Discover how armed forces maintain communications beyond the line of sight, using standoff systems, satellites, airborne relays, and tactical networks.
In summary
In modern military operations, units often have to carry out missions beyond direct line of sight (Beyond Visual Line of Sight – BLOS). This means that they operate at distances or behind obstacles that make traditional line-of-sight communication impossible. To stay connected to their base and to each other, combatants use a heterogeneous architecture of communication systems that combines satellite links, airborne relays, tactical data networks, and standards such as Link 22 to transmit voice, data, video, and telemetry over long distances. These technologies significantly improve the safety of crews and aircraft by allowing them to remain out of direct range of the enemy, while maintaining information superiority in the theater of operations. These systems also facilitate the integration of drones and ISR (Intelligence, Surveillance, Reconnaissance) sensors into a fluid network, which is essential for real-time coordination and decision-making.
The evolution of the concept of beyond line-of-sight communication
The concept of BLOS communication has become established in military doctrine as battlefields have expanded. Traditionally, line-of-sight VHF and UHF radios are limited to a few dozen kilometers, or even less if the terrain is rugged or urbanized. In contemporary conflicts, this is not enough to connect forward units to command posts.
Beyond direct line of sight, forces must transmit orders, situational information, video transmissions, and sensor data with minimal latency and high security. This involves the integration of several complementary technologies:
- military satellite communications (SatCom), using bands such as X-Band or EHF, which enable secure transmissions over very long distances without direct line of sight;
- airborne relays, which use high-altitude aircraft or drones to relay signals between ground units or remote platforms;
- digital tactical links such as Link 22, designed to connect naval, air, and ground units in BLOS in allied operations.
The combination of these technologies overcomes the limitations inherent in each system taken individually. For example, satellites offer global coverage but can be vulnerable to jamming or electronic warfare, while aerial relays increase network resilience while reducing latency and dependence on fixed infrastructure.
Network architectures for standoff and resilience
BLOS communications increasingly rely on decentralized network architectures, integrating satellite links, airborne relays, and tactical ground infrastructure. This model enables continuous connectivity even in the face of electronic jamming or enemy attacks.
In this context, systems such as the US Air Force’s Battlefield Airborne Communications Node (BACN) play a pivotal role. BACN is an airborne communications node that connects different radio standards, serving as a bridge between disparate networks and enabling data translation between units that would otherwise be unable to exchange information. Positioned at high altitude, this type of system can establish robust BLOS links over geographical or electronic obstacles.
Another example is the Link 22 standard, which succeeds the older Link 11 and Link 16 protocols, offering automated long-range tactical data management for allied forces. Link 22 operates in the HF and UHF bands, some of which are optimized for BLOS transmissions, and enables the exchange of structured data between ships, aircraft, and ground units.
Modern networks also tend to incorporate elements of mobile ad hoc networks (MANETs), which allow each combatant or platform to act as a relay for others, thereby improving coverage without creating a single point of failure. This type of network can also incorporate adaptive routing technologies to continuously optimize transmission routes based on the electromagnetic environment or tactical constraints.
The contribution of satellites to standoff communications
Satellite communications are a major component of BLOS connectivity. The armed forces use military or dedicated satellites to establish very long-distance links with high encryption and jamming resistance capabilities. In the X-Band, for example, a good compromise is achieved between weather resistance, robustness against interference, and data transmission capacity.
The multiplicity of constellations, including traditional military systems and low-Earth orbit (LEO) constellations, increases transmission capacity while reducing latency. These links enable not only voice communications, but also the exchange of sensor data, real-time images, and high-definition video streams from remote drones, aircraft, or ground platforms.
This satellite infrastructure is particularly critical for ISR (Intelligence, Surveillance, Reconnaissance) missions, where large volumes of data must be sent back to command centers or analysts for processing. In high-intensity or asymmetric environments, these data exchanges enable faster information fusion and better tactical decision-making.
Airborne relays and tactical platforms
Beyond satellites, airborne relays play a key role in BLOS communication, particularly in environments where satellites may be compromised or unavailable. Platforms such as high-altitude drones or specialized aircraft serve as mobile relay points for radio signals, extending the range of communications beyond terrestrial limitations.
These relays can carry sophisticated radio payloads capable of relaying signals between units separated by hundreds of kilometers, improving operational responsiveness and reducing the risks associated with exposing troops. The use of drones or balloons as relay points also offers the advantage of increased mobility, with repositioning possible during missions to keep pace with dynamic operations.
Airborne relays also integrate into broader network architectures where they collaborate with ground and satellite networks to provide multi-layered and redundant coverage. This approach reduces dependence on a single technology and increases resilience against intentional or accidental disruptions.
Integrating BLOS communications with intelligence and collaborative combat
One of the key advantages of BLOS communications is their integration with modern data fusion and command and control (C2) systems. Intelligence streams from multiple sources—drones, ground sensors, radars—can be shared between units and analysts in real time, providing enriched situational awareness.
This capability is essential in collaborative operations, where units separated by thousands of meters must act in coordination. For example, a drone collecting images can transmit this data via satellite or air relay to a ground team or command center, which analyzes and sends back updated directives. This continuous cycle of exchange relies on reliable and secure BLOS networks, enabling each combatant to act with an up-to-date view of the tactical context.
The ability to transmit large amounts of data in real time also enhances remote command capabilities or unmanned operations, where operators can guide autonomous systems based on remotely shared information, while remaining outside areas of direct contact with the enemy.
Implications for Combatants and Data Collection
For crews and operators, BLOS communications represent a profound change from traditional methods. Soldiers are no longer satisfied with a simple radio link: they are integrated into an interconnected data ecosystem where voice, video, thermal images, and sensor data must flow continuously. This requires more sophisticated equipment, enhanced encryption protocols, and appropriate training to manage complex communication interfaces.
This integration also transforms the nature of missions. Units can move greater distances, with fewer constraints on proximity to command centers, while remaining connected. Improved security levels reduce the need to expose troops to maintain communications, resulting in better protection for personnel in the field.
The collection of operational data is increasing exponentially, but it also poses challenges in terms of processing and analysis. Command centers must have infrastructure capable of absorbing and processing vast volumes of information from multiple sources without causing bottlenecks or critical delays.
Strategic advantages and future implications
BLOS communications offer major strategic advantages. They enable dispersed forces to maintain tactical cohesion and shared battlefield awareness. This reduces reaction time and increases the effectiveness of decisions in the field, while limiting the exposure of forces to hostile actions.
In the future, BLOS systems are expected to evolve further with the introduction of technologies such as artificial intelligence-based communication networks, space-based optical links, and nanonetworks, offering even higher levels of bandwidth, resilience, and autonomy.
Forces that master these technologies will have significant information superiority, which is essential for high-intensity or asymmetric operations. The pursuit of these innovations will largely determine the ability of militaries to operate effectively in contested and highly stretched environments, while minimizing risks to their units.
Sources
Breaking Defense, How warfighters communicate when their missions are beyond visual line of sight.
Wikipedia, Link 22.
Wikipedia, X Band Satellite Communication.
Wikipedia, Battlefield Airborne Communications Node.
Elistair, Tactical Communications: the Role of Tethered Drones.
MSS Defense, Battlefield Connectivity: Advanced Technologies for Military Superiority.
Defense Advancement, Beyond Sight Unmanned Military Communication Strategies.
Annales des Mines, Military Satellite Communications.
War Wings Daily is an independant magazine.