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December 2017

Filling Mobile Coverage Holes: The Wilson Electronics Plan to Boost Passive DAS to 98% of US Commercial Buildings

Filling Mobile Coverage Holes: The Wilson Electronics Plan to Boost Passive DAS to 98% of US Commercial Buildings

Mobile operators boldly advertise their national coverage by filling maps with lots of pink or purple bubbles from coast-to-coast.

But the reality is quite different, for there are lots of tiny white holes in those bubbles where signals are only weakly received inside of buildings, the main culprits being physical barriers such as concrete walls or radio-radiation suppressing windows.

Welcome to a wonderful world of cellular signal repeaters — both Active and Passive DAS systems that enable cellular voice and data services in tough locations that the cell towers can’t reach alone.

And joining me to provide a highly interesting tutorial on the subject is Jeff Gudewicz, Chief Product Officer at Wilson Electronics, the market leader in Passive DAS systems.

In our interview, Jeff does a great job of explaining the technical challenges and economic trade-offs.  He covers: the pros/cons of Active vs.  Passive DAS, the regulatory scene, the virtues of over-the-air and self-tuning repeaters, and the huge opportunity to push DAS solutions to small business commercial buildings.

Dan Baker, Editor, Top Operator: Jeff, first of all, how did Wilson Electronics get started in the business?

Jeff Gudewicz: Dan, forty years ago when Wilson Electronics started, we focused on antennas: for cell towers, semi-trailer trucks, satellites — even two-way radios.  It’s in the 1990s when we first got into the cellular signal booster or repeater market.

Now we serve both consumer and commercial markets.  For instance, our consumer products are sold through Best Buy.  Meanwhile our commercial business, Wilson Pro, sells though a broad national footprint of dealers and integrators.  These integrators typically handle things like in-building security, Ethernet services, and WiFi hotspot deployment.

OK, let’s talk about the cellular repeater business.  How do your systems work?

Well, first of all, the names “repeaters”, “signal amplifiers” and “boosters” describe the same device.

One of the unique ways Wilson addresses the problem is our 100% over-the-air network approach: we simultaneously collects all the cellular signals in a given location through an outside antenna.

All signals collected — both strong and weak — are brought into the system via a single line of coax.  From there it goes to the heart of the system, a bi-directional amplifier.

The key technical challenge is to extract those signals by their Mhz band — 700 LTE, 1700, 1900, 2100, 850 — and then separate them into their channel.  Then each signal is amplified up to the maximum allowable level.  Finally, those channels are combined again into another coax line that goes to a broadcast antenna inside a home, building, office, or even a vehicle where the signal is retransmitted.

So it takes a weak signal, strips it all apart, boosts the signals up, combines the signals again, and re-broadcasts.

Now a key thing to recognize is this: boosting the tower-to-device signal is not enough.  You need to amplify signals in both directions.  So the second half of the problem is boosting the cell phone signals up and sending them back to the towers.

Another very valuable feature is being carrier agnostic: it’s not a single operator device.  Whatever cellular signals are in the air, we enhance them all simultaneously.  We support all cellular bands and standards — legacy 2G, 3G, 4G, 4G LTE.  Basically any modulating signal the operators transmit on their spectrum is enhanced.  We do not boost WiFi however, because WiFi is not transmitted via cellular.

Why does the carrier agnostic approach add value?  Wouldn’t it be useful to break out the traffic for each operator?

We could, but the benefit we provide is to enhance coverage for everybody that’s in the area.

Let’s say you have a small business.  Well, a lot of companies have multiple operators for their employees.  They may have a corporate mobile contract with Verizon who supplies most of their phones, but very often companies will subsidize employees using a cell phone on an AT&T or Sprint network.

And if it’s a public space like a hospital, you want people from all operators to get a boosted signal.

I understand there are some safety issues around the operation of repeaters, causing the FCC to get into the business of regulating them.

Yes, and since Wilson has 30-plus patents in the field, the FCC and operators like Verizon called on us to help develop the technical standards.

Here’s the issue: if you don’t design and operate repeaters properly, one technician with an over-powered amplifier can essentially knock out any cell tower nearby.

Remember, repeaters proliferated, in part, due to necessity.  In remote and fringe cellular coverage areas, repeaters can do a great job of boosting the signal a few bars.

But if you have a repeater system with multiple antennas, and you’re not careful on how you space them, you could drive an oscillation — basically the same feedback problem you get when you put two live microphones near each other and hear a loud sound.

Wilson eventually led the FCC effort to develop technical rules and standards on the proper use of repeaters, which led to the FCC’s Signal Booster rule 20.21.

Those Signal Booster rules went into effect in May 2014, and since then we’re pleased to say not a single major incident has been reported even though there have been hundreds of thousands of repeater deployments by WilsonPro and other firms.

There’s an interesting dynamic around the two basic types of repeaters — Passive DAS vs. Active DAS.

Yes, Wilson’s technology has significantly enhanced the value of “Passive DAS.” Formerly, Passive DAS system had zero amplifiers: they were basically an outside antenna connected directly to an internal antenna — like opening a window and letting the breeze come in.

But now we’ve expanded Passive DAS to include bi-directional amplification, so you can boost the signals coming in and out of a building.

Now Active DAS, small cell, and Carrier DAS — all of those are small venue uses for cellular, say in a stadium, airport, or convention center.

Active DAS is a more expensive solution because it’s powered by a RAN controller in a telecom operator’s network.  A large amplifier sits in a rack somewhere, then there are multiple distribution antennas throughout a large office, stadium, or airport.

