DAS / Small Cell

INTRODUCTION:

For those who don’t have a ready understanding of the difference between commercial cellular and public safety DAS, I thought a simple chart might help to get us started on the right track. This one is definitely worth the refrigerator magnets:

 

QUESTIONS COMMERCIAL CELLULAR DAS PUBLIC SAFETY DAS
WHO USES IT? Five billion people Firefighters, police, paramedics, etc.
HOW DO YOU USE IT? With a cell phone With a two-way radio (Motorola or other)
TO WHAT NETWORK IS IT CONNECTED? AT&T, Sprint, T-Mobile and/or Verizon. Could be one, some or all. The local municipality’s government radio repeater system
WHAT RADIO FREQUENCIES ARE REBROADCAST Varies by carrier and slightly varies by market, but generally consistent across the nation. Varies widely by municipality although generally in the VHF, UHF, 700 MHz and 800 MHz ranges.
WHAT RULES GOVERN IT? Anything the wireless carriers decide. NFPA 1221, IFC 510, governmental statutes and the local Authority Having Jurisdiction (AHJ)
WHAT IF MY BUILDING DOESN’T HAVE IT? People don’t want to come to your building. You might not get a Certificate of Occupancy, and the firefighter in your building might not be able to talk to his captain on his radio.
WHO OPERATES IT? Could be the carrier, a neutral host company or an integrator hired by the building owner. An integrator hired by the building owner.
ACTIVE OR PASSIVE? Commercial DAS are always active, meaning they actively conduct signal processing at multiple remote nodes. Only boosters are passive. Could be active, if a large facility using fiber-fed remotes, or passive in a larger facility that only has a bi-directional amplifier.
WHAT’S COMING DOWN THE ROAD? 4G+ and 5G FirstNet–nationwide broadband public safety network

 

 

PS DAS ORIGINS AND NATURE:

Put simply, the purpose of a PS DAS is to ensure the communication capabilities of the emergency responder working in a building (with his two-way radio), thereby enhancing the safety of the building occupants by making that firefighter, paramedic and police officer more effective and safe.

The origins of PS DAS, in terms of their design and code requirements, is heartbreaking when you consider the technology was available much earlier than it was used for PS DAS. On September 11, 2001, 412 emergency workers died in the infernos of the two World Trade Center towers. As the instability of the structures became apparent to the emergency management leadership, calls went out over the two-way radios to the firefighters, police officers and paramedics in the building to “Get out!” Tragically, because there was no PS DAS in those buildings, many emergency workers did not hear the message. They remained on duty, attempting to rescue building occupants, and died when the buildings fell.

In 2005, the 9/11 Commission made a number of recommendations. Among them was the proposal that high-rise and larger scale buildings be fitted with radio bi-directional amplification systems, tuned to the government emergency responder radio repeater systems for each local municipality, so as to protect emergency responders from ever facing such a horrible situation again. The key to the proposals, and subsequent codifications in the National Fire Protection Association (section 1221) and International Fire (section 510), is that these systems are intended for wherever the ambient signal strength and quality of the municipalities radio repeater system does not meet minimum standards inside buildings. Successive iterations of the NFPA and IFC have refined the signal strength and quality requirements and addressed critical aspects of the system’s survivability (in the event of a fire).

Thus, the system is only needed if the building structure somehow prevents the ingress of the municipality’s radio system. Which means that the signal strength and quality must be measured (which is somewhat difficult to do for a building that is only in the planning stages). And if it passes, then no PS DAS is needed… for the most part.

Certain municipalities, on the West Coast, in Colorado, Texas and Florida and possibly other locales (it’s hard to keep up with all of them because the landscape changes constantly) now require PS DAS regardless of the strength of the ambient signal strength for new, larger buildings. While that mandate makes it easier for a building owner to budget for a PS DAS, the mandates to increase survivability requirements can significantly increase the cost of the system.

