Abstract
Directional modulation (DM) technique has the ability to enhance the physical layer security (PLS) of wireless communications. Conventional DM schemes are usually based on a single antenna array with the basic assumption that eavesdroppers (Eves) and legitimate users (LUs) are in different directions. However, it is possible that Eves are in the same direction as LUs in practical applications. As a result, signals received by Eves will be approximately the same or even in better quality than those received by LUs. To address the neighbor security issue, we introduce a multiple antenna arrays model at the transmitter side with the help of the artificial noise (AN)-aided DM technique to achieve secure and precise DM transmission in this paper. Meanwhile, to recover the mixed useful signals, two novel DM schemes based on single- and multi-carrier multiple antenna arrays model are proposed, respectively. In addition, the symbol error rate (SER), secrecy rate, and robustness performance of the proposed DM schemes were analyzed and simulated. Simulations validate the effectiveness of the proposed DM schemes and demonstrate that multiple antenna arrays model based DM methods outperform single antenna array model aided DM methods in security.
Highlights
Information security has always been an important problem for wireless communications, which provide a wide coverage at the cost of exposing information to undesired users with eavesdroppers (Eves) amongst them [1]
It is easy to see that the symbol error rate (SER) for the legitimate users (LUs) for the proposed Directional modulation (DM) schemes is primarily affected by the information power splitting factor β 1, while the SER for the Eve is dependent on the information power splitting factor β 1 and the eavesdropper steering vector both
Several conclusions can be summarized from Figure the results in Figure 8a: (1) For the LU, when the signal power allocation factor is set as β 1 = 0.9, to achieve the same SER level (e.g., SER = 10−4 ), the signal-to-noise ratio (SNR) per bit needed is approximately 1 dB less than that of the standard QSPK modulation, which indicates that the inserted artificial noise (AN) will cause some degree of SNR loss
Summary
Information security has always been an important problem for wireless communications, which provide a wide coverage at the cost of exposing information to undesired users with eavesdroppers (Eves) amongst them [1]. The above-mentioned single- and multi-beam DM schemes can only achieve angle-dependent secure transmission, the security of which cannot be guaranteed once an Eve is aligned with the desired direction or very close to the desired user To solve this neighbor security problem, one solution is to adopt a frequency diverse array (FDA) to synthesize both angle and range dependent DM [28,29,30,31]; another solution is to utilize a multi-path model, where signals via both line of sight (LOS) and reflected paths are combined at the receiver side [32,33,34,35,36,37,38,39]. (1) A multiple antenna arrays model combined with AN technique is introduced into DM designs to settle the neighbor security problem in traditional single antenna array based DM schemes for PLS enhancement. To recover the intact useful signals, two secure and precise DM transmission schemes based on single- and multi-carrier multiple antenna arrays model are proposed, respectively. “mc”, “sc”, “sa” in the figures of this paper refer to the symbol stream transmitted by transmitter, the multi-carrier multiple antenna arrays DM scheme, the single-carrier multiple antenna arrays DM scheme, and the single antenna array DM scheme, respectively
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