Engineers from the National Institute of Standards and Technology (NIST) built a low-cost computer system that links older public safety radios to state-of-the-art wireless communications networks, showing how first responders could easily take advantage of bandwidth technology that offer voice, text, messaging, video and data capabilities.
The NIST prototype system could help overcome a major obstacle to updating public safety communications. Many of the 4.6 million public safety officials in the United States are still using traditional analogue radios, due to the high cost of switching to digital mobile phones and the slow incorporation of these old familiar and push “push-to-talk” functionality systems critical of them first responders.
“The aim of this NIST project is to develop a prototype infrastructure that commercial entities could use to create a low cost solution for public safety users, enabling them to interconnect their radio systems with broadband networks,” said L ‘NIST engineer Jordan O’Dell. .
“There is no commercial option that can be compared to what we are developing. The aim here is to create a prototype and accelerate technological development in the industry that will fill a significant gap.”
The NIST prototype connects Land Mobile Radio (LMR) analog receivers and repeaters with the most popular wireless standard, Long Term Evolution (LTE) server, which manages operations within a broadband network. The LTE system is called Mission Critical Push-to-Talk, which refers to essential aspects of public safety radios such as high availability and reliability, speaker identification, emergency call, and clear sound quality.
As described in a recent report, the NIST system has three main components:
- Software-defined radio, which uses software rather than hardware to enable flexible frequency selection and interface designs, which interacts with LMR signal interfaces and transmits data to the next unit;
- An open source software environment for managing the radio software, which controls digital signal processing; in
- LTE phone user interface, which allows LMR radio users to talk to LTE network users as if they were both on the same push-to-talk network, with calls being initiated from both sides.
NIST’s design goals included robustness, low cost, and strict compliance with current and future standards. Physical equipment includes computer hardware running all three components, suitable software, and an antenna. The computer must have an Internet connection to the LTE system. The whole setup is about the size of a video game console plus a laptop or desktop computer.
The NIST system costs less than current industry and government efforts to connect radio and cellular networks. One such activity requires a radio system that supports the Project 25 Inter-Radio Frequency subsystem interface, which many public security agencies do not have, or can afford, purchase or modify. Another attempt to connect existing radio receivers to a “box” that connects to the broadband network requires dedicated radios and “donor” interfaces, which are also expensive.
“We want public safety agencies to have a very cost-effective option that can interact with old technology when other options are out of their reach,” O’Dell said.
NIST researchers are continuing to work on the prototype, intending to improve the broadband network interface and connect to other types of radios. To promote technology transfer, they plan to release all features publicly on an open source basis for anyone’s use.
This work was made possible by the Public Safety Trust Fund, which provides funding to organizations across NIST by using NIST’s expertise in communications, cyber security, manufacturing and sensors to investigate critical and life-saving technologies for first responders.