One of the most daunting problems in city structural firefighting today is ensuring that teams can communicate adequately inside major buildings. In-building coverage solutions can be simple or complicated, but in any case they are vital to firefighting. Chiefs should carefully consider their operational requirements first and then examine the technical options available. In all cases, extensive testing is highly recommended because building construction materials and methods vary.

The operational procedures of your department will guide the specifics of in-building coverage implementation. For example, some departments place all fireground communications on a separate tactical channel, and the incident commander handles all communications to dispatch. Other departments want dispatch to monitor and respond directly to fireground communications. Some departments use a single-frequency system for communications, while others have multiple frequencies and use trunking to assign channels. Other departments prefer traditional analog radio technologies, while others are moving to new digital technologies such as Project 25 and OpenSky. These issues can affect the choice of in-building coverage solution.

When planning in-building communications, ask:

• Where does the incident commander typically stage in relation to the incident building (in front or two blocks away)?
• Where are safety officers typically located (inside the building, outside or both) and with whom do they communicate (the IC, the interior teams, the dispatcher)?
• How does the personnel accountability system operate?
• How is interoperability with other agencies accomplished?

A radio system design that includes coverage of buildings of a certain density ensures in-building coverage in small- to medium-sized towns and counties. Radio engineers classify buildings by how much radio signal loss, in decibels, the building creates when you try and talk into it from the outside. Traditionally, buildings are categorized rather arbitrarily by losses in 6dB increments. The best way to actually determine how much loss the buildings in your jurisdiction have is to contract a radio engineer to take the appropriate measurements.

The radio frequency band that a fire department radio system normally uses also has a bearing on in-building coverage. In general, the lower frequency bands (low band and VHF high band) don't cover inside buildings as well as the higher frequency bands (UHF and 700- and 800MHz) because these waves bounce around inside the building. The new 4.9GHz public safety band offers new opportunities because of the benefits of a higher frequency and challenges because of lower power restrictions.

It will be necessary for both small towns and major cities to use some different techniques to obtain reliable in-building coverage.

Permanent systems

There are principally four in-building methods: permanent and temporary systems using either passive or active components. In smaller buildings with fire system base stations nearby, it's sometimes possible to create a passive system by putting an antenna inside the building and one outside the building, connecting them to each other with coax cables without using any amplifiers. A portable radio at one end of the building will talk to the inside antenna, and then its signal will be relayed along the cable to the outside antenna to the system base station nearby, and vice versa. It's relatively easy for your radio service shop to put in a temporary passive system and verify if it will work.

This system has limited applicability, but it may be a solution in less-dense areas. They are low cost, require little maintenance, operate even in power failures, and are relatively easy to engineer and install. However, they are limited to smaller buildings close to the main system. In some cases this solution will not work at all.

Large buildings will require an active system with amplifiers to boost the signal from the outside antenna and distribute the signal throughout the building via cables to inside antennae, which spray the signal inside. Sometimes a special cable (called “radiating coax” or “leaky coax,” analogous to a garden soaker hose) is used to leak the radio signal along its length, thereby acting like an antenna. This has the advantage of allowing a long tunnel to be covered.

In buildings where multiple service coverages are desired (cellular telephone, public safety, maintenance), experts recommend that public safety have its own separate system, even though this costs more and the services can technically be combined. Unauthorized personnel may make changes or adjustments to the in-building system, which may affect public safety use. Coverage can be engineered to ensure all parts of the structure are covered, and filters in the system can help reduce undesired radio interference.

Active systems can be costly. One industry rule of thumb for budgeting the cost of an active system is: basic one-agency systems cost $0.25 to $0.35 per square foot of building that is covered; more complex multi-service systems can cost upwards of $1 per square foot. Covering a major Midwestern city subway system could cost more than $10 million, and covering a major airport could be $4 to $7 million. Because they involve amplifiers, such systems need periodic maintenance, and these costs must be factored in.

For public safety, battery backup must be included. The 2003 blackout on the East Coast and the 2004 Florida hurricane season remind us that power may not be there when we need it. Some areas require 12 hours of operation during a power failure, others from two to four hours, but the events mentioned lasted for many days. An active system also may require passing of local ordinances. Systems can take months or years to install depending on the building complexity. Ongoing maintenance and inspection are needed. If not properly designed and maintained, the amplifiers can create interference either to the fire department channels or to other radio systems.

