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Academic literature on the topic 'Networks with underlay cognitive nodes'

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Published: 6 September 2023

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Journal articles on the topic "Networks with underlay cognitive nodes"

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Hussain, Syed Imtiaz, Mohamed M. Abdallah, Mohamed-Slim Alouini, Khalid Qaraqe, and Mazen Hasna. "Relay selection in underlay cognitive networks with fixed transmission power nodes." Transactions on Emerging Telecommunications Technologies 24, no. 7-8 (July 31, 2013): 734–47. http://dx.doi.org/10.1002/ett.2691.

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Alhamad, Raed, and Hatem Boujemaa. "Intelligent Reflecting Surfaces with Adaptive Transmit Power for Underlay Cognitive Radio Networks." Wireless Communications and Mobile Computing 2022 (August 17, 2022): 1–7. http://dx.doi.org/10.1155/2022/2787466.

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In this article, we study the performance of intelligent reflecting surfaces (IRS) with adaptive transmit power (ATP). The power of secondary source is adapted to have a low interference at primary destination. IRS with ATP offers 14, 20, 26, 32, and 38 dB gains versus the absence of IRS for N = 8,16,32,64 , and 128 reflectors. Rayleigh channels are studied with arbitrary positions of primary and secondary nodes.
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Toan, Hoang Van, and Vo Nguyen Quoc Bao. "Performance Analysis of Cognitive Two-Way Networks with Interference from Primary User over Nakagami-m Fading Channels." Journal of Science and Technology: Issue on Information and Communications Technology 3, no. 1 (March 31, 2017): 29. http://dx.doi.org/10.31130/jst.2017.35.

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A cognitive underlay two-way relay network taking into account interference links from primary transmitter to secondary receivers over Nakagami-m fading channels is analyzed in this article. In this model, a secondary system including two terminal nodes exchanges data through a decode-and-forward (DF) relay node. Under the underlay approach, all secondary transmitter must adjust transmit power to protect the primary communications. We derive the exact and asymptotic closed-form expression for the secondary system outage probability over Nakagami-m fading channels showing the system diversity. Monte-Carlo simulation are performed to verify the analysis results as well as to show the system characteristics
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Kozić, Nadica, Vesna Blagojević, Aleksandra Cvetković, and Predrag Ivaniš. "Performance Analysis of Wirelessly Powered Cognitive Radio Network with Statistical CSI and Random Mobility." Sensors 23, no. 9 (May 6, 2023): 4518. http://dx.doi.org/10.3390/s23094518.

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The relentless expansion of communications services and applications in 5G networks and their further projected growth bring the challenge of necessary spectrum scarcity, a challenge which might be overcome using the concept of cognitive radio. Furthermore, an extremely high number of low-power devices are introduced by the concept of the Internet of Things (IoT), which also requires efficient energy usage and practically applicable device powering. Motivated by these facts, in this paper, we analyze a wirelessly powered underlay cognitive system based on a realistic case in which statistical channel state information (CSI) is available. In the system considered, the primary and the cognitive networks share the same spectrum band under the constraint of an interference threshold and a maximal tolerable outage permitted by the primary user. To adopt the system model in realistic IoT application scenarios in which network nodes are mobile, we consider the randomly moving cognitive user receiver. For the analyzed system, we derive the closed-form expressions for the outage probability, the outage capacity, and the ergodic capacity. The obtained analytical results are corroborated by an independent simulation method.
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Giang, Nguyen Hong, Vo Nguyen Quoc Bao, and Hung Nguyen-Le. "Effect of CSI Imperfection on Cognitive Underlay Transmission over Nakagami-m Fading Channel." Journal of Science and Technology: Issue on Information and Communications Technology 1 (August 31, 2015): 59. http://dx.doi.org/10.31130/jst.2015.13.

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This paper analyzes the performance of a cognitive underlay system over Nakagami-m fading channels, where maximal ratio combining (MRC) is employed at secondary destination and relay nodes. Under the condition of imperfect channel state information (CSI) of interfering channels, system performance metrics for the primary network and for the secondary network are formulated into exact and approximate expressions, which can be served as theoretical guidelines for system designs. To verify the performance analysis, several analytical and simulated results of the system performance are provided under various system and channel settings.
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Han, Xu, Lei Xue, Ying Xu, and Zunyang Liu. "A Radio Environment Maps Estimation Algorithm based on the Pixel Regression Framework for Underlay Cognitive Radio Networks Using Incomplete Training Data." Sensors 20, no. 8 (April 15, 2020): 2245. http://dx.doi.org/10.3390/s20082245.

