Efficient OTA update of ground devices on a LEO constellation
The ability to update content (e.g. firmware) in IoT and other satellite connected ground devices is a necessity to keep offering competitive features to customers and for bug-fixing and improvements.
On satellite networks the update of ground devices is most efficiently done by broadcasting to all devices in parallel, minimizing the satellite transmission time. Certain content updates can be too large to complete during a single satellite pass. Such updates will take multiple satellite passes to receive the complete update leading to a complex situation where devices end up missing different parts of the update. At the final phase of the transmission most devices will be wasting time and power looking for the missing parts (a classic example of the Coupon Collectors Problem).
The solution
Steinwurf has solved this problem by coding the update so every data packet received by the device contributes to the completion of the transfer. In this way, the transfer of the update is complete when enough data packets have been received. I.e. each device just needs to receive a fixed number of packets and will never end in a situation where the device waits for a specific data packet, minimizing the time for and resources required to broadcast an update to all devices.
This is demonstrated in the below animation where an update is sent to a population of ground devices using two different approaches:
Uncoded – where each device needs to receive each and every part of the update at least once, relying on chance to hope devices receive new parts of the update during each satellite pass, and
Using the OTAcast algorithm – where each data packet received is useful.
Even with a small file (split into 100 packets) and a few ground devices (15) the simulation shows that all devices quickly receive the complete file using the OTAcast solution, whereas most devices waste time waiting for their missing parts, when packets are transmitted uncoded. The improvement will be even greater if the number of packets to be transmitted is increased or the population of ground devices is increased.
Use cases
In addition to e.g. firmware updates, the OTAcast solution is equally well suited to other broadcast applications, where data needs to be sent to a population of ground devices, e.g. map updates (weather, ice), broadcast of intelligence information, updates of media files in crew welfare solutions, updates to AI-coefficients in feature extractors etc.
If you want to experiment with our solution - or have a chat about how the solution can be licensed and integrated into your products, please do get in touch.