Active advancements

One new advance in active systems is radio over fiber-optic cable. This provides an increase in the delivered signal level in very remote parts of the building because the radio signal is distributed over an optical-fiber cable rather than a coax cable, which has greater signal loss. The result is a more even distribution of the radio signal and amplifiers that can be lower in output power, which can reduce interference issues.

Let's examine two other issues that chiefs should consider with active systems. First, who pays? Some areas are beginning to implement ordinances requiring in-building coverage systems to be installed in new construction over a certain size or hazard category. Chiefs will have to justify to political and civic officials why this is required, similar to the argument that sprinkler systems and building fire alarms have saved lives since being mandated. Chiefs should research other cities that have implemented ordinances and use these as standard practice examples. Putting such requirements in effect for existing buildings is more difficult, but it has been done because older buildings may pose the greatest risk to firefighters.

In some areas, owners of very large buildings with prestigious tenants have installed in-building coverage systems, which then created a source of recurring revenue from leasing radio capacity to various cellular phone carriers. The fire department can use such a system if it was designed to accommodate two-way radio frequencies, but this is not always a good idea.

The second issue is that ongoing maintenance needs transition. All systems must be tested, inspected and maintained. Active systems are subject to being vandalized or being misadjusted by unauthorized persons. Some vendors now have systems that can be remotely monitored 24/7 for system problems. If the system is not monitored, then inspection and operational verification — at least annually during fire inspections — is recommended.

A variant to permanent or active system solutions that is sometimes overlooked is to simply locate a new fire department base station site onto a building close to the building that requires inside coverage. By using base station antennae, which focus some of the radio signal into the target building, it's sometimes possible to cover most of the target building. If there are only one or two problem buildings that are close to one another, the cost of this may be less than an active system, and it has the advantage of providing additional in-street coverage. When combined with a passive system in the problem buildings, this variant sometimes works well.

Temporary systems

For major urban areas, it may be prohibitively costly to install active systems in high-rise buildings. New York City, for example, has thousands. The cost of such systems could be in the billions and the value would be largely invisible to tax payers and politicians. Mandating building owners to install such systems is politically difficult. Using in-building active systems for cellular phone service creates a fire department dependence on a commercial system.

Technology has provided fire departments with other solutions that don't have these limitations and are completely under the control of the fire department. These are temporary systems that the fire department brings to the building. The system is under the control of the fire department; it can be tested, maintained and trained on like any other fire department equipment. It can be immediately implemented and has no financial impact on building owners.

Temporary systems can be further subdivided into those used inside the structure and those used outside the structure.

Inside the structure, these temporary systems consist of a base or repeater station that can be carried into the building and set up to provide in-building coverage. Usually housed in a suitcase or backpack, they include a small antenna and can be powered by a 12-volt battery. If placed near the fire floor and operated in a repeater mode, they can allow portable radios within a few floors of the device to communicate with one another, even in dense buildings. However, the signals repeated by this suitcase or backpack repeater may not penetrate to the outside of the building sufficiently for the incident commander outside the building to hear the interior teams.

At least one vendor has come up with a solution that allows the suitcase repeater to use two antennae simultaneously via a power splitter. One antenna would be located in a hallway to provide inside coverage, and the other would have a length of cable to allow it to be placed inside a nearby room close to the window, which would allow the signal to get outside of the building. Another method involves the use of a “leaky cable” with an antenna at the end. With the cable placed at a window, this method can simultaneously provide both inside and outside coverage. This same methodology could be used in subway stations, tunnels or underground parking garages.

The temporary system will provide coverage at least one floor above and below the floor in which it is deployed. Additionally, it may provide coverage to the IC outside if an additional antenna is deployed as described above. Interestingly, recent testing by consultants in a large city showed that by placing a suitcase repeater device and its antenna in the hallway near the elevator system, the signal traveled for many floors above and below the suitcase location. It is thought that the elevator shaft acted as a sort of roadway (waveguide) for the signals to move vertically within the building. To rely on this method of operation would require a department to conduct careful testing because it may not work in all buildings, and the placement of the suitcase may be critical.

