## 4 Industrial Applications  
WuR technology has a wide range of applications in industry, health, and for the environment. Several use cases were analyzed [21] in the fields of remote environmental monitoring in rural applications, asset tracking in logistic supply chain, and medical applications for human-body monitoring. These application areas are detailed in the following list, with three new areas: source discovery, process monitoring, and RFID improvements. * Remote environmental monitoring: Many remote environmental monitoring applications currently use LoRa, which can be upgraded through the use of WuR. Using a custom DC-MAC protocol [25], the energy consumption of LoRaWANs can be reduced, even allowing them to be powered entirely by energy-harvesting systems. This indicates that a large portion of current LoRaWAN applications can leverage WuR technology to reduce their consumption and increase their battery lifetime. Future IIoT 5G applications can also be equipped with WuR [60], benefiting from its advantages in terms of energy consumption and reactivity. The use of UAV-aided data collection Section 3.4) is also especially fit for this kind of application. * Medical applications: New developments can use WuR-enabled devices to reduce their energy consumption and take advantage of on-demand communication. WuR-enabled smart lenses [61] can be used to monitor biomarkers in tears, which could find use in the monitoring of worker safety in hazardous industrial environments. * Asset tracking: Asset tracking and localization can be improved using efficient and precise methods using nanodrones, especially in open industrial spaces [62]. The BATS protocol [63] provides a method of tracking wildlife and cattle, which can serve as a basis for improved asset tracking. Sensor networks embedded in concrete or other materials [64] can benefit from the increased lifetime and autonomy provided by WuR. Pairing this with on-demand data retrieval and energy harvesting techniques would enable nodes to perform more complex measurements and data processing tasks. * Source discovery: A novel application of WuR is source localization. Using selective wake up, the source of a sensing observation (e.g., toxic gases) can be found [65]. Industrial safety monitoring would benefit from this application. * Process monitoring: Communication between machines in industrial processes is essential; in the context of the Green IoT, the energy consumption of communication must be reduced while maintaining reactivity. WuR was also proposed as a solution to reduce the energy consumed in machine-type communication (i.e., M2M), in combination with neural networks that predict traffic patterns in MTC networks [66]. * RFID improvements: Using WuR, many challenges faced by RFID technology could be overcome (Figure 7). The inflexibility that is inherent to RFID is resolved by the potential of integrating a WuRx into any device. The relatively high cost of the reader can be mitigated by the ability of WuR-capable devices to use another protocol for main communications, which could act as a WuS for other devices [25]. To prevent message collisions, identity-based WuS addresses specific devices, whereas content-based WuS [48] retrieves only relevant data. Additionally, dedicated WuR anticollision algorithms [43] may be used. The range heavily relies on both frequency and energy consumption (Section 3.2). However, implementing multihop schemes, either with dedicated cluster heads [67] or without cluster heads [68], can effectively mitigate the issue. The use of energy harvesting in a device that is WuR-capable is not restricted by the decline in RF energy, which rapidly diminishes. The distance is regulated by the emission power. A wide range of options is available, depending on the application (Section 3.3). Smartphone support may be lacking, depending on the radio used. In applications requiring such support, Wi-Fi can be used, or either the Bluetooth primary radio or WuRx is preferable, relying on the recent IEEE 802.11 ba amendment to WLAN [69].