be thinking of their path to 5G. They need to think like a carrier and not like a small ISP.

Then, we will see true success in the CBRS.

A high-level history of indoor systems. 

What does that acronym mean?

Oh, some definitions for those of you who are not in the business:

  • 5G – Latest wireless transmission standard encompassing more than just the wireless carrier
  • BBU – Base Band Unit, this is the interface (brain) between the core and the RRH
  • BDA – BiDirectional amplifier
  • CRAN – Centralized RAN
  • cRAN – Cloud RAN
  • DAS – Distributed Antenna Systems
  • DRS – Distributed Radio system
  • iDAS – Indoor DAS
  • LMR – Land Mobile Radio
  • LTE – 4G networks, Long Term Evolution (which is ironic because it’s being replaced so quickly by 5G)
  • oDAS – outdoor DAS
  • PLTE – Private LTE
  • RAN – Radio Access network
  • RRH – Remote Radio head

Indoor Public Safety Systems

So here’s the thing, there is still public safety DAS. It is not going to change because it’s still required in almost every building in the USA so that the first responder can talk within the building.

In case you’re wondering why this is not a DAS discussion, here’s why. First Responders still rely 100% on their 2-way communication in an emergency. While they are looking forward to FirstNet’s deployment of public safety LTE, it’s just not widespread and reliable yet. 

Don’t get me wrong, this is not a knock on Firstnet or AT&T, it’s more about when an emergency hits, what is the first responder going to use. They are going to get on their push to talk radio and communicate as quickly and efficiently as they have for the past 50 years or so. 

If something is working and everyone is trained to use it, then use it!

Even though many first responders now pull out their smartphone when in an emergency to reach additional services, like hospitals or police. They rely on their radios to communicate with each other. 

I see police use their smartphones all the time to research people, like on Facebook, or to reach out to people who may be off duty or working in another branch. 

You would be surprised how many criminals post their stupidity on Facebook, which the police call evidence. 

So, in DAS, the public safety systems are generally stand-alone, normal systems, installed in almost every building. Usually fire bands. Just ask any DAS vendor, they sell a ton of these systems. 

Public safety DAS will be around for many more years. 

LTE is not an acceptable emergency responder solution just yet. I think anyone in the industry understands that. 

These systems are generally passive, maybe have a BDA to pass the signal back and forth. 

If you want to see more on this, 

Just remember that these systems, although somewhat obsolite, are being deployed in almost every new building or remodeled building. In most cities it is mandatory that emergency coverage for first responders is tested and reliable in almost every part of the building.

It must also be alarmed and monitored. So itisn’t like you  put it in and leave it. There has to be some way to see if it’s wokring properly. 

Indoor Carrier Systems Evolution

Here is what I really want to talk about. This is starting to evolve. DAS is still key, but let’s face it, if you’re in the industry, you have seen indoor systems evolve. 

While there may still be passive and BDA systems in some smaller offices that need coverage, those systems are starting to disappear.

Most people now opt in for a small cell of some kind or may even rely on Wi-Fi calling to replace the carrier altogether. 

The carriers have been trying to work on alternatives. 

Sprint came up with the Magic Box which is a small cell that uses a wireless carrier as backhaul. It works very well as long as they have some type of coverage inside where the Magic box is placed. 

You could place the box on or near a window, then it could extend coverage within the building. 

The DAS operators spend more and more time upgrading their systems because technology is moving so fast. If you ever did work in a stadium, you know what I mean. 

We had to upgrade 3G, then add 4G, now it’s 5G.

Not only that but new spectrum is being added all the time. 

A quick overview of indoor systems based on technologies.

3G and before!

When it was 3G, there were mostly passive systems or BDAs that helped get the system out there. This was mostly splitters, coax, and amplifiers all over the place. This was sufficient and added coverage to building, subways, tunnels, underground offices and mall, and so on.

These systems worked very well. 

If you were around for nextel, you remember how most businesses wanted thqat coverage throughout the building. They needed to have everyone in touch all the time. Nextel used iDEN, but it was one of the first networks that even small building owners needed coverage indoors. This was before we used our mobile phones for everything.

Yes, we still relied on landlines back then. Memories!

Then, as we relied on our devices more and more, we added DAS systems everywhere.

Larger venues did have the DAs systems and they spent a fortune to run coax every where. 

It cost a lot to deloy any of these systems, yet carriers footed the bill most of the time so no one seemed to care. 

The carriers had entire divisions dedicated to deploy these systems. 

Along came 4G

When 4G came along, we tried to continue upgrading those systems, but it was not working well. Higher spectrum made it harder and harder to get the signal out there.

So we have to move  the radio heads from the head end otu to the entanns. Hence, the DRS was born. Although they still called it DAS. 

In the beginning most o fthese sytems were still connected by coax to take the midband up to the RRH.

Then, along came the fiber connected RRH. Where the RRH was fed power by copper and data by fiber. This was the evolution of all systems, not just DAS.

Even at macro sites, towers and rooftops the RRH moved from beside the BBU up to beside the antenna. 

RRHs became more reliable, resistant to lighting and weather, and smarter. They coudl take fiber and do all the RF work literally beside the antenna. 

How cool was that?

However, now the DAS systems needed to run fiber and copper everywhere. This is an all new way to connect, at least at that time. 

As spectrum and power demands changes, they have to move the RRH to the antenna. 

Thsi helped boost DAS vendors because now they had to redesign systems and run all new cable sin buildings. This was a lot of work and money that needed to be reinvested.

Suddenly, the carriers were getting sick of paying for all the changes and upgrades. It was beginning to be a drain financially. They knew the model had to change, financially!

They wanted small cells to fil the gap. Small cells like where they had an all inclusing BBU and RRH and antenna all in one small unit. 

The small cell helped, but it could not perform like a full fledged BBU and RRH. Therefore, they never lived up to expectations.

However, now the RRH is getting smarter and smarted and doing more than ever before. So the BBU could be placed farther and farther away,. 

Welcome CRAN, this is where you may have a BBU hotel,. A place where the BBUs can be stacked for multiple sites. The BBUs can all be in one location. This concept was taken form the DAS model where they had a headend in a stadium or building and then connect all the RRHs by fiber. How cool is that?

Now, you can extend the link from a few hundred feet to up to a mile or more. 

CRAN, Centralized RAN is the upgraded version of the oDAS system. It’s taking the BBU Hotel and feeding an entire section of the city. Someday when cRAN booms, we will have one BBU Htel, a cloud BBU, feeding an entire city, perhaps an entire market. Awesome1

This all came about because 4G is a completely digital system and the system relies on IP instead of some specific carrier centralized protocol. This created incredible efficiencies. Evolution once again. 

This is different than older systems. While this migratin was happening in the 3G world, it became the norm in 4G and the expectation in 5G is to increase the use of active antennas.

An active antenna has the radio head and the antenna as one unit.

Now there is 5G

With 5G there will be new challenges, ut eventually it will replace 4G and will follow a similar evolution path. The only question will be what spectrum will it be in. Tha’s going to be the next thing.

How will 5G be put inside and what spectrum will it use?

Spectrum is the key because while LTE is the normal now, it’s almost completely in the sub 6Ghz spectrum except for some exceptions. 

We’ll have to see if mmwave works indoors and if it does, I see that spectrum sominating.



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