System Design: Design an AirTag system.

To design an AirTag system, I would first clarify requirements such as the range of the tracking signal, the number of devices to be tracked, and whether real-time notifications are necessary. Assuming a scenario where an antenna detects if a tagged device leaves a specific area, I'd define a message schema for the antenna to broadcast device presence information. This schema would likely include a unique device identifier and a timestamp. The system would need to handle signals from multiple antennas and potentially aggregate data from numerous devices. Since push notifications aren't a requirement, the focus would be on efficient data collection and storage, possibly using a distributed database to manage device locations and a backend service to process this data. A potential architecture could involve antennas sending data to a central server via a reliable protocol like MQTT, which then processes and stores the information. For scalability, this server could be a cluster of microservices.