# Cooperative Friendly Jamming Techniques for Drone-Based Mobile Secure Zone
## 1 Introduction  
Wireless communication network technology is evolving to meet the needs of users who want to use high-speed, high-capacity multimedia content without the limitations of location and time. However, cases of information leakage have been continually occurring owing to the fundamental limitations of wireless communication, which is vulnerable to eavesdropping [1]. To solve this problem, protocols and mechanisms have been proposed that improve the security or secure safe communication channels within the time, frequency, and space domains [2]. However, conventional wireless secure communication methods require complex hardware, which reduces the energy efficiency and data transmission performance, limiting the application to highly reliable wireless autonomous moving objects that exchange confidential information [3, 4]. Among wireless network technologies, the Internet of Things (IoT) has become an essential element in all industries and everyday life, and accordingly, security vulnerabilities of wireless networks have become a larger issue [5]. Most IoT devices are light in weightwith specifications that are insufficient to apply to regular personal computers or mobile devices. The existing communication systems are vulnerable to side-channel attacks, which are attacks that utilize physical information generated from the physical layer. Thus, the security protocol key can be leaked and encryption can be disabled. As they communicate in open network environments, they are easily exposed to security threats such as eavesdropping. This vulnerability can be exploited to easily collect confidential information [6]. To improve the security in IoT environments that are easily exposed to security threats, security architectures should be designed by considering the light weight and mobility of mobile IoT devices [7]. In this paper, we proposed Cooperative Friendly Jamming Techniques for Drone-based Mobile Secure Zone (CFJ-DMZ) to enhance the security in wireless communication environments for drones, which are IoT devices that can move autonomously while exchanging information with other surrounding devices. As eavesdropping is a passive attack that leaves no evidence of attacks, it is impossible to detect eavesdroppers in a wireless communication environment. Therefore, in this paper, a proactive prevention method was proposed to reduce the eavesdropping probability of unspecified potential eavesdroppers. The CFJ-DMZ uses the mobility and artificial interference of autonomous moving objects to form a secure zone, which guarantees safe data communication in the wireless communication environment of mobile IoT and flexibly controls the zone to be protected, effectively mitigating eavesdropping threats. To evaluate the proposed CFJ-DMZ, we implemented a network simulation model and validated its performance. In the network simulation model, the transmission node moves to near the receiving node, and safe short-range device-to-device (D2D) communication is then conducted in the secure zone formed through a cooperative jammer drone. Here, three drones communicate with each other and create a locally secure zone based on the boundary of the artificial interference signal reaching range to protect the confidentiality of communication between nodes. The main contributions of this paper are as follows:  
* A cooperative friendly jamming technique is proposed to flexibly form a secure zone for confidential communication of lightweight mobile devices. * The effect of the proposed CFJ-DMZ is analyzed through simulation and proved through field test in the implemented test bed. The remainder of this paper is organized as follows. Section 2 introduces studies on conventional wireless communication security technologies and major studies on the wireless communication security of autonomous moving objects. Section 3 then describes the security performance criteria of friendly jamming and the friendly jamming model.