One negative to the temporary system is that it is yet another item for interior teams to carry and deploy. Suitcase units can weigh 30 to 50 pounds plus battery. At very long incidents, the battery may deplete. The device must be placed relatively close to the incident floor, because coverage is only within a few floors. If the fire progresses or there are multiple fire floors, the device must be moved or additional devices deployed. If used as a repeater, the device will usually require its own set of channels, and the portable radios must be configured to provide those additional channels and firefighters must be trained to switch their portable radios to the suitcase repeater channel. The incident commander must be able to access this suitcase repeater channel from the outside, or else the interior teams will be able to talk among themselves but will be isolated from command and may not be able to receive an evacuate order.

External systems

Outside the structure, temporary systems (sometimes called vehicular repeaters) that are located near the incident building can provide a signal that will penetrate many of the floors. Usually these systems are located on selected pieces of fire apparatus, such as command cars or first-in engines. This is essentially the equivalent of locating a fire department radio site close to the building on a temporary basis. For medium-sized cities as well as major urban areas, using a vehicle repeater can be a good answer. In Milwaukee, it was possible to get fire and EMS coverage inside a city jail complex that was impossible to cover before. Vehicle repeater systems consist of special mobile radios with an antenna on the vehicle's roof. New advances in technology can overcome most of the frequency planning problems inherent in older systems, and some even use GPS information, which allows multiple repeaters to operate in the same area without conflicting with each other.

Some systems can provide two capabilities:

1. Extending the range of the existing fire department radio system and

2. Providing an incident area network system in remote areas away from the fire radio system. It also works if the fire radio system should suffer catastrophic failure.

Because the system is deployed outside, the IC and safety officers will be able to talk to the interior teams and order them to evacuate if necessary. There is no battery-life issue because it runs from the vehicle battery. However, these devices will usually require their own set of channels, and the portable radios must be configured to provide these additional channels. Firefighters must be trained to switch their portable radios to the vehicular repeater channel (some newer systems completely automate this function). Additionally, the device may not completely cover a large high-rise building, a subterranean structure or underground subway platform. Multiple devices in close proximity can also create interference or operational problems.

Because not every solution is ideal for every situation, cities may find that deploying a combination of solutions is needed. Initially, the use of temporary systems is a fast and lower-cost method to cover a city with many problem buildings. Some skyscrapers may require several solutions. For example, an active system in the subterranean floors, a temporary outside system for the lower floors, and use of adjacent main system radio sites with focused antennae at the building for the upper floors.

Ordinances

This is a complex subject beyond the scope of this introductory article, but the two sources listed below have extensive information. Many cities have successfully used ordinances to implement in-building systems. Burbank, Calif., began the trend in 1991.

Ordinances have to be carefully constructed to ensure that there is periodic testing (usually every year), provisions for future technologies or frequency bands, and consequences for non-compliance.

Fire departments are licensed by the Federal Communications Commission to use their assigned frequencies. As a result, the FCC holds the department responsible for ensuring that the fire frequencies are properly used and do not create interference to other radio services. Therefore, even if building owners are mandated to install active systems, the fire department is still responsible for ensuring that such systems meet FCC requirements, system equipment has been approved by the FCC, and that such systems will be repaired if found to cause interference. Of course, if temporary systems are employed, this is not a problem.

There are several solutions to in-building coverage using both permanent and temporary methods. There are pros and cons to all of the solutions, and in some cases departments will have to use a combination of methods. New technologies promise to automate or improve these solutions. Chiefs should carefully consider life-cycle cost, the political environment, and maintenance and support issues, but most importantly operational issues, when selecting an in-building solution. Expert advice from vendors and consultants will be important to make the right choice.

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John Facella is the director for public safety markets at M/A-Com Wireless. He has 25 years of experience in radio communications, the majority of it in public safety. Facella has a bachelor's degree from Georgia Tech and is a registered professional engineer. He also is a 20-year firefighter and EMT, nationally certified as a Firefighter I/II.

Concepts to Operations, Jack Daniel Co., John Sweeney Associates, Spectra Associates and David Goldberg contributed.

For More Info

Download a PDF of “Public Safety In-Building Ordinances and Their Benefit to Interoperability,” at www.safecomprogram.gov/SAFECOM/library/technology/1032_PublicSafety.htm

Information on solutions and ordinances is available at www.rfsolutions.com.