P25: Not a One-Size-Fits-All Technology
By Andrew E. Schwartz
Tuesday, February 24, 2015 | Comments

The National Public-Safety Telecommunications Council’s (NPSTC) twice-issued Project 25 (P25) position paper is an affront to the intelligence of all public-safety communications systems managers tasked with maintaining reliable solutions for their agencies/customers. In my home state, first responders use all common public-safety bands. They also lack, similar to most places, the funding to purchase expensive P25 equipment. Most public-safety first responders in my neighborhood still operate on conventional, and affordable, analog FM radios. This holds true for many public-safety first responders around the country.

As it pertains to interoperability, if there were only P25 radios, how does having P25 allow two agencies to speak with one another when one agency is operating in the 150 MHz band and the other in the 800 MHz band? What if one or both are outside their home coverage area while responding in a mutual aid scenario? In that scenario, if they had only P25 radios, they may do better if they each had a CB radio on-scene. Just because two agencies have P25 radios (or analog), doesn’t mean they can interoperate — a term that can mean different things to different people. Interoperability goes well beyond a technical standard. One should refer to the Department of Homeland Security (DHS) Interoperability Continuum graphic often used in Safecom documentation. It is clear from that graphic that interoperability requires more than, and is not limited to, common radio technology.

If the goal is assured interoperable communications using radio between different agencies, the solution is to use a common system. The technology or air interface is irrelevant. This is becoming more the norm for many large first responder organizations that have countywide or statewide areas of responsibility. These common systems provide the capability for all system users to communicate directly with each other, if required. These systems could be analog or digital. They may be P25; they may not. Certainly it is not P25 that would be the only thing required to create interoperability. Interoperability can be achieved between frequency bands and between different technologies using tactical gateways or system-level or console patches. P25 doesn’t have to be a part of the interoperability solution to make interoperable communications happen or to make it successful. Any public-safety communications system manager knows that and doesn’t need to be schooled by NPSTC. With equipment used by my agency, I can easily connect an NXDN radio at 150 MHz to a 450 MHz P25 Phase 1 radio, to a 700 MHz P25 Phase 2 radio. They will all be able to interoperate.

Today’s plain truth for public-safety first responder radio interoperability — short of everybody in the area of operation being on a shared system, is that you need analog capability (not P25), and there better be a gateway — either on-site or in the background — that will allow analog radios on different frequency bands to communicate. P25 doesn’t even come into play as a requirement as long as the users’ radios have an analog mode. That’s reality.

If I were in charge of migrating a small to medium-sized first responder agency from analog to digital, I’d first look to join an established shared network instead of building my own. There are numerous benefits to doing this, and that’s exactly what our police department did. If there isn’t an option to join a shared network, I would seriously consider Digital Mobile Radio (DMR) Tier 2 or 3. It is a highly capable digital mode, much more affordable than P25 Phase 2, provides the same spectral benefits (two-slot TDMA on a 12.5-kilohertz channel), and has many third-party applications, such as CAD and AVL, to leverage the data capabilities. DMR also has an analog mode, and thus would work on the national public-safety interoperability channels appropriate for the agency’s operating band.

On NPSTC’s inclusion of critical infrastructure providers in its position on P25 being necessary for interoperability, I have yet to experience critical infrastructure crews having a need, or the proper training, to communicate directly with public-safety first responders over radio. Communications between critical infrastructure providers/maintainers usually takes place at the emergency operations center (EOC) level where proper coordination and central control of critical infrastructure assets are necessary for an orderly and coordinated response. Anything needed of critical infrastructure providers/maintainers at a scene would be coordinated between the incident commander and the critical infrastructure representative. The critical infrastructure representative would then communicate using his own communications system to affect a response or action. This would take place over a radio system that best meets the business needs of the critical infrastructure entity, and interoperability would probably be low on the list of requirements.

Within my agency, we do not require, nor permit, direct communications between transit assets and first responders. All interoperable communications is handled at the control center/EOC level. Critical infrastructure organizations have much different requirements for radio communications that may not be best met by P25. This trend is beginning to accelerate much to the chagrin of those who would want P25 to be the only available radio technology in the United States.

There is no doubt that public-safety first responders need to be able to communicate with each other. In our post-9/11 world, the importance of interoperable communications is unquestionable, and many mechanisms, both technical and procedural, have been developed to successfully permit such interoperability. P25 is not a requirement for interoperability. Proper regional planning that establishes protocols for interoperable communications is the way to make sure interoperability is effective. Common shared systems can go a long way to ensure compatible/interoperable communications, be they P25 or some other technology. Public-safety communications systems managers and the people they support are intelligent enough to make sure they have solutions for interoperability in their home regions. They don’t need a particular technology spoon-fed to them. P25 is a sound technology — a good technology. However, it is not a one-size-fits-all technology. P25 has its place in the Interoperability Continuum, but the standard is certainly not necessary to achieve reliable, effective public-safety interoperability.

Andrew E. Schwartz has more than 30 years of professional experience in the design, implementation and operation of LMR and public wireless networks serving personal, business and public-safety users. He has worked for companies such as Bell Laboratories and AT&T Wireless Services and currently works for a large public transportation agency.

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