Public safety

In-building public safety communications
Police, fire and other first responders face danger when entering buildings because of the inability of their radios to transmit indoors. The National Fire Protection Association (NFPA) has issued guidelines and many cities and communities are creating new code guidelines as well as implementing these necessary safety systems.

What is it?
A public safety communications system is a wireless communications system used by first responder and emergency services personnel such as police, fire, emergency medical, homeland security, and disaster response agencies to prevent or respond to incidents or situations that pose a threat to people or property.

One of the earliest providers of public safety radio systems is Motorola, who still provides much of the radio technology in use today. Early Motorola Radio systems used for communicating with police and fire departments began to be deployed in the 1930’s

An In-building public safety communication system ensures that radio signals are able to penetrate into all areas of buildings, including areas that are especially difficult for RF to penetrate such as stairwells, elevators, basements, and thick-walled or shielded areas.

How does it work?
The following diagram provides a depiction of a very simple in-building system:

Source: In-Building Working Group Technology Committee of the National Public Safety Telecommunications Council (NPSTC)

Bands of frequencies, especially in the VHF and UHF parts of the spectrum, were allocated by the FCC for communication between fixed base stations and land mobile vehicle-mounted or portable transceivers. Police radio and other public safety services such as fire departments and ambulances have traditionally been found in the VHF and UHF parts of the spectrum. (45MHz, 150MHz, 220MHz, 400MHz, 500MHz). These analog radio systems were primarily designed for voice communications.

Today, new public safety frequencies and systems are using digital technology and include other bands such as the 700 MHz and 800 MHz.

Why is it needed?
In-building public safety communication systems are needed for the same reason that in-building cellular DAS are being installed. Radio signals have limited propagation through various materials. Factors include how deep inside a building the receiver may be, wall composition, whether a building has energy saving “low-e glass” or other energy saving cladding, the specific frequencies in use (low frequencies penetrate better).

When is it mandatory?
The need for in-building wireless communications has driven efforts to develop national model codes by the National Fire Protection Association (NFPA) and the International Code Council (ICC). Codes issued by these groups include the National Fire Code, National Electrical Code, International Fire Code, and International Building Code. Almost every city and county in the United States subscribes and complies with one or more of these codes. The NFPA and ICC continue to develop national level model codes focused on in-building public safety communication systems. National level model codes should also lead to standardization of the quality of equipment and to additional qualified in-building system engineers and installers.

The NFPA and ICC national level model in-building code development is being driven primarily by fire jurisdictions. However, the initiatives are expanded to involve all public safety, including law enforcement and emergency medical services. The NFPA and ICC initiatives are separate but complementary. While the precise provisions of the draft codes vary between the two code development groups, key specifications involve significant commonality across the two initiatives. In addition, all the features of existing local codes are permissible under the new draft national level code framework. Each jurisdiction can “customize” the national level model code to meet any unique local requirements.

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