# Advances of UAVs toward Future Transportation: The State-of-the-Art, Challenges, and Opportunities
## 2 UAVs Overview
### UAV Security and Privacy  
The use of UAVs in various sectors of the industry is rapidly growing as technology advances. However, privacy and security concerns, including proneness to hacking or theft, invasion of privacy, and collision liability, still need to be considered before the large-scale implementation of UAVs in ITS [34]. UAVs cover large areas and often fly in populated areas. This makes the system prone to hacking, and a UAV lacking security detrimental [33]. The weakness of UAV security was investigated in Ref. [35]. There are five ways a cyber-terrorist may hack and disrupt UAV usage, and most of them are highly likely to occur. The first method is signal jamming. In jamming, the culprit generates interference signals at a similar frequency band to disrupt the UAV's reception [17; 36]. Another way of hacking is eavesdropping. In this method, the hacker uses the cellular/WiFi signal produced by the UAV to obtain the information being transmitted. Hijacking is yet another way a cyber-terrorist may misuse a UAV. In this case, the hijacker disrupts a UAV A2G channel and takes control of the UAV [17]. The following way a hacker may misuse the targeted UAV is by spoofing. In spoofing, the hacker acts like an entity with false information. Spoofs typically disrupt the UAV's GPS signals [17; 36]. The last way a cyber-terrorist could threaten a UAV is through Denial of Service (DoS). In a DoS attack, the hacker will send out many server requests, causing congestion in the network, and  
Figure 4: A representation of a UAV swarm.  
users will lose UAV service [17, 37]. To prevent attacks such as eavesdropping or hijacking, higher levels of encryption would need to be put into place. In cases of jamming, one could implement a higher signal-to-noise ratio (SNR), but the power consumption in the UAV limits this method. For spoofing, one could implement a multi-antenna defense [17].  
UAVs can intervene in residents' privacy if the flying path is close to the residences in urban areas, as most UAVs are equipped with cameras. Another issue is the noise of the UAVs, which might become a source of annoyance to the residents. UAV's photography capabilities can be misused. To combat this issue, a set of strict regulations and policies must be put in place by the government, such as the right for individuals to register their home address as a no-fly zone. When the issue involves national security, advanced detection technologies of unregistered drones can be implemented [38]. Moreover, other information such as the GPS location and time can be used to track anyone. Another way a user's privacy can be breached is through malicious software. In a few cases, this software can steal information from the user, such as the application data, if the UAV is operated from the user's cellular device.  
Due to these safety risks and privacy concerns, the use of UAVs must be supervised and regulated by the government or the equivalent of the Federal Aviation Administration (FAA) for countries outside the US. The three main aspects of UAV regulations are controlled use of airspace by UAVs, operational limitations, and administrative procedures such as flight permits, pilot licenses, and data collection authorization [39].