The types of data exchanged between a device and the cloud are application, user, or device management data.
Application or user data are processed measurements gathered from the sensor data by the device. For example, processed data that has gone through a machine learning model.
For sensor applications, you should transfer large amounts of data over the air rarely instead of small amounts often to save on power and network data costs. nRF9160 can provide the application with a collection of the connectivity statistics. This enables tracking of the amount of data transmitted to or received by the device, and helps you in optimizing the network traffic. Mobile Network Operator (MNO)s also provide detailed per-SIM data usage statistics, often in real-time, which allows you to monitor data usage without needing to implement reporting in the firmware.
Device management data refers to the state and configuration of the device. This includes battery level, device health, location, device behavior configuration (for example, switching sensitivity on a motion sensor), and Firmware-Over-The-Air (FOTA) updates. FOTA images are 2-3 times larger in size compared to the other control messages. To limit the time the radio needs to be powered on, it is recommended to suspend all other operations and use all resources on the firmware update. It is also highly recommended to use the LTE-M technology (if available) when doing FOTA to benefit from the higher throughput of the technology. Use the connection parameters evaluation feature in nRF9160 to check the quality of your connection before doing a FOTA to avoid unnecessary high-power consumption.
For a low-power device, it is important to restrict how many cloud services you are connected to at a single time to avoid the added overhead of connecting to several cloud connections. You should strive to limit the number of cloud connections from your device to one and instead focus on cloud-to-cloud services. This means you can have a secure connection to your specific cloud solution, and then gather other cloud services (for example, location services, FOTA services) from nRF Cloud through REST APIs, so you get the benefits from the services as well as the power saving/network costs on the device. In other words, let the cloud handle connections to several cloud services, not the constrained device.
Include the LwM2M carrier library in your application if your product will be certified with these carriers.