NIOSH Firefighter Radio Communications 

TriData Corporation vi September 2003 

EXECUTIVE SUMMARY 

The National Institute for Occupational Safety and Health (NIOSH) commissioned this 

study to identify and address specific deficiencies in firefighter radio communications 

and to identify technologies that may address these deficiencies. Specifically to be 

addressed were current and emerging technologies that improve, or hold promise to 

improve, firefighter radio communications and provide firefighter location in structures. 

Introduction 

One of the most significant problems facing firefighters within a structure on the 

fireground is the ability to communicate reliably between the firefighters themselves and 

between the firefighters and the command post or communications center. In an ideal 

world, firefighters would be able to communicate with one another and the command 

post at all times, regardless of where they are or what they are doing. However, this is not 

the case. Firefighter radio communications to, from and within structures can be 

unreliable, thereby compromising the safety of firefighters on the fireground. 

Over the past decade, incidents involving firefighter injuries and fatalities have 

demonstrated that, despite technological advances in two-way radio communications, 

important information is not always adequately communicated on the fireground or 

emergency incident scene. Also, the events of September 11, 2001, and other emergency 

situations in recent years have highlighted the need not only to improve firefighter radio 

communications, but also the communication systems available to law enforcement 

personnel, emergency management officials, and other public-safety responders. 

The continued incidence of firefighter fatalities where communications are cited as a 

contributing factor as well as the industry-wide lack of consensus on the appropriate 

frequencies to use in fireground communications have prompted NIOSH to more 

thoroughly investigate fire communications and the problems associated with 

communications within, as well as into and from, structures. 

Methodology 

To begin the project, the team members compiled a comprehensive set of 

communications issues that affect radio communications in the fire service from several 

sources – an initial literature survey, knowledge of the project team members, and 

discussions with fire service leaders, NIOSH project team, engineers, and others. Team 

members refined this comprehensive set of issues with NIOSH project personnel to 

identify critical issues that could be addressed by improvements in radio 

communications. A prioritized list of communication and personnel location problem 

areas was developed. In general, the primary focus was clarified to be the identification, 

status, and research recommendations for technologies that could improve in-building 

communications or provide firefighter location within structures. Furthermore, the effort 

was to focus on the radio communications and radio location problems found in large 

structures such as high-rises to include radio transmissions into and out of the structure to 

the command post. Buildings such as these present the most difficult communication 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation vii September 2003 

problems because of their floors both high above the ground as well as basement levels. 

The list of the high priority topics is shown in Table 1. 

TABLE 1: PRIORITY TECHNICAL AREAS AND RELATED TOPICS ADDRESSED IN STUDY

Area Example Issues 

Accountability 

• Integrating Personal Accountability Systems (PAS) with 

communications 

• Electronic accountability 

• Automatic vehicle location 

• Electronic command boards 

Communication Planning and 

Coordination 

• Through building (into/out of) 

• Underground 

• In building 

Monitoring Firefighter Welfare 

and Location On-Scene 

• Role/responsibility of dispatchers 

• Use of field communications units and communications 

coordinators 

• Remote monitoring 

• Vital signs 

• Location 

Reliability 

• Line-of-sight limitations 

• Underground (subways, parking garages) 

• Confined space rescue 

• Communication into and out of buildings (especially high rises)

• Intermittence 

• Communication coverage/dead spots 

Interference 

• Building construction and materials (such as concrete, metal, 

and Lexan) 

• Radio propagation through fire, heat, and smoke 

• Cell phone towers (e.g., Nextel) 

• Terrain 

Unsuitable Equipment • Frequency band unsuitable for structure/ground penetration 

The first phase of the project was an extensive literature search for research and product 

information. The literature search covered a wide variety of government, engineering, 

and scientific databases. The Internet was also used to identify current products as well as 

the abundance of unpublished research posted by various companies and universities. 

