# Cyber4 Drone: A Systematic Review of Cyber Security and Forensics in Next-Generation Drones
## 3 Overview of Drones
### Drone Communications  
Unmanned aerial systems are used for various defense and civilian purposes, including pollutant research, glaciology studies, wildfire management, disaster management, hurricane tracking, flood impact investigations, and illegal narcotic identification. A drone system or UAS must be able to communicate with other entities in its network. WiFi is a common mode of communication between UAVs and base stations. WiFi has a relatively low transmission range, often a few hundred meters. The range of radio communication is thousands of meters. As shown in Figure 2, a general drone network is made up of drones, ground control stations (GCS), navigation satellite systems, and air traffic control systems such as Automated Dependent Surveillance-Broadcast (ADS-B) systems. The following communication links are used to communicate between network entities:  
* _GCS communication_: This datalink supports UAS and ground control station communications, and the GCS uses wireless signals to communicate with UAVs, allowing it to monitor network traffic and direct flight operations. These communications are based on short-range wireless technologies, making them prone to different attacks [25].
* _ADS-B communication:_ Automatic Dependent Surveillance-Broadcast (ADS-B) has been adopted for aircraft Air Traffic Control (ATC) systems. Anonymous ground users and other aircraft can use ADS-B to periodically broadcast general navigation information through long-range RF signals. It operates on 1090 MHz and is a digital protocol. Standard identification and navigational data for the aircraft, such as altitude, GPS, and the aircraft's identification number, are included in ADS-B signals. Drones have lately started using ADS-B [26]. For smaller drones, conventional ADS-B systems are too large; hence, smaller ADS-B modules are required [27]. This enables DAA (detect and avoid) capabilities, enhancing safety for airspace users and providing easier drone identification and tracking.
* _GPS communication:_ The controller must identify the drone's path for collision avoidance in Beyond Line-of-Sight (BLOS) operations. A drone connects with GPS satellites to transmit and receive data and information. As a result, UAVs can develop satellite network connectivity to collect their real-time GPS coordinates. Additionally, satellite communications are beneficial across large distances even without developed infrastructure and enable stable communication with higher data frequency.
* _Video transmission_: 1.3 GHz, 2.4 GHz, and 5.8 GHz are common RF data links for video transmission. (i) 1.3 GHz--This system can have a range of more than 40 miles and better penetration abilities, depending on the amount of power employed. Because of its low data rates, it provides poor video quality. (ii) The range of a 2.4 GHz system can be up to 15 miles. As 2.4 GHz is also utilized for control, using it for video will cause interference. (iii) The most widely used frequency for video transmission is 5.8 GHz because of its short wavelength and high data rate transfer capacity. Compared to the other options, it produces a clear video. However, it can only penetrate a restricted distance of 5 miles due to its small wavelength.