Is Project 25 Public-Safety Grade?
By PTIG Members and Staff
Tuesday, March 08, 2016 | Comments
In simple terms, public-safety-grade (PSG) equipment, systems or networks provide the communications capabilities required by operators and users of the equipment with availability and reliability exceeding that typically provided by commercial communications equipment, systems and networks. Project 25 (P25) in many ways establishes the foundation for implementing PSG systems and equipment, and therefore we can say yes to the question of whether P25 is PSG.

In response to the release of the National Public Safety Telecommunications Council (NPSTC) paper titled “Defining Public-Safety Grade Systems and Facilities,” the Project 25 Technology Interest Group (PTIG) was approached with questions such as, “Is P25 PSG?” and “What does PSG mean in 100 words or less?”

The resulting discussions among manufacturers, technologists and public-safety communications agency user representatives within PTIG revealed that coming up with a single and concise answer that everyone will accept is a difficult task. As an aid to these types of discussions, this article highlights aspects of the P25 suite of standards that contribute to creating PSG communications equipment, systems and networks.

By defining public safety as the collection of federal, state, local and tribal agencies tasked with keeping the public safe, it becomes apparent that the communications needs of these users are diverse and are different than the communications needs of the public. In fact, depending on the respective missions and operating environments, the communications needs of one public-safety agency can be quite different than the needs of another public-safety agency.

Public-Safety Requirements
The P25 user community has identified a broad set of features and services that are important to public-safety communications. The suite of P25 standards defines the functional and operational aspects of these features and services. There are too many to list here, but this includes several types of voice calls, IP and common air interface data bearer services, control signaling services, mobility management services and location services. The standards also include voice and data encryption and security services such as authentication and key management services. Most services are available in both the trunking and conventional operating modes.

The suite of P25 standards defines a variety of interfaces intended to serve the diverse configuration needs of the public-safety community. This includes FDMA and TDMA air interfaces for communications between radio and dispatcher equipment. Several wireline interfaces provide for connecting system components to form communications systems or for connecting systems into wide-area communications networks. These interfaces enable the use of public-safety features and services in a wide variety of configurations. These configurations range from direct simplex radio-to-radio communications to multiband, multichannel, multisite and statewide-networked configurations. This includes simulcast and voting configurations. These interfaces and configurations serve both trunking and conventional operating modes.

In addition to meeting national and international government spectrum regulations, the suite of P25 standards defines additional performance requirements important for public-safety communications. This includes coverage performance modeling and verification methods, receiver and transmitter performance measurement methods, and specifications for both FDMA and TDMA air interfaces. Additionally, it includes voice service access and throughput delay specifications and measurement methods for radios, base stations and trunking systems. P25 also defines a rigorous vocoder intelligibility and background noise performance evaluation process that has resulted in approval of interoperable full-rate and half-rate digital vocoders.

Standards-based interoperable communications has become a top requirement for the public-safety community. The primary purpose of the suite of P25 standards is to enable interoperable implementation of the P25 features, services and interfaces by multiple manufacturers. As of this writing, 35 manufacturers provide equipment or services that are designed to one or more aspects of the P25 standards.

The suite of P25 standards includes test documents to ensure repeatable test results using consistent, industry-approved test methods. These documents cover performance, message, procedure and protocol conformance testing, as well as equipment interoperability testing for the P25 features, services and interfaces. Manufacturers, customers or test labs may use these test documents. To date, all tests included in the Department of Homeland Security’s P25 Compliance Assessment Program (CAP) reference P25 test documents. This ensures interoperability between equipment produced by different manufacturers and between different public-safety agencies.

Public Safety Grade
P25 equipment, systems and networks can be designed and configured to provide the features, services, interfaces, configurations, operating modes and performance required by public safety under conditions that commercial-grade communications equipment and systems are not designed or configured to support. PSG communications is the subject of the NPSTC paper published May 22, 2014, titled “Defining Public Safety Grade Systems and Facilities.” PTIG fully supports the content of the NPSTC report.

The NPSTC report covers a wide variety of topics and best practices that should be considered by anyone who is purchasing, installing, operating and maintaining communications equipment, systems and networks for use by public safety. The principles covered in the report are not unique to P25 equipment, but the report was created by a variety of public safety, commercial and industry participants all familiar with North American public-safety LMR communications systems and equipment including, but not limited to, equipment and systems designed to the P25 suite of standards.

The following excerpts from the NPSTC report highlight the content and intent of that report:

“The term ‘public safety grade’ is a conceptual term that refers to the expectation of emergency response providers and practitioners that their equipment and systems will remain operational during and immediately following a major natural or manmade disaster on a local, regional and nationwide basis.”

“PSG communications systems are systems that are used by public-safety responders and that have been evaluated by public-safety officials to provide reliant and resilient operations in the event of natural or manmade disasters or events.”

