In this paper, we investigate the physical layer security of cooperative two-way relay transmission systems using the amplify-and-forward (AF) protocol in the presence of an eavesdropper. A joint relay selection (RS) and power allocation (PA) scheme is proposed to protect the source-destination transmission against the eavesdropper. However, due to the high computational complexity, it is difficult to obtain the optimal solution for the system secrecy rate. Fortunately, an approximate optimal solution by using the particle swarm optimization (PSO) algorithm is derived. In the simulations, we use random relay selection with optimal power allocation (RRS-OPA) and equal power allocation with optimal relay selection (EPA-ORS) as benchmark schemes to verify the effectiveness of the proposed method. The simulation results show that the proposed method outperforms both RRS-OPA and EPA-ORS and significantly improves the system performance with low complexity.
Synthesis of antenna arrays is a momentous technology possessing many advantages and broad prospects. Dynamic parameters differential evolution (DPDE) with two modifications is proposed for the synthesis of linear sparse arrays (LSA) which aims at reducing peak side‐lobe level. One modification is that the scaling factor decreases monotonically over iterations, making exploration in the later period more efficient and accuracy. The other modification is that the crossover probability changes dynamically during iterative process through a novel self‐adaptive strategy. Experiments of checking on benchmark functions and simulations of synthesising LSA validate that DPDE performs better than reference methods convincingly.
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