امنيت لايه فيزيكي با ايجاد نويز مصنوعي در شبكه هاي رله (تقويت-ارسال )دو طرفه

Wireless communication is one of the important tools for connecting people from any part of the world at any time. Although the preva‎lence of wireless technologies brings many advantages, the undeniable reality is that users are more exposed to attacks from adversaries due to the nature of wireless signal broadcasting. In light of this, the security of communications has received increased attention. The traditional method to enhance communication security involves using encryption techniques to protect user data at higher layers of the communication stack. Even though current efforts provide solutions from specific perspectives, these methods are neither consistent nor flexible enough to offer a robust security mechanism due to computational tasks and system complexity. With the development of wireless communication techniques, physical layer security has become a hot topic. This thesis addresses the issue of physical layer security by creating artificial noise in a relay-assisted network. In the assumed two-way relay network of this thesis, two users intend to send their confidential messages to each other. It is assumed that the distance between the users is very large, and direct information exchange between them is not possible. Therefore, the exchange of information between users is facilitated by a multi-antenna relay that is within the radio coverage range of both target users. In other words, the signals sent by the users are only transmitted to each other through the relay path. In this scenario, there is one user who attempts to eavesdrop on the private messages exchanged between the two target users without authorization. Hence, to disrupt the eavesdropperʹs channel, the relay sends artificial noise along with its signal. Simulation results show that when the relay sends artificial noise with its signal, the eavesdropperʹs received rate decreases, which in turn increases the total achievable rate. Additionally, according to simulation results, it can be concluded that despite not having access to the eavesdropperʹs channel information, the proposed method can achieve acceptable performance such that with an increase in the total power of the relay and the number of antennas at the relay, we can achieve performance similar to that when no eavesdropper exists in the network. Furthermore, in eva‎luating the probability of confidentiality breach, since artificial noise takes a larger share of the total power of the relay, as the relay power increases, the probability of confidentiality breach gradually decreases and approaches zero.

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