HomeCase StudiesIn-Building Cellular Solutions for the Middleprise: Separating Fact from Fiction - Nextivity

In-Building Cellular Solutions for the Middleprise: Separating Fact from Fiction – Nextivity

indoor cellular coverage

In a world with more than five billion unique mobile subscribers, reliable indoor cellular coverage is no longer considered a nice-to-have. Whether your tenants, customers, or employees use their phones for business, pleasure, or both, chances are high that they’ve experienced dropped or poor-quality sessions when inside a building, or simply can’t get a signal despite the numerous cell towers in proximity. That’s because topography, such as mountains or trees, and interference caused by building materials like concrete walls and Low-E glass can block signals from getting inside.

Not all solutions to this problem are created equally. By separating fact from fiction, you can determine which indoor cellular coverage solution is best for your specific requirements and budget, especially if your building lands in the middleprise category (buildings up to 500,000 square feet).

Below is a recap of some of the most popular in-building coverage technologies.


5G is a hot topic. As the industry continues to make great strides toward making this high-performing platform a reality, the fact is that 4G LTE isn’t going away soon and will continue to provide the lion’s share of cellular voice and data coverage. Additionally, 5G is not one thing, as it is commonly marketed. Current-generation 5G mostly represents slight improvements over 4G, whereas the amazing features marketed with 5G – such as ultra-low latency and substantial throughput improvements – will become available in three to five years’ time with future iterations of 5G.

Not only is it a costly and time-consuming process for carriers to migrate spectrum to 5G bands, but much of the global marketing around 5G to date actually relates to 5G mmWAVE technology. mmWave 5G delivers extremely high data rates to support advanced IoT applications – think driverless cars, remote surgical equipment, and robotics – that are simply not in the purview of most building owners at this time.

That said, you can still get 5G ready. For most building owners, this simply means selecting infrastructure that can transition seamlessly to this next-generation technology.


Citizen Broadband Radio Service (CBRS) has been touted as the next big thing in in-building cellular coverage, particularly in the middleprise. Proponents suggest that CBRS is the Wi-Fi of the future for companies because it provides a seamless and broader coverage range. Rumor has it that you can also save a lot of money using CBRS. While this may be the case, it’s important to understand the trade-offs.

CBRS will have two primary use cases: Private LTE and Neutral Host Networks (NHN). Private LTE has some very compelling features for very large enterprise, because it puts wide area connectivity into the control of the IT administrators rather than the carriers. It features strong security and access controls, which is particularly useful for companies concerned with users’ data and application access to internal systems.

The NHN value proposition is extremely exciting. Unfortunately it is 100% hype at this point, because no solution provider has come forward with a commercial offering. The idea is that CBRS equipment could be purchased and installed by the venue owner (or partners), and subsequently mobile phones will simply roam on to these systems when users are inside those buildings. The technology to enable this sort of connectivity has been available for years, but no commercial solution has emerged because the network operators (carriers) control the handsets, customer (billing), and SIMs. The carriers are not incentivized to bear the cost of support for these NHN systems, which is why it’s unlikely that they’ll gain significant traction in the market.

“… the fact is that 4G LTE isn’t going away soon and will continue to provide the lion’s share of cellular voice and data coverage.”


According to Ericsson (2018), by 2023 there will be more than 3.5 billion cellular IoT devices on the market, making cellular technology a major communication enabler of IoT. And while it’s true that some legacy technologies can support IoT applications, they have battery life and latency issues that negatively impact mission-critical business operations, and impact cost.

Less costly alternatives are LTE-based devices, which have extended battery life and are easier to reach from the network infrastructure. LTE-based IoT systems, offered by companies such as Sierra Wireless, CalAmp, and Digi, can be incorporated into existing LTE networks, making them easier and more cost-effective to deploy.


Prevailing wisdom suggests that fiber is necessary to provide high-quality cellular signal inside a building. But in facilities less than 500,000 square feet, it can be an unnecessary expense.

Typically deployed in active Distributed Antenna Systems (DAS) to connect the cellular signal source to remote units – which in turn connect to antennas placed throughout the building to distribute the signal – fiber supports extensive bandwidth requirements over long distances. In larger buildings, hundreds of meters (or more) of fiber are the norm.

But the cost – which ranges from $3 to $5 per linear foot – makes it less than ideal for the middleprise budget. Instead, Ethernet cable (copper, CAT5e and above) costs between $0.30 to $0.35 per linear foot, is fast and easy to install, provides excellent quality of service, and can be used in the installation of an active DAS hybrid solution (more on that later).


For many carriers, small cells (including femtocells and picocells) are an important part of their network plan, helping to meet the increasing demand for mobile device connectivity. When cellular capacity is the concern, small cells have served as a go-to solution. But they are expensive, ranging from $3,000 to $5,000 each, and the installation wait time can be long.

