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International Journal of Communication Systems

Exploiting secure performance in power domain–based multiple access: Impacts of relay link/direct link and secure analysis

Dinh‐Thuan Do, Minh‐Sang Van Nguyen, Thi‐Anh Hoang

Published Aug 6, 2019• 3 citations
Publisher

Abstract

Summary A new design of secure nonorthogonal multiple access (NOMA) deployed together with cooperative relaying network is investigated in two modes including direct link and relay link. This paper proposes a mathematical analysis under secrecy considerations of a downlink two‐user NOMA systems. In particular, physical layer security of NOMA is studied in two specific metrics to achieve secure performance analysis such as the secrecy outage probability (SOP) and probability of strictly positive secrecy capacity (SPSC). It should be further explored the situation as the illegal user which is assumed to be eavesdropper at the information level, it attempts to decode the information intended to legal users while NOMA scheme is employed for legal users. The transmission techniques of NOMA equipping relaying architecture (dual‐hop transmission) have proposed due to improving the spectrum efficiency greatly compared with the traditional single‐hop networks. Finally, this study shows the advantages of NOMA over the traditional orthogonal multiple access in the studied problems analytically and numerical analysis is further provided. As important achievement, new exact and closed‐form expressions of the SOP and SPSC are derived, and they will be confirmed by simulation, ie, Monte Carlo simulations are performed to verify the proposed analytical results. Ultimately, the effects of some critical factors are studied on secure performance through these simulation results.

