基于空域加扰的保密无线通信统一数学模型及其窃密方法

基于空域加扰的方法如人工噪声、天线阵列随机加权等可以在物理层保障无线通信的安全.二者有着共同的物理实质,即在期望用户方向上传递保密信息,而在其正交方向上发射人工干扰.但由于发射天线个数的限制,该人工干扰在空域并非白噪声,窃听用户可以借助接收多天线技术抑制干扰进而解调秘密信息.本文为上述空域加扰的两种方法建立了一致的数学模型,并且在此基础上,利用通信符号的有限码集特性,提出了一种MUSIC-like窃听算法.仿真结果表明,当窃听者比发射端有更多的天线时,该窃听算法可以有效截获保密信息.

A unified mathematical model for spatial scrambling based secure wireless communication and its wiretap method

The spatial scrambling based wireless transmission methods,such as artificial noise and antenna array weighted randomly,can secure wireless communication at the physical layer.They have a common physical essence,that is,the private message is transmitted in the desired direction while deliberate interference is transmitted in other orthogonal directions.Unfortunately,the interference is not white in spatial domain due to the limitation of the transmit antenna number.An eavesdropper can eliminate the directional interferences by the aid of multiple antennas.In this paper,a unified mathematical model for the above physical-layer methods is established,based on which,a MUSIC-like wiretap algorithm is proposed by exploiting the finite alphabet property of communication symbols.Simulation results show that if the eavesdropper has more antennas than that of the transmitter,the proposed algorithm can intercept information effectively.