Modern buildings are quietly creating their own wireless blind spots.

As police stations, hospitals, offices, schools, hotels, and retail spaces depend more heavily on mobile connectivity, many owners and facility managers are discovering that the strong signal outside often collapses once it moves indoors. When that happens, operations can stall, and in critical settings, safety can be put at risk.

That breakdown became especially evident at a multi-story police facility in San Bernardino County, California, where officers and staff struggled to maintain dependable connectivity throughout the building.

“That little valley where the PD is located has limited coverage,” explained Robert Trimble, sales director at WP Electric & Communications. “We had to put in special long-range antennas and really fine-tune the signal coming into the building.”

Working with Wilson Connectivity, WP Electric designed a hybrid in-building wireless system that turned the facility from a connectivity liability into a communications asset.

How Building Envelopes Block Signal

Many buildings now struggling with coverage weren’t designed with cellular in mind. Ironically, the same materials that enhance energy performance also weaken RF penetration. Radio frequency (RF)—the spectrum used for cellular, Wi-Fi, and public safety radio—is easily blocked or absorbed by today’s construction.

“Modern buildings are essentially RF fortresses,” noted John Bramfeld, senior director at Mobile Communications America (MCA). “They’re doing exactly what they’re designed to do, which is keep the outside out.”

Low-E glass and tight building envelopes improve efficiency but also block RF, creating dead spots. “Today’s low-E glass, though it is great for LEED-type buildings, is terrible for RF penetration,” said Trimble. “We’d rather point antennas through a brick wall than through that glass.”

Metal-dense construction can have a similar effect, acting like a partial Faraday cage that traps or weakens wireless signals inside.

Carrier Pullback and Aging Systems

For years, wireless operators funded and installed distributed antenna systems (DAS) inside buildings. “That pace was fantastic for a long time,” Bramfeld said. “But over the past five years, that amount of investment has proven very hard for carriers to absorb.”

As carrier spending has pulled back, the responsibility for in-building cellular coverage has moved to property teams. Many DAS networks deployed during earlier wireless generations were never upgraded, leaving offices, hospitals, and campuses with aging infrastructure they may not fully understand—or even know they have. Bramfeld estimates that 10,000 to 20,000 older DAS systems nationwide now need modernization.

Public safety coverage is often an even bigger gap. While owners tend to focus on cellular performance, public safety DAS—the systems that support fire, police, and emergency radio—are frequently overlooked until late in a project, despite being required in many jurisdictions.

Inside the San Bernardino Fix

To solve the coverage issues at the San Bernardino police facility, WP Electric and Wilson Connectivity combined two technologies: a bi-directional amplifier (BDA) to capture the weak outdoor signal, and a fiber-based, wideband DAS to deliver consistent coverage throughout the building. The upgrade meant officers and staff could finally depend on their devices to reach dispatch.

“Fiber has far less signal loss than coaxial cable,” explained Payam Maveddat, GM of Enterprise at Wilson Connectivity. Fiber also reduces interference, including passive intermodulation (PIM). “The fiber allows us to reduce PIM to near zero,” added Trimble.

Because the system is wideband, it can support multiple carriers and add new services over time. WP Electric also monitors the system, so the department doesn’t have to guess whether it’s working. Trimble said the technology is stable and easy to maintain.

For the department, the upgrade turns wireless from an unpredictable headache into a managed part of their mission-critical infrastructure.

Different buildings require different levels of capacity, and right-sizing matters. In high-density venues like stadiums, carriers need their full spectrum, noted Bramfeld. In commercial offices, the goal is simply ubiquitous coverage without paying for capacity you’ll never use.

Multi‑Carrier Support Matters

Even when an organization issues staff phones on a single carrier, buildings serve a wide range of users, including visitors, contractors, and vendors. Maveddat pointed out that it’s typically an even split among the three major carriers. “Being multi-carrier is really the best option,” he said.

In multi-tenant offices, coverage can directly impact user decisions. “In a Class A building, if there’s not cell coverage, it tends to have fewer leases,” Trimble pointed out.

From Static Systems to Monitored Resiliency

“The single biggest predictor of a DAS’s performance is whether it’s being monitored and operated,” Bramfeld explained. Active management means catching failing components early and keeping service interruptions completely invisible to the building.

Manufacturers are seeing growing demand for remote monitoring and automation, including sensors that detect when an outside cell site or frequency band goes down—before users notice any loss of service.

“As you move toward artificial intelligence, automation, and zero touch, the expectation is that these systems be remotely monitored and generate alerts when incidents are detected,” explained Maveddat.

For facility teams without RF engineers—and IT departments already stretched—remotely monitored and managed models can turn in-building cellular from a technical burden into a supported utility.

Not Just in Emergencies

Emergency communications remain the most immediate concern: officers reaching dispatch, hospital staff calling from a basement, or store employees dialing 911 during an incident. However, everyday operations and user experience are now just as important.

“Resiliency isn’t just about a single technology—it’s about options and fallbacks,” Bramfeld pointed out. “Cellular, public safety radio, Wi-Fi, emergency mass notification, security systems, monitoring platforms—all of these come together, and the resiliency is built from those layers.”

Maveddat recalled losing coverage inside a department store and having to walk outside to call his spouse to confirm a purchase. “Once I leave the building to make the call, I may not come back and they may lose business,” he said.

For building owners and facility leaders, resiliency now means more than “bars in the lobby.” It’s whether the building can reliably support all the people and systems that depend on wireless—on every floor, in stairwells and basements, and in the spaces where failure matters most.