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-boarders missions, drones have evolved into commercial and industrial platforms operating in many different residential industries.
From agriculture to security automated missions, through different levels of inspection tasks, mapping, surveillance and up to delivery of goods and medical aids, drones are playing a major and 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 environment is so challenging that a stable and a 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 and these systems are called UTM (Unmanned Traffic Management) systems.
The dynamic nature of drone’s operation should be looked at with a ‘network’ planning perspective rather than a ‘link’ based perspective. All drones are utilizing 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 being used also by other platforms such as Wi-Fi systems, the major obstacle for a reliable communication is interferences. The larger the number of drones in a given area is, the more fragile each link becomes due to other systems inferences which is a significant challenge for interoperability of multi-drones in a given environment.
If we take, for example, the delivery market, which is one of the most complex drone application 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 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. The overall requirements though from a drone communication system operating in a crowded sky must include dynamic configuration, fast responding to changes and transparent to the user as eventually, the entire operation will be fully automated from takeoff to landing.
There are different solutions that overcome these and other challenges, some relates to the core technology utilized by the communication systems itself, for example features which can 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 from one hand and greater immunity to interferences by switching frequencies in-flight from the other 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.