While added capacity is the strength of the small cell, its ability to distribute the coverage is its weakness. The layout of the indoor space requiring coverage dictates the coverage footprint of a small cell, taking into consideration building material and other factors that may stand in the way of securing a strong signal. Small cells also often require the skills of an IT professional to configure specific and detailed IP settings, as well as to maintain them on an ongoing basis. And finally, interference can still wreak havoc and create dead or low-performance areas.

So despite the hype around small cells, the reality is that they can take a while to deploy, require specialized skills to set up and maintain, and their performance is not always guaranteed. However, these issues are resolved when a small cell is the signal source of an Active DAS Hybrid Supercell, as discussed later in this paper.


Although expensive, if you own a building that is larger than 500,000 square feet, you should consider an active DAS solution to get the quality of service required in large spaces.

But if your building (or a portion of it) is less than 500,000 square feet with several hundred to a few thousand occupants, you can save your money. That’s because a traditional DAS is considered to be overkill for the quality of service required to support phone calls, videos, social media, and most other mobile apps.

Even cellular-based IoT applications – such as a more reliable connection for point-of-sale or payment processors, video feed from security sensors, or vending machines with remote management – don’t require the bandwidth and distance that a traditional active DAS with fiber provides. In fact, hybrid solutions offer cellular coverage at a fraction of the cost, and can be installed in weeks rather than the months or longer that it takes to install an active DAS.


Passive DAS solutions can be a very cost-effective way to improve in-building cellular coverage, but it does have its limits – and can cost more than most people think.

A passive DAS based on a bi-directional amplifier (BDA) is less expensive than an active DAS because the equipment is less expensive, and there is less of it. However, it can be quite difficult to deliver great user experiences if external network conditions are not ideal, or if the building is large (30,000+ square feet), or user density is high.

The reason behind this is simple: Traditional passive DAS solutions rely heavily on the quality of signal received from existing carrier towers. In poor conditions, a BDA-based passive DAS simply can’t support a large number of users at the service levels they’ve come to expect. These systems have limited ability to manage gain per carrier, based on their analog technology, resulting in mixed user experiences.

Passive DAS solutions rely on cellular signal distribution over coax cable. This adds to installation costs and time compared to the Ethernet cable used in digital systems.


An active DAS hybrid is flexible enough to support numerous configurations that can deliver service quality at a cost-effective price point for the middleprise market. It can also be installed in a matter of weeks.

There is actually no fiction to be dispelled in the statement above. The unique strength of a hybrid, such as Cel-Fi QUATRA, is the ability to support different coverage needs, signal source availability, and building layouts. For example, a single Cel-Fi QUATRA coverage unit (CU) can provide coverage for a large, open setting with high ceilings and low (or no) interior walls. It can also be mounted quickly, and uses Cat 5e cable for power and signal.

“So despite the hype around small cells, the reality is that they can take a while to deploy, require specialized skills to set up and maintain, and their performance is not always guaranteed.”

Likewise, in an area with obstacles or other signal blockers, an installer can use a single Cel-Fi QUATRA CU as a remote source to power a passive DAS instead of using multiple CUs. Using coax cable to distribute coverage between the CU’s external antenna ports and antennas, QUATRA can amplify each carrier independently up to 100 dB, versus the traditional passive DAS application of one gain value for all operators. In addition to the higher gain, each of the four internal amplifiers is independently gain-controlled, allowing each band to reach maximum downlink power regardless of the input signal strength.

If the environment has no available signal or struggles with capacity challenges, the Cel-Fi QUATRA Supercell configuration is a perfect solution. The Supercell combines the strength of the Small Cell as a donor source, with superior distribution capability of the Active DAS Hybrid. The Supercell becomes an ideal solution for larger venues where multiple small cells would be cost prohibitive and difficult to plan.

In short, each of the solutions above has their place in the market, but not all are built to meet the unique needs of the middleprise. That’s why a hybrid approach is the most likely to give you the flexibility and quality of service required at a reasonable price point.

For more information, download “The Ultimate Buyers Guide to Solving Cellular Coverage Issues” at


Joe Schmelzer is the Senior Director of Products at Nextivity. He has 20 years of experience driving the creation of products and solutions for chipset vendors, device OEMs, and service providers, including Sony, Qualcomm, Google, Verizon Wireless, AT&T, Dell, and HP. Mr. Schmelzer has previously held positions with Wavecom, Sierra Wireless, and Inseego (formerly Novatel Wireless). He was also a founding member of CTIA’s Wireless Internet Caucus. For more information, contact or visit www.cel-fi-com.

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