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In the underlay cognitive radio networks, the radio environment maps (REMs) estimation is the main challenge in sensing the idle wireless spectrum resources. Traditional deep learning-based algorithms estimate the REMs on the basis of the high-quality, large-scale complete training images. However, collecting the complete radio environment images is time-consuming and requires a numerous number of power spectrum sensing nodes. For this reason, we propose a generative adversarial networks-based pixel regression framework (PRF) for underlay cognitive radio networks. The PRF algorithm relaxes the requirement of the complete training images, and estimates the radio environment maps only on the basis of the incomplete REMs images, which are easier to be collected. First, we transform the radio environment maps estimation task into a pixel regression task through the color mapping progress. Then, to extract helpful information from the incomplete training data, we design a feature enhancing module for the PRF algorithm, which intelligently learns and emphasizes the important features from the training images. Finally, we use the trained pixel regression framework to reconstruct the radio environment maps in the target area. The proposed algorithm learns accurate radio environment characteristics from the incomplete training data rather than making direct biased or imprecise radio propagation assumptions as in the traditional methods. Thus, the PRF algorithm has a better REMs reconstruction performance than the traditional methods, as verified by simulations.
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Raj, K. Shashi. "Interference resilient stochastic prediction based dynamic resource allocation model for cognitive MANETs." Indian Journal of Science and Technology 13, no. 41 (October 10, 2020): 4332–50. http://dx.doi.org/10.17485/ijst/v13i41.687.

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Background/Objectives: Being dynamic in nature, Mobile Ad-hoc Network (MANET) requires robust resource allocation strategy that can ensure both optimal transmission reliability and resource efficiency to meet Quality of Service (QoS) demands. The objective of this research is to address interference resilience requirement in MANETs which is must due to greedy nature of nodes especially when accessing resource or bandwidth and develop a highly robust stochastic prediction based resource allocation strategy. Methods: The proposed Interference Resilient Stochastic Prediction based Dynamic Resource Allocation model for Cognitive MANET (ISP-DRACM) intends to enable optimal resource allocation under interweave and underlay network setup with instantaneous as well as average interference conditions. It employs a joint power management and resource allocation strategy where it intends to maximize the weighted sum-rate of the secondary users under certain defined conditions like average power and stochastic interference level. Findings/Novelty: Inculcating resource allocation problem as controlled Markov Decision Process using Hidden Markov Model (HMM) and Lagrange relaxation, our proposed model achieves better resource allocation under limited noise or interference condition and hence achieves both costeffectiveness as well as QoS provision. This method has exhibited satisfactory performance towards spectrum allocation to the secondary users without imposing any significant interference for both interweave as well as underlay Cognitive Radio setup. Keywords: Cognitive mobile ad-hoc network; stochastic prediction; interference resilience; channel state information; dynamic resource allocation; underlay and overlay cognitive MANET
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Bakht, Khush, Furqan Jameel, Zain Ali, Wali Ullah Khan, Imran Khan, Guftaar Ahmad Sardar Sidhu, and Jeong Woo Lee. "Power Allocation and User Assignment Scheme for beyond 5G Heterogeneous Networks." Wireless Communications and Mobile Computing 2019 (November 16, 2019): 1–11. http://dx.doi.org/10.1155/2019/2472783.

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The issue of spectrum scarcity in wireless networks is becoming prominent and critical with each passing year. Although several promising solutions have been proposed to provide a solution to spectrum scarcity, most of them have many associated tradeoffs. In this context, one of the emerging ideas relates to the utilization of cognitive radios (CR) for future heterogeneous networks (HetNets). This paper provides a marriage of two promising candidates (i.e., CR and HetNets) for beyond fifth generation (5G) wireless networks. More specifically, a joint power allocation and user assignment solution for the multiuser underlay CR-based HetNets has been proposed and evaluated. To counter the limiting factors in these networks, the individual power of transmitting nodes and interference temperature protection constraints of the primary networks have been considered. An efficient solution is designed from the dual decomposition approach, where the optimal user assignment is obtained for the optimized power allocation at each node. The simulation results validate the superiority of the proposed optimization scheme against conventional baseline techniques.
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Tran Tin, Phu, Dang The Hung, Tan Nguyen, Tran Duy, and Miroslav Voznak. "Secrecy Performance Enhancement for Underlay Cognitive Radio Networks Employing Cooperative Multi-Hop Transmission with and without Presence of Hardware Impairments." Entropy 21, no. 2 (February 24, 2019): 217. http://dx.doi.org/10.3390/e21020217.

