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The Evolution of Public Safety Communications and Distributed Antenna Systems

Emergency Responder Communications Have Evolved Immensely

Public safety agencies faced enormous difficulties on September 11, 2001. First responders, individuals in need of help, family and friends of victims, and everyone within the immediate area could not utilize the publicly available networks due to several factors, including incredibly congested networks and damage to the infrastructure. 

In the aftermath, public safety agencies around the country banded together to lobby congress to implement a First Responders network for the exclusive use of public service agencies. The result of this effort is the FirstNet Authority which oversees the National Public Safety Broadband Network (NPSBN). Funded in 2012 with $7 billion, Congress passed legislation to create the NPSBN, build out and deploy the infrastructure nationwide, and reserve 20 MHz of radio spectrum specifically for first responders.

First Responders having access to a dedicated network that allows them to communicate outside of the public networks is an incredible resource, but without a properly installed in-building Distributed Antenna System (DAS), signal strength may still be an obstacle to overcome during an emergency. 

For this reason, property developers of large commercial and residential buildings need to ensure that they have adequate cellular communications systems and are also installing and operating approved and certified public safety communications systems.

What Causes Public Safety Communications Failures?

Since the 1930s, the public safety industry has relied on Land Mobile Radio (LMR) for its communications. However, as technology and society have progressed, and new systems have been deployed across the nation, there have been issues with interoperability across jurisdictions and agencies.

Specifically, in areas where there are large buildings close to jurisdictional (city, county, or state) lines or even in densely populated urban areas, there are often a wide variety of frequencies and services available to first responders that add to the complexity and cost of interoperability.

In addition to the issues of interoperability, there are other reasons that public safety communications fail, including the population density of a specific area, the location of network towers, and advances in building materials.

Population Density

Cellular towers and population density are inextricably linked. The more people there are in a given area, the more towers are needed in order to provide service to each device. However, in some areas, it’s not feasible to put in more towers. And, in the cases of large one-off events where a large population is transient, such as an event venue, it may not make sense to increase cell tower coverage for an occasional situation.

Population Density Effects Public Safety Communications

In large-scale emergency situations, there can often be an influx of people and devices arriving at the scene. These devices are trying to get onto a network that is already being utilized and can create a log jam of network traffic that causes weak signals and/or dropped calls. This is – of course – especially dangerous during emergency situations as first responders are not able to communicate with each other or with individuals who require assistance.

Network Tower Location

The location of towers is also probably the reason for public safety communications – and any cellular communications – failures that most people are familiar with. The further a device is from the tower, the weaker the signal will be. If an emergency situation occurs in an area that already has low signal, the arrival of first responders and influx of devices on the network will only diminish the signal further.

Tower Locations Effect Public Safety Communications

Building Materials

As communications technology has advanced, so too have building technologies. While materials such as concrete and steel certainly make buildings stronger and sturdier, they also make their walls thicker and denser, therefore inhibiting the signals’ ability to penetrate them. 

Building Materials Effect Public Safety Communications

Additionally, in today’s eco-friendly age, more and more buildings are being built to meet LEED certification requirements. The materials used to meet the criteria create a particularly challenging situation since they are often coated with substances that make buildings more energy-efficient and tend to block or weaken signal strength.

Differences Between Commercial Cellular Services and Public Safety Systems

Having great cellular device service in a location is fantastic for the convenience of those who live, work, or shop there – but it isn’t the same as having a true public safety system. 

Public safety systems are more than just an amplified cellular network – they also meet strict compliance requirements from various organizations such as the International Fire Code (IFC), National Fire Protection Association (NFPA), and the National Electrical Manufacturers Association (NEMA). Every piece of the equipment needs to be up to standard, not just the radios themselves. 

Additionally, coverage needs to be more than just available

When designing a property, one of the first thoughts may be for inhabitant convenience. Developers may ensure that cellular connectivity is available in most of the common spaces, such as the lobby, hallways, and parking lots but for system to be a public safety system the coverage needs to be everywhere that someone might be during an emergency. This means taking into consideration other, less frequently used spaces such as closets, vaults and storerooms, elevators and stairwells, rooftops, and at all points of ingress and egress.

The Anatomy of a Public Safety Communication System

As mentioned, a public safety system is more than simply ensuring there’s strong radio or cellular coverage within a single building. It is, unfortunately, not uncommon for commercial systems providers to lead property developers down a winding path of off-the-shelf components that are cobbled together into a system that, at the end of the day, isn’t a true public safety communications system. This is because while the components are all there to do the job, they aren’t properly configured to ensure the correct amounts of coverage or backup required in the event of a true emergency.

