|
Getting your Trinity Audio player ready...
|
Reading time: 8 minutes
What You Will Learn
- What is the Importance of Datalinks in UAS and how it’s a crucial component.
- What are the two main communication methods for UAV datalinks.
- Learn about the typical frequency ranges for RF drone communications (433 MHz to 5.8 GHz) and the trade-offs between range and data throughput.
- Discover how advancements in 4G and 5G technology are being utilized for drone communications.
- Understand the limitations of RF communications, particularly the need for line-of-sight and how cellular connections enable BVLOS.
- What is Data Throughput and what are Latency Benefits
- You will understand the advantages of cellular bonding in terms of redundancy and resilience.
The datalink is one of the most essential components of an unmanned aerial system (UAS), providing command and control for the operator as well as allowing the aircraft to send telemetry and payload data back to base. In this article we will look at and compare two communications methodologies that can be used to establish UAV datalinks – the commonly-used RF (radio frequency), and cellular bonding.
Before we continue, a note on terminology – although cellular communications are also carried out via waves in the radio frequency portion of the spectrum, the term “RF” is often used as a shorthand for non-cellular and non-SATCOM communication methods.
RF drone datalinks for commercial systems most commonly fall into certain portions of the spectrum that lie between 433 MHz and 5.8 GHz. Many of these bands are labelled as ISM (industrial, scientific and medical), meaning that they can be used without a separate radio operator license. In general, RF communications have a tradeoff between range and data throughput – low-frequency, long-wavelength signals can travel further but carry less information, and higher frequency, shorter-wavelength signals have a greater data capacity but their propagation distance is much less.
With the advent of 4G and 5G technology, cellular drone communications are beginning to be explored as a potential alternative. To improve further on the capabilities provided by a single link, cellular bonding technology can be incorporated into a drone’s communication system. Cellular bonding combines two or more cellular links, either from the same or different providers, allowing drones to aggregate the capacity of the combined links and to use them for redundancy.
Table of Contents
Range considerations and BVLOS
One of the main disadvantages of RF communications is range. RF datalinks require line of sight between the drone and its GCS (ground control station) or controller, meaning that long-range drone operations can be thwarted by factors and obstacles such as buildings, mountains, and the curvature of the Earth. RF range is also dependent on transmission power, and getting the most out of a datalink, especially a high-frequency one, may require a SWaP (size, weight and power) budget that is out of reach for many smaller UAVs.
A cellular connection allows a drone to operate as far away from its control station as required, as long as it is within range of a cell tower belonging to one of its networks. This unlocks truly BVLOS (beyond visual line of sight) applications without the need for a SATCOM terminal, which can often be large and bulky and requires an expensive subscription service to use.
As cellular bonding allows you to install SIM cards from multiple providers, this provides an additional range advantage, as it allows the drone to continue operating over a wide geographical area that may not be served by a single provider.
Spectrum crowding and interference
As the number of wirelessly broadcasting devices continues to increase, spectrum crowding has become an issue, leading to interference as vast numbers of devices all try to use the same frequencies at the same time. This is particularly an issue with the ISM bands, on which many commercial and civilian drones operate.
The vision of future smart cities and connected landscapes includes large numbers of drones and robotic vehicles all operating within a busy urban landscape, and wireless RF systems alone will hit their limit in trying to support this vision. Cellular connections can help solve this problem, and 5G looks particularly promising with its theoretical capacity of a million mobile devices per square kilometre.
Data throughput and latency
Cellular communications can provide faster data speeds and more throughput than RF datalinks, with 5G potentially delivering up to 10 gigabits per second. This makes them ideal for many modern data-intensive streaming drone applications such as ultra-high definition video and the transfer of massive amounts of mapping data. Cellular bonding is particularly advantageous, as it can aggregate the capacity of all connected datalinks, providing more bandwidth for data transfer.
5G also provides latency of as little as 1 millisecond. Rapid response times on this level could be a game-changer for autonomous BVLOS drones, which require features such as hazard recognition and collision avoidance to be as fast as possible.
Redundancy and resilience
One of the major advantages of cellular bonding is the built-in carrier diversity. Network conditions and coverage may change over time and as you move from area to area, and cellular bonding allows the drone to seamlessly switch between connections when signal strength is diminished or when networks are congested.
Having multiple connections for redundancy is also crucial for BVLOS operations. These operations are highly regulated in the vast majority of countries around the world, and aviation regulators will only approve BVLOS drone flights if constant uptime can be assured. Incorporating a reliable failover mechanism into your BVLOS drone platform is therefore essential to getting it off the ground.
A tried and tested cellular bonding solution for UAVs
Elsight’s Halo connectivity platform is ideal for exploring the potential of cellular bonding technology as an alternative to traditional RF drone datalinks. The low-SWaP solution can be provided in an OEM form factor, enabling deep integration with your drone platform’s RF communications system.
The 5G-capable Halo can aggregate up to four unique cellular datalinks from multiple providers, allowing you to take advantage of the enhanced reliability and redundancy of cellular bonding communications. Halo has also received FCC and CE certifications, allowing it to be freely deployed in the United States and in Europe.
To find out more about harnessing the advantages of cellular bonding for BVLOS drones with Halo, please get in touch!
FAQs
1. How does cellular bonding work, and how does it compare to traditional RF datalinks?
Cellular bonding combines multiple cellular networks into a single logical link, routing traffic across the best available connections and eliminating a single point of failure. Unlike traditional RF datalinks, which require line-of-sight and operate on limited spectrum, cellular enables beyond line-of-sight coverage using existing infrastructure. RF is effective at short range, while cellular bonding supports longer-range operations with higher resilience and scalability.
2. What are the SWaP and integration requirements for adding Elsight’s Halo to my UAV?
Halo is designed as a low-SWaP embedded module that enables continuous connectivity without compromising endurance, payload capacity, or power budget. The compact, 93-gram, palm-sized hardware has low power consumption and integrates via standard interfaces into the drone’s communication stack. It supports multiple SIMs and RF inputs, enabling multi-network bonding without significantly impacting payload or flight time.
3. What performance (range, throughput, latency) can I expect from cellular bonding versus RF in real-world conditions?
Traditional RF links offer predictable low latency and throughput at short ranges but are limited to line-of-sight conditions and can degrade in congested spectrum environments. Cellular bonding can significantly extend the operational range, with higher throughput and variable latency depending on network conditions. The multi-link bonding improves reliability by rerouting traffic when individual links degrade.
4. How do the drone switches seamlessly among multiple SIMs during flight?
The Halo communication platform aggregates multiple links from different carriers into a single logical connection. It continuously monitors link quality and automatically routes traffic across the best-performing links. Packet-level switching occurs in real time, with no manual intervention and no interruption.
5. What regulatory steps and documentation are typically required to get BVLOS approval?
Operators must demonstrate reliable C2 connectivity, including redundancy, latency, and failover performance. Documentation should include flight testing, link performance data, and contingency procedures. Regulators focus on proving continuous control across the full mission profile, especially in degraded conditions.
Related Content