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In this paper, we consider a cooperative multi-hop secured transmission protocol to underlay cognitive radio networks. In the proposed protocol, a secondary source attempts to transmit its data to a secondary destination with the assistance of multiple secondary relays. In addition, there exists a secondary eavesdropper who tries to overhear the source data. Under a maximum interference level required by a primary user, the secondary source and relay nodes must adjust their transmit power. We first formulate effective signal-to-interference-plus-noise ratio (SINR) as well as secrecy capacity under the constraints of the maximum transmit power, the interference threshold and the hardware impairment level. Furthermore, when the hardware impairment level is relaxed, we derive exact and asymptotic expressions of end-to-end secrecy outage probability over Rayleigh fading channels by using the recursive method. The derived expressions were verified by simulations, in which the proposed scheme outperformed the conventional multi-hop direct transmission protocol.
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Minh Nam, Pham, Ha Duy Hung, Lam-Thanh Tu, Pham Viet Tuan, Tran Trung Duy, and 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, no. 22 (November 8, 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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Dissertations / Theses on the topic "Networks with underlay cognitive nodes"

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Jasbi, Fahimeh Jafarali. "Hybrid overlay/underlay cognitive radio networks with MC-CDMA." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/hybrid-overlayunderlay-cognitive-radio-networks-with-mccdma(435d45a5-82c0-4507-9c53-23aa248988c9).html.

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There has been a growing demand for wireless communication services in the past few years. Recent reports reveal that the demand will not only increase in the number of subscribers but also in more diverse applications such as Machine-to-Machine (M2M) communications and the Internet of Things. With such demand for capacity increase, there is a necessity to shift from today’s Static Frequency Allocation (SFA) to Dynamic Spectrum Access (DSA). The change will make efficient use of spectrum by utilizing the unused parts in different times, frequencies and spaces. With this regard, cognitive radio (CR) is a powerful potential candidate for the spectrum scarcity problem. This work addresses the two main current discussions in Cognitive Radio Networks (CRN), spectral efficiency and interference mitigation problem. There are two main spectrum sharing techniques in CRN, overlay and underlay, which have been thoroughly investigated in the literature. Unlike the relative works which separate the use of overlay and underlay, this works considers the joint overlay and underlay as a hybrid system to enhance the spectral efficiency and Bit Error Rate (BER) performance in CRNs. MC-CDMA is proposed for underlay transmission for two main advantages. Firstly, for low power spectral density due to spreading. Secondly, for its capability to mitigate high interference. Two hybrid MC-CDMA schemes are proposed in this work. The first scheme spreads the underlay signal through the whole bandwidth to mitigate PU interference and benefit from the frequency diversity. To maximize data rate, overlay utilizes the available bands while keeping orthogonality with underlay using Orthogonal Variable Spreading Factor (OVSF) codes. To further increase capacity, an overload MC-CDMA system is proposed. In this scheme, overlay utilizes the full signal dimension, while underlay overloads the system. Two layered spreading is applied to differentiate overlay and underlay users. In order to detect the underlay signal, the overlay signal is detected first and is cancelled from the received signal. The underlay data is then detected from this modified signal. The framework is then extended to a multi-user underlay scenario. A code allocation algorithm is proposed in order to achieve low cross-correlation between the overlay and underlay users. The results show that the proposed overload system maintains good performance even in high PU interference level. Furthermore, the proposed hybrid capacities are optimized and compared with the two available hybrid systems in the literature. The proposed overload system showed to increase capacity significantly, both in AWGN and fading environment, in compared with the existing methods.
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Al-Hraishawi, Hayder Abed Hussein. "DESIGN AND ANALYSIS OF COGNITIVE MASSIVE MIMO NETWORKS WITH UNDERLAY SPECTRUM SHARING." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/dissertations/1412.

