Ensuring secure and reliable military communications in tactical networks

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September 14, 2026

There exist a number of fundamental challenges inherent in establishing and maintaining secure and reliable communication networks within dynamic military tactical environments. Deploying land-mobile radio (LMR) and software-defined radio (SDR) technologies in such environments can prove problematic. In particular, issues of signal integrity, protocol verification, network performance optimization, and encryption functionality verification are essential for mission-critical voice and data transmission. Over-the-air testing methodologies, infrastructure validation procedures, and precise cable and antenna diagnostics can help personnel in the field uphold robust and secure military communication links.

Military communications have always emphasized security, resilience, and operational flexibility. However, the scene is evolving from traditional LMR systems to include cellular networks and emerging technologies. This convergence, including the use of 5G and IoT devices, brings new capabilities for both tactical and base-level military operations, but also presents unique security and interoperability challenges.

The growing interoperability between LMR and cellular networks is a central trend in current public-safety and military communications. Major manufacturers of LMR devices are now embedding cellular user equipment (UE) into the radios that they design and offer to these communities. This convergence enables personnel to have a single communications device that takes advantage of both LMR and cellular network services and in some cases grants access to a talk group (think “channel”) via either network.

To bridge these two distinctly different technologies, their respective networks use proprietary cloud services that require presubscription to enable seamless communication across different network types. Each manufacturer typically provides their own ecosystem, facilitating LMR and cellular-based network interoperability tailored to their product suite and addressing critical aspects such as security, including end-to-end encryption.

Interoperability mechanisms

There are some systems used within the dispatch or in the field designed to enable LMR network bridging that have been extended to include cellular and even landline phone systems. The bridging can be implemented in the network core or in edge devices. There are a few offerings already on the market where the LMR and cellular networks can be bridged in the user terminal. With all these external bridging capabilities, care needs to be taken not to create interference through the introduction of duplicate paths or loops. Further, while these bridging systems offer voice communications interoperability, key features of a particular LMR or cellular system may be unavailable.

Mission-critical services

To resolve key interoperability gaps, equipment vendors are increasingly aligning with 3GPP standards and building 3GPP-based network cores that support a suite of mission-critical services (MCX). MCX solutions standardize interoperability and streamline communication across platforms, bridging the gap between legacy radio systems and modern cellular technologies. MCX services include mission-critical push-to-talk (MCPTT) alongside mission-critical data (MCData) and mission-critical video (MCVideo). For example, MCPTT offers advanced features such as group calling and instant voice communication while preserving essential features such as encryption, unit identification, geolocation, and man down. The MCX package of services is highly integrated and a notable improvement when compared to most bridging technology solutions, but it comes with complexities that can lower resilience. Some vendors are building resilient distributed network cores that place the functionality both in a remote cloud and at the tactical edge close to the tactical operator.

Commercial devices and 5G

The adoption of commercial off-the-shelf (COTS) devices, especially 5G smartphones, is expanding within military environments. These devices present distinct advantages for tactical communications, enabling low-cost, high-availability solutions that leverage the rapid development cycles of the commercial sector. On military bases, COTS 5G handsets are often used within closed environments, but are augmented with government-mandated security features to safeguard sensitive operations.

COTS handsets may also operate on public networks, both domestically and during deployments. In such contexts, devices must be capable of blending into the local environment to avoid detection. Typical measures include the ability to alter the IMEI [International Mobile Equipment Identity], which can be particularly important to preserve device anonymity and operational security in covert operations.

COTS radios can also supplement standard-issue military and cellular radios for some units both domestically and overseas. They are often chosen for their cost-effectiveness and ease of deployment, while military-specific secure radios remain in use where additional security, specialized waveforms, or anti-intercept features are required.

Dual-technology devices – those supporting both LMR and cellular – are becoming more common, offering greater flexibility and redundancy. Equipped with SIM cards, these radios can be granted focused access to specific cellular networks, enhancing operational security and control. Some military bases now host 5G networks from multiple vendors, further complicating the communications landscape but providing diverse and redundant infrastructure.