The next phase of the project included two areas: identifying communication problems 

experienced by fire departments and investigating the current state of technology research 

and development. This research was used in the third phase of the project to identify gaps 

between the problems and issues of firefighter communications and the technologies to 

address these issues. 

In final phase of the project, recommendations were made for areas of research, which if 

completed, could lead to improved firefighter communications in structures. The 

technologies identified in this phase included current applications, potential applications, 

and how these potential applications could be relevant to firefighter communications. 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation viii September 2003 

This phase is addressed in Chapter V, “Current Technology Status, Knowledge Gaps, and 

Research Needs”. Past and current research is described as well as important issues 

remaining to be overcome if the technology area is to be feasible for firefighters. 

Communication Issues 

Communication problems commonly encountered by firefighters (and others) can be 

broadly divided into two categories. First are mechanical or technical issues related to 

unsuitable equipment, system design, inadequate system capacity (too much radio 

traffic), and building construction, among others. The second category of problems 

relates to human factors. 

Fire departments consistently have problems maintaining effective communications while 

operating in large structures, such as high-rise office buildings and apartments, and 

warehouses. Similar issues exist in structures with a large number of windows (or areas 

of glass) with reflective coatings. Communications from areas below grade (e.g., 

basements, parking garages, subway systems, tunnels) tend to be uneven. For the typical 

home, communications are generally not a problem. The technical issues associated with 

the physical structures themselves (building materials, height, etc.) are discussed further 

in the body of the report. Communications problems encountered by fire departments are 

discussed further in the body of the report. Solutions currently used by fire departments 

range from increasing the number of repeaters to migrating to trunked communications 

systems. 

Human factors, such as radio discipline, training, and tactical decisionmaking, also affect 

firefighter radio communications. These factors, while not technical issues themselves, 

adversely affect communications, especially when combined with technical and 

equipment issues. These issues, while not under the scope of this report, are discussed as 

background in the body of the report. 

Technology Summary 

The literature search identified a number of technologies that could contribute to solving 

firefighter communications problems. Some of these technologies can be used as 

standalone technologies while others are technologies that enhance performance of 

wireless links. Mobile area networks (MANet), ultra wideband (UWB), bi-directional 

amplifiers (BDAs), power line communications (PLC), medium frequency (MF), very 

low frequency (VLF), and radio frequency over heating and ventilation materials (RF 

over HVAC) all can be used standalone to build a communications system. Smart 

antennas, spread spectrum modulations, channel coding and interleaving, and automated 

electronic status systems are enhancing technologies. 

The ideal technology would provide robust in-building firefighter communications 

without equipment setup or equipment beyond personal communication devices (e.g., a 

handheld radio, personal tag, or the like). For providing a practical communications 

system, this technology does not yet exist. Current firefighter communications suffer 

from inconsistent in-building performance and may require additional equipment such as 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation ix September 2003 

repeaters. Untapped technologies provide other opportunities, but have limitations as 

well. VLF signals have been used to penetrate hundreds of feet through the earth in 

mining applications but the band is so narrow it can carry only one analog voice channel. 

MF through-the-air-signaling was tested in England as a means of communicating with 

firefighters in high-rises. This application used antennas that were looped around the 

entire building, making the antenna size a serious drawback. Furthermore, neither VLF 

nor MF has spectrum allocated for this use. A MANet does not require any infrastructure, 

but it does require that a firefighter always be with in range of a sufficient number of 

other firefighters who act as a network of repeaters. In practice, this may be impossible as 

firefighters may be out-of-range of each other in high-rise stairwells or building 

basements. Other technologies have similar issues. 

The next best choice to provide robust in-building fire communications would be one that 

couples personal communication devices with standard infrastructure found throughout a 

building (e.g., ac power lines and telephone lines) and little or no portable infrastructure 

(e.g., repeaters). Such a system would require some setup to interface the personal 

communication devices with the infrastructure. Using a PLC system would require the 

firefighters to plug a wire access point (WAP) into the building ac outlets to connect to 

the building’s ac power lines. It may also require a portable range extender to placed as 

needed. A MANet may require additional fixed wireless nodes (similar to a repeater) to 

enhance its range. 

