一种基于多载波的多播系统物理层安全方案

A Multicarrier-based Physical Layer Security Scheme for the Multicast Systems

受限于发送方天线数目,无线多播系统整体信道通常不存在零空间,无法利用传统的物理层安全技术保证其安全传输。针对这一问题,该文提出一种基于多载波的多播系统物理层安全方案。首先,建立了多载波多播系统物理层安全通信模型;之后,通过分配载波产生合法用户的信道零空间,在零空间内引入人工噪声保证系统的安全传输;最后,以最大化保密传输速率为目标,在系统总功率受限情况下,利用Kuhn-Tucher条件对各子载波功率进行了优化。仿真结果表明:该方案不受限于发送方天线数目,并且所提功率分配方法的系统保密传输速率比等功率分配方法提升约2 bit/(s Hz)。

Traditional physical layer security methods, such as artificial noise, commonly require that the sender has more antennas than eavesdroppers, which is not practical in the multicasting system. To solve this problem, a multicarrier-based physical layer security scheme for the multicast systems is proposed, which takes the advantage of both space and frequency domain to form a relatively virtual multi-antennas system. Through subearrier allocation the existence of null space in every subcarrier channel matrix is guaranteed, so that the artificial noise can be added to ensure a secure communication. Based on the Kuhn-Tucher condition, an optimal power allocation method is also proposed to maximize the security rates under the restriction of total power. Simulation results indicate that this scheme is unlimited by the amount of the sender antennas, and it improves the security rates by 2 bit/（s. Hz） than the average power allocation method.