The promise of FirstNet: Public safety communications of the future
Future public safety communications will use those ubiquitous cell phone towers, but will operate on channels that can't be clogged with traffic by regular cellular users in an emergency
By Tim Dees
It didn't get a lot of press when it happened but a bill signed into law last February has the potential to change the nature of public safety communications for the foreseeable future.
The new initiative is called FirstNet, and you'll be hearing a lot about it in the years to come.
The problem is one that has been more apparent in the fire service than in law enforcement. Public safety agencies have wildly dissimilar communications systems. Some work on VHF-Low, some on VHF-High, and some on UHF (VHF: Very High Frequency, 30 to 300 MHz, UHF: Ultra High Frequency, 300 to 3000 MHz), and a radio capable of sending and receiving on one of these bands typically won’t work on another.
As many firefighters know all too well, when a crew is sent out of their jurisdiction to provide mutual aid on large fires they often find upon arrival that they can't communicate with the command center and each other. Police have similar problems when the city cops are on UHF and the county sheriff and highway patrol are on VHF.
To aggravate the problem, there aren't enough channels to serve everyone's needs. Project 25, which halves the bandwidth of channels from 25 MHz to 12.5 MHz, has been rolling out for several years, and the FCC is mandating compliance by the end of 2012. Anyone who hasn't upgraded their old radios to work on the narrower channels can have their operating license cancelled unless they have obtained a waiver.
FirstNet takes advantage of the allocation of the D-Block — 20 MHz of bandwidth — of the 700 MHz for the exclusive use of public safety agencies. That might not sound like a lot, but the wireless technology that makes our cell phones and other gadgets work can cram a great deal of information into a narrow channel.
Before that band was awarded to public safety, the FCC was asking $1.3 billion from the cellular companies that wanted it. You can get an idea of how fragmented the spectrum is from this chart.
Traditional land mobile radio (LMR) has relied on both direct communications between users and relays via repeater towers that are usually linked to a command center by a landline. In most of the country, the ability to send and receive from your portable radio depends on whether the radio can "see" a repeater.
The radios have to be fairly powerful — typically three to 20 watts — to reach the repeaters and be reliable. This takes a lot of power, and is the reason most of the weight of your radio is the battery. A cell phone uses between 0.75 and 1.0 watts, because the cell phone towers are typically more plentiful and closer together.
Future public safety communications will take advantage of those ubiquitous cell phone towers, but will be sending and receiving on channels that can't be clogged up with traffic by regular cellular users in an emergency.
The hardware will be a lot cheaper than public safety radios are now, because they will be based on consumer phone technology. The only difference will be the frequency on which they operate.
This new system will pave the way for all sorts of broadband utilities including voice, data and streaming video that are already common with most smartphones. It will also be possible to establish a secure ad hoc network between any set of users in the country, no matter how far apart they might be.
The stumbling block
If there is a stumbling block here, it's probably the fragility of the existing cellular network. The network is dependent on cell towers that are powered by the same public utilities the rest of us use.
In a disaster situation, those towers that don't have an independent power source would go silent, and so would a lot of cellular phones and modems. Some sites are already hardened to survive a disaster, and the network providers have portable, independently powered towers to bring in to an afflicted area. This would still be a problem for the first hours of a widespread emergency.
The full governing board of FirstNet was appointed in August at the annual APCO conference, and it will be a while before public safety users start seeing gear and procedures for using the new bandwidth. In the meantime, keep an eye out for news about FirstNet, because it will probably change the way you talk to your co-workers.
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