Artigos de revistas: "Cognitive radio transmitter"

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Lafia, Diafale, Mistura Laide Sanni, Rasheed Ayodeji Adetona, Bodunde Odunola Akinyemi e Ganiyu Adesola Aderounmu. "Signal Processing-based Model for Primary User Emulation Attacks Detection in Cognitive Radio Networks". Journal of Computing and Information Technology 29, n.º 2 (4 de julho de 2022): 77–88. http://dx.doi.org/10.20532/cit.2021.1005297.

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Cognitive Radio Networks (CRNs) have been conceived to improve the efficiency of accessing the spectrum. However, these networks are prone to various kinds of attacks and failures that can compromise the security and performance of their users. One of the notable malicious attacks in cognitive radio networks is the Primary User Emulation (PUE) attack, which results in underutilization and unavailability of the spectrum and low operational efficiency of the network. This study developed an improved technique for detecting PUE attacks in cognitive radio networks and further addressed the characteristics of sparsely populated cognitive radio networks and the mobility of the primary users. A hybrid signal processing-based model was developed using the free space path loss and additive Gaussian noise models. The free space path loss model was used to detect the position of the transmitter, while the additive Gaussian noise model was used to analyze the signal transmitted, i.e., energy detection in the spectrum at the detected location. The proposed model was benchmarked with an existing model using the number of secondary users and the velocity of the transmitter as performance parameters. The simulation results show that the proposed model has improved accuracy in detecting primary user emulation attacks. It was concluded that the proposed hybrid model with respect to the number of secondary users and the velocity of the transmitter can be used for primary user emulation attack detection in cognitive radio networks.

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Oni, Phillip Babatunde, Ruifeng Duan e Mohammed Elmusrati. "Dual Analysis of the Capacity of Spectrum Sharing Cognitive Radio with MRC under Nakagami-m Fading". Conference Papers in Engineering 2013 (28 de maio de 2013): 1–8. http://dx.doi.org/10.1155/2013/572383.

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In this study, the maximum achievable information transmission rate of spectrum sharing cognitive radio with maximal ratio combining (MRC) antenna diversity technique is investigated when the channel between the secondary transmitter and the primary receiver and that between the secondary transmitter and the secondary receiver suffer Nakagami-m fading. With an assumption that both channels encounter Nakagami-m fading and the transmission of the secondary transmitter is subject to average interference power constraint, the approximated expressions for analyzing the effective capacity and the ergodic capacity of cognitive radio users with MRC are presented. The two capacity models are compared. In the case of the effective capacity, it is shown that different applications or users with different quality of service (QoS) requirements can be supported in cognitive radio, and when the delay QoS decreases, the effective capacity approaches the ergodic capacity.

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Rahman, Md Zia Ur, P. V. S. Aswitha, D. Sriprathyusha e S. K. Sameera Farheen. "Beamforming in cognitive radio networks using partial update adaptive learning algorithm". ACTA IMEKO 11, n.º 1 (31 de março de 2022): 8. http://dx.doi.org/10.21014/acta_imeko.v11i1.1214.

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<p>Cognitive radio technology is a promising way to improve bandwidth efficiency. Frequency which is not used in any aspect will be utilized by using some of the most powerful resources in this cognitive radio. One of the main advantages of cognitive radio signal is to detect the different channels which are there in the spectrum and it can modify the frequencies which is utilized frequently. It allows the licensed users to gain the licensed bandwidth under the condition to protect the licensed users from harmful interference i.e., from secondary users. In this paper, we would like to implement cognitive radio using the beamforming technique, by using power allocation as a strategy for the unlicensed transmitter which is purely form on the result of sensing. It is on the state of the primary user in a various cognitive radio network whereas the unlicensed transmitter gives a single antenna and it modify its power transmission. For the cognitive radio setup, we have used normalized adaptive learning algorithms. This application would be very useful in medical telemetry applications. Nowadays wireless communication plays a vital role in healthcare applications for that we have to build a separate base. It reduces the effort of the building of separate infrastructure for medical telemetry applications.</p>

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Lin, Pin-Hsun, Shih-Chun Lin, Chung-Pi Lee e Hsuan-Jung Su. "Cognitive Radio with Partial Channel State Information at the Transmitter". IEEE Transactions on Wireless Communications 9, n.º 11 (novembro de 2010): 3402–13. http://dx.doi.org/10.1109/twc.2010.092410.090725.

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Goel, Paurav, Avtar Singh e Ashok Goel. "Transmit power control and data rate enhancement in cognitive radio network using computational intelligence". International Journal of Electrical and Computer Engineering (IJECE) 12, n.º 2 (1 de abril de 2022): 1602. http://dx.doi.org/10.11591/ijece.v12i2.pp1602-1616.

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Underutilized radio frequencies are the chief apprehension in advance radio communication. The radio recourses are sparse and costly and their efficient allocation has become a challenge. Cognitive radio networks are the ray of hope. Cognitive radio networks use dynamic spectrum access technique to opportunistically retrieve and share the licensed spectrum. The licensed users are called primary users and the users that opportunistically access the licensed spectrum all called secondary users. The proposed system is a feedback system that work on demand and supply concept, in which secondary receivers senses the vacant spectrum and shares the information with the secondary transmitters. The secondary transmitters adjust their transmission parameters of transmit power and data rate in such a way that date rate is maximized. Two methods of spectrum access using frequency division multiple access (FDMA) and Time division multiple access (TDMA) are discussed. Interference temperature limit and maximum achievable capacity are the constraints that regulate the entire technique. The aim of the technique is to control the transmitter power according to the data requirements of each secondary user and optimizing the resources like bandwidth, transmit power using machine learning and feed forward back propagation deep neural networks making full use of the network capacity without hampering the operation of primary network.

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Et. al., Dr Mahesh Kumar N,. "Analytical Model for Mitigating Primary User Emulation Attack using Hypothesis Testing in Cognitive Radio Networks". Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, n.º 11 (10 de maio de 2021): 486–500. http://dx.doi.org/10.17762/turcomat.v12i11.5912.

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The Cognitive Radio (CR) is the key technology to deal with spectrum scarcity by allowing unlicensed CR users to coexist with existing users in licensed spectrum bands without interfering with binding communications. Cognitive technology provides the spectrum ability to be shared with licensed networks. This radio system can adjust its transmitter and recipient parameters on the basis of interaction with the current conditions in the environment. Due to this flexibility cognitive radios are exploring different types of threats and security attacks. In this paper, we focus primarily on the Primary User Emulation Attack (PUEA) which is a major attack in the cognitive radio network. PUEA is similar to a Denial-of-service attack that can seriously disrupt the spectrum sensing process and deny other legitimate secondary users to access the available spectrum. We proposed a Neyman-Pearson composite hypothesis test (NPCHT) based analytical model to study the impact of PUEA in a fading wireless communication environment. Simulation results show that the proposed techniques can substantially reduce the impact of the malicious attack on the network

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Zhang, Xiaodong, Xiaowei Zhu, Jing Liu e Changjiang You. "A low EVM zero-IF RF transmitter for cognitive radio application". Journal of Electronics (China) 27, n.º 5 (setembro de 2010): 723–27. http://dx.doi.org/10.1007/s11767-011-0500-5.

