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P25 Standards: Why they were established and how they help

As public safety agencies and other first responders look at their future radio needs, many are finding that radio spectrum is scarce and the demand for data transmission is more pronounced and often unachievable in narrow-band systems. Furthermore, increased functionality and secure communication is a growing necessity.

Luckily, a number of possible solutions are available, including a variety of digital technologies, but upgrading a communications network is expensive and time-consuming. Plus, the variety of platforms available can make the task of choosing a digital technology seem daunting. Each agency must take into account its individual needs and unique situation.

To help public safety agencies with this monumental transition, many look to the Association of Public Safety Communications Officials (APCO) and the Project 25 (P25) set of standards. The P25 standards were created in 1989 by and for public safety under state, local and federal representatives and Telecommunications Industry Association (TIA) governance. APCO International, the National Association of State Telecommunications Directors (NASTD) and the National Communications System (NCS) participated in the joint effort, and P25 was standardized by TIA.

The P25 suite of standards involves digital land mobile radio (LMR) services for local, tribal, state and federal public safety organizations and agencies. It is a multi-phase, multi-year project to establish a standards profile for the operations and functionality of new digital narrowband LMR systems needed to satisfy the service, feature, and capability requirements of the public safety communications community for procuring and operating interoperable LMR equipment. As technologies evolve and the state of the art advances, new requirements may be defined, while existing requirements may be modified or deleted. The standards development is an evolutionary process, and ongoing adaptation is necessary as the needs of users and the capabilities of new technology advance. From its inception, the APCO Project 25 Steering Committee sought to establish open system standards to increase interoperability and allow multiple vendors to make competing products that are compatible.

The P25 systems available today are being deployed globally. They are gaining worldwide acceptance for public safety, security, public service and commercial applications. Many organizations and grantors have mandated that new land mobile radio system purchases follow P25 standards.

The equipment available today offers so much more than what was offered a few years ago. Just something as simple as being able to use any vendor’s portable radio on a single land-based system is a huge departure from the past. Project 25 and 700 MHz spectrum reallocation are all part of the new land-based radio future for first responders.

Mike Snyder, the public relations director at TIA, said the spectrum reallocation is a very complicated situation with a lot of interested parties, which is why the process is slow and arduous. “It’s a big tug of war,” he said. “It’s recognized where you talk spectrum that it’s kind of a finite resource and allocation of it is a big issue. Sooner or later you need it to be freed up to establish these networks, which will benefit everyone. They continue to address that and look into solutions.”

TIA is a trade association that represents the information and communications technology industries through standards development, government affairs, business opportunities, market intelligence, certification and worldwide environmental regulatory compliance. TIA facilitates such work through its role as the ANSI-accredited Standards Development Organization (SDO) and has developed in TR-8 the 102-series of technical documents. The standards development part of P25 is going quite well, according to Snyder, and TIA just released several new standards for people to purchase and implement.

Every aspect of Project 25 is designed to benefit public safety professionals who seek a new level of performance, efficiency, capabilities and quality in two-way radio communications. Four key objectives guided the APCO Project 25 Steering Committee through this open process: to provide enhanced functionality with equipment and capabilities focused on public safety needs; to improve spectrum efficiency; to ensure competition among multiple vendors through open systems architecture; and to allow effective, efficient and reliable intra-agency and inter-agency communications.

The committee was striving to provide “user friendly” equipment for users, “user friendly” being defined as the least amount of mental and physical interaction by the operator. And yet another goal was to provide a graceful path from present analog technologies through all phases of Project 25.

By adhering to these objectives, APCO P25 makes it easier for users to make the most informed decision possible when planning to convert existing analog systems to digital systems. Vendors’ P25-compliant systems can be accurately compared because they are determined by an agreed-upon baseline set of standards. This allows users to compare the direct features and benefits of both entire systems and individual radio products, making the bidding processes more competitive among prospective vendors. Plus, users have the opportunity to mix and match equipment among Project 25-compliant suppliers because their equipment will follow all basic standards. Within the past year, a Project 25 Compliance Assessment Process has been developed to test and declare equipment compliant to the standards. There is currently no official mark to indicate that compliance testing has been done. There is a P25 logo, but its application is not tied to any official testing program, according to the TIA.

“The people who develop these standards come from hundreds of different companies,” Snyder said. “Some are wireless, some are cable, some are satellite and some are fiber,” he said. Both users and manufacturers have played an important role in shaping P25. Overall, the P25 land-mobile radio vendor community has worked well together to provide a safe and effective two-way communications platform. The variety of people on the panels and the fact that many of them are competitors makes for a well-rounded and balanced set of standards.

P25 SoR

The objective of the APCO Project 25 Statement of Requirements (SoR) is to establish a standards profile for the operations and functionality of new digital public safety radio systems. The document, dated Aug. 15, 2009, can be seen in its entirety at

The P25-compliant radios should be able to communicate in analog mode with legacy analog radios and in either digital or analog mode with other P25 radios. In addition, P25 systems should be able to be maintained and upgraded more cost effectively over the system’s lifecycle, thus meeting user requirements, achieving interoperability and security, promoting committed manufacturers to provide compliant products, fostering competition, and achieving cost-effective emergency/safety communication solutions.

There are actually two phases of P25 development: Phase 1, which specifies a 12.5 kHz bandwidth, is for the most part completed. Phase I defines the services and facilities for a compliant system and ensures that any manufacturer’s compliant radios have access to the services described in the SoR (including other systems, across system boundaries, backward compatibility, etc.), regardless of system infrastructure. In addition, the P25 system provides an open interface to the radio frequency (RF) subsystem to facilitate inter-linking of different vendors’ systems.

Phase 2 deals with the overall lack of spectrum and increasing demand. It refers to P25 requirements and standards for a digital common air interface (TDMA- or FDMA-based) using a 6.25 kHz channel or equivalent bandwidth and for the supporting system (i.e., radios and infrastructure).

Both Project 25 Phase 1 FDMA standards and the more recent Phase 2 TDMA Standards will function well in both a rural and urban environment. However, in large urban areas where spectrum is a scarce commodity, the Phase 2 standards will provide both superior coverage and improved spectrum efficiency than may otherwise be available.

“There is still a ways to go,” Snyder said. “Obviously, we advocate for increased spectrum that can be allocated so these networks can be established so the P25 equipment can be mobilized and actually used. So we’re still kind of waiting for some of the pieces to fall into place.”

Published in Public Safety IT, Jan/Feb 2010

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