Single SIM vs Multi-SIM
Drone Connectivity

When considering the cost, weight & range of C2 systems for drone BVLOS operations, mobile connectivity is the optimal solution, as has also been proven in a recent joint FAA-Verizon study. Choosing to base your drone C2 around mobile networks is a good starting point, but for truly safe and secure connectivity to enable your BVLOS drone operations, using a single SIM solution is not suitable.

Single SIM vs Multi-SIM

In a single SIM solution, you are only able to connect to a single specific network, choosing between either 3G, LTE or 5G on that network, using a single band and without the ability to seamlessly change mid-flight should circumstances require.

A single SIM also has zero redundancy or backups should it experience network issues or a drop in connectivity due to technical issues, entering an area with low connectivity or reception, or even an area with good reception but which is overloaded with many users trying to use the same cell all at once.

A multi-SIM solution, on the other hand, provides the redundancy needed to maintain constant connection to your drones, especially when operating BVLOS, even in the case where one network becomes unsuitable or unusable.

Single SIM
  • Single network
  • No redundancy
  • Frequent connection loss
  • Unstable C2 connection
  • Not recommended by regulators
  • Unsafe drone operations
Multi SIM
  • Multiple networks
  • Up to triple redundancy
  • 99.98% connectivity uptime
  • Unbreakable C2 connection
  • Recommended by the FAA
  • Safe drone operations

RF environment: Reception holes in the sky

Source: Qualcomm

Cellular networks are largely optimized for users and devices at ground level. This means that the RF environment at the altitudes that drones typically fly at is very different. According to research performed by Ericsson, a major factor affecting the RF environment experienced by drones is the radiation pattern. Most cellular towers utilize directional antennas, which are designed to radiate as much power as possible in one particular direction, towards the ground.

In addition to this main, downward-facing radiation lobe, these directional antennas also create side lobes of radiation. These lower-power emissions, in directions that are usually not required for the main purpose of the antenna, are what drones flying above a certain altitude will be using to maintain connectivity. The nature of these side lobes means that the pattern of cells the drone may connect to is much more scattered than on the ground.

What does this mean for drone operations? When flying a drone connected to one particular cell via a side lobe, the drone may suddenly experience a massive drop in signal strength as it moves through the air and outside of the current side lobe (see image). This in turn, results in a drop in communications before handover to another cell or side lobe can be completed.
It is specifically for situations like this where a single SIM solution is not suitable, and a multi-SIM solution, like the Elsight Halo is required.

BVLOS drone operations: Prioritizing, monitoring and controlling data streams

During BVLOS drone operations, a large amount of data is sent over the network, including telemetry, C2, video and more. The connectivity solution needs to determine what of this data is critical and what is of a lower priority. When using one SIM card, there is no way to prioritize at all, and there is no redundancy. If the connection is disconnected, the entire data stream is lost, including the most important data packets. A multi-SIM solution like the Halo provides redundancy over the most important data, allowing to split traffic over multiple streams, leading to a speedier transfer.

The Halo: the standard C2 solution for BVLOS operations

Halo is the standard C2 solution for BVLOS operations, a purpose-built solution that supports multiple network providers, as well as RF and SatCom, and uses automatic link monitoring to ensure absolute connection confidence. Utilizing up to four different cellular links from multiple network providers, Halo monitors all available connections and leverages the best possible network at any given time and place should network strength decrease on one of the networks in use. Halo uses 6th Sense, an AI-powered cellular bonding algorithm to aggregate the bandwidth of all usable connections into one robust and cybersecure link.

Not a failover solution

In standard fail-over solutions, the device completely disconnects from the primary link before it is able to begin using the secondary link, and vice-versa – remains on the secondary link until it disconnects, even if a stronger network is in place. The same happens with E-SIMs, where a complete disconnect occurs before a new network can be connected. With the Halo, disconnects don’t happen. Even in areas of low network strength or other problems with the network, transfers between the networks are all done internally using the 6th Sense algorithm, allowing Halo to seamlessly steer traffic between networks, links and carriers, while using them all at the same time.

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