7.2 Design Architecture

The following chapter provides details about the design architecture, data flows, and specific mechanisms of the SBDT feature.

7.2.1 Sidewalk Data Transfer Supported Flows

A successful file transfer (for the purpose of OTA or generic file) requires complex coordination between devices, device firmware, network connectivity, and cloud. The file transfer architecture is chosen to ensure that devices receive the latest file/updates more efficiently and that the process saves both time and processing effort and needs to be scalable to handle fleets of devices. The architecture also depends on the devices themselves (WAN vs PAN, internal policies) and the availability of the gateways as that dictates the file transfer/OTA flow that can be used to efficiently deliver the updates to the device.

Our approach emphasizes file integrity, safeguarding against image corruption end-to-end during file transfer. The architecture’s flexibility is evident in features like real-time transfer status monitoring, allowing users to track and confirm successful updates. Additionally, the capability to schedule file transfers at a predetermined time optimizes network usage.

The diagram below demonstrates the current support flow of Sidewalk bulk data transfer by using the cloud driven flow over the Sidewalk BLE connectivity. The current flows doesn’t require any Sidewalk Gateway involvement as it is treated as pass through.

fig 7.1 End to End Architecture for SBDT

7.2.2 Messaging

The end to end feature uses a combination of application layer and network layer messaging to deliver the file from the developer application to the end device. All the down link and uplink messages are encrypted and sent uni-cast to each device. The application layer messages are control and handshake messages between the application server and the device and the network layer messages are the data transport messages in the Sidewalk file transfer between the network server and the device.

7.2.3 File Transfer Delivery Mechanisms

The (SBDT) feature incorporates a file transfer protocol designed to handle down link file transfers between cloud device and end nodes on the Sidewalk network. The file transfer is initiated by the developer’s application when it uploads the File into an S3 bucket and starts a File transfer session through the application server using the AWS IoT FUOTA APIs.

Cloud-to-device transfer are initiated through a File Updates Over The Air (FUOTA) task API, triggered by the cloud application service.

7.2.3.1 Cloud Driven Delivery

For this mechanism, files are delivered to reachable devices as soon as they are uploaded and triggered from AWS IoT Core for Amazon Sidewalk. The cloud immediately attempts to transfer files to target devices that are available at the time of release and devices that are constrained like performing critical activities, low on battery, flash and RAM limited will receive the files the next time they become available. This allows us to deliver to targeted reachable devices and at the same time avoid disrupting active devices.