But wait, there’s more! Some municipalities and even states (Florida in 2016, for example) have now mandated that PS DAS be implemented retroactively in existing buildings, where ambient signal strength or quality metrics are not met. So an existing building owner must hire a competent PS DAS integrator, obtain signal strength and quality test readings, and then submit those readings to the AHJ. If the building passes, you’re finished. By the way, never has one of our PS DAS tests successfully passed an entire building. Usually it’s the lower floors that fail, and because of the detailed testing requirements of the NFPA and IFC, if even a small area on one floor fails to meet the requirements, then a PS DAS is needed.

And to top it off, new building construction materials, such as low-e glass, significantly impede RF signal propagation. Put simply, modern, LEED certified buildings kill radio signals. If radio signals cannot get in, then you need a PS DAS.  (It’s worth mentioning that you’ll also need a cellular DAS unless you don’t care if consumers come to your building).

 

WHAT’S INCLUDED IN A PS DAS?

Because the municipality radio repeater system operates in a much simpler fashion than a cellular network, the PS DAS is correspondingly simpler and less expensive than a commercial cellular DAS. Again, a simple diagram might be of some use here:

 

 

In almost all cases, the PS DAS connects to the municipality’s radio repeater network through a donor antenna located on a rooftop, which connects by coaxial cable to an in-building repeater. This particular PS DAS is active, in that it is a large building system with multiple fiber remotes that take the amplified signal from the in-building repeater and distribute it throughout the building across antennas.

Relevant to the discussion of investment is that a PS DAS is monitored through the building’s Fire Alarm Control Panel (FACP). Often fire alarm integrators are, therefore, asked to design and implement the PS DAS. But the competency to do so, as well as the usage of very expensive tools and software that are necessary, typically rests in the hands of integrators who have significant radio frequency (RF) experience—either through a background in commercial DAS, or two-way radio systems.

 

PRICING, AND WHETHER COMMERCIAL AND PS DAS SHOULD BE TWO SEPARATE SYSTEMS OR BE COMBINED INTO ONE SYSTEM:

Yes, it is completely feasible to combine PS DAS and commercial DAS. But, in many, perhaps most cases, the economics of combining the systems are less attractive than providing two separate systems.

The PS DAS requires “hardening” of all active electronics, which means encasement in NEMA 4 enclosures. All of those electronics must have 12 hours or more of electrical power back up, which, if a building generator isn’t acceptable then UPSs are needed for all of them—again, in NEMA 4 enclosures. Trunk cables for PS DAS are required to have a two-hour survivability rating, which can be quite expensive if not inside a rated riser closet. In some municipalities, that two-hour rating also applies to the branch cabling extending to the antennas. Finally, the PS DAS, being simpler, on different frequencies and for powerful five-watt radios, requires fewer remote nodes and antennas.

What these various differences mean is that combined systems have more remote nodes and antennas than is needed by the PS DAS, but all those remote nodes, riser cables (and in some cases branch cables) must have expensive NEMA 4 enclosures or two-hour fire ratings not necessary for commercial cellular DAS. Sometimes it makes sense to purchase a combined system, but we recommend that a conscientious building owner allow for pricing both ways, just to be sure.

For stand-alone PS DAS, we recommend budgeting $.35-$.50/foot. The cost increases as the building size requires an active instead of a passive system, but then scales down in cost as the size of the building grows.

 

FIRSTNET:

Over fifteen years ago the federal government planned for FirstNet as television broadcast transitioned from analog to digital. Remember those digital convertor boxes you had to get in order to watch shows on your fat tube TV? That conversion freed up bandwidth in the 790 MHz range, which was set aside for a national broadband network.

It’s taken all of that time for FirstNet to go from plan to reality. In March of 2017, the federal government finally awarded to AT&T the contract to build the nation’s common frequency (called Band 14), broadband network for emergency responders. Today, all municipal radio networks are simple duplex. They allow radio communication back and forth (with that annoying “Over” whenever what you’re saying is over), but no kind of high bandwidth, full duplex audio and video communications. Plus, they use all sorts of various frequencies, so there is no uniformity.

FirstNet will change all of that. Firefighters will have video displays on their uniforms that allow them to see footage from a surveillance camera, a map of the building, or reported dangerous locations. FirstNet will help make it possible for first responders to locate persons, whether persons trapped in fire or active shooters or other, through telemetry with their cell phones.

