Evaluating LMR and LTE Coverage for Mission Critical Voice Communications

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September 3, 2024 by Dominick Arcuri


Most public safety communications experts agree that traditional Land Mobile Radio (LMR) systems and wireless broadband 4th generation (4G) and 5G systems, based on Long Term Evolution (LTE) technologies, will likely coexist as key voice and data communications tools for public safety agencies for many years to come. As a result, the time is coming when first responder agencies will be evaluating both technologies as possible solutions for their mission critical voice communications needs. While there are well-established Telecommunications Industry Association (TIA) standards-based procedures to test and quantify the quality of public safety LMR coverage, evaluating public safety LTE mission critical voice coverage quality and reliability requires both established LMR techniques and new ones.

Televate is currently assessing the operational options and benefits of public safety LMR and LTE voice communications for first responder agencies for one of our in-progress projects. Based on Televate’s extensive work with the Nationwide Public Safety Broadband Network (NPSBN or FirstNet), and our experience with existing LMR testing processes, we are well prepared for this new challenge. Televate is engaged with a county in the Southeastern United States that is advancing a solution to replace their public safety LMR system. Their legacy radio system does not provide reliable coverage throughout the county, and it lacks modern features and capabilities. To address the county’s needs, Televate performed a user needs assessment, interviewing all public safety user groups, and documenting their operational requirements and existing critical communications gaps (coverage, capacity, encryption, etc.).

Televate then developed a conceptual design to establish the feasibility of a new LMR system, estimate the cost of the project, and to establish requirements for a competitive procurement process. The conceptual LMR network design included coverage propagation simulations predicting the coverage experienced at various radio usage levels, including mobile, portable, and portable in-building. An example simulation of a typical coverage prediction is shown in the propagation simulation above.

Televate then developed a requirements-based Request For Proposal (RFP) and guided the county through the procurement process. Proposals were received from multiple LMR vendors, in addition to a proposal from a vendor offering push-to-talk voice services over a commercial cellular network and using a service marketed as “mission critical.”

In performing a thorough coverage evaluation of all offerings, the county looked to Televate for guidance. Respondents to the LMR system RFP proposed radio systems anchored on specific design parameters and coverage simulations claiming that they satisfied all RFP-defined coverage requirements. This allowed Televate to compare each of the proposed designs with a common simulation model and equivalent parameters to provide an apples-to-apples comparison. The RFP developed by Televate also required a detailed coverage prediction and test procedure, anchored on TIA-102 standards, to illustrate and test the final system to ensure compliance with the stated county user requirements. An example coverage test grid sample plot, depicting the communications “pass” (green) and “fail” (red) test data points, is illustrated in the sample coverage testing grid. Conducting detailed grid-by-grid coverage tests to quantify the extent of coverage and the Digital Audio Quality (DAQ), verified by objective end user testing, is common in the public safety LMR industry and recommended by TIA documents.

The responding commercial cellular carrier did not provide the same type of relevant technical details behind their service quality coverage map illustrations, and cellular carriers do not design their networks based on TIA standards established for public safety LMR. Therefore, a different evaluation process was required.

While there are multiple differences between LMR and LTE—the type, form factor and gain of the handheld device (radio vs. smartphone) antennas, as well as device output power (3 watts for LMR at 700/800 MHz, and 0.2 watts for LTE) — quantifying reliable cellular coverage still requires high resolution coverage mapping and a certifiable testing approach. To do so, Televate worked with the county to conduct signal quality testing over the carrier’s existing network.

The County employed Televate’s smartphone-based software application, Pinpoint™, on multiple smartphones to test and map the existing coverage provided by the cellular network. Pinpoint is a coverage collection and analysis service that allows users to crowd-source the collection of cellular network availability and performance data. Designed for ease of use, Pinpoint automatically collects over 50 unique data elements—including service availability, device location, signal strength, signal quality, cell information, network latency and data throughput—and uploads the data to Televate’s secure cloud service. Easy-to-understand maps, charts and graphs allow users to visualize the data.

Whereas coverage maps advertised by wireless carriers use a statistical average to predict service, Pinpoint provides the empirical evidence of the service level – not a prediction. In this case, the customer collected the data using smartphone devices[1] provided by the vendor and Televate processed and analyzed the data, which provided an affordable field verified solution for the customer. A sample of the data collected by Pinpoint is shown in the map above. This data depicts the signal levels received by the device and identifies areas in red where the vendor suggests signal levels are insufficient for mission critical push-to-talk voice communications. Other Pinpoint maps highlight parameters such as service availability, ping performance, download and upload speeds, etc., using the actual smartphone testing approach, which best represents the end user’s experience.

While there are additional elements of the proposal evaluation process that must also be assessed for the cellular-based mission critical voice approach, those considerations are outside the scope of this paper. Televate hopes to discuss them in a future paper.

This one project provided Televate with an opportunity to utilize various coverage prediction and verification tools and approaches to assist our client with their emergency communication system replacement. We anticipate that these types of analyses and evaluations will be required more often as technology progresses and public safety agencies receive more proposals for mission critical voice services. Televate is prepared with the tools and experience necessary to support public safety agencies during this period. Find out more about Pinpoint at https://televate.com/pinpoint/, and for more details on our public safety communications services visit us at www.televate.com.


[1] The smartphone devices did not use an external antenna. Other devices, such as an LMR-based radio with LTE capability and an external antenna, may provide somewhat better coverage.

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