## 1 Introduction
WFRFT, as a new transformation domain signal processing method based on Fourier transform [27], is gradually being applied to the wireless communication systems. WFRFT is actually the process of rotating the signal in the time-frequency plane to realize the time-frequency redistribution of signal power, and only when the users rotate the signal in same angle, but the opposite direction can the signal power be concentrated. Therefore, due to its power redistribution on the time-frequency plane, WFRFT technology can be regarded as a cryptographic method to further improve secrecy performance [28; 29; 30; 31]. Furthermore, in [32], a synthesis scheme combining WFRFT and FDA DM was investigated to achieve power efficiency multi-beam secure communication. The contributions to physical layer security were promising. Apart from the above-mentioned WFRFT schemes based on a single parameter, the multiparameter WFRFT synthesis approaches have also been investigated intensively [33; 34]. The MP-WFRFT system has a good parameter resistance, allowing it to detect in the condition of the eavesdroppers with a known signal transformation mode; in particular, this method can be combined with the existing DM technology, which can further improve the capacity for anti-interception and anti-detection based on the original system confidentiality. SM, as an emerging information modulation technology, has gradually been introduced into wireless communication in recent years due to its high data rate and spectral efficiency. The basic idea of SM is to use the transmit antenna number as an additional information bearing unit to transmit more information bits than the single modulation symbols. However, in this paper, unlike previous works which applied SM to the multiple-input multiple-output (MIMO) system [35; 36; 37; 38], the authors use SM technology based on FDA with cooperative LUs in order to avoid high interchannel interference at receivers and complicated estimate algorithms (e.g., maximum likelihood [35] and MRRC [38]) are required. On the basis of the previous work, we propose a spectrally efficient and power-efficient multi-beam security communication scheme with the joint use of multiple techniques including MP-WFRFT, SM, and FDA-DM. Our main contributions can be summarized as follows. (1) The proposed scheme combining MP-WFRFT realizes the embedding process of \"AN\" from the modulation level of digital baseband signal. Therefore, the proposed scheme based on MP-WFAFFT avoids the power resource waste compared with traditional AN added scheme. (2) In this paper, we apply SM technology into the FDA system with cooperative LUs, which can transmit additional information bits by using LUs number information compared to single modulation symbols to improve the capacity of communication system. Furthermore, the proposed scheme can ensure communication security when Eves are proximal to LUs or even in same locations. (3) Unlike conventional beamforming method for multi-beam DM, we design the FDA beamforming matrix based on the minimum transmission messages power rule, which also can accurately control the received power of LUs. The rest of this paper is organized as follows. Section 2 provides a review of DM PHY, MP-WFRFT and SM. Then, in Section 3, we propose the SM- and MP-WFRFT-aided scheme based on FDA. The performance is deduced in Section 4 and is numerically evaluated in Section 5. Finally, Section 6 draws conclusions.