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Ammar, Mahmoud Ali. "Performance Metrics in Cognitive Radio Networks". AL-MUKHTAR JOURNAL OF SCIENCES 36, n.º 1 (31 de março de 2021): 73–79. http://dx.doi.org/10.54172/mjsc.v36i1.21.

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In Cognitive Radio Networks (CRN), the main aim is to allow the secondary users (SUs) to identify the empty bands and use them to transmit or receive data opportunistically. Primary users (PUs) have the priority to use a channel, while the secondary users must vacant this channel once a primary user requests it. An attack known in cognitive radio networks as a Primary User Emulation Attack (PUEA) aims to prevent the SU from using the empty bands. In this paper, an analytical and experimental approach is presented to mitigate the PUEA. This approach is based on obtaining the Probability Density Functions (PDFs) of the received powers at the secondary users from malicious nodes and also from the primary transmitter in the cognitive network. Then, these obtained PDFs are used in Neyman-Pearson composite hypothesis test to measure the performance metrics (probability of false alarm and miss detection in the network). The results proved that the performance metrics were greatly influenced by the network area, where the secondary user is located, and the threshold value λ used in the decision rule. Also, there are boundaries for the λ choices that cannot be overtaken.

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UM, Jung-Sun, Sung-Hyun HWANG, Chang-Joo KIM e Byung Jang JEONG. "A Novel Transmitter and Receiver Structure for Cognitive Radio Based OFDM Systems". IEICE Transactions on Communications E94-B, n.º 4 (2011): 1070–71. http://dx.doi.org/10.1587/transcom.e94.b.1070.

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Tran, Hoai Trung. "Proposed Precoder for the Secondary Transmitter in the Cognitive MIMO Radio Network". International Journal of Computer Applications 183, n.º 22 (18 de agosto de 2021): 20–26. http://dx.doi.org/10.5120/ijca2021921587.

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Myung, Jungho, Yan Chen, K. J. Ray Liu e Joonhyuk Kang. "Non-Cooperative Feedback Control Game for Secondary Transmitter in Cognitive Radio Network". IEEE Signal Processing Letters 20, n.º 6 (junho de 2013): 571–74. http://dx.doi.org/10.1109/lsp.2013.2257755.

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Ho-Van, Khuong, e Thiem Do-Dac. "Relaying Communications in Energy Scavenging Cognitive Networks: Secrecy Outage Probability Analysis". Wireless Communications and Mobile Computing 2019 (6 de maio de 2019): 1–13. http://dx.doi.org/10.1155/2019/2109837.

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This paper exploits a self-powered secondary relay to not only maintain but also secure communications between a secondary source and a secondary destination in cognitive radio networks when source-destination channel is unavailable. The relay scavenges energy from radio frequency (RF) signals of the primary transmitter and the secondary source and consumes the scavenged energy for its relaying activity. Under the maximum transmit power constraint, Rayleigh fading, the primary outage constraint, and the interference from the primary transmitter, this paper suggests an accurate closed-form expression of the secrecy outage probability to promptly assess the security performance of relaying communications in energy scavenging cognitive networks. The validity of the proposed expression is verified by computer simulations. Numerous results demonstrate the security performance saturation in the range of large maximum transmit power or high required outage probability of primary users. Moreover, the security performance is a function of several system parameters among which the relay’s position, the power splitting factor, and the time splitting factor can be optimized to achieve the minimum secrecy outage probability.

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Yadav, Suneel, Anshul Pandey, Dinh-Thuan Do, Byung Moo Lee e Adão Silva. "Secure Cognitive Radio-Enabled Vehicular Communications under Spectrum-Sharing Constraints". Sensors 21, n.º 21 (28 de outubro de 2021): 7160. http://dx.doi.org/10.3390/s21217160.

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Vehicular communication has been envisioned to support a myriad of essential fifth-generation and beyond use-cases. However, the increasing proliferation of smart and intelligent vehicles has generated a lot of design and infrastructure challenges. Of particular interest are the problems of spectrum scarcity and communication security. Consequently, we considered a cognitive radio-enabled vehicular network framework for accessing additional radio spectrum and exploit physical layer security for secure communications. In particular, we investigated the secrecy performance of a cognitive radio vehicular network, where all the nodes in the network are moving vehicles and the channels between them are modeled as double-Rayleigh fading. Furthermore, adopting an underlay approach, the communication between secondary nodes can be performed by employing two interference constraint strategies at the primary receiver; (1) Strategy I: the secondary transmitter power is constrained by the interference threshold of the primary receiver, and (2) Strategy II: the secondary transmitter power is constrained by both the interference threshold of the primary receiver and the maximum transmit power of the secondary network. Under the considered strategies, we derive the exact secrecy outage probability (SOP) and ergodic secrecy capacity (ESC) expressions over double-Rayleigh fading. Moreover, by analyzing the asymptotic SOP behavior, we show that a full secrecy diversity of 1 can be achieved, when the average channel gain of the main link goes to infinity with a fixed average wiretap channel gain. From the ESC analysis, it is revealed that the ESC follows a scaling law of ΘlnΩm2Ωe2 for large Ωm and Ωe, where Ωm and Ωe are the average channel gains of the main link and wiretap link. The numerical and simulation results verify our analytical findings.

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Saher, Maria, Asjad Amin, Imran Ali Qureshi, Muhammad Ali Qureshi e Muhammad Moazzam Jawaid. "Efficient Advanced Encryption Standard for Securing Cognitive Radio Networks". October 2018 37, n.º 4 (1 de outubro de 2018): 645–54. http://dx.doi.org/10.22581/muet1982.1804.16.

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During the last decade, the CR (Cognitive Radio) came into view as a major wireless technology to resolve the issue of spectrum secrecy and efficient spectrum utilization. However, due to unlicensed (secondary) users, there are various security threats to the CRN (Cognitive Radio Networks). Some malicious users may access the CRN and mislead the secondary users to vacate the occupied channel, which may stop the communication. In this work, we propose a new cryptographic-based algorithm, CRAES (Cognitive Radio-Advanced Encryption Standard), inspired by the traditional AES to secure the CRN. The data of the primary and secondary users is encrypted at the transmitter and decrypted at the receiver. Unlike the conventional AES, we introduce the data-dependent key-generation and shift-rows process. We also reduce the rounds of AES from 10-6 to improve the computational efficiency without compromising the overall security. The experimental results demonstrate the effectiveness of the proposed CR-AES in terms of better security, reliability, and computational efficiency.

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Li, Quanzhong, e Sai Zhao. "Robust Secure Beamforming Design for Cooperative Cognitive Radio Nonorthogonal Multiple Access Networks". Security and Communication Networks 2021 (18 de março de 2021): 1–9. http://dx.doi.org/10.1155/2021/5526485.

