Biblio

This paper investigates the physical layer security of a cognitive radio (CR) non-orthogonal multiple-access (NOMA) network supported by an intelligent reflecting surface (IRS). In a CR network, a secondary base station (BS) serves a couple of users, i.e., near and far users, via NOMA transmission under eavesdropping from a malicious attacker. It is assumed that the direct transmission link from the BS and far user is absent due to obstacles. Thus, an IRS is utilized to support far user communication, however, the communication links between the IRS and near/primary users are neglected because of heavy attenuation. The exact secrecy outage probability (SOP) for the near user and approximate SOP for the far user are then derived in closed-form by using the Gauss-Chebyshev approach. The accuracy of the derived analytical SOP is then verified through Monte Carlo simulations. The simulation results also provide useful insights on the impacts of the number of IRS reflecting elements and limited interference temperature on the system SOP.

Physical Layer Security (PLS) is used to accomplish perfect secure communication between intended network nodes, while the eavesdropper gets zero information. In this paper, a smart antenna technology i.e., Massive multiple-input-multiple-output (mMIMO) and Non-Orthogonal Multiple Access (NOMA) technology is being used to enhance the secrecy performance of a 5G communication network. Small scale Rayleigh fading channels, as well as large scale pathway loss, have to be taken into consideration. An eavesdropper with multiple antennas, an amplify-and-forward (AF) relay with multi antenna has been proposed. Spider Monkey Algorithm (SMO) is used in adding Artificial Noise (AN) for refining secrecy rate. The findings revealed that the suggested technique improves the security and the quality of Wireless communication.

Physical layer security is an emerging security area to tackle wireless security communications issues and complement conventional encryption-based techniques. Thus, we propose a novel scheme based on swarm intelligence optimization technique and a deep neural network (DNN) for maximizing the secrecy energy efficiency (SEE) in a cooperative relaying underlay cognitive radio- and non-orthogonal multiple access (NOMA) system with a non-linear energy harvesting user which is exposed to multiple eavesdroppers. Satisfactorily, simulation results show that the proposed particle swarm optimization (PSO)-DNN framework achieves close performance to that of the optimal solutions, with a meaningful reduction in computation complexity.

Non-orthogonal multiple access (NOMA) is emerging as a popular radio access technique to serve multiple users under the same resource block to improve spectral efficiency in 5G and 6G communication. But the resource sharing in NOMA causes concerns on data security. Since power domain NOMA exploits the difference in channel properties for bandwidth-efficient communication, it is feasible to ensure data confidentiality in NOMA communication through physical layer security techniques. In this work, we propose to ensure resistance against internal eavesdropping in NOMA communication through a secret key derived from channel randomness. A unique secret key is derived from the channel of each NOMA user; which is used to randomize the data of the respective user before superposition coding (SC) to prevent internal eavesdropping. The simulation results show that the proposed system provides very good security against internal eavesdropping in NOMA.

In this fifth generation of vehicular communication, the security against various malicious attacks are achieved by using malicious vehicles identification and trust management (MAT) algorithm. Basically, the proposed MAT algorithm performs in two dimensions, they are (i) Node trust and (ii) information trust accompanied with a digital signature and hash chain concept. In node trust, the MAT algorithm introduces the special form of key exchanging algorithm to every members of public group key, and later the vehicles with same target location are formed into cluster. The public group key is common for each participant but everyone maintain their own private key to produce the secret key. The proposed MAT algorithm, convert the secrete key into some unique form that allows the CMs (cluster members) to decipher that secrete key by utilizing their own private key. This key exchanging algorithm is useful to prevent the various attacks, like impersonate attack, man in middle attack, etc. In information trust, the MAT algorithm assigns some special nodes (it has common distance from both vehicles) for monitoring the message forwarding activities as well as routing behavior at particular time. This scheme is useful to predict an exact intruder and after time out the special node has dropped all the information. The proposed MAT algorithm accurately evaluates the trustworthiness of each node as well as information to control different attacks and become efficient for improving a group lifetime, stability of cluster, and vehicles that are located on their target place at correct time.

We consider the physical layer security (PLS) of non-orthogonal multiple access (NOMA) enabled multiple-input multiple-output (MIMO) visible light communication systems in the presence of a passive eavesdropper (Eve). In order to disrupt the decoding process at Eve, we propose a novel precoding scheme reinforced with random constellation coding. Multiple legitimate users (Bobs) will be served simultaneously using NOMA. For the proposed precoder design, we exploit the slow-fading characteristics of the visible light channel so that the transmitted symbols are successfully decoded at Bob, while Eve suffers from very high bit error ratios (BERs) due to precoding-induced jamming. Via computer simulations, we show that Bob can successfully decode their own information in various user configurations and receiver diversities. It is also shown that the BER at Eve's side is increased to the 0.5-level for similar and the asymmetrical positioning of Bob with respect to the transmitter, thus PLS is ensured by the proposed preceding technique.

Fifth-generation (5G) network demands of higher data rate, massive user connectivity and large spectrum can be achieve using Sparse Code Multiple Access (SCMA) scheme. The integration of cognitive feature spectrum sensing with SCMA can enhance the spectrum efficiency in a heavily dense 5G wireless network. In this paper, we have investigated the primary user detection performance using SCMA in Centralized Cooperative Spectrum Sensing (CCSS). The developed model can support massive user connectivity, lower latency and higher spectrum utilization for future 5G networks. The simulation study is performed for AWGN and Rayleigh fading channel. Log-MPA iterative receiver based Log-Likelihood Ratio (LLR) soft test statistic is passed to Fusion Center (FC). The Wald-hypothesis test is used at FC to finalize the PU decision.

In this paper, we address the problem of joint user association and power allocation for non-orthogonal multiple access (NOMA) networks with multiple base stations (BSs). A user grouping procedure into orthogonal clusters, as well as an allocation of different physical resource blocks (PRBs) is considered. The problem of interest is mathematically described using the maximization of the weighted sum rate. We apply two different swarm intelligence algorithms, namely, the recently introduced Grey Wolf Optimizer (GWO), and the popular Particle Swarm Optimization (PSO), in order to solve this problem. Numerical results demonstrate that the above-described problem can be satisfactorily addressed by both algorithms.

This paper investigates physical layer security of non-orthogonal multiple access (NOMA) in cognitive radio (CR) networks. The techniques of NOMA and CR have improved the spectrum efficiency greatly in the traditional networks. Because of the difference in principles of spectrum improving, NOMA and CR can be combined together, i.e. CR NOMA network, and have great potential to improving the spectrum efficiency. However the physical layer security in CR NOMA network is different from any single network of NOMA or CR. We will study the physical layer security in underlay CR NOMA network. Firstly, the wiretap network model is constructed according to the technical characteristics of NOMA and CR. In addition, new exact and asymptotic expressions of the security outage probability are derived and been confirmed by simulation. Ultimately, we have studied the effect of some critical factors on security outage probability after simulation.