DOI
10.1002/dac.4110

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Summary A new design of secure nonorthogonal multiple access (NOMA) deployed together with cooperative relaying network is investigated in two modes including direct link and relay link. This paper proposes a mathematical analysis under secrecy considerations of a downlink two‐user NOMA systems. In particular, physical layer security of NOMA is studied in two specific metrics to achieve secure performance analysis such as the secrecy outage probability (SOP) and probability of strictly positive secrecy capacity (SPSC). It should be further explored the situation as the illegal user which is assumed to be eavesdropper at the information level, it attempts to decode the information intended to legal users while NOMA scheme is employed for legal users. The transmission techniques of NOMA equipping relaying architecture (dual‐hop transmission) have proposed due to improving the spectrum efficiency greatly compared with the traditional single‐hop networks. Finally, this study shows the advantages of NOMA over the traditional orthogonal multiple access in the studied problems analytically and numerical analysis is further provided. As important achievement, new exact and closed‐form expressions of the SOP and SPSC are derived, and they will be confirmed by simulation, ie, Monte Carlo simulations are performed to verify the proposed analytical results. Ultimately, the effects of some critical factors are studied on secure performance through these simulation results.
Summary The secrecy performance of a nonorthogonal multiple access (NOMA) system is examined in this study by employment of a dual‐hop decode‐and‐forward (DF) relay under existence of eavesdropper. Due to the fact that the relay is trusted or untrusted device and thus eavesdropper may wiretap information from the base station or the relay. In this regard, three scenarios related to trusted and untrusted relays are proposed, with different assumptions on the information overhearing ability of the eavesdropper; ie, the first scenario is that an eavesdropper overhears signal from the relay while the BS is overheard by eavesdropper in the second scenarios. More specifically, we derive closed‐form expressions for the secure probability metrics when the direct and relay links experience independent Rayleigh fading. There metrics include strictly positive secrecy capacity (SPSC) and the secure outage probability (SOP). Furthermore, secure performance of traditional orthogonal multiple access (OMA) is also provided as further comparison with NOMA counterpart. We analyze the influence of main coefficients such as the target rates and the transmit SNR factors on the secrecy performance. Our results specify that for reasonable selection of such parameters, secrecy performance can be enhanced remarkably. Numerical results are delivered to corroborate the derived results.
Abstract We analyze the secrecy attributes of an energy‐harvesting‐enabled decode‐and‐forward relay‐based cooperative nonorthogonal multiple access (NOMA) system in the presence of an eavesdropper. Information flow through the wireless channel exposes legitimate users to eavesdropping by unintended users on confidential information. We study the secrecy performance of two‐user NOMA systems by calculating the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC). An eavesdropper overhears the signal from a source and relays it from a relay node. We evaluate the secrecy performance of both nodes (i.e., relay node ( ) and distant node ( )) by developing a novel closed‐form expression for node . For node , we evaluate an analytical but intractable expression of SOP and tractable analytical expression of ESC. We examine the effects of network parameters on secrecy and link outages. We also observe the reliability of the link outage probability of node and system outage probability. Monte Carlo simulations are conducted to verify the analytical results and evaluate the effect of SOP on imperfect channel state information and perfect channel state information.
In this paper, we design a secure transmission scheme in uplink and downlink of non-orthogonal multiple access (NOMA) system. In this scenario, two pairs of base stationuser can operate under the presence of eavesdropper. The relay plays an important role to forward signals from group of base stations to serve distant users. However, the eavesdropper can overhear signal which leads to secure performance need be reconsidered. To provide secure performance, we derive the closed-form expressions for strictly positive secrecy capacity (SPSC). In addition, we rely on relay for enlarge coverage area. The channel conditions meet imperfect channel state information (CSI) which shows degraded secure performance. Results confirm the relationship between transmit power at the source and and SPSC how many main parameters affecting secure performance metric. Furthermore, simulation results show that the uplink and downlink NOMA technique improves secure performance in the low SPSC region. We further conduct analysis by using Monte-Carlo simulations.
In this paper, we study the secrecy outage probability (SOP)and the strictly positive secrecy capacity (SPSC)of cooperative non-orthogonal multiple access (NOMA)system with a single antenna over Rayleigh fading channel in which there are a source, a relay node, two destinations and one eavesdropper. The relay adopts amplify-and-forward (AF)and decode-and-forward (DF)relaying schemes. The SOP and SPSC performance are analyzed to evaluate the level of security granted to legitimate users for both AF and DF protocols. The effects of the optimal power allocation value on system performance are also discussed and provided through numerical results.
We study the secrecy transmission of uplink non-orthogonal multiple access (NOMA) with single antenna and multi-antenna users in presence of an eavesdropper. Two phases are required for communications during each time frame between the users and the base station in cellular networks. We study the case where an eavesdropper overhears the relay and direct links from the users to the base stations. In terms of the secure performance analysis, we focus on two main metrics including secrecy outage probability (SOP) and strictly positive secrecy capacity (SPSC) with the assumption that the eavesdropper is able to detect the signals. Analytical closed-form expressions for the SOP and SPSC are derived to evaluate the system secure performance achieved by the proposed schemes. Furthermore, the asymptotic analysis is presented to gain further insights. The analytical and numerical results indicate that the proposed schemes can realize better secrecy performance once we improve the channel condition and signal-to-noise ratio (SNR) at the base station. Our results confirms that the secrecy performance gaps exist among the two users since different power allocation factors are assigned to these users.
Abstract Secure transmission is essential for future non-orthogonal multiple access (NOMA) system. This paper investigates relay–antenna selection to enhance physical-layer security of cooperative NOMA system in the presence of an eavesdropper, where multiple antennas are deployed at the relays, the users, and the eavesdropper. In order to reduce expense on radio frequency chains, selection combining (SC) is employed at both the relays and the users, whilst the eavesdropper employs either maximal-ratio combining or SC to process the received signals. Under the condition that the channel state information of the eavesdropping channel is available or unavailable, two effective relay–antenna selection schemes are proposed. Additionally, the closed-form expressions of secrecy outage probability (SOP) are derived for the proposed relay–antenna selection schemes. In order to gain more deep insights on the derived results, the asymptotic performance of the derived SOP is analyzed. In simulations, it is demonstrated that the theoretical results match well with the simulation results and the SOP of the proposed schemes is less than that of the conventional orthogonal multiple access scheme obviously.