The Project 25 Technology Interest Group (PTIG) has published their latest Whitepaper titled: 

How to Extend your P25 System for LTE Interworking 

The full Whitepaper can be downloaded using the link below:

How to Extend your P25 System for LTE Interworking October 2023

This whitepaper begins with a section offering an overview of current P25 LMR and LTE technologies including advantages and disadvantages of each taken from the SAFECOM NCSWIC whitepaper: Land Mobile Radio/Long Term Evolution (LMR/LTE) Integration: Best Practices  

The second section describes the ATIS/TIA Interworking Study. The information in this section is drawn from the ATIS/TIA JLMRLTE Working Group paper and Project 25 TIA TR-8 Standards documents including the latest updates supporting LMR-LTE Interworking.

The third section offers concept definitions on the best use of P25 Interfaces to interoperate with the diverse set of LTE networks and products. The focus is on a P25 System Administrator’s perspective answering the question “Here is what you could do to extend your P25 Trunked or Conventional System for LTE Interworking.”

The fourth Section describes system, network, and radio testing which are relevant to all mission critical communications systems. This is followed by a specific discussion of testing and performance characteristics in the context of LMR-LTE interconnected networks using the four different interface types: P25 Common Air Interface (CAI), P25 Digital Fixed Station Interface (DFSI), and P25 Inter SubSystem Interface/Console SubSystem Interface (ISSI/CSSI).

About the Authors:
Andy Davis is the Senior Resource Manager, Project 25, Motorola Solutions; & Chairman TIA TR-8
Jeremy Elder is Director of Product Management for Systems and Devices, L3Harris Technologies
Dominick Arcuri is a Subject matter Expert at Televate
James Downes is Senior Advisor–Encryption and Project 25 Standards and Security,
Cybersecurity and Infrastructure Security Agency (CISA) & P25 Steering Committee Chair
Doug Chapman is Executive Vice President, Etherstack
Ed Latimer is the Director for Radio Test at Viavi Solutions
Hermina Koshinski is the Chief of Radio Operations Engineering & Support for the Pennsylvania State Police PA-STARNet system
Scott Wright is the Senior Telecommunications Engineer 2 with the Connecticut Department of Emergency Service and Public Protection
Stephen Nichols is Executive Director, Project 25 Technology Interest Group (PTIG)