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Recently, massive multiple-input multiple-output (MIMO) systems have gained significant attention as a new network architecture to not only achieving unprecedented spectral and energy efficiencies, but also to alleviating propagation losses and inter-user/inter-cell interference. Therefore, massive MIMO has been identified as one of the key candidate technologies for the 5th generation wireless standard. This dissertation thus focuses on (1) developing a performance analysis framework for cognitive massive MIMO systems by investigating the uplink transmissions of multi-cell multi-user massive MIMO secondary systems, which are underlaid in multi-cell multi-user primary massive MIMO systems, with taking into consideration the detrimental effects of practical transmission impairments, (2) proposing a new wireless-powered underlay cognitive massive MIMO system model, as the secondary user nodes is empowered by the ability to efficiently harvest energy from the primary user transmissions, and then access and utilize the primary network spectrum for information transmission, and (3) developing a secure communication strategy for cognitive multi-user massive MIMO systems, where physical layer secure transmissions are provisioned for both primary and secondary systems by exploiting linear precoders and artificial noise (AN) generation in order to degrade the signal decodability at eavesdropper. The key design feature of the proposed cognitive systems is to leverage the spatial multiplexing strategies to serve a large number of spatially distributed user nodes by using very large numbers of antennas at the base-stations. Moreover, the fundamental performance metrics, the secondary transmit power constraints, which constitute the underlay secondary transmissions subject to a predefined primary interference temperature, and the achievable sum rates of the primary and secondary systems, are characterized under different antenna array configurations. Additionally, the detrimental impact of practical wireless transmission impairments on the performance of the aforementioned systems are quantified. The important insights obtained throughout these analyses can be used as benchmarks for designing practical cognitive spectrum sharing networks.
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Kabiri, Charles. "On the Performance of Underlay Cognitive Radio Networks with Interference Constraints and Relaying." Doctoral thesis, Blekinge Tekniska Högskola [bth.se], Faculty of Computing - Department of Communication Systems, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00609.

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Efficiently allocating the scarce and expensive radio resources is a key challenge for advanced radio communication systems. To this end, cognitive radio (CR) has emerged as a promising solution which can offer considerable improvements in spectrum utilization. Furthermore, cooperative communication is a concept proposed to obtain spatial diversity gains through relays without requiring multiple antennas. To benefit from both CR and cooperative communications, a combination of CR networks (CRNs) with cooperative relaying referred to as cognitive cooperative relay networks (CCRNs) has recently been proposed. CCRNs can better utilize the radio spectrum by allowing the secondary users (SUs) to opportunistically access spectrum, share spectrum with primary users (PUs), and provide performance gains offered by cooperative relaying. In this thesis, a performance analysis of underlay CRNs and CCRNs in different fading channels is provided based on analytical expressions, numerical results, and simulations. To allocate power in the CCRNs, power allocation policies are proposed which consider the peak transmit power limit of the SUs and the outage probability constraint of the primary network. Thus, the impact of multiuser diversity, peak transmit power, fading parameters, and modulation schemes on the performance of the CRNs and CCRNs can be analyzed. The thesis is divided into an introduction and five research parts based on peer-reviewed conference papers and journal articles. The introduction provides fundamental background on spectrum sharing systems, fading channels, and performance metrics. In the first part, a basic underlay CRN is analyzed where the outage probability and the ergodic capacity of the network over general fading channels is derived. In the second part, the outage probability and the ergodic capacity of an underlay CRN are assessed capturing the effect of multiuser diversity on the network subject to Nakagami-m fading. Considering the presence of a PU transmitter (PU-Tx), a power allocation policy is derived and utilized for CRN performance analysis under Rayleigh fading. In the third part, the impact of multiple PU-Txs and multiple PU receivers (PU-Rxs) on the outage probability of an underlay CCRN is studied. The outage constraint at the PU-Rx and the peak transmit power constraint of the SUs are taken into account to derive the power allocation policies for the SUs. In the fourth part, analytical expressions for the outage probability and symbol error probability for CCRNs are derived where signal combining schemes at the SU receiver (SU-Rx) are compared. Finally, the fifth part applies a sleep/wake-up strategy and the min(N; T) policy to an underlay CRN. The SUs of the network operate as wireless sensor nodes under Nakagami-m fading. A power consumption function of the CRN is derived. Further, the impact of M/G/1 queue and fading channel parameters on the power consumption is assessed.
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Tran, Hung. "Performance Analysis of Cognitive Radio Networks with Interference Constraints." Doctoral thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00550.

