Applications of Flying Ad-hoc Network During COVID-19 Pandemic

The 2019 novel coronavirus (2019-nCoV), with a beginning stage in Wuhan (China), has spread quickly among people living in different nations and has affected more than 6 million lives. Researchers around the globe are trying to device a solution in the form of the vaccine but unfortunately, till date, there is no full-proof vaccine for 2019-nCoV. Most of the countries are adopting prolonged lockdown and social distancing strategies to counter this pandemic. Flying Ad-hoc Network (FANET) on the other hand, can provide several services such as the delivery of essential items, disinfecting common areas, surveillance, traffic monitoring, communication, temperature monitoring, etc. Availing such services using FANETs during Corona Virus Disease (COVID-19) outbreak is like a boon that can minimize the general problems of mankind to some extent during lockdowns. Nowadays, it is foremost required to deploy solutions that can automate the process of availing several services using FANETs and the same is attracting researchers in great demand. This paper has presented a brief survey of several applications of FANETs (especially UAVs and Drones) that can facilitate mankind in coping with the general problems during COVDI-19 outbreak and subsequent lockdowns. We hope that this survey has covered most of the applications of UAVs and can provide new insights into the research community.


Introduction
In FANET (Flying Ad-hoc Network), flying drones or UAVs act as hubs that communicate with each other when they fly in the air without any physical link. UAVs enable communication systems, cameras, and sensors. FANET is the special shape of ad hoc network in which nodes fly in the air, and even as flying within the air they can communicate with every other node, transfer the data and alerts between each other without any human expert and any physical network between the UAVs [1]. In Flying Ad-Hoc Network (FANET), the node known as UAV is connected in ad hoc mode is reviewed as the special form of VANET and MANET [2]. FANETs are created with the help of very small unmanned aerial vehicles (UAV) which is very reasonable in cost, fast to organize, and adaptable. These points make FANET and its nodes (UAVs) remarkable attractive innovation for many applications [3]. According to the World Health Organization's 134th situation report dated June 02, 2020, there are 6194533 COVID-19 confirmed cases globally. Out of these 6.19 Million cases, 0.37 Million has been deceased [4]. This pandemic enables us to re-examine how communities' governments and organizations around the globe can work with minimum or no physical contact [5]. Today, the frontline legends and warriors of the country are police, medical staff, doctors, garbage collectors, and private security guards. Technologies, for example, autonomous machines, GIS, Big Data, IoT, location technology, and artificial intelligence (AI) assume an expanding job in reacting to the COVID-19 pandemic. Nonetheless, in this war against this invisible rival, FANETs and its nodes assume a key job in helping specialists and individuals in different approaches to forestall the further spread of the coronavirus pandemic. This paper is arranged as follows: Section 2 is presenting the basics of the unmanned aerial vehicle and its types. Several applications of UAV and drones to cope with the COVID-19 pandemic are discussed in section 3. Finally, section 4 concludes the study with future directions.

Types of UAV
This enormous interest in drones has led to the development of different types of UAVs of various sizes and shapes to work in different responsibilities [9]. For this paper, four classes of UAVs are mentioned, that is the single rotor, multi-rotor, fixed-wing, and hybrid UAVs. Each of the UAVs has its merits and demerits that allow us to decide which one is most suitable for the application. Based on the activity to be performed, four types of UAVs [10] as shown in figure 1 are briefly discussed as follows:

Single Rotor
These UAVs have the core rotor for routing and a back rotor for route control. Typically, they can take off vertically and do not need airflow on the blades to move forward, however, the blades themselves produce the necessary airflow. Piloted helicopters are accepted in the aviation sector, but the unmanned version is not as trendy in the UAVs research group. The single-rotor helicopter can be powered with the aid of a gas engine for even longer dragging than multi-rotor. The most important positive point is that it may bring weighty payload (e.g. manipulator, sensors) during suspended IOP Publishing doi:10.1088/1757-899X/1099/1/012005 3 activities in a large outdoor area. The demerits of these UAVs are the danger of its large rotor, cost, and mechanical complexity.

Multi-Rotor
The UAVs in this category can be isolated according to the number of rotor blades. The most widely considered UAVs are hexacopter and quadrotor. Besides, octa-copters or tri-helicopters have been created. Typically, they can take-off and land vertically and need not airflow on the blades to forward, but the blade themselves create the necessary airflow. The multi-rotor can be utilized inside and outside and are quick and spry stages that carry out requesting military exercises. They can likewise float or move along a close-by target. The weaknesses of these types of UAVs are the flight time and constrained payload limit. Furthermore, the electrical and mechanical complication is commonly low.

