Reliable Operation in a Multi-Drone Environment
From their origin in the military space a few decades ago, carrying sophisticated systems and running remote, cross-boarder missions, drones have evolved into commercial and industrial platforms operating in many different residential industries.
From agriculture to automated security missions, through different levels of inspection tasks, mapping, surveillance and up to delivery of goods and medical aids, drones play a significant role in the next generation of automated and autonomous vehicles. The vision of multiple drones filling in the public sky, running various missions smoothly is slowly becoming a reality.
In fact, the actual operation of drones in such an environment is so challenging that stable and reliable communication with the drone during the flight is crucial for obtaining a safe mission. The infrastructure of such communication must be designed to provide carrier-class availability, ensuring control and telemetry signals are available in real-time and that critical data can smoothly flow between the drone and the operation control centers. On top of that, automated airspace management systems must guarantee full coordination between different vehicles using the same air space. These systems are called UTM (Unmanned Traffic Management) systems.
The dynamic nature of the drone’s operation should be looked at with a ‘network’ planning perspective rather than a ‘link’ based perspective. All drones utilize RF (radio frequencies) to communicate with their respective ground stations and they will eventually also communicate with each other.
As frequency bands and channels are scarce and are also used by other platforms such as Wi-Fi systems, the major obstacles for reliable communication are interferences. The larger the number of drones in a given area, the more fragile each link becomes due to other system interferences, which poses a significant challenge for interoperability of multi-drones in a given environment.
Communication Challenges in a Multi-Drone Environment
If we take, for example, the delivery market, which is one of the most complex drone applications as it requires running multiple drones in parallel, by different service providers, we can list some of the related communication challenges.
- Near-End Interference – Interferences generated by other drones launched from the same or nearby network operating centers.
- Far-End Interferences – Interferences generated closer to the landing area, from Home Routers such as WIFI or other systems operating nearby such as agriculture drone systems.
- In-Flight interferences – From other drones flying nearby, Radio Control (RC) recreational vehicles.
- BVLOS operation – Flying in an urban area can generate signal loss and fading due to high-rise buildings and other obstacles.
- Terrain Obstacles – Rural operation may introduce signal fading due to Fresnel zone blocking by a hilly terrain.
- Interoperability with mobile networks – Utilizing dual combined communication can increase reliability but must include a smooth switchover mechanism when the public network is congested or out of reach.
Each challenge can be discussed in more details and requires a different solution. However, the overall requirements from a drone communication system operating in a crowded sky must include dynamic configuration, fast response to changes and transparency to the user as eventually, the entire operation will be fully automated from takeoff to landing.
Solutions for Reliable Operation in a Multi-Drone Environment
There are different solutions for overcoming these and other challenges. Some relate to the core technology utilized by the communication systems themselves, such as features thatcan guarantee higher reliability due to diversity and redundancy. Others relate to switchover mechanisms between different technologies, utilizing the LTE/5G networks for long range urban operation for example. Minimizing interferences on one hand, and greater immunity to interferences by switching frequencies in-flight on the other hand, are also crucial for a secured safe operation.
By integrating and adopting such capabilities as a standard by the drone operator’s community, alongside with administrative and airspace usage coordination systems, we can overcome many of above challenges and guarantee a reliable and safe operation in a multi drone environment.