Understanding FirstNet makes sense of why more and more municipalities are going beyond the NFPA/IFC testing requirements and insisting on installing a PS DAS regardless. As FirstNet becomes a reality, and emergency responders’ ability to assist civilians increases, none of that investment will have any value if the Band 14 signals cannot be received inside a building.

 

HOW TO PLAN AND BUDGET FOR PS DAS:

There are a number of arguments to be made for budgeting and installing PS DAS in a new, large commercial building as a standard. These are:

  1. Predictability and lowest cost for the PS DAS: if preliminary testing is dispensed with, and the PS DAS planned from the outset, the system should cost less than one developed iteratively in stages. Plus, the codes allow the elimination of firefighter jacks in buildings that have a PS DAS.
  2. Humanitarian and risk mitigation: the presence of PS DAS means there would be an increased chance that first responders can do their job effectively with reduced legal liability for the building owner in the event of a situation resulting in injury or death.
  3. Synergies with local, in-house two-way radio systems; most PS DAS systems allow for the re-amplification of the building’s in-house Motorola (or other) radios, used by back-of-house staff.
  4. Trending requirements; more and more municipalities are requiring systems regardless, even retroactively, so it’s very possible that a PS DAS would have to be provisioned later anyway. Plus, a new building erected next to your own, just a few years later, can effectively kill signals that used to penetrate your building.

Assuming I haven’t persuaded you to forge ahead with a PS DAS every time, (and I wasn’t really trying to twist your arm), what is the best way for a building owner to plan and budget for PS DAS?

  • First, identify the state and local requirements. In some cases, you won’t have a choice. As of today, in most cases the municipality will require a PS DAS only if signal tests fail. But they often have significant, detailed requirements. Plus, often they are operating under an earlier code version than the latest one, which argues for careful research ahead of time.
  • Second, recognize your dilemma and plan accordingly. You won’t know if you need a PS DAS until your building is nearly finished. At that point, it’s going to be very difficult to have the system installed in time to satisfy your need to obtain a Certificate of Occupancy. But you don’t want to contract and pay for a PS DAS if you don’t need it. So, we recommend you obtain a quote for a PS DAS at the outset.
  • Third, obtain a quote for a PS DAS in three parts:
    • Preliminary testing for when the building reaches approximately 80-85% completion. Soon enough to measure the RF environment accurately but with enough time to install a system if needed. If it passes, then the money expenditure ends.
    • The “core” system, including headend, donor antenna, connection to the FACP, etc. and coverage for the likely deficient areas—typically all underground floors, the first one or two above ground floors, and areas that are deep inside concrete walled interiors. These are likely to be needed regardless.
    • A per unit price to expand coverage to additional areas (typically these are in approximately 10,000’2 increments)
  • Finally, don’t forget to budget for annual inspections, which require a complete retest of signal strength throughout the building and recertification of the PS DAS components, monitoring effectiveness, etc.

 

CONCLUSION:

I find that once the information about PS DAS is communicated, it isn’t as difficult to figure out as seemed at first. Confusion with commercial cellular systems, which hopefully we’ve eliminated here, accounts for much of the mystery. Differing local codes create another large portion of misperception, and there’s no simple solution—you must research based upon the building location. After those two, the main issue is figuring out how to plan for a PS DAS when you don’t have a building “built” yet. See section above, in case you missed it.

Final word. It does actually take some sophistication to design, implement and test PS DAS. Software and testing equipment are costly and difficult to use without good training. Check on your integrator and make sure he has real bona fides. After all, this is a life safety system.

[Featured on Network Technologies, Inc.’s website: http://www.nticonsultants.com/2017/09/12/public-safety-distributed-antenna-systems-part-ii-of-the-in-building-wireless-systems-series]

[For more info on DAS, Public Safety DAS, ERRCS, etc. read Eric Fichtner’s article HERE]

If ever there was a realm of building technology systems, and a point in time, where more confusion, hype and wasted dollars have been strewn about, it’s got to be today in the area of in-building wireless systems.