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To support the rapidly increasing number of mobile users and mobile multimedia services, and the related demands for bandwidth, wireless communication technology is facing a potentially scarcity of radio spectrum resources. However, spectrum measurement campaigns have shown that the shortage of radio spectrum is due to inefficient usage and inflexible spectrum allocation policies. Thus, to be able to meet the requirements of bandwidth and spectrum utilization, spectrum underlay access, one of the techniques in cognitive radio networks (CRNs), has been proposed as a frontier solution to deal with this problem. In a spectrum underlay network, the secondary user (SU) is allowed to simultaneously access the licensed frequency band of the primary user (PU) as long as the interference caused by the SU to the PU is kept below a predefined threshold. By doing so, the spectrum utilization can be improved significantly. Moreover, the spectrum underlay network is not only considered as the least sophisticated in implementation, but also can operate in dense areas where the number of temporal spectrum holes is small. Inspired by the above discussion, this thesis provides a performance analysis of spectrum underlay networks which are subject to interference constraints. The thesis is divided into an introduction part and five parts based on peer-reviewed international research publications. The introduction part provides the reader with an overview and background on CRNs. The first part investigates the performance of secondary networks in terms of outage probability and ergodic capacity subject to the joint outage constraint of the PU and the peak transmit power constraint of the SU. The second part evaluates the performance of CRNs with a buffered relay. Subject to the timeout probability constraint of the PU and the peak transmit power constraint of the SU, system performance in terms of end-to-end throughput, end-to-end transmission time, and stable transmission condition for the relay buffer is studied. The third part analyzes a cognitive cooperative radio network under the peak interference power constraint of multiple PUs with best relay selection. The obtained results readily reveal insights into the impact of the number of PUs, channel mean powers of the communication and interference links on the system performance. The fourth part studies the delay performance of CRNs under the peak interference power constraint of multiple PUs for point-to-point and point-to-multipoint communications. A closedform expression for outage probability and an analytical expression for the average waiting time of packets are obtained for point-to-point communications. Moreover, the outage probability and successful transmission probability for packets in point-to-multipoint communications are presented. Finally, the fifth part presents work on the performance analysis of a spectrum underlay network for a general fading channel. A lower bound on the packet timeout probability and the average number of transmissions per packet are obtained for the secondary network.
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Sibomana, Louis. "Performance Analysis of Cognitive Radio Networks under Spectrum Sharing and Security Constraints." Doctoral thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11739.

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The cognitive radio network (CRN) concept has been proposed as a solution to the growing demand and underutilization of the radio spectrum. To improve the radio spectrum utilization, CRN technology allows the coexistence of licensed and unlicensed systems over the same spectrum. In an underlay spectrum sharing system, secondary users (SUs) transmit simultaneously with the primary users (PUs) in the same frequency band given that the interference caused by the SU to the PU remains below a tolerable interference limit. Besides the transmission power limitation, a secondary network is subject to distinct channel impairments such as fading and interference from the primary transmissions. Also, CRNs face new security threats and challenges due to their unique cognitive characteristics.This thesis analyzes the performance of underlay CRNs and underlay cognitive relay networks under spectrum sharing constraints and security constraints. Distinct SU transmit power policies are obtained considering various interference constraints such as PU outage constraint or PU peak interference power constraint. The thesis is divided into an introduction and two research parts based on peer-reviewed publications. The introduction provides an overview of radio spectrum management, basic concepts of CRNs, and physical layer security. In the first research part, we study the performance of underlay CRNs with emphasis on a multiuser environment.In Part I-A, we consider a secondary network with delay-tolerant applications and analyze the ergodic capacity. Part I-B analyzes the secondary outage capacity which characterises the maximum data rate that can be achieved over a channel for a given outage probability. In Part I-C, we consider a secondary network with delay constrained applications, and derive expressions of the outage probability and delay-limited throughput. Part I-D presents a queueing model that provides an analytical tool to evaluate the secondary packet-level performance with multiple classes of traffic considering general interarrival and service time distributions. Analytical expressions of the SU average packet transmission time, waiting time in the queue, andtime spent in the system are provided.In the second research part, we analyze the physical layer security for underlay CRNs and underlay cognitive relay networks. Analytical expressions of the probability of non-zero secrecy capacity and secrecy outage probability are derived.Part II-A considers a single hop underlay CRN in the presence of multiple eavesdroppers (EAVs) and multiple SU-Rxs. In Part II-B, an underlay cognitive relay network in the presence of multiple secondary relays and multiple EAVs is studied.Numerical examples illustrate that it is possible to exploit the physical layer characteristics to achieve both security and quality of service in CRNs while satisfying spectrum sharing constraints.
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Chu, Thi My Chinh. "On the Performance Assessment of Advanced Cognitive Radio Networks." Doctoral thesis, Blekinge Tekniska Högskola [bth.se], Faculty of Computing - Department of Communication Systems, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00611.

