Extending NLOS Situational Awareness for Military and Defense Unmanned Systems

By Roee Kashi CTO | April 8th, 2024

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The Critical Role of Non Line of Sight (NLOS) Communication for Military and Defense

The importance of NLOS connectivity in military and defense applications cannot be overstated. Military operations often occur in complex urban environments, dense foliage, or rugged terrain, where direct line-of-sight communication is severely limited or impossible. Critical intelligence hangs in the balance. NLOS communication acts as a game-changer, extending the operational range for better situational awareness of unmanned systems such as drones/UAVs (Unmanned Aerial Vehicles) and UGVs (Unmanned Ground Vehicles). It ensures a continuous flow of information both via video and data, regardless of physical barriers, delivering situational awareness to coordinate operations and execute mission-critical tasks while saving lives.

Understanding Line of Sight (LOS) and Non Line of Sight (NLOS)

Line of sight (LOS) or visual line of sight (VLOS) communication systems rely on a direct, unobstructed path between the transmitter and receiver. In LOS conditions, the signal travels without encountering significant obstacles or obstructions. If an object blocks the view, it would be considered out of sight or an obstructed line of sight. While effective in open environments, LOS communication becomes impractical when obstacles impede direct transmission paths. Additionally, the earth’s curvature has been a limiting factor for lines of sight: as two objects move further apart, the earth will obstruct the LOS between them.

In contrast, non line of sight (NLOS) or BVLOS (beyond visual line of sight) communication systems illuminate environments where direct line-of-sight is not available or feasible. It may be due to various factors, such as terrain obstructions, buildings in urban environments, or simply, hostile conditions where the risk to life is much too great. Non line of sight (NLOS) communication transcends the constraints of geography, employing advanced techniques to maintain connectivity even in the most demanding situations. For unmanned systems, such as UAVs and UGVs, maintaining NLOS connectivity in complex environments unlocks many tactical advantages and can mean the difference between mission success and failure.

The NLOS Communication Challenges


While non line of sight (NLOS) connectivity unlocks a new era of unmanned system operations, it presents unique challenges that must be addressed to ensure safe and effective operation:

  • Always-on connection—Maintaining a reliable and unbroken connection is akin to having a lifeline for an unmanned system. Without it, control over the drone becomes compromised, jeopardizing mission objectives and potentially leading to safety hazards. Developing unmanned systems with robust, always-on communication systems is crucial for military and defense missions.
  • Transmission security or jamming — Malicious actors may attempt to intercept data streams or disrupt transmissions, potentially compromising sensitive information or even hijacking drone control and jeopardizing missions’ safety and success. Robust security measures are essential for safe operation.
  • Design efficiency—NLOS drone communication modules operate under demanding conditions. Their design must optimize efficiency across several parameters, such as compact size to fit into any drone, lightweight to enable longer operational time and range, and low heat and power consumption.

NLOS Range Extending Techniques

Drone technology in service for commercial applications has proved to work best when powered by public multilink cellular connectivity, enabling unmanned aerial vehicles (UAVs) to maintain communication and control uptime as they traverse different locations. These mobile networks serve as the backbone for drone communications, facilitating real-time control, data exchange, and situational awareness. When drone communication leverages a combination of widely available networks, including 3G, LTE/4G, and 5G technologies, they offer extensive coverage and high data transmission rates.

Drone operators constantly seek ways to improve communication availability, reliability, and data transmission capabilities. Some of the most employed methods include:

  • One singular cellular link: 3G, 4G, and 5G cellular networks enable drone NLOS operations. However, coverage may vary, especially outside urban areas, the transmission can be jammed, and there is no redundancy.
    Relay Nodes: Strategically placed relay nodes can extend the range of NLOS communication by receiving and retransmitting signals, effectively acting as intermediaries between the transmitter and receiver. In cases where the distance between communicating nodes is too far, multi-hop UAVs are required, introducing a joint optimization problem of the positions or trajectories of multiple UAVs as well as increased delay.
  • Mesh Networks: Mesh networks create a self-configuring and self-healing network topology, where each node can act as a relay, enabling signals to find the most efficient path around obstructions dynamically. Drones, for example, can establish a network amongst themselves, relaying signals and extending the overall reach. Yet mesh networks are costly and have higher power requirements as all the nodes must always remain active. They also introduce a forwarding delay that increases latency.
    Satellite Communication: Leveraging existing or dedicated communication satellites allows for long-range data transmission, even in remote locations. However, the satcom solution is typically expensive, with high latency and low bandwidth. It requires open skies and has no redundancy.
  • High-Altitude Platforms (HAPs): These unmanned aerial vehicles operate at extremely high altitudes, acting as airborne communication hubs and extending the range for lower-flying drones. Hovering at an altitude of 20 to 50 km, the critical challenge of HAPs is withstanding sudden wind gusts, resulting in temporary or total loss of communication.

Utilizing NLOS Drone connectivity in Military and Defense Applications

Drones are key in modernizing military operations, but more outstanding benefits for reconnaissance, logistics and combat may be derived from their type of connectivity used. Drones that utilize multilink cellular communication systems provide operators and command centers with real-time video, images, and sensor data for surveillance, situational awareness, and precise targeting. Military-grade drone connectivity typically employs encryption to secure communication links and prevent interception or disruption by adversaries. And just as important is the SWaP (size, weight and power) of the connectivity platform as the smaller it is, the more portable it is for use in remote areas.