While the category of “in-building wireless” does include wireless LAN, better known as WiFi, this article will principally address the more confusing and dynamic technologies of cellular distributed antenna systems (DAS) and public safety DAS, which, as per the code book, is more accurately labeled Emergency Responder Radio Coverage Systems (ERRCS). WLAN technologies are routinely handled well by client IT departments, and while they can be challenging to design and manage, especially with the surfeit of devices in this bring-your-own-device (BYOD) world, they are in general well-defined in terms of their costs and benefits.

With cellular DAS (or for the sake of brevity in this article just “DAS”) and ERRCS, mystery and the potential for costly mistakes abound. Because of the complexities, we’re going to generate a series of three articles. This first one will tackle the current state of DAS, and the related cellular booster technologies, which enhance cell coverage inside buildings.

  • What technologies exist today?
  • What sort of cost expectations are realistic?
  • What potential jeopardies exist if I, the building owner, choose not to spend my money on one of these systems?

Also, we’ll spend some time reviewing the pros and cons of DAS versus boosters, both from the perspective of the cost and features of each as well as how the wireless service provider (WSPs), also known as carriers, (AT&T, Verizon, T-Mobile and Sprint) view the different technologies. There have been some exciting developments in making DAS more affordable to the enterprise building owner, and we see these trends developing rapidly in this (what some people are calling the) “fourth utility.”

The second article will take on ERRCS, especially in light of changing jurisdictional requirements and the related concerns of risk mitigation—it does, after all, concern life safety. We’ll explain FirstNet, the nationwide broadband first responder network. The federal government just awarded the buildout contract for FirstNet to AT&T, after much delay, so it’s a coming reality. We’ll also Identify ERRCS trends as they relate to the requirements being imposed by particular states and cities. Both in the first and second article we’ll make sure that the commonalities and differences of DAS versus ERRCS are clear—because there’s just that much confusion. One obvious one that often is overlooked: DAS is used by cellular device consumers, while ERRCS is only used by first responders, i.e., firefighters, paramedics, and police.

The final article peers into the future, to the cellular 4G+ and 5G technologies, which are not nearly as far down the road as most people believe.  For example, I have a friend who participated in a 5G trial with a major wireless carrier almost two years ago. He downloaded an HD copy of the movie “Interstellar” in 3 seconds while driving 60 mph. We’ll start seeing commercial 5G deployments in select markets next year.  The last article shall address how to prepare for 4G & 5G technologies wisely without being sucked into incurring massive costs that don’t provide real benefit today.

THE CURRENT STATE OF DAS

Some people are surprised to learn that DAS deployments in commercial buildings have been taking place for almost twenty years. Phil Ziegler, CTO for Whoop Wireless, recalls efforts during his tenure at Verizon Wireless when VzW, Qualcomm, University of Colorado professors, and Lucent technologists collaboratively developed functional and test requirements for 4G DAS and OTAR product performance objectives.  “Those requirements had venues such as airports, stadiums, convention centers and other places where large crowds gathered in mind.  Now we are faced with the realization that increased data demand is being felt throughout the ecosystem and not only in the largest facilities.  So, just as small cells are reduced power and capability base stations, affordable commercial grade DAS platforms are needed in the enterprise space to accommodate the small cell paradigm.“

A number of large and respectable neutral host companies, such as American Tower, Crown Castle, Boingo and Extenet, have built a profitable business model on deploying DAS. These companies serve as liaisons between venue owners and the WSPs and attempt to generate as much participation on the DAS as is possible.  It must be understood that the priorities of the WSPs are as different as are their budgets across vertical markets, and so there are many cases where neutral host and carrier-owned DAS have less than full participation from the four major cellular carriers.

In today’s BYOD world, perhaps the first lesson in deciding on implementing any in-building cellular enhancement system—whether it’s DAS or a simple booster technology—is: Does it offer access to all the major players? The trend is veering away from corporate environments where a carrier obtained a contract to provide cell phone to all the users and agreed to implement a one-carrier DAS in return. The modus operandi for today’s consumer, be she an employee, visitor or guest, ischoice. We’re seeing this sharp turnabout in all market verticals, but perhaps most vigorously where the building houses numerous non-employees. These types of buildings include hotels, apartments and condos, higher education, and, perhaps surprisingly, medical centers. As many as 85% of the people who work in a hospital can be contractors. The hospital IT staff struggles against overwhelming odds to overcome obstacles around giving WLAN access to these non-employees while complying with HIPA requirements. They would much rather see the BYOD contractor workers fulfill their broadband needs through the cellular networks.