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Due to the rapid development of wireless communications together with the inflexibility of the current spectrum allocation policy, radio spectrum becomes more and more exhausted. One of the critical challenges of wireless communication systems is to efficiently utilize the limited frequency resources to be able to support the growing demand of high data rate wireless services. As a promising solution, cognitive radios have been suggested to deal with the scarcity and under-utilization of radio spectrum. The basic idea behind cognitive radios is to allow unlicensed users, also called secondary users (SUs), to access the licensed spectrum of primary users (PUs) which improves spectrum utilization. In order to not degrade the performance of the primary networks, SUs have to deploy interference control, interference mitigating, or interference avoidance techniques to minimize the interference incurred at the PUs. Cognitive radio networks (CRNs) have stimulated a variety of studies on improving spectrum utilization. In this context, this thesis has two main objectives. Firstly, it investigates the performance of single hop CRNs with spectrum sharing and opportunistic spectrum access. Secondly, the thesis analyzes the performance improvements of two hop cognitive radio networks when incorporating advanced radio transmission techniques. The thesis is divided into three parts consisting of an introduction part and two research parts based on peer-reviewed publications. Fundamental background on radio propagation channels, cognitive radios, and advanced radio transmission techniques are discussed in the introduction. In the first research part, the performance of single hop CRNs is analyzed. Specifically, underlay spectrum access using M/G/1/K queueing approaches is presented in Part I-A while dynamic spectrum access with prioritized traffics is studied in Part I-B. In the second research part, the performance benefits of integrating advanced radio transmission techniques into cognitive cooperative radio networks (CCRNs) are investigated. In particular, opportunistic spectrum access for amplify-and-forward CCRNs is presented in Part II-A where collaborative spectrum sensing is deployed among the SUs to enhance the accuracy of spectrum sensing. In Part II-B, the effect of channel estimation error and feedback delay on the outage probability and symbol error rate (SER) of multiple-input multiple-output CCRNs is investigated. In Part II-C, adaptive modulation and coding is employed for decode-and-forward CCRNs to improve the spectrum efficiency and to avoid buffer overflow at the relay. Finally, a hybrid interweave-underlay spectrum access scheme for a CCRN is proposed in Part II-D. In this work, the dynamic spectrum access of the PUs and SUs is modeled as a Markov chain which then is utilized to evaluate the outage probability, SER, and outage capacity of the CCRN.
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Devanarayana, Chamara. "Spectrum access in cognitive radio networks based on prediction and estimation." EURASIP Journal on Wireless Communications and Networking, 2011. http://hdl.handle.net/1993/31605.

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In the literature, Cognitive radio (CR) as well as full-duplex (FD) communication technologies are proposed to increase the spectrum efficiency. The main contribution of this thesis is to introduce prediction and estimation techniques with low control overhead, and use the predicted or estimated information in resource allocation in CR networks, both in the overlay networks and the underlay networks. Prediction and estimation are important in increasing the data rate and keeping the interference at a low level. In the overlay scheme, I modeled the primary user (PU) traffic characteristics of the channels using the Probabilistic Suffix Tree (PST) algorithm. Then using this PST algorithm, I introduced a frequency hopping based control channel and derived its theoretical properties. Then I proposed two methods for selecting a channel set for transmission, which took into account both the PU channel usage statistics and, secondary user (SU) channel usage statistics as perceived by an SU of interest. The first scheme selected channels having the highest probability of successful transmission, while the second calculated a net reward using a marked Markov chain. Then using simulations, I showed that our scheme caused acceptable interference to the PUs and has better throughput performance, compared to a scheme selecting channels randomly. Then I proposed two joint channel assignment and power allocation schemes for a bi-directional FD underlay CR network with network assistance. The first scheme used the information on the number of total SU pairs present in the network. In the second scheme, I used least squares based estimation and Kalman filtering to estimate the interference at the monitoring stations using the local interference. It reduced the control overhead of keeping track of active SUs. In both of these schemes each SU pair decided on the channels to be used in the half-duplex mode and the full-duplex mode using local information. This joint optimization was done running channel assignment and power allocation algorithms alternatively. In the power allocation problem, I used a technique called monotonic optimization. After simulating both of these schemes I showed that the scheme based on estimation performs satisfactorily given that it has less control overhead.
October 2016
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Samarasekera, Andawattage Chaminda Janaka. "The Performance of Dual-Hop Decode-and-Forward Underlay Cognitive Relay Networks with Interference Power Constraints over Weibull Fading Channels." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3201.

