Firmware updates (FUOTA)

Firmware in Silvanet Devices is updated over the air (FUOTA) which requires variable times depending on how many sensors and gateways need to be updated.

When the current firmware and/or ML Model in a Site's Silvanet Border Gateways, Mesh Gateways or Wildfire Sensors require updating, Dryad Engineering uses FUOTA (Firmware Update Over The Air) to send updates via the Site's Silvanet Cloud simultaneously to the devices.

The Silvanet Cloud uses LoRaWAN which supports FUOTA and End-to-End 128-bit AES encryption. FUOTA is a standard for distributing firmware updates using Unicast (one-to-one communication) or Multicast (one-to-many communication). The Silvanet Mesh Network 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 updated using a chunked image transfer (no compression).

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.

Update times

Firmware update times are dependent on strength of device communication as well as supercapacitor energy storage levels. See below.

Scheduling FUOTA

Dryad engineering checks the current firmware versions of the sensors and if an update is required then three days are usually needed to send the updates to the sensors. This is because updates are sent in data packets of a restricted size and then are reconstituted in the sensor before an update is done.

Notifications

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

Factors affecting the length of time for FUOTA include:

• Strength of device communication (good vs poor communication)

• Supercapacitor energy storage levels (high vs low energy storage).

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 even to a week.