The Roles of Unmanned Systems in Modern Warfare

UAVs and UGVs have emerged as indispensable assets in modern military and defense operations, offering unparalleled advantages in critical missions:

Intelligence, Surveillance, and Reconnaissance (ISR) in hostile environments or vast/rugged terrains deliver critical real-time intelligence and surveillance data, empowering strategic planning and informed decision-making to safeguard troops on the ground.
Coordinated strategic maneuvers utilize real-time intelligence to enhance the efficacy of joint exercise.
Logistics and resupplying frontline units employ unmanned systems to mitigate risk to human life while ensuring that troops are adequately provisioned, even in the most challenging operational environments.

Communication relay in areas where communication infrastructure is compromised maintains connectivity among various military units, facilitating seamless coordination and information exchange and ensuring continuous situational awareness.
The accuracy of electronic warfare is significantly improved with non line-of-sight visibility and situational awareness.
Search and rescue missions, locating lost or injured individuals, particularly in remote or hazardous environments are more effective given the transmission of video information from various sources to a command center.
Aerial asset inspection offers a swift and secure method for assessing the condition of military assets, enabling timely maintenance and ensuring operational readiness without exposing personnel to potential risks.

Unmanned Ground Vehicles (UGVs) are unlocking new potentials for armed forces in conducting semi-autonomous and fully autonomous reconnaissance missions. UGVs can venture into dangerous or hostile areas without putting soldiers at risk. They play a crucial role in detecting and neutralizing explosives and defending against nuclear, biological, and chemical (NBC) threats, keeping troops safe from these deadly weapons. UGVs also play a crucial role in supporting medical and logistics units, enhancing operational efficiency, and minimizing risks to human personnel.

The Benefits of Unmanned Systems in NLOS Missions

Robust non line of sight (NLOS) connectivity with a low SWAP offers far-reaching advantages for military and defense operations, empowering armed forces with a strategic edge and greater agility to dynamically adapt and swiftly respond to evolving threats:
Expand operational reach to maintain uninterrupted connectivity and information flow across vast geographical areas and harsh environments.
Informed decision-making processes based on enhanced situational awareness to accurately deploy resources and gain tactical advantage.
Minimize the exposure of human personnel in hostile or risky environments by significantly reducing the risks associated with conducting operations in challenging conditions.
Facilitate better coordination among various operational elements with situational awareness, enabling efficient joint maneuvers and mitigating the risk of friendly fire incidents.

Emerging Technologies for Reliable NLOS Communication

Continuous research, development, and investment in NLOS technologies with greater emphasis on resilience and adaptability is crucial to maintaining a strategic advantage and ensuring the safety and effectiveness of military operations.

Cognitive radio is an adaptive and intelligent system that dynamically adapts to the communication environment, selecting the best available frequency channels and modulation techniques to ensure reliable NLOS transmissions. By sensing and analyzing the radio frequency spectrum, cognitive radio systems can detect vacant channels and instantly move without causing any interference.

Software-defined radios (SDRs) offer a flexible and reconfigurable platform for implementing advanced communication protocols and techniques. By leveraging SDRs, NLOS communication systems can adapt modulation schemes, coding rates, and frequency bands in real-time, optimizing performance based on specific operational conditions. SDRs also enable the implementation of cutting-edge technologies like cognitive radio, beamforming, and mesh networking, further enhancing the capabilities of NLOS communication systems.

Quantum communication is an emerging field that leverages the principles of quantum mechanics to enable secure and tamper-proof communication. Technologies like quantum key distribution (QKD) and quantum cryptography can provide unprecedented levels of security for NLOS communication systems, ensuring the confidentiality and integrity of transmitted data, even in the presence of sophisticated adversaries.

Bonding technology, also known as link aggregation or channel bonding, is an innovative approach that combines multiple communication links to create a “pipe” of high-bandwidth, robust connectivity. The technology aggregates all the channels’ quality, guaranteeing constant uptime and connection between drones and ground control stations automatically. In NLOS communications, bonding technology can leverage various wireless communication technologies, such as cellular networks, satellite links, and tactical radios, to establish a robust and redundant communication channel.

Elsight’s Halo: Pioneering NLOS Communication Confidence for Military Drones

Standing at the forefront of NLOS communication innovation, Elsight ensures uninterrupted and secure unmanned systems communication in military and defense applications. Elsight’s Halo merges multiple communication links using a cutting-edge bonding algorithm to create a versatile, network-agnostic solution ideal for NLOS missions. With a capacity of up to four SIM cards across different carriers and technologies (3G, LTE, 5G), SatCom, and proprietary RF, Halo smartly navigates through “dead zones” to achieve uninterrupted NLOS communications. It automatically aggregates all available links to maintain robust, mission-critical connectivity.

Elsight’s Halo provides:

High bandwidth and redundancy: Halo seamlessly fuses multiple IP links (Cellular & RF) in a given location to maintain a robust network tunnel that continuously transmits vital data, including video, audio, and telemetry.

Enhanced security: Halo safeguards mission data and controls against cyber threats using advanced encryption, data-splitting, and multi-link transmission, protecting the data. Jamming is typically not an issue as the enemy would have to jam multiple systems, which also closes the channel for their own use.

Failover protection: Halo’s sophisticated algorithm aggregates all the channels for uninterrupted data transmission.
Low-SWaP design: Halo’s compact, lightweight design and low power consumption offer unparalleled versatility for easy portability and set up with most systems, regardless of size or form factor.

With Elsight’s connectivity confidence, military forces can reduce the risk of its personnel with unmanned systems while benefiting from extended situational awareness, and execute missions with unparalleled efficiency, even in the most challenging NLOS scenarios.

Unlock Elsight’s NLOS connectivity for military and defense UAVs and UGVs.

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