Another choice would be one that couples the personal communication devices with 

specially engineered, permanently installed building infrastructure. BDAs and RF over 

HVAC are examples. If these systems are in place and designed correctly to give the 

firefighters the coverage required at the frequencies required, they work well. 

Using these criteria, the top technologies potentially suitable for firefighter 

communications are shown below in Table 2. A summary of each of these technologies 

follows. A complete discussion of these and other technologies investigated is presented 

in Chapter V. 

TABLE 2: SUMMARY OF STANDALONE TECHNOLOGIES WITH POTENTIAL TO IMPROVE INBUILDING RADIO COMMUNICATIONS

Existing Structure 

Technology Built-in 

Infrastructure 

Required 

Modifications 

Required 

Portable Add-on 

Equipment for 

System 

Enhancement 

Limitations 

Potentially 

Applicable 

Enhancing 

Technologies 

MANet — — 

• Fixed wireless 

nodes 

• PLC wireless 

access point 

(hybrid system) 

• Network size 

(number of radios) 

• Wireless range 

• Smart Antenna 

• Spread Spectrum 

• Channel Coding 

• Elec. Status 

UWB — — 

• To be determined 

based on outcome 

of FCC final 

rulings 

• Current FCC 

restrictions 

• Smart Antenna 

• Spread Spectrum 

• Channel Coding 

• Elec. Status 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation x September 2003 

Existing Structure 

Technology Built-in 

Infrastructure 

Required 

Modifications 

Required 

Portable Add-on 

Equipment for 

System 

Enhancement 

Limitations 

Potentially 

Applicable 

Enhancing 

Technologies 

PLC • Uses existing 

ac power lines — • Range extender • Range 

• Smart Antenna 

• Spread Spectrum 

• Channel Coding 

• Elec. Status 

MF 

• Uses existing 

telephone 

• Uses existing 

ac power lines 

— • Undetermined 

• Limited research on 

in-building 

propagation 

• Spread Spectrum 

• Channel Coding 

• Elec. Status 

BDA • Cable, 

antennas 

• Installation of 

cable, 

antennas if 

not built-in 

— 

• Pre-installation 

required 

• Frequency must 

match that of fire 

department 

• Smart Antenna 

• Elec. Status 

VLF — — — 

• Narrow frequency 

band limits 

usefulness 

• Channel Coding 

• Elec. Status 

RF on 

HVAC • HVAC ducts 

• Modification 

to existing 

HVAC 

— 

• Pre-installation or 

modifications 

required 

• Duct size must 

accommodate/pass 

frequency used by 

fire department 

• Elec. Status 

STANDALONE TECHNOLOGIES

MANet 

Mobile area networks could provide firefighters with voice and data communications as 

well as supporting radio location technology. MANets for commercial applications is a 

field of intensive research and product development. 

In a MANet, each firefighter carries a networked radio. As soon as two radios are within 

range of each other they form a network over which voice and data can be sent and 

received. As more radios move with in range they automatically join, too. If two radios 

are out of range of each other but on the same network, the networked radios between 

them relay the voice and data from one radio to another until the destination is reached. 

National Institute of Standards and Technology (NIST) has demonstrated this networked 

radio approach to communication and location on its first responder test bed. [189] A 

MANet can also include the use of wireless access points to a local area network (LAN) 

such as the HomePlug LAN (described below) to provide range extension into especially 

difficult coverage areas. 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation xi September 2003 

There are no regulatory issues with MANet but there are technical areas to be addressed. 

Currently, quality of service measures (e.g., the time delay from source to destination) 

and communications capacity degrade rapidly as the network adds radios. Extensive 

research is needed to improve routing protocols to address this and other issues. 

