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Extending FirstNet Coverage Indoors

The events that took place on 9/11 revealed a number of holes in America’s emergency communications infrastructure.

On the ground at the World Trade Center that day, first responders from all across the eastern seaboard converged to provide assistance. Cellular and radio communication among emergency personnel was seriously challenged, making it difficult to coordinate rescue and control operations. There were several underlying reasons.

States, counties, cities, municipalities, and even individual police and fire stations within each municipality, had selected their own communications hardware, service configurations, channels, and protocols as a matter of routine. Different jurisdictions had assigned different frequencies and channels to their departments, preventing centralized communications, and central command. Many of the first responders on the scene that day were not on official duty and did not have their public safety radios in their possession. While off duty first responders may have had their personal mobile phones with them, cellular phone service was quickly overwhelmed and incapacitated. According to the New York Times, there were approximately two hundred 911 operators on hand that morning. In the first 18 minutes more than 3,000 calls were received. Nearly 57,000 calls were received within 24 hours. Emergency management had to resort to ad hoc methods (like physical runners) to try to keep the various agencies coordinated.

From the ashes of this tragedy arose the public will to create a better communications network for first responders. That network is FirstNet, a nationwide broadband network that gives first responder communications priority and pre-emption on all bands over the existing AT&T network, with additional high-quality spectrum dedicated to nationwide public safety that has been set aside by the government (Band 14). All 50 states and six U.S. territories including the District of Columbia (DC) have opted to participate in FirstNet as their public safety communications network. As of July this year, Band 14 had been added to more than 2,500 AT&T sites across the country, with the process for 10,000+ more underway.

The FirstNet goal is to provide wireless coverage that will reach more than 99 percent of Americans, extending to 2.74 million square miles, covering 76.2 percent of the continental United States. To deliver on this promise, infrastructure needs to be built-out to accommodate locations where AT&T coverage is spotty, such as in remote rural areas, but also needs to serve heavily populated cities, where congestion can be problematic during an incident. In addition, FirstNet compatible devices need to be purchased by public safety agencies, and those agencies need to subscribe to the FirstNet service.

As of the end of August, 2,500 public safety agencies have subscribed to FirstNet. It has been used by first responders and emergency personnel across the country in critical situations such as the west coast wild fires, severe weather evacuations, to solve crimes, and to find missing children.

First responder priority service is provided to subscribers through intelligence in the network core. FirstNet customers get special SIMs (subscriber identity modules) that inform the core network about the priority of the user and attached device. When an incident occurs, emergency communications – whether on the Band 14 service or on one of AT&T’s commercial bands – are assigned priority.

However, when first responders or other public safety officials respond to an emergency inside a building, even on FirstNet, they may still experience dropped calls, spotty connections, poor voice quality, or black service holes that plague building occupants every day. Interior rooms, rooms surrounded by RF-shielding materials like rebar, thick concrete, energy efficient windows, metal roofs or walls all prevent a strong, clean cellular signal from penetrating a building. It is important to note that communications are two-way – not only does the outside signal need to come in, the inside signal from the first responders has to get out.

To resolve this problem, Nextivity has launched CEL-FI GO RED, a new smart signal booster that extends FirstNet service into spaces in buildings where cellular signals are weak or non-existent. Whether driven by building construction, a remote rural or congested city location, or other external obstacles such as weather or terrain that prevents a signal from penetrating a building, CEL-FI GO RED can make the difference in life and death situations when cellular communication over FirstNet is vital. A single CEL-FI GO RED system is designed to boost FirstNet service in spaces up to 15,000 square feet.

A typical installation consists of an external antenna, located for example on the rooftop, with coaxial cable leading to the CEL-FI GO RED smart signal booster. GO RED cleans the signal and amplifies it up to 100 dB, then sends the signal along a second coaxial cable to wherever an internal coverage antenna has been placed, like a basement, stairwell, or any interior space. Coverage is broadcast from the internal antenna throughout the space up to 15,000 square feet, providing excellent signal and service to any first responders at that location. For larger spaces, multiple GO RED systems can be layered together, without creating interference. Portable kits developed by partners for GO RED can also be deployed in minutes by first responders in cases when they find they are not able to access FirstNet inside a building.

For more information on CEL-FI GO RED, visit


A version of this article was originally published by RCR Wireless