Fixed-Wing
The fundamental standard of this type of UAV is an inflexible wing with a particular aerodynamic profile that can fly relative to the pickup created by the forward speed [11]. Route control is given by explicit control surfaces in the wings called rudder (yaw), lift (roll) and ailerons (pitch). The biggest advantage of this type of UAVs is their straightforward structures compare then other UAVs. Their aerodynamics helps in long flight distances and high-speed walks and movements. Besides, these UAVs can convey heavier payloads than multi-rotor, while the detriment of this type of UAV is the requirement for a runway to take off and land. Landing is likewise very critical to the secure retrieval of the UAV.

The hybrid
UAV is an enhanced form of Fixed-Wing UAVs. Hybrid UAVs can float and vertically take off and land [12]. These types of UAVs are still in the improvement phase as shown in Figure 1. Generally, UAVs with rotors are increasingly appropriate for applications like inspection and support due to float abilities and their deft moving. Then again, fixed-wing UAVs fit better in aeronautical reconnaissance and mapping of enormous zones from more noteworthy statures.

Applications of FANET
FANET devices have several applications in our real-life. This section will present some of the applications which are playing a vital role in coping with the COVID-19 outbreak. FANET applications are so vast and varying, but majorly classified into two categories viz. air to air communication and air to ground communication. On the other hand, FANET devices can be categorized according to the altitude of operation, size, speed of mobility, power requirements, topology requirements, etc. [13][14] [15]. Major applications of FANET are classified into six classes viz. establishing inspection and surveillance, public announcements, disinfecting common areas, delivery of essential goods, temperature measurement, and traffic monitoring as shown in figure 2. Nowadays, the COVID-19 outbreak has presented researchers the opportunities where FANET can perform its role ingeniously. Chamola et al. [12] presented the roles of such devices in coping with the COVID-19 pandemic. UAV's specifically drones can do most of the jobs for the healthcare sector in this outbreak. Reliable communication and security are the two main requirements of these devices. This section deals in presenting some of the tremendous applications of drones, UAVs, and other FANET in the COVID-19 outbreak.

Surveillance and Inspection
One of the main applications of drones is the inspection and surveillance in remote and hotspot areas (where COVID-19 cases are in masses). 2019-nCoV is so mysterious that it has affected many health workers i.e., Doctors, Nurses, Cleaning staff, Security staff, etc. With the help of drones, security personnel can track the activities, monitor unnecessary movements in hotspot areas without going to them. They can capture the images of suspected persons who are violating the precautionary guidelines issued by Governments from time to time. There are so many advantages of doing this kind of surveillance through drones i.e., preventing security personnel from being infected by COVID-19, saving fuel and other resources which are generally consumed during physical surveillance, any time anywhere surveillance, etc. In the absence of drones, police staff is worrying to go to hotspots, but being a part of essential duty, they must go. It is the duty of the Government also to prevent the security personnel from being affected by COVID-19, hence most of the governments are proving the facility of drones to their surveillance departments. Government authorities are revising their policies for the inclusion of several FANET devices to the COVID-19 task forces. Along with surveillance, security staff can instruct people about not to gather in masses, reducing person-to-person contact, the importance of social distancing, etc. They can even control the activities in the outreach areas as well as in public areas as shown in figure 3 (a) and (b).  Figure 3. (a) Security Personnel Inspecting Activities using Drones in Outreach Areas [13] (b) Surveillance by Drones at Public Places [14] Drones can even monitor the activities in these areas also where human intervention is very less. It takes too much time and energy to monitor these areas. One of the biggest challenges in implementing the drone-based surveillance to citizens is the violation of privacy rights. However, Governments are trying to comply with these rights by issuing guidelines on public interests.

Broadcasting Messages
Drones enabled with speakers are playing a key role in broadcasting messages, especially in the outbreaks. These drones can help authorities to some extent in sending their important messages, especially where communication channels are inoperable. During lockdowns, these drones can prove themselves as one of the biggest communication mechanisms. Municipal corporations can take advantage from these sky speakers enabled drones to communicate essential messages (i.e., information about the lockdown, updates about an extension of lockdown, which shops are permitted during a lockdown and which are not, health-related communications, implementation of social distancing and other precautionary guidelines, etc.) to the citizens under their localities. This type of communication can remove barriers among municipal corporations and the citizens because most people depend on TV-based communications; in that case, they usually didn't found updates about their locality especially in rural areas. Figure 4 (a) demonstrates the working of UAVs equipped with a loudspeaker for conveying public announcements and keeping people safer at their homes. Nowadays many countries including China, the US, Spain, Britain are using speaker enabled drones for communicating people in the COVID-19 pandemic.
China police, on the other hand, taking advantage of UAVs by putting aerial QR codes for scanning drivers coming to Shengzhen city [15]. The QR code is being scanned by the driver who is returning to Shengzhen for registration as shown in figure 4 (b). These UAVs has flown near highway exits or tollbooths so that every incoming vehicle should register themselves and police can track their movement in the city.  Notwithstanding communicating only, these speaker-enabled drones can also help provide essential communications, warnings during severe missions or rescue operations. While coping with disasters like floods, earthquakes, fire, etc. these drones can prove themselves to be efficient weapons in expansive, dense, and complicated areas. Despite these advantages during disasters and outbreaks, they can keep officials away from close contacts, thus avoiding any chance of being infected out of dangerous activities and ensuring them to discharge their essential duties with confidence.