Common questions about DAS

  • What about cost?
  • Aren’t DAS implementations ridiculously expensive?
  • Can’t I just put in a low-cost booster that works just as well as DAS?
  • Won’t one of the carriers pay for a DAS in my building if I just wait long enough?
  • And finally, shouldn’t the carrier’s broad, tower-based cellular network (industry jargon—they call it the “macro network”)  pump enough signal into my building so that I don’t need an in-building cellular enhancement system?

Let’s peel these layers back in reverse order:

WHY DO I NEED AN IN-BUILDING CELLULAR ENHANCEMENT SYSTEM ANYWAY?

The answer to that question boils down to a cost/benefit analysis, as you decide whether to rely exclusively on what AT&T, Verizon, T-Mobile and Sprint do to make your building a desirable destination or you determine to supplement their buildout efforts. Do you, as a building owner, gain enough of a competitive, and therefore revenue, advantage to justify the cost of a DAS or booster? And to answer that question, there are three factors to consider.  They are interference, capacity and demand.

First, building construction technologies increasingly create radio frequency (RF) interference that limits the signal strength within a building. Triple pane, low –E glass, for example, has a 40 dB impact on RF signal strength. Doesn’t sound like much? In case you’ve forgotten your logarithms, a 40 dB loss in signal strength means the signal inside the building is only 1/10,000 as strong as the signal outside the building. Honestly. Building iron, hurricane shutters, other buildings, even furnishings can significantly impact the signal strength within a building, creating dead zones or even an entirely “dark” building. With or without triple pane glass, we routinely see a 30 -50 dB drop in signal strength, making what was a fine cell experience outside the building excruciating once you step inside.

The second factor in considering whether you will supplement the macro network with an in-building wireless system involves capacity. What once was an empty lot on a carrier’s macro network map transforms into a 32-story high rise hotel. Even if you can walk throughout your high-rise hotel at 5AM and obtain excellent cell signal everywhere, you may well encounter the circle of death when the building is fully occupied and active as you attempt to download critical content. The reason? Hundreds of other building occupants are attempting the very same thing, at the same time, and the macro network wasn’t built to handle all of you occupying the same dot on a map. Thus, excellent cell coverage, that is, signal strength, often does not always translate into excellent cell performance, due to the lack of capacity.

Along with this second factor of capacity is the related third factor of the increasing user demand for more bandwidth—broader and deeper Internet experiences by each and every one of us. We are like a pack of ravenous wolves when it comes to expecting HD, 3D, VR and more and more high information content on our cell devices. How will that increasing demand be delivered to users? Nearly everyone assumes that the carriers will just take care of it. But Verizon, and the other carriers, too, have gone on record as stating it will be impossible for their macro network to accommodate the increasing bandwidth demand. As a hypothetical, Verizon asked how many additional cell towers it would take, if that were the only means utilized, to cover usage demands in the US in seven years. The answer? Three million. There are only 300,000 cell towers today. Does anyone in his right mind believe the citizens of the United States will accept increasing the number of cell towers tenfold? Verizon has a plan to meet the demand, which includes a few more towers, a lot of technology advancements, and for the vast majority of that increased demand, “in-building wireless systems” (IBTUF 10 Conference general session, January, 2016). Yes, Verizon expects that you, the building owner, will install a system to “densify” its network. So do AT&T, T-Mobile and Sprint. They won’t thank you; in fact, they’ve historically made it difficult and expensive for you to do so. But they expect it nonetheless. And they won’t pay for it in most cases.

 CARRIER-FUNDED DAS FOR ME?

Carriers do still pay for DAS. If you’re building a stadium, arena, high-end and sizable mall, massive hotel and conference center (as in something over a million square feet), Wynn-like casino, or a major medical complex, the chances are fair that you can attract a benevolent carrier or neutral host company (who are largely funding their buildouts with carrier funding). Since most buildings in the enterprise space do not fall into those categories, the reality is that carriers do not have the capital budget, and even if they do they do not intend to pay for your 300,000’ building DAS.