Distributed Antenna Systems

In large buildings, it can often be difficult for a single network signal to cover the entire area and to extend through every wall and into each nook and cranny. Distributed Antenna Systems (DAS) are a network of antennas that amplify signal strength throughout a building. They can work on both radio networks and 4G/LTE networks and connect to various vital components, including Bi-Directional Amplifiers (BDA) and HEU Control Units.

Distributed Antenna Systems Boost Public Safety Communications


Each jurisdiction may have its own set of equipment preferences and pre-defined frequencies. When considering interoperability between jurisdictions and agencies, it’s important to take into consideration the limitations that certain systems may face. For example, many vendors do not support VHF frequencies, while FirstNet is a newer technology that isn’t available in every area yet.

Optimal Coverage for Two-Way Radios Require Distributed Antenna Systems

Pathway Survivability

Pathway Survivability defines how long different components of a system, such as conduits and risers, must be able to survive a fire. Each jurisdiction and housing authority may have different parameters and they may also provide approved alternative methods.

NFPA-72 Mandates Distributed Antenna Systems to Require Pathway Survivability

Battery Backup

For a system to truly be considered a public safety system, it must have battery backup. This is because when the fire department arrives on the scene of an incident, they’re likely to cut the power immediately to avoid further damage. A “public safety system” without a battery backup will quickly become inoperable during an actual emergency. Most current guidelines dictate that a public safety system must have a battery backup that can last at least 12 hours, while some even require 24 hours. 

NFPA-72 Mandates Distributed Antenna Systems to Require Battery Backup Units

If there’s a generator located on-site that is installed according to exacting specifications may afford a building a waiver if there is no battery backup available, however, a commercial system that does not include some form of approved power backup may be eliminated as a public safety system.


Public safety systems are meant to be instantly and reliably available at a moment’s notice… but they may not be used very often (or hopefully ever!). Due to their infrequent use, they may fall into disrepair – or even be inadvertently damaged – without proper monitoring. Many jurisdictions now require monitoring systems that will trigger alarms and alerts if a component of the system is defective and may result in a system failure.

NEMA Rating

Both sets of standards from the NFPA and IFC specifically require that all equipment supporting the public safety network must be housed in NEMA-4 compliant enclosures.

The NEMA 4X definition, as established by the National Electrical Manufacturers Association, is a rating for an outdoor electrical enclosure that has the following protective qualities: Includes a gasket designed to protect against liquid and solid ingress. Suitable for indoor or outdoor use. Resistant to corrosion.

NFPA-72 Mandates Distributed Antenna Systems Be NEMA-4 Compliant

A NEMA 4 rating is the same as a NEMA 3 rating, but it adds protection against hose directed water. The testing for NEMA 4 consists of spraying the enclosure with water at 65 gallons per minute from a 1-inch hose. This is a lot more water than in the NEMA 3 test, which is a water spray at 5 psi.


A decade after it was initially funded, FirstNet has made huge strides. There are nearly 20,000 public safety agencies with over 3 million connections across all 50 states, Washington D.C., and 5 U.S. territories. It boasts 95% nationwide coverage, with an additional 100,000 square feet added to the footprint in 2020 alone.  When FirstNet® is not in use by first responders, it is also available for public use, which is proving hugely beneficial to individuals and businesses in rural and typically underserved areas as the network continues its expansion.

FirstNet Boosts Coverage for Public Safety Communications


Typically, pricing for in-building ERRCS systems is made up of three factors: a service agreement, labor, and equipment (MCA has a six-step process). Labor and equipment are the two highest costs, with the equipment type determining labor costs. In some scenarios, the equipment used may be more expensive than other options but require less labor to install, while in others – such as an all-passive, traditional BDA-style system – the labor may be more intensive but the equipment itself is less expensive.  The service agreements are typically a small portion of the overall cost, and the availability of remote monitoring can impact long-term service costs.


It’s important that property owners and/or managers work with design and installation partners who are familiar with local codes and requirements, as well as the Authority Having Jurisdiction (AHJ). By having a deep understanding of the relevant code and AHJ interpretations and tests, they’ll be able to ensure that the system meets the needs of both LMR and FirstNet. 

About MCA

For over 30 years, MCA has provided expertly tailored communications solutions to property developers and builders in need of two-way radios, job-site connectivity, and wireless signal enhancement systems. Our team provides top-tier support for every aspect of your business and mission-critical communications projects from start to finish. Our engineers assess your needs, design custom solutions, and install systems that fit your organization’s exacting requirements.

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