Fuente: WIPO "tomato" A shipment monitoring system includes a plurality of asset-affixed tracking devices, at least one gateway, and a remote server. Tracking devices store distinct identifiers and include a wireless communication interface, one or more sensors, a controller, and a log for time-stamped event data associated with a respective asset. The gateway receives tracking data, including identifier and sensor data, from one or more tracking devices and transmits the tracking data over a communications network to the remote server. The remote server aggregates tracking data from multiple tracking devices to provide shipment status information. In some embodiments, the tracking devices are implemented as labels or reusable trackers and support Bluetooth Low Energy, LoRa, or Wi-Fi-related communications. The sensors may include temperature or shock sensors, and the system may support route monitoring, alert generation, low-power operation, mesh relaying, and cryptographic integrity verification.