Disinfecting Surfaces and Common Areas
As the number of cases of COVID-19 is growing exponentially, it is evident that most of the cases are due to surface contacts of common areas including tables, chairs, railings, door handles, lift buttons, public transport, shopping malls, etc. The mysterious 2019-nCov can survive from hours to several days on these surfaces depending upon the climate circumstances. For avoiding secondary transmission, it is foremost required to disinfect these surfaces and areas. Generally, disinfection can be achieved by two common ways viz. air disinfection and surface disinfection. Surface disinfection proved to be effective in coping with the COVID-19 pandemic as compared to air disinfection. However, air disinfections can provide psychological relief, emotional assurance that authorities are trying to cope with the situations and keep rodents away. Spraying drones can prove themselves to be effective amongst several mechanisms for air disinfection. They usually come in different varieties based on power and tank capacities. Figure 5 shows a general model of spraying UAV equipped with a small tank. Generally, a spraying drone can cover 100,000 m2 in an hour with a spraying tank of 16L. These UAVs can be easily operated and mobilized and keeps the operator away from getting infected, because there may be chances that sanitization workers may be exposed to viral infections while discharging their essential duties. Besides various advantages, air disinfection, on the other hand, is unable to prove to be an effective solution in the spreading of viruses [16]. An excessive spray of alcohol-based and other chemicals on air, vehicles and humans are very harmful, which needs to be stopped immediately. Public spaces may be disinfected with the help of spraying drones during the absence of people i.e., end of day or holidays. The use of agriculture-based sprays should not be adopted in any case because they are more harmful than air disinfectants.

Product delivery
Cargo drones are a special type of drones that can play a key role in the COVID-19 pandemic by delivering and supplying essential items such as household goods (i.e., milk, bread, and other grocery items), medical equipment's, medicines, etc. As many countries around the globe are trying to cope with this pandemic, they have forced lockdowns in some or all regions, marking some areas as hotspots or containment zones for restricting unnecessary movements and avoiding any chances of being exposed to viral infections. Especially in these areas, cargo drones prove themselves to be effective utility in resuming the suspended supply chain activities. Many countries are adopting this trending as well as contactless delivery during the pandemic. Enabling transportations of essential items through these drones can provide relief to both the consumers as well as suppliers. In the absence of these UAV devices, both consumers, as well as suppliers, feel stressful and as a result, they may take inappropriate action which may lead to exposure to viral infections. Despite several advantages, the use of these drones is not available and utilized at full scale in most of the countries. It is foremost required that Governments should focus more on these types of utilities especially during pandemics.
Besides transporting household and grocery items, these drones help deliver medical essentials from one place to another place as shown in figure 6 (a) and (b). GPS-enabled UAVs called autonomous UAVs can do this activity very efficiently if destinations are far from the source. Without GPS-enabled UAVs are also successful for contactless delivery of essentials. Some of the cargo UAVs can also be customized according to the size and specifications of items being delivered. SpiceJet (India's air cargo operator) is also planning to provide the fast as well as cost-effective delivery of essential goods, medical, pharma, and other e-commerce supplies [17]. An approval from the Director-General of Civil Aviation (DGCA) has already received to conduct the trials. Some of the countries like the USA, China, and Australia are already using these services particularly in red zones where physical movements are restricted to a large scale.

