Improvement of Security in Wireless Communication Networks with Directional Modulation and Artificial Noise

Directional modulation(DM) is an emerging technology for securing wireless communication at the physical layer and is mostly used in the line of sight propagation channels such as millimeter wave communications, next-generation cellular, satellite, and radar networks. This promising technology, unlike key-based cryptographic methods and the key-based physical layer security approaches, locks information signals without any requirement of keys. The locked information can only be fully recovered by the legitimate receiver(s) priory known by DM transmitters. This technology can be implemented in different ways. In the phased array method, modulation is implemented in the antenna. In this method by changing the phase of each element, the angle-dependent modulation is constructed. for this reason, the modulation constellation points in the undesired directions are distorted and deviate from the standard mode.In this article, DM is implemented in the baseband by using the orthogonal vector method and separating the information radiation pattern from the interference radiation pattern (random artificial noise). This is a new method for simultaneously sending several signals with DM and random artificial noise. In this method, the bit error rate (BER) probability in the direction of the legitimate receiver(s) is improved from 10^(-3) to 10^(-5) and at least the signal secrecy rate is also increased one bit per second per hertz (bandwidth unit). Also, the results of the simulations show that as the number of antennas increases, the secrecy rate increases, the amount of power allocated to artificial noise decreases, and the power efficiency of the transmitter increases.