Public safety networks still can not communicate with each other
years ago, it was discovered through testing that much of the equipment advertised as P25-compliant was unable to interoperate with P25 equipment manufactured by other companies and, in some cases, even with earlier P25 equipment manufactured by the same company,” Boyd said.
Jackson notes that this spurred development, in coordination with NIST, of the DHS P25 Compliance Assessment Program (CAP). The first group of laboratory assessments under CAP began in December 2008 and by April 2009 DHS had recognized the first eight laboratories. Four manufacturers have had emergency communications equipment complete the P25 CAP process — EF Johnson, Harris, Motorola, and Tait — out of eleven manufacturers making P25 walkie-talkies.
This program is voluntary, however, and testing so far is available for only the two completed standards. Companies are free to market products as P25 compliant without certification, although DHS grant money can be spent only on CAP-approved equipment.
“NIST hopes that within two years, the P25 CAP has a fully functional program including performance, conformance, and interoperability testing for at least the CAI and ISSI interfaces which are crucial to interoperability,” Orr said. “Achieving this will require significant commitment and focus by all parties, and for its part, NIST is prepared to assist in meeting this worthy goal.”
Jackson writes that Project 25 was established in 1989 as an end user-led effort between the Association of Public Safety Communications Officials, the National Association of State Telecommunications Directors and the Justice Department. It is being carried out within the Telecommunications Industry Association, a recognized industry standards-making body, and NIST and DHS have since become involved in the program.
It is a suite of standards that will specify eight open interfaces for land mobile radios:
- Common Air Interface: Defining wireless access between mobile radios, and between mobile radios and base stations.
- Inter-RFSubSystem Interface: Permitting users to communicate between systems in differing departments and jurisdictions.
- Fixed Station Interface: Describing the signaling and messages used to administer the fixed station as well as the subscribers communicating through the fixed station.
- Console Sub-System Interface: Similar to the fixed station interface, but it defines the signaling between the RFSubSystem and the console, the position that a dispatcher or a supervisor would occupy.
- Subscriber Data Peripheral Interface: Characterizing the signaling for data transfer between the subscriber radios and the data devices that may be connected to them.
- Network Management Interface: Allowing administrators to control and monitor network fault management and network performance management.
- Data Network Interface: Describing the connections to computers, data networks, external data sources, and so on.
- Telephone Interconnect Interface: Allowing field personnel to make connections through the public switched telephone network by using their radios rather than cellular telephones.
