P25 Meetings Update Phase 1 and 2 Standards, Identify User Needs in Encryption, Geolocation
Tuesday, July 30, 2019 | Comments

The Project 25 standards groups coordinated through the Telecommunications Industry Association (TIA) updated both FDMA and TDMA standards and identified user needs for encryption and geolocation during in-person meetings June 18 – 20 in Des Moines, Iowa.

Significant progress was made in P25 standards development and evolution as well as in-depth discussions between manufacturer representatives and P25 users during the meetings, officials said.

Progress included a revision of the Phase 1 FDMA Transceiver Measurement Methods standard, which was approved for ballot. This revision adds a method of measurement to evaluate the ability of a P25 receiver to reject an unwanted broadband base station signal, thereby preventing degradation to the reception of a desired signal. Performance specifications are expected to follow completion of the measurement method.

The group also finalized revisions of the Two-Slot TDMA MAC Layer Specification standard and the Two-Slot TDMA MAC Layer Messages standard. The revisions and a new Two-Slot TDMA MAC Layer Procedures standard were approved for ballot. This restructures the P25 Phase 2 TDMA air interface standards for voice and control channels to address errata that have been collected and in preparation for the addition of Link Layer Encryption (LLE).

Revisions of the Trunking Overview standard, Tier 1 Location Services Specification standard and IP Data Bearer Service Specification were all approved for ballot. These revisions address errata that have been collected since the last publications.

There was agreement to begin work to modify the Inter RF Subsystem Interface (ISSI) standard to accommodate interoperability and interworking with Third Generation Partnership Project (3GPP) mission-critical Long Term Evolution (LTE) services based on the Joint LMR and LTE (JLMRLTE) working group Phase 1 study document.

New user needs were identified in the areas of encryption and geolocation. These included the need for a globally unique identifier for Tier 1 GPS devices in P25 systems. This would ensure accurate location tracking of each individual subscriber during a wildland fire or other public-safety incident.

Another identified need is the ability to affiliate P25 subscriber units with multiple P25 key management facilities (KMF). This would provide for the concurrent over-the-air affiliation of a subscriber unit with multiple KMFs, allowing seamless roaming with secure encryption updates for users from multiple systems responding to an event or incident.

The Federal Partnership for Interoperable Communications (FPIC) updated its ongoing work with the P25 ISSI/Console Subsystem Interface (CSSI) focus group.

An update on the DHS OIC Compliance Assessment Program highlighted recently published documents that include ISSI/CSSI conformance testing requirements, templates, test pass/fail criteria and a series of conformance test cases. Compliance Assessment Program (CAP) draft documents for compliance assessment bulletin (CAB) testing rules and future ISSI/CSSI interoperability testing requirements and templates are out for public review and comment.

P25 user representatives for the state of Iowa and the Des Moines region presented a series of case studies describing the incidents leading up to the development of the new Iowa Statewide Interoperable Communications System (ISICS), a description of the new system, capabilities and users, and a case study of how the system performed during the Solheim Cup Golf tournament held in Des Moines.

P25 in-person meetings are held three times a year in major cities across the United States. The quorum meetings are where work status reports are provided and project, ballot and publication approvals are made. Working meetings of individual subcommittees and working groups are held as needed, some monthly, some weekly. This work reflects the fact that the P25 standard is an evolving standard that continues to be maintained and expanded as technology evolves and as the communications needs of the public-safety community changes.

Stephen Nichols is director of Project 25 Technology Interest Group (PTIG), a not-for-profit organization dedicated to the promotion and application of the Project 25 (P25) digital radio standard for LMR technology. PTIG’s members include radio users, manufacturers and consultants involved with the development and operation of P25 public safety, government and commercial radio systems. In December of 2013 he retired from Thales Defense and Security after working for Thales since 1997 leading business development activities for the company’s P25 radio product lines. He has more than 30 years of experience in the industry. Contact him at director@project25.org.

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On 8/8/19, Tom said:
Where is the P25 TDMA conventional?
Oh wait, the radio companies will lose money. ...Never mind. If you're doing a public-safety system, go Digital Mobile Radio (DMR) — two slots for every channel. BIG cost savings and better performance.

On 8/1/19, Leon van der Linde said:
I thought they are replacing P25 with cellphones. Why upgrade a system that will be replaced? Rather spend the time and money to get the cellphones up to the superior standard of two-way radio since it will replace two-way radio.

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