In the insecure transmission environment, compared with the passive eavesdropper (Eve), the active Eve plays a more threatening role in the physical layer security (PLS), since it can wiretap and jam the signals. To simultaneously decrease the wiretap massage for Eve and improve secrecy outage probability (SOP) for the legitimate users, an enhanced decoding protocol in PLS is proposed for the device-to-device (D2D) non-orthogonal multiple access (NOMA) system under an active Eve attack. In addition, the partial NOMA (P-NOMA) is firstly introduced into PLS to further enhance the performance of the proposed system. The provided closed-forms of SOPs are verified via simulations, whose results show the superiority of our proposed schemes over the conventional NOMA schemes.
In the insecure transmission environment, compared with the passive eavesdropper (Eve), the active Eve plays a more threatening role in the physical layer security (PLS), since it can wiretap and jam the signals. To simultaneously decrease the wiretap massage for Eve and improve secrecy outage probability (SOP) for the legitimate users, an enhanced decoding protocol in PLS is proposed for the device-to-device (D2D) non-orthogonal multiple access (NOMA) system under an active Eve attack. In addition, the partial NOMA (P-NOMA) is firstly introduced into PLS to further enhance the performance of the proposed system. The provided closed-forms of SOPs are verified via simulations, whose results show the superiority of our proposed schemes over the conventional NOMA schemes.
NOMA (Non-Orthogonal Multiple Access) has been recognized as new multiple access technology for wireless communication networks of the fifth generation and beyond, owing to its ability to improve spectral efficiency, support massive connectivity, and provide user fairness. However, it has been observed that the superposition-based transmission principle of NOMA is highly susceptible to eavesdropping attacks, especially in an open wireless network where all wireless communications are inherently broadcast in nature. Hence, ensuring secure wireless communications for NOMA systems has now become an important area of research. This research aims to improve the secrecy level of wireless communications for NOMA systems by employing Physical Layer Security (PLS) techniques. Specifically, two prominent PLS techniques, Artificial Noise (AN) and Cooperative Jamming (CJ), have been employed to provide security against passive eavesdropping attacks. The cooperative NOMA system architecture is considered, and the secrecy enhancement is analyzed for two possible scenarios when the eavesdropper is close to the relay node and when the eavesdropper is close to the base station. The secrecy performance of the proposed system is analyzed through various parameters, namely, Secrecy Outage Probability (SOP), Secrecy Capacity (SC), Secrecy Rate (SR), and Secrecy Energy Efficiency (SEE) in terms of the Signal to Noise Ratio (SNR). The numerical results for the secrecy metrics are obtained through MATLAB-based simulations, whereas the system-level model is developed using the Simulink platform to verify the suggested system's functionality in the presence of AN and CJ for the legitimate NOMA users and the eavesdropper. The results show that the secrecy performance is significantly enhanced with the introduction of AN and CJ, and the system shows robust performance in terms of energy efficiency. This paper provides significant insights into the design of the NOMA system from the secrecy perspective and validates the potential of PLS techniques for the design of the future wireless system.
In order to improve the Physical Layer Security (PLS) perspective, this paper aims to empower function of PLS by considering a backhaul Non-Orthogonal Multiple Access (NOMA) system in two practical situations. In the proposed schemes, the untrusted user intercepts information transmitted to the far user, or the external eavesdropper overhears confidential information sent to the far user in the context of NOMA technique. Unlike the conventional NOMA systems, this paper emphasizes the actual situations of the existence of actual illegal users and legitimate users, especially the reasonable use of relay selection architecture to improve the confidentiality performance. To evaluate the security properties of the proposed scheme, a comprehensive analysis of the Security Outage Probability (SOP) performance is first performed, and then the corresponding SOP asymptotic expressions are derived for real scenarios related to eavesdroppers and untrusted users. Numerical results are performed to verify the analysis in terms of the secure performance metric.
In this letter, we consider a non-orthogonal multiple access (NOMA) network with a half-duplex (HD) decode-and-forward (DF) relay to improve physical layer security (PLS) of two users. Two legitimate users of U1 and U2 are far from the multi-antenna base station (BS). Thus, a relay with multi-antenna is used to enhance communication and obtain diversity gain. In the first stage, the BS transmits the superimposed signal to the relay via NOMA. Meanwhile, U1 generates the jamming signal to the eavesdropper (Eve). In the second stage, the relay forwards the signal to two users while the BS transmits the jamming signal to disrupt the eavesdropping. It is assumed that the Eve has strong eavesdropping ability. Thus, we need to introduce jamming to guarantee security. Furthermore, we use U1 instead of a full-duplex (FD) relay to send the jamming signal in the first stage to avoid self-interference. To measure the secrecy performance, a closed-form expression of secrecy outage probability (SOP) is derived for the two users. Simulation results are provided to verify the correctness of the proposed scheme.
The growth of internet-of-things (IoT) inspired use cases in different run of the mill environments such as cities, industries, healthcare, agriculture, and transportation, has led to a greater desire for safer IoT data gathering and storage. However, securing IoT is challenging due to form-factor, complexity, energy, and connectivity limitations. Conventional coding-based security techniques are unsuitable for ultra-reliable low-latency and energy-efficient communication in IoT. Numerous research studies on physical layer security (PLS) techniques for fifth generation (5G) have emerged recently, but not all of the solutions can be used in IoT networks due to complexity limitations. Non-orthogonal multiple access (NOMA) is billed as a possible technology to solve connectivity and latency requirements in IoT. In this study, we exploit the power allocation characteristics of NOMA to enhance security in a downlink deviceto-device (D2D) decode and forward (DF) IoT network infiltrated by an eavesdropper. Our performance metric of choice is the secrecy outage probability (SOP). We formulate exact SOP results for different users. Simulation results demonstrate the positive impact of NOMA on SOP in a D2D IoT-NOMA network.
This article presents a physical layer security (PLS) technique for non-orthogonal multiple access (NOMA), which can provide joint secrecy, fairness, and bit error rate (BER) improvement. The approach employs power hopping (PH), where users’ power coefficients are dynamically varied according to the instantaneous channel conditions. By randomizing both the detection order and the effective power allocation, PH obscures the underlying NOMA structure from a passive eavesdropper (Eve), thereby severely degrading the data detection capability. To enable secure coordination, a precoding-based mechanism is developed for sharing the PH patterns among legitimate users, leveraging the random and independent nature of wireless channels. The BER and secrecy outage probability (SOP) of the proposed framework are analytically characterized and compared to conventional NOMA under various channel and eavesdropping configurations. The obtained analytical results, corroborated by Monte Carlo simulations, confirm the effectiveness of the proposed scheme, where the SOP of legitimate users is never compromised regardless of Eve’s channel conditions, while incurring only negligible additional complexity compared to conventional NOMA. Furthermore, the fairness and BER performance of stronger users are significantly improved through the combined use of PH and optimal power allocation.
This paper investigates physical layer security (PLS) in hybrid automatic repeat request (HARQ)-assisted non-orthogonal multiple access (NOMA) networks, where a security-required user is paired with a quality of service (QoS)-required user to perform NOMA in presence of an eavesdropper (Eve). We derive the closed-form expressions for connection outage probability (COP) of security-required and QoS-required users. In addition, the closed-form expressions for secrecy outage probability (SOP) secrecy transmission probability (RSP), and effective secrecy throughput (EST) of security-required user are also derived. Although the expression of SOP demonstrates that HARQ increases the risk of leaking confidential message to eavesdropper (Eve), however, from the perspective of Eve and security-required user, secrecy performance improves significantly, in terms of EST and RSP, when applying HARQ.