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By the integration of cooperative cognitive radio (CR) and nonorthogonal multiple access (NOMA), cooperative CR NOMA networks can improve the spectrum efficiency of wireless networks significantly. Due to the openness and exposure of wireless signals, secure communication is an important issue for cooperative CR NOMA networks. In this paper, we investigate the physical layer security design for cooperative CR NOMA networks. Our objective is to achieve maximum secrecy rate of the secondary user by designing optimal beamformers and artificial noise covariance matrix at the multiantenna secondary transmitter under the quality-of-service at the primary user and the transmit power constraint at the secondary transmitter. We consider the practical case that the channel state information (CSI) of the eavesdropper is imperfect, and we model the imperfect CSI by the worst-case model. We show that the robust secrecy rate maximization problem can be transformed to a series of semidefinite programmings based on S-procedure and rank-one relaxation. We also propose an effective method to recover the optimal rank-one solution. Simulations are provided to show the effectiveness of our proposed robust secure algorithm with comparison to the nonrobust secure design and traditional orthogonal multiple access schemes.

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Ho-Van, Khuong, e Thiem Do-Dac. "Security Enhancement for Energy Harvesting Cognitive Networks with Relay Selection". Wireless Communications and Mobile Computing 2020 (29 de setembro de 2020): 1–13. http://dx.doi.org/10.1155/2020/8867148.

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Relay selection is proposed in this paper as an efficient solution to secure information transmission of secondary users against eavesdroppers in energy harvesting cognitive networks. The proposed relay selection method selects a secondary relay among available secondary relays, which are capable of harvesting radio frequency energy in signals of the secondary transmitter and correctly restore secondary message, to curtail signal-to-noise ratio at the wire-tapper. In order to evaluate the security performance of the suggested relay selection method, an exact intercept outage probability formula accounting for peak transmit power confinement, Rayleigh fading, and interference power confinement is firstly derived. Monte-Carlo simulations are then generated to corroborate the proposed formula. Numerous results expose that positions of relays, the number of relays, and parameters of the energy harvesting method significantly influence the security performance while the power confinements on secondary transmitters cause the performance saturation.

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Guo, Lili, Qingwei Li, Fei Gao, Jiangzhi Fu e Pei Guo. "A New Method of Generating Spectral Nulls at the Transmitter in Cognitive Radio". Wireless Personal Communications 88, n.º 4 (10 de fevereiro de 2016): 819–37. http://dx.doi.org/10.1007/s11277-016-3207-y.

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S, Er Gowsalya,. "IDsMA: AN INTEGRATED DIGITAL SIGNATURE AND MUTUAL AUTHENTICATION MECHANISM FOR SECURING THE COGNITIVE RADIO NETWORKS". INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, n.º 04 (20 de abril de 2024): 1–5. http://dx.doi.org/10.55041/ijsrem31071.

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IDsMA, an Integrated Digital Signature and Mutual Authentication mechanism, is proposed to enhance the security of Cognitive Radio Networks (CRNs). With the proliferation of wireless communication, CRNs face increasing vulnerabilities to unauthorized access and malicious attacks. IDsMA addresses these concerns by offering a robust solution that combines digital signatures and mutual authentication protocols. By employing digital signatures, IDsMA ensures the authenticity and integrity of transmitted data, mitigating the risk of data tampering or forgery. Additionally, mutual authentication protocols establish trust between communication entities, verifying the identities of both the transmitter and receiver. This two-way authentication mechanism enhances the overall security posture of CRNs, safeguarding against unauthorized access and potential threats. IDsMA's integrated approach provides a comprehensive security framework tailored to the dynamic and heterogeneous nature of CRNs, enabling reliable and secure communication in wireless environments. Through its effective deployment, IDsMA aims to foster trust, confidentiality, and integrity in CRNs, facilitating their widespread adoption and utilization in modern wireless networks.

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Yu, Gui Cai, Cheng Zhi Long e Man Tian Xiang. "Research on Dynamic Threshold Based Energy Detection in Cognitive Radio Systems". Advanced Materials Research 462 (fevereiro de 2012): 506–11. http://dx.doi.org/10.4028/www.scientific.net/amr.462.506.

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In cognitive radio networks, nodes should have the capability to decide whether a signal from a primary transmitter is locally present or not in a certain spectrum within a short detection period. Traditional spectrum sensing schemes based on fixed threshold are sensitive to noise uncertainty, a fractional fluctuate of average noise power in a short time can lead the performance of spectrum detection drop seriously. This paper presents a new spectrum detection algorithm based on dynamic threshold. Theoretical results show that the proposed scheme debate the noise uncertainty, and good detection performance can be gained, if suitable dynamic threshold is chosen. In other words, the proposed scheme can enhance the robustness against noise and improve the capacity of spectrum sensing.

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Abbasi-Jannatabad, Mohsen, e Seyyed Mohammad Javad Asgari Tabatabaee. "Cooperative beamforming in cognitive radio systems without feedback of receiver beamforming vectors to transmitter". Wireless Networks 27, n.º 3 (12 de fevereiro de 2021): 2067–79. http://dx.doi.org/10.1007/s11276-021-02541-1.

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Abraham, Shiny, e Dimitrie C. Popescu. "Joint transmitter adaptation and power control for cognitive radio networks with target SIR requirements". Physical Communication 9 (dezembro de 2013): 223–30. http://dx.doi.org/10.1016/j.phycom.2012.05.009.

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Yi, Na, Yi Ma e Rahim Tafazolli. "Underlay Cognitive Radio with Full or Partial Channel Quality Information". International Journal of Navigation and Observation 2010 (25 de julho de 2010): 1–12. http://dx.doi.org/10.1155/2010/105723.

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Underlay cognitive radios (UCRs) allow a secondary user to enter a primary user's spectrum through intelligent utilization of multiuser channel quality information (CQI) and sharing of codebook. The aim of this work is to study two-user Gaussian UCR systems by assuming the full or partial knowledge of multiuser CQI. Key contribution of this work is motivated by the fact that the full knowledge of multiuser CQI is not always available. We first establish a location-aided UCR model where the secondary user is assumed to have partial CQI about the secondary-transmitter to primary-receiver link as well as full CQI about the other links. Then, new UCR approaches are proposed and carefully analyzed in terms of the secondary user's achievable rate, denoted by C2, the capacity penalty to primary user, denoted by ΔC1, and capacity outage probability. Numerical examples are provided to visually compare the performance of UCRs with full knowledge of multiuser CQI and the proposed approaches with partial knowledge of multiuser CQI.

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Xiao, Haitao, Limeng Dong e Wenjie Wang. "Intelligent Reflecting Surface-Assisted Secure Multi-Input Single-Output Cognitive Radio Transmission". Sensors 20, n.º 12 (19 de junho de 2020): 3480. http://dx.doi.org/10.3390/s20123480.

