Hello,
We have experience with IoT project and we would be able to deploy the network requested using a raspberry pi as the fog node (working as the gateway).
We would be able to connect the nodes to the raspberry pi using one of the multiple interface types (such as wifi, bluetooth, or others).
All of the data collected by the raspberries would then be uploaded to the AWS server cloud, and in the case any of the fog nodes (raspberry) looses it's internet connectivity, the data can be stored and sent back again when the internet connection is restored.
For more details please contact us, and we would be happy to help you out with your requirements.