On base and battlefield

On military installations, security protocols often mirror those used by local police departments, albeit on different frequencies and with added military-specific safeguards. Warehouse operations and other logistical functions on base are transitioning more and more to 5G technologies, necessitating equipment with MCPTT interoperability and, in some cases, a cellular gateway within the network core to maintain seamless communications between LMR and cellular systems – both private military and public networks.

Modern subscriber radios offer enhanced situational awareness and safety features. For example, LMR devices may add man-down detection implemented with inertial sensors or an emergency button, as well as connecting to other personal devices like a smart holster to alert dispatch and command units when a sidearm is withdrawn – vital functionality for personnel operating in hazardous conditions.

On the battlefield, LMR systems enable users to beacon their location, supporting real-time tracking and coordination. Meanwhile, 5G radios increasingly support advanced capabilities such as video streaming and Internet access. Currently, the U.S. Office of the Undersecretary of Defense for Research & Engineering is actively developing specifications to guide the secure use of such devices by military personnel.

Device miniaturization continues to be a focus, particularly for covert operations, with both LMR and cellular UEs able to be reduced in size to facilitate concealment. In addition, Internet of Things (IoT) devices are beginning to play a role in tactical deployments due to their flexibility and affordability: IoT devices leveraging RedCap or reduced capacity 5G is an emerging tool for the military as it is in the civilian market.

Testing integrated communications systems

Testing of these integrated systems has many touchpoints: First, the LMR radios and network infrastructure; second, the cellular device and network infrastructure; and last, the interoperability capabilities and any resilience testing that arise from the operational environment in which these devices will need to perform. (Figure 1.)

[Figure 1 ǀ COTS radio test sets, such as the VIAVI CX700, CX300/200, are available to help test network-infrastructure and user equipment to established government standards for secure operation on cellular networks.]

Various standard CX-series radio test sets are available off-the-shelf to help test LMR radios and network infrastructure equipment according to established industry and government standards for technically proper and secure operations using various technologies including SSB, AM, FM/PM, P25, DMR, NXDN, TETRA, and proprietary classified waveforms. Signal integrity, protocol verification, and security capabilities can all be tested using test sets in the depot or in the field. Using the industry-accepted Standard Commands for Programmable Instruments (SCPI), maintainers can script the desired method of procedure (MOP) to reduce user workload and produce consistent results in an efficient manner. Scripting automates rapid testing and alignment of radios.

Further, scripting can guide the use of the two-port vector network analyzer (VNA) functions to perform the complex tasks of testing and alignment of multicouplers, filters, coaxial cables, and antennas ensuring both device and system performance and compliance to industry standards.

Cellular infrastructure testers enable the user to test and activate the cellular infrastructure and reduce errors and rework associated with site commissioning. More­over, engineers and technicians can use the tools to troubleshoot issues within the site and using its fiber-optic or microwave infrastructure. These testers have grandmaster timing test capabilities that can monitor and detect interference challenges to GNSS timing references, which are frequently targeted by malicious agents; plus the capability to perform spectrum/channel clearance from malicious or unintentional interference.

J. Gordon Beattie, Jr. is Senior Principal Research Scientist for RF and Wireless Architecture at VIAVI Solutions. He holds 167 U.S. patents spanning microwave communications, VDSL, switching, cellular radio, and digital watermarking. He specializes in resilient network management and interoperability across terrestrial, airborne, and space platforms, and co-chairs O-RAN nGRG RS08.  Stephen E. Jeffries is Radio Test Product Line Management at VIAVI Solutions, with more than 35 years of experience in product-line management, systems engineering, and land mobile radio development. A former Motorola Solutions engineer (21 years), he serves on the P25 Technology Interest Group Board and is an Amateur Radio Operator (KA9ZRU).

VIAVI Solutions   https://www.viavisolutions.com/