Ultra Wide Band (UWB) Communications 

UWB technology addresses in-building communications and locations needs. UWB can 

propagate better through materials and is degraded less by multipath than narrower band 

communications techniques. 

This is a field of intensive research because of its in-building propagation characteristics 

and the high data rates that can be achieved. For communications, the majority of the 

research is directed at using UWB as the wireless link technology in LANs such as 

MANets. 

The major barrier to this field is regulatory. The FCC has restricted both the band and 

transmitted power level resulting in severely reduced range and data transmission rates. 

The fire service should evaluate this technology, develop requirements, and encourage 

the FCC to implement rules so that fire services needs can be met. Despite this barrier, 

UWB holds much promise. 

Power Line Communications (PLC) 

A PLC communication system could provide improved firefighter communications 

wherever power lines run. There are two types of PLC, HomePlug and Access PLC. Both 

use standard ac power lines for propagating high frequency (HF) signals. HomePlug is 

the only power line LAN standard used within structures and products are widely 

available in stores. There are several proprietary Access PLC standards in the trial stage 

competing to deliver Internet service to end-users. 

Standard HomePlug devices provide the ability to quickly setup a fully functional LAN. 

One available device of particular interest is a wireless-access-point-to-HomePlug 

interface. In this type of application, the HomePlug network is used for range extension 

of a wireless network. Firefighters equipped with a MANet communication system could 

carry these devices into a building with them and plug them into ac receptacles as needed 

to provide coverage in areas where they are out of range of the MANet. Their radio 

communications would be carried by the ac lines to other identical wireless-to-HomePlug 

interfaces plugged into other areas of the building and where firefighter MANet radios 

would be able to receive and relay the communications. 

HomePlug devices do not have regulatory issues, as HomePlug is an accepted standard. 

There are technical issues, however. The ability of these devices to provide range 

extension for a wireless communications system such as a MANet needs further study. 

Studies to-date have been technology demonstrations for home use. These have found 

that a percentage of the ac receptacles do not support adequate network performance. 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation xii September 2003 

This effort needs to be expanded to cover additional structure types and their ac 

distribution schemes. 

Alternative Frequencies (MF and VLF) 

These frequencies are not currently used for firefighter communications but are used in 

underground mines for voice communications because of their unique propagation 

characteristics. 

The MF band has been used in underground mines because of its ability to couple with 

conductors in tunnels and propagate for several miles on the conductors. In this system a 

base station takes exterior communications (e.g., a phone system), converts it to an MF 

radio frequency signal and couples it onto a conductor such as the ac power lines. Miners 

use portable radios and wear portable antennas built into a vest or worn bandolier style to 

receive and send voice communications. 

Frequencies in the VLF band can propagate through hundreds of feet of earth. The entire 

VHF band is about the same bandwidth as a single trunk radio channel, which severely 

limits the capacity for voice and data communications. One practical use of VLF is as a 

one-way emergency evacuation pager to miners. The transmitter and antenna can be 

located on the surface and still reach miners equipped with portable emergency receivers. 

VLF based systems have been used to locate miners below ground as well but the 

inherent lack of location accuracy may not provide performance sufficient for firefighter 

applications. 

These technologies’ applicability to firefighter communications and location need to be 

tested as their use has been limited to underground mines where the propagation is 

heavily dependent on the tunnel characteristics. In addition, commercial developments in 

this area appear to be at a very low level as the bulk of the research and testing was 

performed over 10 years ago. There may be spectrum regulatory issues as these bands are 

currently allocated for other uses. 

TECHNOLOGIES USING BUILDING INFRASTRUCTURE

Bi-directional Amplifiers (BDA) 

BDAs provide improved in-building communications. This approach installs cable and 

interior antennas for distributing radio signal throughout a building to provide extended 

in-building coverage. They are difficult to retrofit into existing buildings, costly to retrofit 

or include in new construction, and require special RF engineering expertise when 

designing each installation, as each installation will be unique. BDAs also require 

periodic maintenance to ensure the system continues to function as designed. 

