Firmware updates (FUOTA)

Dryad updates firmware in Silvanet Devices using FUOTA (Firmware Update Over the Air). Update times vary depending on device energy levels and communication strength between devices.

About FUOTA

FUOTA is a standard for distributing firmware updates to many devices as the same time in an efficient and secure manner.

The Silvanet Cloud uses LoRaWAN which supports FUOTA. Updating Wildfire Sensors use End-to-End 128-bit AES encryption.

Overview

When the firmware needs updating, Dryad Engineering uses FUOTA (Firmware Update Over The Air) to send updates simultaneously to specific Silvanet devices in a Site from the Silvanet Cloud.

FUOTA uses Multicast as it is the most efficient and secure method to update a Site's firmware. During an update, the LoRaWAN Network Protocol is temporarily switched to allow two-way communication. Firmware is then updated using a chunked image transfer (no compression).

Updates are sent in data packets of a restricted size and then are reconstituted in the Silvanet devices before an update is done.

• Border Gateways: If the firmware in Silvanet Border Gateways require updating, Dryad sends a command for the Silvanet Cloud to update Border Gateways.

• Mesh Gateways: If the firmware in Mesh Gateways require updating, Dryad sends a command for the Border Gateway(s) to update the Mesh Gateways.

• Wildfire Sensors: If the firmware in Wildfire Sensors require updating, Dryad sends a command for either Border Gateways or Mesh Gateways to update the Wildfire Sensors.

About updating Border Gateways

When Silvanet Border Gateways require firmware updates, large file transfers are successfully made securely and reliably even with eventual interruptions of power supply and, consequently, sensor operation.

Scheduling FUOTA

The Wildfire Sensors come with a factory install of firmware. If this version of the firmware is not the latest, Dryad engineering checks the current firmware version and updates are scheduled, sometimes during the Calibration phase of the Sensors.

Notifications

Dryad engineering notifies the customer before performing any firmware updates to a Silvanet deployment.

Update times

The update times vary depending on a number of factors.

• Number and type of Silvanet devices to be updated.

• Connectivity strength between the Silvanet Wildfire Sensors and Mesh Gateways or between Mesh/Border Gateways. For more information, see Connectivity is not optimal.
• Full or charging status of a Silvanet device, which reflects the supercapacitor energy storage levels (high vs low energy storage). For more information, see Charging is not optimal.

To cope with low power and the various regional regulatory requirements, both the downlink fragment size as well as the periodicity are highly configurable allowing for stretching a FUOTA process to a week or more.