Temperature Monitoring
Out of several symptoms of 2019-nCoV, fever is one amongst them. During COVID-19 pandemic handheld contactless thermometers as shown in figure 7 are widely used and becoming so popular. Earlier, they were used to check the temperature of objects in industries. They measure temperature based on InfraRed (IR) radiations [19]. Contactless thermometers are playing an important role during the COVID outbreak because they are faster and easy to operate. Their accuracy depends on distanceto-spot ratio [19], which is the ratio of target size and distance of measurement. If someone is measuring the temperature of a hot surface in a cold environment, then the result averages the temperature of both hot surfaces as well as a cold environment. Also, the distance-to-spot ratio needs to be optimum. Un-trained health workers may provide inaccurate readings, that may lead to an increasing number of patients. However, temperature alone is not the only criterion to determine that a patient is suffering from COVID-19. In general, these handheld contactless thermometers are generally used to perform an initial screening by examining elevated temperature, which may be followed by some secondary clinical examinations. Nowadays, UAVs are also able to perform the initial screening by measuring temperatures. Temperature checking by UAVs can be classified into two categories viz. by contactless thermometers and by thermal imaging. Recently we have understood the working of contactless thermometers; thermal imaging, on the other hand, is a very popular as well as a powerful tool for measuring the temperature of objects as depicted in Figure 8 (a) and (b). Thermal cameras are responsible for measuring IR emissions emitted by objects and surfaces. Thermal camera-enabled UAVs need specialized firmware and need to be operated from a smaller distance, usually 2 meters for getting reliable readings. It is non-evident and still unclear that to which extent they can be helpful in this outbreak.
(a) (b) Figure 8. (a) In-house Temperature Measurement using Thermal Camera Enabled Drones (b) Out-House Temperature Measurement using Drones [13] To cope with the COVID-19 pandemic, a Canada based company 'dragonfly' is planning to develop 'Pandemic Drones' from their project called "Vital Intelligence" by collaborating with the Australian Defence Department and University of South Australia [20]. They aim to develop an intelligent UAV that can perform several tasks at once such as identifying cough, sickness symptoms, etc. and sending updates to a centralized server. The idea is to use thermal imaging along with several other sensors i.e., heart rate monitor, blood pressure monitor, etc. because thermal cameras alone cannot detect fever accurately.
Along with temperature measurement, some UAVs are nowadays powered with Deep Learning techniques for automatic analysis of human behavior. This type of behavior analysis can be limited to some specific activities which are related to COVID-19 symptoms i.e., coughing, sneezing, tiredness, etc. Figure 9 shows cough monitoring along with temperature measurement using thermal imaging enabled UAVs.

Traffic Monitoring
To overcome the limitations of traditional traffic monitoring, nowadays traffic police personnel are using UAVs to monitor activities in a city as shown in figure 10. During the COVID-19 pandemic, where several countries have enabled complete or partial lockdown, monitoring of traffic becomes a challenging task. There may be chances that security personnel can be exposed to viral infections while discharging their essential services. Also, there may be chances that due to lack of security personnel, Government officials may restrict the deputation of only a few of their staff members. UAVs on the other hand the capability to fulfill the gap of manpower shortage. Generally, large manpower and resources are required to monitor the activities of a city, but UAVs can do this activity in less amount of time as well as cost. They can also monitor the activities in narrow and congested streets. Even they don't demand complex infrastructure and training pre-requisites. They are easy to operate, lightweight, and convenient to use. Multiple UAVs of a city can be connected via a wireless IOP Publishing doi:10.1088/1757-899X/1099/1/012005 10 network for making a FANET, thus producing real-time monitoring at a single place. FANET architecture of such a network can vary from simpler to complex structures depending upon the layout of roads and the city. Besides several advantages these UAVs can have some drawbacks too i.e., creating air traffics, exposure to physical damages, getting injured with hobby drones, irritate citizens, etc. However, pandemic drones can prove themselves to be effective weapons in monitoring social distancing and other activities during the outbreak. Even, traffic police can take advantage of these UAVs to provide real-time traffic updates to the citizens for reducing traffic jams to some extent. One of the biggest applications of these UAVs is to quickly trace run-away patients from hospitals. During the quarantine period, few patients used to run-away because of stress and other mental problems. These patients can easily infect other people. So, to track these types of patients, UAVs can ease the task of searching. To enforce law and order during critical situations, UAVs can record the photographs and videos, which may be further used as proof to track and control culprits. Chmaj and Selvarj [21] presented several other applications of UAVs/ drones for facilitating distributed processing applications [22].

Conclusion
During the unprecedented COVID-19 outbreak, researchers are working hard to come up with technological solutions to cope with the crucial situation. FANETs have a tremendous set of IOP Publishing doi:10.1088/1757-899X/1099/1/012005 11 applications that can ease several tasks especially in a difficult time and can generate lots of revenue as an opportunity. In this regard, this paper has presented several insights into FANETs using real-life scenarios and examples. Drones, a special type of UAV can be combined to facilitate the distributed processing capabilities. Every node can provide its services directly or to the other member node in the network. However, there are still several open challenges that need attention i.e., the establishment of efficient communication protocols, security, etc. In this paper, we have classified various applications of FANET devices into six main categories viz., Inspection and surveillance, Communication, Spraying, Cargo, Temperature measurement, and Traffic monitoring. We hope that this work can act as a compendium as well as a guiding path for the researchers to solve open issues. In the future, the integration of more AI and data science-based approaches to UAVs is highly encouraged to solve the general problems of mankind.