We’ve seen the ROI models the carriers use in determining to pay for DAS; there must be enough foot traffic to justify their investment. And they measure foot traffic in the thousands, not hundreds, when they generate their payback models. Even then, they will often still fight to make it a single carrier DAS, if not forever then at least for an extended period in order to recoup their investment.

There are exceptions. We’ve seen a few cases in recent years where a carrier has agreed to cover DAS costs for a smaller facility—a recent corporate headquarters, for example, that was only 550,000’. But, that carrier is angling for a 4000-line mobility contract and wants access to that corporation’s many other facilities and mobility contracts. It’s a carrot on a stick, though; they won’t foot the DAS bill for the remaining buildings.

 DAS OR BOOSTER?

If I as a building owner am persuaded that sooner or later I’m going to have to foot the bill for enhancing the cell coverage in my building, why would not just put in a booster and some antennas instead of a full blown DAS? My low voltage contractor told me that I don’t need DAS.

In case it isn’t clear, we do endorse boosters—In the right application. We also endorse several different DAS product sets—in the right application. There is no A-Z solution for any type of product, no one type of boat or clothing or food that satisfies every situation. The same goes for cellular enhancement.

Boosters are best suited in smaller environments. We generally recommend to clients to use boosters in facilities under 50,000’. The FCC has approved the use of these boosters, and as long as your contractor properly registers these booster installations on your behalf with all four carriers, you should experience a much better cell environment with relatively little cost and no risk.

The disadvantages with boosters are why they’re so low in cost. Unlike a DAS, a booster is akin to a massive firehose of cell signal that is sprayed throughout a building. There is no intelligent distribution, no constant measuring of cell activity and adjustment of signal strength and quality between multiple active remote nodes. A DAS is more like a very smart sprinkler system, with valves and meters, that delivers the precise amount of water to the exact area needing it.

To overcome the passive nature of the signal distribution with boosters, contractors will often attempt to install multiple boosters in larger buildings. This situation could not be worse, because these multiple, unintelligent boosters create oscillation—standing RF waves that cause massive noise to flow back into the macro network. To a cell carrier Radio Access Network (RAN) engineer, it sounds like a microphone stuck in front of a speaker. The carriers will find that system, and they will shut it down. Because they paid billions for the spectrum, they have the right to do so and can have the FCC levy the building owner (not the contractor) with fines in the tens of thousands of dollars per day range.

If a booster system has been registered with the carriers, they will cordially instruct the building owner to shut it down if they detect any backflow of noise into the macro network—without generally threatening fines. If they find a rogue, unregistered noisy booster(s), all bets are off, however. Depending upon the trouble your rogue system has caused, they might decide to make an example of you.

Finally, boosters do not accommodate RF source inputs from carriers across broadband landlines. They cannot, in other words, increase capacity, only coverage. They can only take what signal is in the air (over the air or OTA) and amplify it. They increase coverage (along with some noise) but they don’t do anything to increase the density of the cellular capacity. The lack of additional capacity may be OK, for a while. We’ve had customers with small areas of poor coverage and no budget, and we’ve not denounced their decision to install a booster as a temporary coverage-only solution. We have advised them, however, that sooner or later they will want to upgrade to an intelligent, capacity increasing system, i.e., a DAS, for all the reasons mentioned above.

In contradistinction to boosters, therefore, a DAS is an intelligent, actively monitored, often self-optimizing system that, done right, will actually reduce RF noise in the facility while significantly increasing cell coverage and capacity. It has a headend and multiple remote nodes distributed throughout the building. It will make your building occupants very happy. But it costs more—and you get what you pay for.

 DAS OPTIONS AND COSTS

Five years ago, when we had (a very few) enterprise clients with a conviction they needed a DAS, we were seeing all-in DAS costs averaging $3-4/foot—sometimes more, depending upon what requirements the carriers imposed. It’s asking a whole lot of any building owner to swallow that kind of cost impact, even for a putative fourth utility. Thankfully, two significant changes have taken place in the interim to make the costs much more palatable.