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Intelligent reflecting surface (IRS) is a very promising technology for the development of beyond 5G or 6G wireless communications due to its low complexity, intelligence, and green energy-efficient properties. In this paper, we combined IRS with physical layer security (PLS) to solve the security issue of cognitive radio (CR) networks. Specifically, an IRS-assisted multi-input single-output (MISO) CR wiretap channel was studied. To maximize the secrecy rate of secondary users subject to a total power constraint (TPC) for the transmitter and interference power constraint (IPC) for a single antenna primary receiver (PR) in this channel, an alternating optimization (AO) algorithm is proposed to jointly optimize the transmit covariance R at transmitter and phase shift coefficient Q at IRS by fixing the other as constant. When Q is fixed, R is globally optimized by equivalently transforming the quasi-convex sub-problem to convex one. When R is fixed, bisection search in combination with minorization–maximization (MM) algorithm was applied to optimize Q from the non-convex fractional programming sub-problem. During each iteration of MM, another bisection search algorithm is proposed, which is able to find the global optimal closed-form solution of Q given the initial point from the previous iteration of MM. The convergence of the proposed algorithm is analyzed, and an extension of applying this algorithm to multi-antenna PR case is discussed. Simulations have shown that our proposed IRS-assisted design greatly enhances the secondary user’s secrecy rate compared to existing methods without IRS. Even when IPC is active, the secrecy rate returned by our algorithm increases with transmit power as if there is no IPC at all.

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Lin, Ruiquan, Hangding Qiu, Weibin Jiang, Zhenglong Jiang, Zhili Li e Jun Wang. "Deep Reinforcement Learning for Physical Layer Security Enhancement in Energy Harvesting Based Cognitive Radio Networks". Sensors 23, n.º 2 (10 de janeiro de 2023): 807. http://dx.doi.org/10.3390/s23020807.

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The paper studies the secrecy communication threatened by a single eavesdropper in Energy Harvesting (EH)-based cognitive radio networks, where both the Secure User (SU) and the jammer harvest, store, and utilize RF energy from the Primary Transmitter (PT). Our main goal is to optimize the time slots for energy harvesting and wireless communication for both the secure user as well as the jammer to maximize the long-term performance of secrecy communication. A multi-agent Deep Reinforcement Learning (DRL) method is proposed for solving the optimization of resource allocation and performance. Specifically, each sub-channel from the Secure Transmitter (ST) to the Secure Receiver (SR) link, along with the jammer to the eavesdropper link, is regarded as an agent, which is responsible for exploring optimal power allocation strategy while a time allocation network is established to obtain optimal EH time allocation strategy. Every agent dynamically interacts with the wireless communication environment. Simulation results demonstrate that the proposed DRL-based resource allocation method outperforms the existing schemes in terms of secrecy rate, convergence speed, and the average number of transition steps.

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Tang, Kun, Wenjuan Tang, Entao Luo, Zhiyuan Tan, Weizhi Meng e Lianyong Qi. "Secure Information Transmissions in Wireless-Powered Cognitive Radio Networks for Internet of Medical Things". Security and Communication Networks 2020 (24 de fevereiro de 2020): 1–10. http://dx.doi.org/10.1155/2020/7542726.

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In this paper, we consider the issue of the secure transmissions for the cognitive radio-based Internet of Medical Things (IoMT) with wireless energy harvesting. In these systems, a primary transmitter (PT) will transmit its sensitive medical information to a primary receiver (PR) by a multi-antenna-based secondary transmitter (ST), where we consider that a potential eavesdropper may listen to the PT’s sensitive information. Meanwhile, the ST also transmits its own information concurrently by utilizing spectrum sharing. We aim to propose a novel scheme for jointly designing the optimal parameters, i.e., energy harvesting (EH) time ratio and secure beamforming vectors, for maximizing the primary secrecy transmission rate while guaranteeing secondary transmission requirement. For solving the nonconvex optimization problem, we transfer the problem into convex optimization form by adopting the semidefinite relaxation (SDR) method and Charnes–Cooper transformation technique. Then, the optimal secure beamforming vectors and energy harvesting duration can be obtained easily by utilizing the CVX tools. According to the simulation results of secrecy transmission rate, i.e., secrecy capacity, we can observe that the proposed protocol for the considered system model can effectively promote the primary secrecy transmission rate when compared with traditional zero-forcing (ZF) scheme, while ensuring the transmission rate of the secondary system.

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Liu, Rongpeng, Ziyang Wang, Xuerui Wang, Jingwei Lu, Yawei Wang, Yizhou Zhuo, Ruihuan Wu, Zhongchao Wei e Hongzhan Liu. "Performance Analysis of Soft-Switching FSO/THz-RF Dual-Hop AF-NOMA Link Based on Cognitive Radio". Photonics 10, n.º 10 (27 de setembro de 2023): 1086. http://dx.doi.org/10.3390/photonics10101086.

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This paper presents a promising solution to address the scarcity of spectrum resources and enhance spectrum efficiency in the context of cognitive radio (CR)-based soft-switching free-space optical (FSO)/terahertz (THz) radio frequency (RF) dual-hop amplify-and-forward (AF)–non-orthogonal multiple access (ROMANO) links. The impact of maximum tolerable interference power in the primary network, transmit power in the secondary transmitter, and maximum relay transmission power on the link are thoroughly studied. The numerical results ultimately validate the effectiveness of this link in improving performance, and a comparative analysis is conducted with the without-CR scheme, highlighting the distinctive characteristics of the proposed link.

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Ghamari Adian, Mehdi. "Beamforming with Reduced Complexity in MIMO Cooperative Cognitive Radio Networks". Journal of Optimization 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/325217.

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An approach for beamforming with reduced complexity in MIMO cooperative cognitive radio networks (MIMO-CCRN) is presented. Specifically, a suboptimal approach with reduced complexity is proposed to jointly determine the transmit beamforming (TB) and cooperative beamforming (CB) weight vectors along with antenna subset selection in MIMO-CCRN. Two multiantenna secondary users (SU) constitute the desired link, one acting as transmitter (SU TX) and the other as receiver (SU RX) and they coexist with single-antenna primary and secondary users. Some of single antenna secondary users are recruited by desired link as cooperative relay. The maximization of the achievable rates in the desired link is the objective of this work, provided to interference constraints on the primary users are not violated. The objective is achieved by exploiting transmit beamforming at SU TX, cooperation of some secondary users, and cooperative beamforming. Meanwhile, the costs associated with RF chains at the radio front end at SU RX are reduced. Through simulations, it is shown that better performance in the desired link is attained, as a result of cooperation of SUs.

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Diet, Antoine M., Nicolas Ribière-Tharaud, Martine Villegas e Geneviève Baudoin. "Front-end HPA/antenna for multi-radio". International Journal of Microwave and Wireless Technologies 4, n.º 5 (1 de maio de 2012): 483–93. http://dx.doi.org/10.1017/s1759078712000372.