Active DAS makes sense in large facilities that need to cover the needs of tens — even hundreds — of thousands of people.  However, Active DAS is not an over-the-air system, so you pull in fiber bundles with high capacity that are hooked to a telco through a RAN, and that’s turned into RF signals that broadcast throughout a large building.

How do the economics of Passive DAS stack up to Active DAS?

Well, to answer that question you really need to do a little research on the cellular needs of buildings of different sizes.

A lot of people talk about dollar per square foot of coverage, but the bigger issue is the scale of solution needed in a given location.

Active DAS require an investment of 6 to 7 figures for a system.  So for an airport with a million square feet, you can usually justify a dollar a square foot cost for Active DAS.

The RAN controller and head end equipment alone will cost you $500K to $800K.  So if you put that in a 100K square foot building, it becomes cost prohibitive.

Another key issue is that Active DAS is installed for one carrier only.  So if you want to have a building serving Verizon, AT&T, Sprint and T-Mobile all covered, you have to build out an Active DAS solution for each one.

So at that point the price goes through the roof.  And that’s why the building size of 200,000 feet or smaller is usually the point where the economics favor a Passive DAS solution like WilsonPro provides.

Now the research says there are 5.6 million commercial buildings in the US.  It’s a huge number that includes every retail store, industrial building, etc.  And 5.5 million of those commercial buildings are less than 200,000 square feet.  In other words, 98% of the building market is 200,000 square foot or less buildings.

Breaking it down still further you discover that 80% of those 5.6 million commercial buildings are less than 25,000 square feet and about 90% of the buildings employ 25 to 50 employees.

In short, Passive DAS’s biggest potential market is to small business.  And when you consider the surveys, they tell us 70% of buildings experience some level of cellular quality degradation, that’s a huge market opportunity, we think.

Why are small businesses facing transmission quality issues?

In a majority of cases the signal is very good outside, but getting it inside the building is the problem.

We often find issues with “green buildings” that were designed for maximum heating and cooling efficiency.  The problem is the wall insulation and/or high quality glass that blocks thermal radiation also blocks radio signals.

So what we do is take the signal inside and rebroadcast it.  It’s very effective.

In border line buildings of around 200,000 square feet, how do you win business against Active DAS systems?

Well, let’s say it’s a hospital.  Certainly the carrier offering the Active DAS system will want to blanket the entire hospital with coverage.

However, we often find they don’t require signal boosting for the entire building, only a portion of it.

In a hospital, the issue is getting coverage in the deeper rooms of the building.  For instance, the radiology department of a hospital is usually located behind lots of concrete walls to help reduce radiation to protect people, so it’s hard to get cellular signals in and out of there.

So what we do is strategically insert better cell coverage.  And if the hospital’s budget is tight, we go in and “light up” portions of the building in phases, say, every 6 months we improve the signal in a different corner of the hospital.

I guess every McDonalds restaurant in the US is equipped with WiFi.  Can they get any benefit from Passive DAS?

The biggest reason a small restaurant would opt for DAS is security.  Often data breaches happen because their transaction data is going out through a local server.  Typically the IT contractor leaves a portal open and a hacker finds it.

So a small footprint retail store like a McDonalds or a coffee shop can enhance the security of their transactions by switching that over to cellular.

I understand another advantage of your over-the-air system is it has automated self-tuning features.

Yes, there are some key cost savings inherent in Wilson’s repeater design.

For instance, carriers are constantly shifting signals from one spectrum to another based on the particular need at a location.  If the LTE spectrum is overloaded, carriers will re-farm LTE onto other spectrum they’ve paid millions of dollars to acquire.  Maybe they’ll put 4G LTE over some legacy 3G in the 1700 or 1900 MHz band.

Now since Wilson is enhancing all bands simultaneously, as carriers move their LTE signals around, they don’t have to worry about tuning the repeaters at all.

Another advantage of having an over-the-air system is it takes away the problem of, say, managing the flow of people transiting through a train station before and after work.

In a RAN scenario, the carrier ends up “steering” its towers to allocate more signal to areas of heavy usage.  So signals constantly ebb and flow.  The networks are breathing and the cell bubbles around the towers kind of go in and out depending on the usage.

But in our products every 300 microseconds the bands are checked for the available tower capacity.  And as soon as it drops, our system reacts to that change and through an automatic gate control (AGC) adjusts so the repeater is operating at its optimal level.

Even at night when traffic goes down, our system can back off safely so it’s not interfering with the network.  We do that better than anybody else in the Passive DAS space.

Jeff, you’ve opened our eyes to the benefits of Passive DAS, and Wilson’s over-the-air technology sounds impressive.  Thanks for the briefing.

Copyright 2017 Top Operator Journal


About the Expert

Jeff Gudewicz

Jeff Gudewicz

Jeffrey Gudewicz, also known as Jeff, is the Chief Product Officer for Wilson Electronics.  Jeff has served as the Vice President of Product Development at Wilson Electronics, LLC since January 01, 2015 and served as Director of Business Development and Product Line Management at Wilson Electronics, LLC since October 7, 2013.

His prior experience featured business development, marketing, sales, business unit and engineering management roles at RFMD, Sirenza Microdevices, Vari-L and JFW Industries.

He has a diverse background in technical management, product development, marketing, sales and business development.  Gudewicz holds a bachelor’s degree from Southern Illinois University in Aviation Sciences and an MBA from Regis University with a concentration in Operations Management.   Contact Jeff via

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