Abstract
The reconfigurable intelligent surface (RIS) aided non-orthogonal multiple access (NOMA) network is applied to improve spectral efficiency and energy efficiency of wireless systems. Due to the incorporation of NOMA, RIS-aided NOMA system suffers from physical layer security (PLS) problem when an internal near user (NU) is the eavesdropper. In this case, it is difficult to always guarantee positive secrecy rate. Therefore, a scheme of artificial noise (AN) cooperative jamming and beamforming design is proposed against internal eavesdropper for RIS-aided NOMA in this paper. It is proved theoretically that the positive secrecy rate can be guaranteed if providing sufficient power. In addition, the power allocation of base station is further studied to minimize the total power consumption under the constraints of data rate and secrecy rate, and the closed-form solutions are achieved. Simulation results show that the performance of the proposed scheme is superior to the existing solutions.
Highlights
Non-orthogonal multiple access (NOMA) is considered a promising technology because it can improve the spectral efficiency of next-generation networks [1]
In [30], the ‘‘dead zone’’ problem was solved by adopting reconfigurable intelligent surface1 (RIS), and physical layer security (PLS) of RIS-aided non-orthogonal multiple access (NOMA) with near user (NU) eavesdroppers was improved by beamforming, which aims the signal at far user (FU) to increase the channel gain of FU
POWER OPTIMIZATION According to the previous part, the positive secrecy rate can always be obtained if providing sufficient power, and power allocation will affect the performance of system
Summary
Non-orthogonal multiple access (NOMA) is considered a promising technology because it can improve the spectral efficiency of next-generation networks [1]. In [22], the imperfect channel state information of eavesdropper was considered, and a robust beamforming scheme with AN is proposed to ensure the secure RIS-aided NOMA transmission. In [24], a power efficient scheme was presented to design the secure transmit power allocation and the reflecting phase shift in RIS-aided multi-antenna transmission, and the transmission power of legitimate user was optimized under the constraint of secrecy rate. The authors of [25] studied the passive eavesdropping problem of internal users in the RIS-assisted NOMA, and minimized the total transmit power by jointly optimizing the beamforming vectors and the RIS reflecting factors. In [30], the ‘‘dead zone’’ problem was solved by adopting RIS, and PLS of RIS-aided NOMA with NU eavesdroppers was improved by beamforming, which aims the signal at FU to increase the channel gain of FU.
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