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This paper focuses on multi-radio front-end transmitter, a function implied by cognitive radio (0.5–6 GHz). S and C bands standards (wireless local and metropolitan area networks) present a challenge, due to the signal modulation schemes (orthogonal frequency division multiplex (OFDM)/WCDMA, wideband code division multiple access) dynamic (tens of dBs), driving us to a mandatory transmitter linearization. The idea is to provide frequency, flexibility, and average power control of a multi-radio high-efficiency front end for such signals (polar/envelope elimination and restoration (EER) structure). The study implies antennas design and average power control demonstration. Based on a switched mode power amplifier (PA), a discrete detuning is possible to adapt the PA at both “WiMAX” and “Wifi5” frequencies. This architecture amplifies signals with amplitude information. This is coded here by the ΣΔ/PWM (pulse width modulation) technique, to present a constant envelope signal. The amplitude information is restored by a pass-band radio frequency (RF) filter. The antenna can be designed with a notch, to reduce the filtering constraints (selectivity and standards coexistences) and to help in the restoration of amplitude information. Average power control is illustrated by voltage supply variation and results are a possible dynamic of 9.5 dB. To complete the analysis, the simulation of the propagation channel, including antennas, with CST (free space, line of sight) is imported under AGILENT-ADS.

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Zhao, Feng, Hongsheng Wu, Hongbin Chen e Wen Wang. "Game-Theoretic Beamforming and Power Allocation in MIMO Cognitive Radio Systems with Transmitter Antenna Correlation". Mobile Information Systems 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/427847.

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Multi-input multioutput (MIMO) technique provides a promising solution to enhance the performance of wireless communication systems. In this paper, we consider antenna correlation at the transmitter in practical cognitive MIMO systems. What is more, a game-theoretic framework is conducted to analyze the optimum beamforming and power allocation such that each user maximizes its own rate selfishly under the transmitting power constraint and the primary user (PU) interference constraint. The design of the cognitive MIMO system is formulated as a noncooperative game, where the secondary users (SUs) compete with each other over the resources made available by the PUs. Interestingly, as the correlation parameter grows, the utility degrades. Nash equilibrium is considered as the solution of this game. Simulation results show that the proposed algorithm can converge quickly and clearly outperforms the strategy without game.

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Ho-Van, Khuong, e Thiem Do-Dac. "Impact of Artificial Noise on Security Capability of Energy Harvesting Overlay Networks". Wireless Communications and Mobile Computing 2021 (19 de junho de 2021): 1–12. http://dx.doi.org/10.1155/2021/9976837.

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Artificial noise, energy harvesting, and overlay communications can assure design metrics of modern wireless networks such as data security, energy efficiency, and spectrum utilization efficiency. This paper studies impact of artificial noise on security capability of energy harvesting overlay networks in which the cognitive transmitter capable of self-powering its operation by harvesting radio frequency energy and self-securing its communications against eavesdroppers by generating artificial noise amplifies and forwards the signal of the primary transmitter as well as transmits its individual signal concurrently. To quantify this impact, the current paper firstly suggests accurate expressions of crucial security performance indicators. Then, computer simulations are supplied to corroborate these expressions. Finally, numerous results are demonstrated to expose insights into this impact from which optimum specifications are determined. Notably, primary/cognitive communications can be secured at distinct degrees by flexibly controlling multiple specifications of the suggested system model.

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Chen, Xiaolong, Xiangbo Meng, Xiaoshi Song, Yuting Geng e Chun Shan. "Coverage probability in cognitive radio networks powered by renewable energy with primary transmitter assisted protocol". Information Sciences 400-401 (agosto de 2017): 14–29. http://dx.doi.org/10.1016/j.ins.2017.03.012.

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Zhao, Cai Dan, Fu Jia Yan, Ming Hui Gao e Lian Fen Huang. "Transient Signal Feature Extraction Based on Box Dimension and the Largest Lyapunov Dimension". Advanced Materials Research 756-759 (setembro de 2013): 3607–10. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.3607.

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Cognitive radio is one kind of wireless communication technology, which is to effectively improve the spectrum efficiency by the way of wireless spectrum sensing. Besides of varieties of security issues of the traditional wireless communication, it also has some new problems, such as Primary User Emulation (PUE) attack. This essay presents that based on the fractal dimension of the transient signal characteristics extraction to protect the PUE attack from the cognitive wireless networks, and then extract the fractal dimension of wireless transmitter through experiments to provide reliable characteristic parameters for the next signal recognition, finally to prevent PUEs attack.

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Liu, Zhangyu, Ji Wang, Hao Jiang, Jun Wang, Xingwang Li e Wenwu Xie. "Physical Layer Security Performance Analysis of IRS-Aided Cognitive Radio Networks". Electronics 12, n.º 12 (9 de junho de 2023): 2615. http://dx.doi.org/10.3390/electronics12122615.

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Cognitive radio (CR) acts as a significant player in enhancing the spectral efficiency (SE) of wireless telecommunications; simultaneously, the intelligent reflecting surface (IRS) technique is a valid technique for increasing the confidentiality properties of wireless telecommunications systems through the modulation of the amplitude and phase shift of the channel. Therefore, we take into consideration an IRS-assisted multiple-input single-output (MISO) CR system to raise the confidentiality rate, which is composed of a primary network with a primary receiver (PR) and an eavesdropping link, as well as a secondary network with a secondary receiver (SR) and SR transmitter (SR-TX). In particular, we minimize the SR’s transmit power under the interference temperature (IT) and confidentiality capacity constraints via the joint optimization of the beamforming vector and artificial noise (AN) constraint matrix at SR-TX together with the phase shift matrix of IRS. Numerical outcomes indicate that various transmit antenna values and the IRS element numbers at SR-TX can greatly reduce transmit power while assuring secure communication.

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Sadhana D. Poshattiwar, Sandip B. Shrote ,. "Dynamic Spectrum Sensing For 5G Cognitive Radio Networks Using Optimization Technique". Journal of Electrical Systems 20, n.º 3s (4 de abril de 2024): 1221–31. http://dx.doi.org/10.52783/jes.1433.

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With increasing development of 5G technology, the rapid growth of various technologies and the growth of various wireless devices, demand for wireless spectrum becomes more urgent. Wireless communication technologies have been advancing rapidly, leading to the emergence of 5G communication systems .Spectrum sensing is the key model utilized to access the spectrum dynamically in CRN. Various researchers are done in spectrum sensing scenario and different methods are designed to perform the task of spectrum resource sharing. Most of the methods design a decision statistics for identifying the signal by analyzing the features of noise and signals. One promising approach to address the challenges of spectrum sensing in cognitive radio networks for 5G communication is the integration of deep learning with hybrid optimization techniques. By combining the power of deep learning algorithms with optimization methods, it becomes possible to improve the efficiency and accuracy of spectrum sensing in dynamic and diverse communication scenarios. One of the key advantages of MIMO-based spectrum sensing is its ability to exploit the spatial diversity inherent in the environment. By using multiple antennas at both the transmitter and receiver, MIMO systems can distinguish between signals arriving from different directions, thereby improving the accuracy of spectrum sensing. Moreover, MIMO technology also enables the cognitive radio network to utilize the available spectrum more efficiently. With the ability to establish multiple parallel communication links, MIMO-based cognitive radio networks can achieve higher data rates and improved spectral efficiency, especially in dynamic and challenging radio environments. Research in this field is focused on further enhancing the performance of MIMO-based spectrum sensing in cognitive radio networks through advanced signal processing algorithms and machine learning technique Spectrum sensing detect existence of primary users (PUs) and it becomes a main research topic of CRN in industry and academic domain. This research developed a new framework based on algorithm to progress the mechanism of spectrum sensing in the CRN by detecting the availability of free channel. The signal components are extracted from the received signal and thereby spectrum availability of detected through fusion center using proposed Feedback Artificial Optimization Algorithm-based Deep Q network. However, Simulation results show that the proposed multiple-input-multiple-output(MIMO) spectrum sensing method achieves good performance Cognitive Radion Network attains maximum probability of detection and minimum probability of false alarm as 70%, and 38% for Rayleigh channel.