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With the rapid development and the increasing use of wireless devices, spectrum scarcity has become a problem. The higher frequencies have bad propagation characteristics and the lower frequencies have low data rates, therefore the radio spectrum that is available for efficient wireless transmission is a limited resource. One of the proposed solutions for this problem is cognitive relay networks (CRNs), where cognitive radio is combined with a cooperative spectrum sharing system to increase the spectrum utilization. In this thesis, the outage probability performances of underlay CRNs with interference power constraints from the primary network over Weibull fading channels have been investigated for three different scenarios. The maximum transmit power of the secondary network is governed by the maximum interference power that the primary network's receiver can tolerate. The first scenario is a cognitive dual-hop decode-and-forward (DF) relay network over independent non-identically distributed (i.n.i.d.) Weibull fading channels. In the second scenario, the CRN consists of a DF relay plus the direct link transmission with a selection combining receiver at the destination over i.n.i.d. Weibull fading channels. The third CRN considered has multiple DF relays where the best relay selection scheme is employed over independent identically distributed (i.i.d.) Weibull fading channels. The analytical results have been derived using the statistical characteristics of end-to-end signal-to-noise ratios, and have been verified by Monte-Carlo simulations.
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Lu, Lu. "Spectral-efficient design in modern wireless communications networks." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53902.

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We investigate spectral-efficient design and develop novel schemes to improve spectral efficiency of the modern wireless communications networks. Nowadays, more and more spectrum resources are required to support various high-data-rate applications while spectrum resources are limited. Moreover, static allocation and exclusive access in current spectrum assignment policy caused a lot of licensed spectrum bands to be underutilized. To deal with the problem, cognitive radio (CR) has been developed, which allows unlicensed/secondary users to transmit with licensed/primary users as long as the former ones do not generate intolerable interference to the latter ones. The coexistence of users and networks requires careful and dynamic planning to mitigate interference. Otherwise, the network performance will be severely undermined. We study both spectrum sensing and spectrum access techniques and propose several transmit schemes for different types of cognitive ratio networks, including spectrum overlay and spectrum underlay systems. The proposed algorithms can improve spectral efficiency of the networks efficiently and have potentials to be used in future wireless communications networks.
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Moteka, Leutsoa. "User pairing and power allocation in underlay cognitive NOMA networks." Thesis, 2020. https://hdl.handle.net/10539/31115.

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A dissertation submitted in the fulfilment of the requirements for the degree of Master of Science in Engineering (MSc. Eng.) in the School of Electrical and Information Engineering in the Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2020
The unique structure of Non-Orthogonal Multiple Access (NOMA), a candidate for multiple access techniques for fifth-generation mobile networks, poses formidable design challenges when the number of users in the network rises. Fifth generation networks, however, demand hyper connected societies with phenomenal number of users. In a multi-channel NOMA system with a large number of users, the literature has shown that the best performance is achieved if no more than three users share a channel. Most research typically allocates two users to a channel. One of the key issues then is user pairing, which must be done in order to maximize the network capacity. A number of user pairing schemes have been derived in the literature, but these have been done mostly for non-cognitive radio networks. A need for user pairing schemes in cognitive networks has therefore risen. Developed schemes need to take into account a plethora of complications such as energy consumption and an increase in interference raised in the cognitive environment. The main focus of this dissertation is to mathematically model a framework to optimize power allocation and user pairing in a cognitive NOMA network. In particular, we determine various power allocation schemes that can cope with the severe energy constraints of an underlay cognitive network and employ these schemes for use indifferent user pairing schemes. First, we employ an underlay random pairing algorithm and an underlay channel state sorting pairing algorithm, for use in a large-scale network. Because of the low complexity of these algorithms, we use their performance to study and compare with other pairing algorithms. Then we propose a near-optimal preference list matching algorithm (PLMA) based on matching theory to perform user pairing. Performance evaluation of the proposed schemes is presented through simulations. Results show how that the preference list matching algorithm effectively outperforms other pairing algorithms and can also perform better that the Hungarian algorithm
CK2021
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Book chapters on the topic "Networks with underlay cognitive nodes"

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Deka, Sanjib K., and Nityanada Sarma. "Channel-Usage Model in Underlay Cognitive Radio Networks." In Lecture Notes in Electrical Engineering, 115–23. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-6154-8_12.

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Mei, Yanan, Yanhui Lu, Xiaomin Mu, and Xin Liu. "Distributed Fast Convergent Power Allocation Algorithm in Underlay Cognitive Radio Networks." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 345–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30493-4_34.

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Kim, Su Min, and Junsu Kim. "Buffer-Aided Relay Selection with Primary Sensing in Underlay Cognitive Radio Networks." In Lecture Notes in Electrical Engineering, 319–26. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-1536-6_42.

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ElShaarany, Ahmed M., Mohamed M. Abdallah, Salama Ikki, Mohamed M. Khairy, and Khalid Qaraqe. "Best Relay Selection for DF Underlay Cognitive Networks with Different Modulation Levels." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 282–94. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24540-9_23.

