In this paper, space-time codes for MIMO radar are used to achieve high resolution at target range and speed. The two-dimensional ambiguity function is known as a tool to compare radar performance in terms of resolution. A space-time code can be designed based on minimi More
In this paper, space-time codes for MIMO radar are used to achieve high resolution at target range and speed. The two-dimensional ambiguity function is known as a tool to compare radar performance in terms of resolution. A space-time code can be designed based on minimizing the distance between the actual target parameters in range, speed and angle. For this purpose, high resolution can be achieved by analyzing the ambiguity function and narrowing it down as much as possible. In this paper, the ambiguity function with two variables of amplitude and speed mismatch is considered and a new criterion to achieve high resolution performance in this field is proposed. In this case, by optimizing the proposed cost functions, the optimal space-time code is extracted. The proposed design can also be extended to phased-MIMO radar. The simulation results also show that our proposed scheme has a very narrow ambiguity function around the origin, while it has a performance very close to the optimal state in terms of target identification probability.
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The directional modulation is a prominent and practical technique for enhancing the physical layer security in modern communication systems. In this method, the message signal is modulated by an array of antennas and transmitted in a specific direction to the legitimate More
The directional modulation is a prominent and practical technique for enhancing the physical layer security in modern communication systems. In this method, the message signal is modulated by an array of antennas and transmitted in a specific direction to the legitimate receiver, such that in other directions, the signal is destroyed and not receivable by eavesdroppers. By incorporating random frequency diverse array directional modulation, secure communication can be achieved in both angular and distance dimensions for the legitimate receiver. However, when the eavesdropper is located near the legitimate receiver, the confidentiality performance of this solution significantly deteriorates. To address this issue, this paper proposes a novel approach that combines artificial noise with random frequency diverse array directional modulation and optimizes power allocation to attain the maximum secrecy rate. Simulation results demonstrate that our proposed approach improves the secrecy rate of the physical layer security by at least one bit per second per hertz compared to the method without artificial noise, and by at least two bits per second per hertz compared to the phased array directional modulation.
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