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Liu, Xiaoying, Ming Xia, Ping Hu, Kechen Zheng e Shubin Zhang. "Optimal Time Allocation for Energy Harvesting Cognitive Radio Networks with Multichannel Spectrum Sensing". Wireless Communications and Mobile Computing 2022 (21 de agosto de 2022): 1–11. http://dx.doi.org/10.1155/2022/3940132.

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From the perspective of time domain and frequency domain, we investigate the energy harvesting cognitive radio networks (EH-CRNs) with multichannel, where the secondary transmitter (ST) opportunistically accesses the licensed subchannels to transmit packets by consuming the harvested energy. To explore the spectrum holes and improve the lifetime of the EH-CRNs, the ST scavenges energy from the radio-frequency (RF) signal in the wide band during the energy harvesting (EH) phase and exploits the harvested energy for sequential sensing and packet transmission during the rest of the time slot. Under the energy constraint, the secondary throughput is improved by optimizing the time allocation among the EH phase, sensing phase, and transmission phase. We formulate the secondary throughput with respect to the durations of the three phases, prove the existence of the optimal time allocation, and discuss the secondary throughput in three cases of the EH-CRNs. Finally, numerical results validate the theoretical results about the secondary throughput and explore the impacts of key system parameters.

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Ho-Van, Khuong, e Thiem Do-Dac. "Relay Selection for Security Improvement in Cognitive Radio Networks with Energy Harvesting". Wireless Communications and Mobile Computing 2021 (19 de junho de 2021): 1–16. http://dx.doi.org/10.1155/2021/9921782.

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This paper selects an unlicensed relay among available self-powered relays to not only remain but also secure information transmission from an unlicensed source to an unlicensed destination. The relays harvest energy in signals of the unlicensed source and the licensed transmitter. Then, they spend the harvested energy for their relaying operation. Conditioned on the licensed outage restriction, the peak transmission power restriction, Rayleigh fading, and the licensed interference, the current paper proposes an exact closed-form formula of the secrecy outage probability to quickly evaluate the secrecy performance of the proposed relay selection method in cognitive radio networks with energy harvesting. The proposed formula is corroborated by computer simulations. Several results illustrate the effectiveness of the relay selection in securing information transmission. Additionally, the security capability is saturated at large peak transmission powers or large preset outage probabilities of licensed users. Furthermore, the security capability depends on many specifications among which the power splitting ratio, the relays’ positions, and the time switching ratio can be optimally selected to obtain the best security performance.

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Lee, Wilaiporn, Kornkamol Thakulsukanant, Kanabadee Srisomboon e Akara Prayote. "Adaptive Two-stage Spectrum Sensing under Noise Uncertainty in Cognitive Radio Networks". ECTI Transactions on Electrical Engineering, Electronics, and Communications 14, n.º 1 (23 de dezembro de 2015): 21–35. http://dx.doi.org/10.37936/ecti-eec.2016141.171084.

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To utilize licensed spectrum bands efficiently, spectrum sensing needs to be accurate and fast. The occurrence of noise uncertainty and the lower in received PU signal power due to the distance between the transmitter and the receiver, path loss, are the main challenges that has a great impact on the accuracy of spectrum sensing. In this paper, we propose a new scheme of two-stage spectrum sensing, “Adaptive Two-stage Spectrum Sensing (ATSS)”, under noise uncertainty environment. ATSS is a modified of a conventional two-stage spectrum sensing where the decision threshold of both stages are adapted on the distance, estimated noise variance and calculated noise uncertainty interval. Therefore, ATSS improves the detection performance of the existing spectrum sensing and is robust to noise uncertainty. The contribution of this paper is three-fold. First, an unreliable detection and wasted stage activation of a conventional two-stage spectrum sensing are reduced. Second, noise uncertainty is addressed. Third, a new parameter, critical distance ( ), is proposed in order to reduce computational burden and sensing time of the first stage.

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Awe, Olusegun Peter, Daniel Adebowale Babatunde, Sangarapillai Lambotharan e Basil AsSadhan. "Second order Kalman filtering channel estimation and machine learning methods for spectrum sensing in cognitive radio networks". Wireless Networks 27, n.º 5 (10 de maio de 2021): 3273–86. http://dx.doi.org/10.1007/s11276-021-02627-w.

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AbstractWe address the problem of spectrum sensing in decentralized cognitive radio networks using a parametric machine learning method. In particular, to mitigate sensing performance degradation due to the mobility of the secondary users (SUs) in the presence of scatterers, we propose and investigate a classifier that uses a pilot based second order Kalman filter tracker for estimating the slowly varying channel gain between the primary user (PU) transmitter and the mobile SUs. Using the energy measurements at SU terminals as feature vectors, the algorithm is initialized by a K-means clustering algorithm with two centroids corresponding to the active and inactive status of PU transmitter. Under mobility, the centroid corresponding to the active PU status is adapted according to the estimates of the channels given by the Kalman filter and an adaptive K-means clustering technique is used to make classification decisions on the PU activity. Furthermore, to address the possibility that the SU receiver might experience location dependent co-channel interference, we have proposed a quadratic polynomial regression algorithm for estimating the noise plus interference power in the presence of mobility which can be used for adapting the centroid corresponding to inactive PU status. Simulation results demonstrate the efficacy of the proposed algorithm.

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Liu, Zi Jun, Zhan Gao, Guo Xin Li e Hai Tao Zhang. "Optimal Beam-Forming Design in Cognitive Relay Networks under Interference Threshold". Advanced Materials Research 850-851 (dezembro de 2013): 561–66. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.561.

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Recently, a new model for cognitive radio networks appears, in which a cognitive user (CU) can relay the primary data stream to improve the performance of the primary user s communication. Traditionally, the transmitter of the cognitive users will send data to the receiver of the cognitive users and relay the data sent from the primary user (PU) in different time slots. However, Multiple Input Multiple Output (MIMO) provides a remarkable increase in the spectral efficiency, which can transmit multiple independent data streams in a time slot with MIMO antenna. Based on the MIMO technique, we propose a novel framework, in which the cognitive user near by the primary user is equipped with MIMO antenna. In this paper, we search for the maximum sum-rate of the cognitive user, limiting the interference to the primary users. Simulation results show that the proposed method can really improve the performance of the cognitive relay networks.

