Physical Layer Security for Cooperative NOMA Systems

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.

“…These illustrations verify exact matching between theoretical experiment and Monte Carlo simulation. Furthermore, SOP in the proposed system is better than that in Chen et al …”

Section: Simulation Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Evaluating secrecy performance of cooperative NOMA networks under existence of relay link and direct link

Nguyen

2019

“…[11][12][13] Lin et al 14 address the physical-layer security problem for proximal legitimate user and eavesdropper in millimeter-wave transmissions. [11][12][13] Lin et al 14 address the physical-layer security problem for proximal legitimate user and eavesdropper in millimeter-wave transmissions.…”

Section: Introductionmentioning

confidence: 99%

Secrecy sum rate optimization in MISO nonorthogonal multiple access systems with orthogonal space‐time block coding

Yan

Zhang

et al. 2019

Self Cite

In this paper, we investigate the secrecy sum rate optimization problem for a multiple-input single-output (MISO) nonorthogonal multiple access (NOMA) system with orthogonal space-time block codes (OSTBC). This system consists of a transmitter, two users, and a potential eavesdropper. The transmitter sends information by orthogonal space-time block codes. The transmitter's precoder and the power allocation scheme are designed to maximize achievable secrecy sum rate subject to the power constraint at the transmitter and the minimum transmission rate requirement of the weak user. We consider two cases of the eavesdropper's channel condition to obtain positive secrecy sum rate. The first case is the eavesdropper's equivalent channel is the weakest, and the other is the eavesdropper's equivalent channel between the strong user and weak user. For the former case, we employ the constrained concave convex procedure (CCCP)-based iterative algorithm with one-dimensional search. While for the latter, we adopt the method of alternating optimization (AO) between precoder and power allocation. We solve a semidefinite programming to optimize the precoder and drive a closed-form expression of power allocation. The simulation results obtained by our method demonstrate the superiority of our proposed scheme.KEYWORDS multiple-input single-output (MISO), nonorthogonal multiple access (NOMA), orthogonal space-time block codes (OSTBC), security, precoder, power allocation

Leakage rate analysis with imperfect channel state information for cooperative nonorthogonal multiple access networks

Özduran

2020

This paper investigates the imperfect channel state information that is caused by the channel estimation error and feedback delay effects on the leakage rate analysis for the cooperative nonorthogonal multiple access networks. The investigation considers a dual hop one-/two-way nonorthogonal multiple access-based information exchange process with the aid of half-/full-duplex untrustworthy wireless relaying network for the leakage rate analysis. The channel estimation error causes system coding gain losses while the feedback delay does not have any effect on the users' outage performance at untrustworthy relay terminal in low signal-to-noise ratio regimes. Conversely, the channel estimation error effects become negligible while the feedback delay causes system coding gain losses on the users' outage performance at untrustworthy relay terminal in high signal-to-noise ratio. Results also reveal that the untrustworthy relay terminal, which is under the effect of the channel estimation error and feedback delay, is being active between −10 and 25-30 dB. Beyond 25-30 dB, the untrustworthy relay terminal becomes out of order and saturates. The Monte Carlo-based simulation results are in agreement with the analytical and asymptotic derivations. KEYWORDScooperative communications, leakage rate analysis, nonorthogonal multiple access INTRODUCTIONWireless information exchange process has become vulnerable to cyber attacks. This is because of the open medium of wireless communication and broadcasting nature. This results in an information leakage on the legitimate terminals' information exchange process. The literature contains several types of techniques to mitigate the information leakage. Until Wyner's wiretap channels, 1 the secure information exchange processes were compensated with the help of the higher layer encryption techniques, which are data encryption standard (DES), 2 triple data ecryption standard (TDES), 3 Rivest-Shamir-Adleman (RSA), 4 and advanced encryption standard (AES). 5 The drawback of the aforementioned higher level encryption techniques is the receiver needs to have a secret key to decode the cipher text. Wyner showed that the physical layer (PHY) security could be an alternative solution to mitigate the information leakage. Friendly jammers and/or legitimate terminals send artificial noise/interference to confuse the illegitimate terminals. There are several other Abbreviations: LRA, leakage rate analysis; NOMA, nonorthogonal multiple access; CC, cooperative communications Int J Commun Syst. 2020;33:e4387.wileyonlinelibrary.com/journal/dac