First, all the traditional DAS OEMs and spate of new ones are bringing new, enterprise-centric products to market. These new products do not have the sophistication and layers of Bellcore engineering as the technologies that are needed in complex RF environments such as stadiums. But those additional features are completely unnecessary in enterprise environments, where there may be only hundreds of users in a very simple, stacked building RF environment. Corning Mobile Access and Commscope, the two major DAS industry OEMs, have released new products recently to address the need for a lower cost, enterprise grade solution. In fact, Commscope’s system is termed Ion-E—“E” for enterprise. Along with them are products from SOLiD, ADRF, JMA, and scores of others.

Even better cost savings can be had with some of the non-traditional, new DAS OEMs who are making their mark with increasing wins. Some examples include Zinwave, and especially Whoop Wireless, whose total, turnkey installations including RF sources from the carriers often come in at close to $1/foot. These new OEMS are employing non-traditional approaches to providing an intelligent DAS, for example Whoop’s two-stage gain, modular design and upgradable (through flash) 5G roadmap.

The second important advancement in reducing costs has been due to the carriers themselves. Whereas for prior DAS implementations carriers routinely required a full base terminal station (BTS) buildout, typically costing $100,000 or more per carrier per sector, they are now offering small cell devices that increase capacity at a cost of only a few thousand dollars. Plus, these small cells have vastly lower real estate, power and cooling needs. An entire DAS headend, with all the carrier small cells, can often fit inside one 19” rack.

NOW WHAT? 

So what’s an owner to do in light of this fluid environment where the only constant is the insatiable bandwidth demand of the consumer?

Our recommendation if fairly simple and falls into four categories:

  • New construction, more than 500 occupants at peak: Swallow your medicine and plan for a DAS. Thank your personal deity that costs have dropped dramatically. Make sure you engage a quality technology partner who knows you’ve read this article and are expecting all-in costs to be less than $2/foot and closer to $1/foot.
  • New construction, fewer than 500 occupants or less than 150,000’: Engage a quality technology partner to prepare a preliminary design (using an industry tool known as iBwave) to identify antenna and equipment locations, and pay the cabling contractor to install the cable during construction. The cost will be quite low—at most in the tens of thousands of dollars total. Wait until your building opens, then test for cell quality and strength. If it’s good, thank that same personal deity and wait to install the DAS (which has been cabled already so that you’ll have no construction mess in public areas) whenever demand demonstrates that you need it. Or, if signal is not so great, install that DAS that you’ve already had designed and for which you’ve gotten all the construction mess resolved.
  • Existing construction, more than 50,000’: If it ain’t broke, don’t fix it. But if you have problems, engage a quality technology partner who will address coverage, signal quality, and capacity issues instead of just offering an immediate coverage bandage. In other word, put in a DAS that works now and has a smooth technology roadmap to 5G. Don’t cheat yourself, or worse, incur potential fines, with a low cost booster.
  • Existing construction, less than 50,000’: Install a high-quality booster to address coverage needs, and wait and see what DAS or small cell technologies might emerge in the future to address capacity needs you’ll have later.

We haven’t addressed ERRCS much at all in this article.  That’s for next time. But do note that some manufacturers offer integrated systems that combine DAS and ERRCS. There’s some potential viability there, and very high-end, sophisticated systems such as the one at Atlanta’s Hartsfield Airport deploy just such a system. However, we have found these integrated systems, so far, to cost more than the new technology platforms that separate the two. Plus, there are very real life safety concerns that argue for separation. Even at Hartsfield, although the system is integrated, the DAS and ERRCS antennas are separated by a minimum of 15’. That separation is critical to eliminate the “skirting” effect of contiguous frequencies. That last thing anyone would want to have happen would be for a firefighter, in a critical life safety situation, to have bleed from a cellphone conversation on his radio. More on this and other aspects of ERRCS to come . . . .

[Featured on Network Technologies, Inc.’s website: http://www.nticonsultants.com/2017/05/23/in-building-wireless-systems-das-and-errcs-myth-fact-fiction-and-reality]

[For more info on Public Safety DAS, read Eric Fichtner’s article HERE ]