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Xu, Ding, e Qun Li. "Optimal Power Allocation for CC-HARQ-based Cognitive Radio with Statistical CSI in Nakagami Slow Fading Channels". Frequenz 71, n.º 1-2 (1 de janeiro de 2017): 65–72. http://dx.doi.org/10.1515/freq-2015-0268.

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Abstract This paper addresses the power allocation problem for cognitive radio (CR) based on hybrid-automatic-repeat-request (HARQ) with chase combining (CC) in Nakagamimslow fading channels. We assume that, instead of the perfect instantaneous channel state information (CSI), only the statistical CSI is available at the secondary user (SU) transmitter. The aim is to minimize the SU outage probability under the primary user (PU) interference outage constraint. Using the Lagrange multiplier method, an iterative and recursive algorithm is derived to obtain the optimal power allocation for each transmission round. Extensive numerical results are presented to illustrate the performance of the proposed algorithm.

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Ge, Weili, Zhengyu Zhu, Zhongyong Wang e Zhengdao Yuan. "AN-Aided Transmit Beamforming Design for Secured Cognitive Radio Networks with SWIPT". Wireless Communications and Mobile Computing 2018 (13 de agosto de 2018): 1–13. http://dx.doi.org/10.1155/2018/6956313.

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We investigate multiple-input single-output secured cognitive radio networks relying on simultaneous wireless information and power transfer (SWIPT), where a multiantenna secondary transmitter sends confidential information to multiple single-antenna secondary users (SUs) in the presence of multiple single-antenna primary users (PUs) and multiple energy-harvesting receivers (ERs). In order to improve the security of secondary networks, we use the artificial noise (AN) to mask the transmit beamforming. Optimization design of AN-aided transmit beamforming is studied, where the transmit power of the information signal is minimized subject to the secrecy rate constraint, the harvested energy constraint, and the total transmit power. Based on a successive convex approximation (SCA) method, we propose an iterative algorithm which reformulates the original problem as a convex problem under the perfect channel state information (CSI) case. Also, we give the convergence of the SCA-based iterative algorithm. In addition, we extend the original problem to the imperfect CSI case with deterministic channel uncertainties. Then, we study the robust design problem for the case with norm-bounded channel errors. Also, a robust SCA-based iterative algorithm is proposed by adopting the S-Procedure. Simulation results are presented to validate the performance of the proposed algorithms.

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Nguyen, Binh Van, Hyoyoung Jung, Dongsoo Har e Kiseon Kim. "Performance Analysis of a Cognitive Radio Network With an Energy Harvesting Secondary Transmitter Under Nakagami- ${m}$ Fading". IEEE Access 6 (2018): 4135–44. http://dx.doi.org/10.1109/access.2018.2791581.

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Dung, Le, e Seong-Gon Choi. "Connectivity Analysis of Cognitive Radio Ad-Hoc Networks with Multi-Pair Primary Networks". Sensors 19, n.º 3 (29 de janeiro de 2019): 565. http://dx.doi.org/10.3390/s19030565.

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In this paper, we study the connectivity of cognitive radio ad-hoc networks (CRAHNs) where primary users (PUs) and secondary users (SUs) are randomly distributed in a given area following a homogeneous Poisson process. Moreover, for the sake of more realistic CRAHNs, contrary to previous works in the literature, we consider the case that primary network is comprised of multiple communication pairs which are spatial-temporal distributed in the network area. We also take into consideration the differences in transmission range and interference range of both PUs and SUs. The connectivity of such CRAHN is studied from three viewpoints. First, we mathematically analyze the probability of isolated secondary transmitter and secondary receiver. Second, we derive the approximation expression of the link probability between two adjacent SUs. Third, we investigate the path connectivity between two arbitrary SUs by using the simulation analysis approach. The correctness of our mathematical expressions is confirmed by comparing analytical results with simulation results. The results in this paper provide insights into how multiple communication pairs in primary network affect the connectivity of secondary network, which can be useful guidelines for the design of CRAHNs.

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Sultan, Kiran. "Computational-Intelligence-Based Spectrum-Sharing Scheme for NOMA-Based Cognitive Radio Networks". Applied Sciences 13, n.º 12 (14 de junho de 2023): 7144. http://dx.doi.org/10.3390/app13127144.

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The integration of non-orthogonal multiple access (NOMA) technology and cognitive radio networks (CRNs) promises to enhance the spectrum utilization efficiency of 5G and beyond-5G (B5G) mobile communication systems. In this article, a NOMA-based spectrum-sharing scheme is proposed for dual-hop CRNs in which a primary transmitter separated by a long distance from the primary receiver communicates via NOMA-based CRN. In this scenario, we mathematically formulate a constrained optimization problem to maximize the sum rate of all secondary users (SUs) while maintaining the total transmit power of the system. Inspired by the effectiveness of computational intelligence (CI) tools in solving non-linear optimization problems, this article proposes three CI-based solutions to the given problem aiming to guarantee quality of service (QoS) for all users. In addition, an enhanced version of the classic artificial bee colony (ABC) algorithm, referred to here as the enhanced-artificial-bee-colony (EABC)-based power allocation scheme, is proposed to overcome the limitations of classic ABC. The comparison of different CI approaches illustrates that the minimum power required by the secondary NOMA relay to satisfy the primary rate threshold of 5 bit/s/Hz is 20 mW for EABC, while ABC, PSO and GA achieve the same target at 23 mW, 27 mW and 32 mW, respectively. Thus, EABC reduces power consumption by 13.95% compared to ABC, while 29.78% and 46.15% power-saving is achieved compared to PSO and GA, respectively.

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Khalid, Waqas, Heejung Yu e Song Noh. "Residual Energy Analysis in Cognitive Radios with Energy Harvesting UAV under Reliability and Secrecy Constraints". Sensors 20, n.º 10 (25 de maio de 2020): 2998. http://dx.doi.org/10.3390/s20102998.

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The integration of unmanned aerial vehicles (UAVs) with a cognitive radio (CR) technology can improve the spectrum utilization. However, UAV network services demand reliable and secure communications, along with energy efficiency to prolong battery life. We consider an energy harvesting UAV (e.g., surveillance drone) flying periodically in a circular track around a ground-mounted primary transmitter. The UAV, with limited-energy budget, harvests radio frequency energy and uses the primary spectrum band opportunistically. To obtain intuitive insight into the performance of energy-harvesting, and reliable and secure communications, the closed-form expressions of the residual energy, connection outage probability, and secrecy outage probability, respectively, are analytically derived. We construct the optimization problems of residual energy with reliable and secure communications, under scenarios without and with an eavesdropper, respectively, and the analytical solutions are obtained with the approximation of perfect sensing. The numerical simulations verify the analytical results and identify the requirements of length of sensing phase and transmit power for the maximum residual energy in both reliable and secure communication scenarios. Additionally, it is shown that the residual energy in secure communication is lower than that in reliable communication.

