## 3 The Proposed Scheme: Threefold Functionality
### Threefold Functionalities  
As depicted in Section 1, the key 3 FFs help to reduce or overcome the effect of this health emergency pandemic. The WHO has also issued various guidelines regarding the implementation of these 3 FFs. In-person implementation is slow as well as risky for people involved in it. So, UAVs are the best alternative to perform the 3 FFs, as shown in Figure 2. Sanitization of disinfectants at the locations which are highly infected (red and orange zones) with COVID-19 is of utmost importance to reduce the effect of the pandemic. Agricultural drones can be used for sanitization. Another way to minimize the effect of the novel pandemic is social distancing, which aims to reduce in-person contact (i.e., between normal and infected persons) [8]. Social distancing can be monitored from the aerial view with the help of UAVs and generate an alarm in case people violate the specified norms (maintain 6 feet distances). The third functionality is the inspection of people's body temperature and heart rate, which are the basic symptoms of coronavirus. Healthcare drones equipped with infrared cameras can be used for this purpose. So, different types of drones can perform 3 FFs, reducing risk, saving cost, and with high precision. The detailed description of the functionalities and their controlling body are explained in Section 4. Before delving into the proposed scheme, we analyze some potential challenges to implementing the 3 FFs in our proposed scheme. The challenges are aligned as follows.  
* _UAV data management_--In our 3 FFs, we consider social distancing and thermal inspection of regions by UAVs. It would require high-end image processing algorithms, which could drain the useful battery of UAV swarms (grouped UAVs) by a considerable fraction. Thus, it becomes crucial to offload important tasks to nearby edge servers, which run federated learning (FL) for task learning. This would save essential battery consumption, and the UAV network lifetime would increase drastically.
* _Non-stationary frames_--To effectively realize the 3 FFs, we assumed that persons (objects under consideration for thermal inspection, or social distancing) might be present in a moving frame-of-reference (FoR). For the persons, they are stationary, but for UAVs (outside the moving FoR), the motion is relative. Thus, the persons are moving, and we require a geo-fencing operation to locate the person in a moving FoR. In this case, we divide our FoR into coordinate frames (North, South, West, and East) and find the relative location of a person in the coordinate frame through a GPS tracker (which is installed in the personal application). We form a revised bounding-box estimation based on moving FoR to form the position estimate.  
* _Blockchain for COVID-19 vaccine registration and supply management_--Regarding the supply of COVID-19 vaccines after detection, the governance layer would raise the requirements of vaccine distribution to the nearest medical centers, which can deploy ground logistics (or UAVs) to carry the vaccines, maintaining the cold-chain process. The recent literature by authors in [6; 37; 38] indicates the use of blockchain for transparent monitoring and distribution of vaccines at the ground level.