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Rawat, Danda B., Min Song, and Sachin Shetty. "Resource Allocation in Spectrum Underlay Cognitive Radio Networks." In Dynamic Spectrum Access for Wireless Networks, 13–24. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15299-8_2.

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He, Xiaoli, Hong Jiang, Yu Song, and He Xiao. "Optimal Resource Allocation for Underlay Cognitive Radio Networks." In Cloud Computing and Security, 358–71. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00015-8_31.

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Karim, Hezerul Abdul, Hafizal Mohamad, Nordin Ramli, and Aduwati Sali. "Multiple Description Video Coding for Underlay Cognitive Radio Network." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 643–52. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-24540-9_53.

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Jia, Jian, Ting Jiang, Wei Guo, and Xiaoying Qiu. "Physical Layer Security of a Buffer-Aided Relay Selection for Underlay Cognitive Radio Network." In Lecture Notes in Electrical Engineering, 999–1006. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6508-9_121.

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Han, Hui, Xiang Chen, and Yun Lin. "Novel Cognitive Radio Network Setup Mechanism Using Underlay as Control Channel to Enhance Efficiency." In Lecture Notes in Electrical Engineering, 61–67. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6571-2_8.

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Harounabadi, Mehdi, André Puschmann, Oleksandr Artemenko, and Andreas Mitschele-Thiel. "TAG: Trajectory Aware Geographical Routing in Cognitive Radio Ad Hoc Networks with UAV Nodes." In Ad Hoc Networks, 111–22. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-25067-0_9.

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Conference papers on the topic "Networks with underlay cognitive nodes"

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Dhungana, Yamuna, and Chintha Tellambura. "Outage probability of underlay cognitive relay networks with spatially random nodes." In GLOBECOM 2014 - 2014 IEEE Global Communications Conference. IEEE, 2014. http://dx.doi.org/10.1109/glocom.2014.7037366.

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Chen, Dan, Hong Ji, and Xi Li. "Distributed best-relay node selection in underlay cognitive radio networks: A restless bandits approach." In 2011 IEEE Wireless Communications and Networking Conference (WCNC). IEEE, 2011. http://dx.doi.org/10.1109/wcnc.2011.5779303.

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Jeong, Youngmin, Tony Q. S. Quek, and Hyundong Shin. "Downlink beamforming optimization for cognitive underlay networks." In Its Applications (Isita2010). IEEE, 2010. http://dx.doi.org/10.1109/isita.2010.5649545.

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Seyfi, Mehdi, Sami Muhaidat, and Jie Liang. "Relay selection in underlay cognitive radio networks." In 2012 IEEE Wireless Communications and Networking Conference (WCNC). IEEE, 2012. http://dx.doi.org/10.1109/wcnc.2012.6214285.

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Kaushik, Ankit, Ralph Tanbourgi, and Friedrich Jondral. "Operating characteristics of underlay cognitive relay networks." In 2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). IEEE, 2014. http://dx.doi.org/10.1109/pimrc.2014.7136351.

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Chakravarthy, Vasu, Zhiqiang Wu, Michael Temple, Fred Garber, and Xue Li. "Cognitive Radio Centric Overlay/Underlay Waveform." In 2008 IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN). IEEE, 2008. http://dx.doi.org/10.1109/dyspan.2008.20.

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Tourki, Kamel, Khalid A. Qaraqe, and Mohamed-Slim Alouini. "Outage analysis for underlay relay-assisted cognitive networks." In GLOBECOM 2012 - 2012 IEEE Global Communications Conference. IEEE, 2012. http://dx.doi.org/10.1109/glocom.2012.6503284.

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Lameiro, Christian, Ignacio Santamaria, Wolfgang Utschiclk, and Peter J. Schreier. "Maximally improper interference in underlay cognitive radio networks." In 2016 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). IEEE, 2016. http://dx.doi.org/10.1109/icassp.2016.7472361.

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Marques, Antonio G., Sergio Molinero, and Georgios B. Giannakis. "Underlay multi-hop cognitive networks with orthogonal access." In 2015 IEEE 16th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM). IEEE, 2015. http://dx.doi.org/10.1109/wowmom.2015.7158197.

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Tanab, Manal El, Yasmine Fahmy, and Mohamed M. Khairy. "Opportunistic splitting algorithm for underlay cognitive radio networks." In 2014 Sixth International Conference on Ubiquitous and Future Networks (ICUFN). IEEE, 2014. http://dx.doi.org/10.1109/icufn.2014.6876738.

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