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K. S., Nandini, e S. A. Hariprasad. "Optimal Spectrum Sensor Assignment in Multi-channel Multi-user Cognitive Radio Networks". Journal of Telecommunications and Information Technology 8 (28 de dezembro de 2018): 88–96. http://dx.doi.org/10.26636/jtit.2018.124017.

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Accurate detection of spectrum holes is the most important and critical task in any cognitive radio (CR) communication system. When a single spectrum sensor is assigned to detect a speciﬁc primary channel, then the detection may be unreliable because of noise, random multipath fading and shadowing. Also, even when the primary channel is invisible at the CR transmitter, it may be visible at the CR receiver (the hidden primary channel problem). With a single sensor per channel, a high and consistently uniform level of sensitivity is required for reliable detection. These problems are solved by deploying multiple heterogeneous sensors at distributed locations. The proposed spectrum hole detection method uses cooperative sensing, where the challenge is to properly assign sensors to diﬀerent primary channels in order to achieve the best reliability, a minimum error rate and high eﬃciency. Existing methods use particle swarm optimization, the ant colony system, the binary ﬁreﬂy algorithm, genetic algorithms and non-linear mixed integer programming. These methods are complex and require substantial pre-processing. The aim of this paper is to provide a simpler solution by using simpler binary integer programming for optimal assignment. Optimal assignment minimizes the probability of interference which is a non-linear function of decision variables. We present an approach used to linearize the objective function. Since multiple spectrum sensors are used, the optimal constrained assignment minimizes the maximum of interferences. While performing the optimization, the proposed method also takes care of the topological layout concerned with channel accessibility. The proposed algorithm is easily scalable and ﬂexible enough to adapt to diﬀerent practical scenarios.

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Garcia, Carla E., Mario R. Camana e Insoo Koo. "Secrecy Energy Efficiency Maximization in an Underlying Cognitive Radio–NOMA System with a Cooperative Relay and an Energy-Harvesting User". Applied Sciences 10, n.º 10 (24 de maio de 2020): 3630. http://dx.doi.org/10.3390/app10103630.

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Security is considered a critical issue in the deployment of 5G networks because of the vulnerability of information that can be intercepted by eavesdroppers in wireless transmission environments. Thus, physical layer security has emerged as an alternative for the secure enabling of 5G technologies and for tackling this security issue. In this paper, we study the secrecy energy efficiency (SEE) in a downlink underlying cognitive radio (CR)—non-orthogonal multiple access (NOMA) system with a cooperative relay. The system has an energy-harvesting (EH) user and an eavesdropper, where the transmitter provides direct communication with a close secondary user and a distant secondary user via the relay. Our objective is to maximize the SEE of the CR-NOMA system under the constraints of a minimum information rate for the secondary users, a minimum amount of energy harvested by the EH user, and maximum power availability at the transmitter and the relay that still prevents them from causing unacceptable interference with the primary user. The proposed solution to maximize the SEE is based on the low-computational—complexity particle swarm optimization (PSO) algorithm. For validation purposes, we compare the optimization outcomes obtained by the PSO algorithm with the optimal exhaustive search method. Furthermore, we compare the performance of our proposed CR-NOMA scheme with the conventional orthogonal multiple access (OMA) scheme.

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Minh Nam, Pham, Ha Duy Hung, Lam-Thanh Tu, Pham Viet Tuan, Tran Trung Duy e Tan Hanh. "Outage Performance of Interference Cancellation-Aided Two-Way Relaying Cognitive Network with Primary TAS/SC Communication and Secondary Partial Relay Selection". Electronics 11, n.º 22 (8 de novembro de 2022): 3645. http://dx.doi.org/10.3390/electronics11223645.

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In this paper, we propose a two-way relaying scheme using digital network coding in an underlay cognitive radio network. In the proposed scheme, the transmit antenna selection and selection techniques are combined using a primary transmitter and a primary receiver, respectively. In the secondary network, two source nodes that cannot directly communicate attempt to exchange their data with each other. As a result, the relaying technique using partial relay selection is applied to assist the data exchange. Particularly, at the first time slot, the selected secondary relay applies an interference cancellation technique to decode the data received from the secondary sources. Then, the selected relay uses digital network coding to send XOR-ed data to the sources at the second time slot. We first derive the outage probability of the primary network over block the Rayleigh fading channel. Then, the transmit power of the secondary transmitters including the source and relay nodes are calculated to guarantee the quality of service of the primary network. Finally, the exact closed-form formulas of the outage probability of the secondary sources over the block Rayleigh fading channel are derived, and then verified by computer simulations using the Monte Carlo method.

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Sudha, Y., e V. Sarasvathi. "A Model-Free Cognitive Anti-Jamming Strategy Using Adversarial Learning Algorithm". Cybernetics and Information Technologies 22, n.º 4 (1 de novembro de 2022): 56–72. http://dx.doi.org/10.2478/cait-2022-0039.

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Abstract Modern networking systems can benefit from Cognitive Radio (CR) because it mitigates spectrum scarcity. CR is prone to jamming attacks due to shared communication medium that results in a drop of spectrum usage. Existing solutions to jamming attacks are frequently based on Q-learning and deep Q-learning networks. Such solutions have a reputation for slow convergence and learning, particularly when states and action spaces are continuous. This paper introduces a unique reinforcement learning driven anti-jamming scheme that uses adversarial learning mechanism to counter hostile jammers. A mathematical model is employed in the formulation of jamming and anti-jamming strategies based on deep deterministic policy gradients to improve their policies against each other. An open-AI gym-oriented customized environment is used to evaluate proposed solution concerning power-factor and signal-to-noise-ratio. The simulation outcome shows that the proposed anti-jamming solution allows the transmitter to learn more about the jammer and devise the optimal countermeasures than conventional algorithms.

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Kollár, Zsolt, Lajos Varga, Bálint Horváth, Péter Bakki e János Bitó. "Evaluation of Clipping Based Iterative PAPR Reduction Techniques for FBMC Systems". Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/841680.

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This paper investigates filter bankmulticarrier (FBMC), a multicarrier modulation technique exhibiting an extremely low adjacent channel leakage ratio (ACLR) compared to conventional orthogonal frequency division multiplexing (OFDM) technique. The low ACLR of the transmitted FBMC signal makes it especially favorable in cognitive radio applications, where strict requirements are posed on out-of-band radiation. Large dynamic range resulting in high peak-to-average power ratio (PAPR) is characteristic of all sorts of multicarrier signals. The advantageous spectral properties of the high-PAPR FBMC signal are significantly degraded if nonlinearities are present in the transceiver chain. Spectral regrowth may appear, causing harmful interference in the neighboring frequency bands. This paper presents novel clipping based PAPR reduction techniques, evaluated and compared by simulations and measurements, with an emphasis on spectral aspects. The paper gives an overall comparison of PAPR reduction techniques, focusing on the reduction of the dynamic range of FBMC signals without increasing out-of-band radiation. An overview is presented on transmitter oriented techniques employing baseband clipping, which can maintain the system performance with a desired bit error rate (BER).

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