These systems have been installed in a large number of buildings and face no technical or 

regulatory issues. Use of them as a standard firefighting tool has been resisted because of 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation xiii September 2003 

implementation costs. Local jurisdictions are reluctant to require them by code, as they 

must compete with other areas for business. A nationwide or regional approach should be 

investigated requiring these systems in new construction. 

RF Distribution Using HVAC Ducts 

This approach could provide better in-building communications. It takes advantage of 

existing heating and ventilation ducts as RF waveguides for distributing radio signal 

throughout a building. It would potentially provide a low cost method for distributing 

radio communications analogous to BDAs. 

For this approach to work, the ventilation system must be modified to enable RF signals 

to bend around obstacles, such as fans and dampers, found in ducts. Also, room vents 

would need to be replaced with ones that would be RF-friendly. Very little research is 

being pursued in this area and has attracted little commercial interest as well. This 

technology should be monitored; if commercial interest develops it could provide a lower 

cost alternative to BDAs. 

ENHANCING TECHNOLOGIES

The following four technologies can also be used to enhance the function of existing 

digital communications system regardless of the system architecture. All are being 

intensively researched and all should be considered for inclusion in firefighter 

communication systems. Smart antenna technology can be applied to both analog and 

digital systems. 

Smart Antennas 

Smart antennas are under intensive research for many communications applications, 

including use in wireless LANs such as MANets and commercial cellular systems. They 

promise to significantly extend the range and data rate that wireless links support. This 

may help address the data rate shortcomings in MANets as radios are added to the 

network. Smart antennas products have been announced for inclusion in wireless access 

points. 

Channel Coding, Interleaving and Encryption 

These techniques are present in almost all digital communications systems. Systems 

using these techniques function well indoor as they are less susceptible to conditions, 

such as multipath and interference, that cause errors. Firefighter radio systems cannot be 

retrofitted with these techniques and new radio systems would need to be developed. 
NIOSH Firefighter Radio Communications Executive Summary 

TriData Corporation xiv September 2003 

Spread Spectrum Modulation 

Spread spectrum modulations provide improved communications because they can 

mitigate reception problems caused by multipath and interference from narrow band 

radios. Again, firefighter radio systems cannot be retrofitted with this and new systems 

would need to be developed. 

Electronic Status Systems 

The newly announced electronic status systems automatically track firefighter status to 

address the difficulty faced by Incident Commanders in tracking personnel on the 

fireground. Radio channels are assigned to incident command sectors and the system 

tracks them and displays status on a laptop. Future enhancements will include the ability 

to poll individual firefighter radios to determine if they are in a coverage area. If they are 

out of coverage for too long a warning will be displayed. If the ability to determine radio 

location were integrated, it could further enhance firefighter safety. 

Conclusion 

Current firefighter communications systems were chosen more for mobility or 

availability of spectrum than for suitability to the job of providing robust, reliable 

communications into, from, and within structures. It is not surprising that they can fail to 

provide adequate communications in buildings, which are the most challenging of radio 

communication environments. 

The technologies discussed in this report offer the possibility to significantly improve 

radio communications in large structures as well as in basement and other below grade 

areas. But it also appears that one technology alone will not be sufficient. Combining 

technologies together to make a hybrid system may be necessary. A MANet system 

provides the firefighter the mobility he needs; when coupled with a PLC or MF 

communications system, a MANet system may provide coverage even into difficult areas 

where radio waves cannot penetrate. Enhancing technologies can be integrated into this 

hybrid system to give even further improvements. 

Many of the technologies considered in this report are undergoing commercial 

development at a fast pace. This promises to keep the underlying cost of the technology 

reasonable, although the special requirements of the fire service may impose additional 

costs. Commercial development should be encouraged, as the benefits of these 

technologies will improve fireground communications.