Artificial Noise Sheltered FH Broadcasting With Frequency Mismatch: Secrecy Analysis and Power Allocation

To protect military broadcasting against both hostile interference and eavesdropping, an artificial noise (AN) sheltered frequency hopping (FH) broadcasting (ANS-FHB) architecture is proposed in this paper, and the secrecy capacity is employed to measure its secrecy performance. Besides, considering the inevitable frequency mismatch after synchronization will degrade system secrecy in practical applications, the optimal transmitting power allocation (PA) for the confidential information (CI) and AN is provided to maximize secrecy capacity in presence of frequency mismatch. Moreover, to be adapted to various application scenarios, the proposed optimal PA scheme is further simplified according to the frequency synchronization ability and relative channel quality. The analysis and simulations show that the proposed ANS-FHB system can achieve a non-negative secrecy rate even when existing multiple eavesdroppers. In addition, the optimal power ratio of AN to CI shows a downward trend from one to zero as frequency mismatch increases to mitigate the secrecy loss.