“Communications is vital to both public-safety field and command personnel during routine, local incidents and even more so during major incidents covering a larger area. Public safety voice LMR networks today are among the most reliable networks available in the United States. Today’s commercial wireless networks are not built to the same standard.”

“Any system builder must carefully consider these best practices and requirements. It is acknowledged that some requirements and recommendations may be impossible to meet at a particular site while others may be economically impractical.”

“The best practices and requirements provided in this document (the NPSTC document) are intended to address the steps necessary to make a communication site highly available, even in the event of a disaster. They are intended to capture the typical efforts of public-safety network builders to ‘harden’ their communication sites with the objective of achieving this high level of service availability.”

“This report seeks to further define the phrase ‘public safety grade’ and to provide measurable characteristics which would differentiate a mission-critical communications system from a standard or commercial-grade network.”

The public-safety community requires a wide variety of interoperable, standards-based communications services, configurations and capabilities with well-defined performance, interoperability and testing specifications. This is the essence of the P25 suite of standards as it relates to PSG communications systems.

• A PSG communications standard, first and foremost, provides a set of features, capabilities and services required by the diverse group of public-safety users.

• The P25 User Needs Subcommittee (UNS) has defined those required features, and the P25 suite of standards supports those features.

• Manufacturers take the features and specifications defined by the P25 standard and implement them in reliable software, hosted on rugged hardware platforms that are exhaustively tested to meet the performance and interoperability specifications prescribed by the P25 suite of standards.

• These software and hardware platforms are then combined and implemented as a P25 system in a highly reliable, highly resilient manner, with redundant elements, backup power, etc. These systems are designed to cover a specified geographic area with extra margin for coverage reliability. Equipment that is built to P25 standards and has been tested to P25 standard tests and is installed, operated and maintained per the NPSTC document to the maximum extent practical, creates an interoperable PSG communications system.

• Multivendor solutions enabling interoperability between devices, public-safety individuals and groups, fleets and teams that can be can be linked across local, regional, state and national networks exist. They offer public-safety agencies competition and options for cost-effective sourcing.

• Public-safety practitioners have been doing this with the P25 suite of standards for close to 30 years and there are more than 700 P25 systems in operation providing PSG, life- saving communications for day-to-day operations as well as emergency situations.

• Thus, PSG P25 is the foundation of North American public-safety communications and the cornerstone of many PSG systems around the world.

The P25 “user-driven” technology approach continues to guide the decision-making process for P25 technologists and engineers into the future. The result will be updates and improvements to existing standards and the development of new P25 standards that result in capability and performance improvements for P25 products and services.

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PTIG is a group of individuals and organizations that share the mutual interest of advancing the refinement, development, deployment and applications of the digital communications technology represented by P25 industry standards. PTIG members include two-way radio communications experts, public-safety professionals and equipment manufacturers. PTIG members recognize the need for, and have a direct stake in, the continued development of the critical communications capabilities represented in the P25 standards. For more information, visit project25org.

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On 3/17/16, Scott Pearce said:
Public safety grade to me means large companies lobbying for rules and laws that may or may not truly benefit most departments. Often a cash-strapped community has a choice and that's to stay away from a standard designed by a company whose sole purpose is to provide a return to stockholders. Capitalism is not a bad thing. However when small communities are required or think they are required to update equipment to unsustainable technology then it truly costs the public. When grants pay for equipment, that's great. However often grants are not continual for repairs and replacement. Replacing a $3,000+ radio is often beyond the reach of small departments and those departments who rely on volunteers.

Other technologies are less costly and do work. Analog isn't perfect but it's simple. And simple works when the net goes down.

After all the grant money. tax dollars spent since 9/11. many agencies still have competing systems. This is one of the biggest insults to the taxpayers since Social Insecurity.

On 3/10/16, Leon van der Linde said:
This defines Digital Mobile Radio (DMR), NXDN and TETRA as well. This equipment actually conforms to these specifications. The result is the present digital standards and protocols are rugged enough and interoperable, as well as interfaceable to conform to public safety grade (PSG). Project 25 (P25) is an older technology that has been caught up to and passed by DMR, NXDN and TETRA.
Something to think about and consider.

On 3/9/16, Larry Schaefer said:
This is a great article that goes to the intent of the public-safety-grade (PSG) report. It is important for all standards and policy developmental bodies to consider these definitions in the move to adopting new technologies to minimize our exposure to the growing threats we face. With the adoption of IP-based technologies it is essential for mission-critical systems and key resources to sufficiently address DHS' top two identified threats: cybersecurity and EMP. The philosophy of protecting from cyber threats has to be a comprehensive enterprise and networkwide solution with active intrusion mitigation strategies as well as robust analytics that assist in fully identifying the source of the intrusion for the development of a comprehensive profile, which then provides the information for a program of predictive analytics to be developed for future engagements. The second threat of EMP is a whole different topic. Again excellent article that gives me hope that the attempt to compromise the expectations for commercial gains are being kept in check.


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