The Experts below are selected from a list of 12729 Experts worldwide ranked by ideXlab platform
Arumugam Nallanathan - One of the best experts on this subject based on the ideXlab platform.
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on the throughput and spectrum sensing enhancement of opportunistic spectrum access Cognitive Radio networks
IEEE Transactions on Wireless Communications, 2012Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Cognitive Radio has attracted an increasing amount of interest over the past few years as an effective method of alleviating the spectrum scarcity problem in wireless communications. One of the most promising approaches in Cognitive Radio is the opportunistic spectrum access, which enables unlicensed users to access licensed frequency bands that are detected to be idle. In this paper, we propose a novel Cognitive Radio System that exhibits improved throughput and spectrum sensing capabilities compared to the conventional opportunistic spectrum access Cognitive Radio Systems studied so far. More specifically, we study the average achievable throughput of the proposed Cognitive Radio System under a single high target detection probability constraint, as well as its ergodic throughput under average transmit and interference power constraints, and propose an algorithm that acquires the optimal power allocation strategy and target detection probability, which under the imposed average interference power constraint becomes an additional optimization variable in the ergodic throughput maximization problem. Finally, we provide simulation results, in order to compare the achievable throughput of the proposed Cognitive Radio System with the respective throughput of the conventional Cognitive Radio Systems and discuss the effects of the optimal power allocation and target detection probability on the ergodic throughput of the proposed Cognitive Radio System.
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enhancing the capacity of spectrum sharing Cognitive Radio networks
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Spectrum sharing has attracted a lot of attention in Cognitive Radio recently as an effective method of alleviating the spectrum scarcity problem by allowing unlicensed users to coexist with licensed users under the condition of protecting the latter from harmful interference. In this paper, we focus on the throughput maximization of spectrum sharing Cognitive Radio networks and propose a novel Cognitive Radio System that significantly improves their achievable throughput. More specifically, we introduce a novel receiver and frame structure for spectrum sharing Cognitive Radio networks and study the problem of deriving the optimal power allocation strategy that maximizes the ergodic capacity of the proposed Cognitive Radio System under average transmit and interference power constraints. In addition, we study the outage capacity of the proposed Cognitive Radio System under various constraints that include average transmit and interference power constraints, and peak interference power constraints. Finally, we provide simulation results, in order to demonstrate the improved ergodic and outage throughput achieved by the proposed Cognitive Radio System compared to conventional spectrum sharing Cognitive Radio Systems.
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on the outage capacity of sensing enhanced spectrum sharing Cognitive Radio Systems in fading channels
IEEE Transactions on Communications, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Spectrum sharing has received an increasing amount of attention in Cognitive Radio over the past few years as an effective method of alleviating the spectrum scarcity problem in wireless communications by allowing unlicensed users to use the same spectrum as the licensed users under the condition of protecting the latter from harmful interference using a received interference power constraint at the licensed receivers. In this paper, we study the outage capacity and the truncated channel inversion with fixed rate (TIFR) capacity of a sensing-enhanced spectrum sharing Cognitive Radio System under two different scenarios, namely with and without missed-detection interference power constraints for the protection of the primary users, for both Rayleigh and Nakagami-m fading channels. In our analysis, we consider various constraints on the capacity that include: (i) average transmit power constraints, (ii) peak interference power constraints, (iii) average interference power constraints and (iv) target detection probability constraints, and derive the power allocation strategy, as well as the TIFR and outage capacity for each scenario. Finally, we provide simulation results, which indicate that the sensing-enhanced spectrum sharing Cognitive Radio System can achieve higher outage and TIFR capacity compared to the conventional non-sensing spectrum sharing Cognitive Radio System.
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optimal sensing and power allocation strategy for an efficient Cognitive Radio System
International Conference on Communications, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Cognitive Radio has attracted a lot of attention recently as an effective method of alleviating the spectrum scarcity problem in wireless communications. However, the constraints imposed on Cognitive Radio networks as secondary networks restrict their achievable throughput and highlight the importance of efficient spectrum sensing and power allocation. In this paper, we focus on maximizing the ergodic throughput of the opportunistic spectrum access Cognitive Radio System proposed in [1] under both average transmit and interference power constraints. More specifically, we propose an algorithm that obtains the optimal power allocation strategy and target detection probability, which under the imposed average interference power constraint becomes an additional optimization variable in the ergodic throughput maximization of the Cognitive Radio System. Finally, we provide simulation results and discuss the effects of the power allocation and target detection probability on the achievable ergodic throughput of the Cognitive Radio System.
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overcoming the sensing throughput tradeoff in Cognitive Radio networks
International Conference on Communications, 2010Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:In a Cognitive Radio network that employs opportunistic spectrum access, the users are allowed to access a frequency band only when it is not being used by licensed users. Hence, spectrum sensing is of utmost importance, in order to efficiently exploit the unused spectrum and effectively protect the quality of service of licensed networks. For this reason, a time slot has been allocated for spectrum sensing at the beginning of each frame in the Systems proposed so far. During this slot, data transmission is prohibited, which results in the sensing-throughput tradeoff problem. In this paper, we propose a novel Cognitive Radio System that overcomes the sensing-throughput tradeoff by performing spectrum sensing and data transmission at the same time, which maximizes both the sensing time and the throughput of the Cognitive Radio network. We introduce a novel receiver and frame structure for Cognitive Radio and analytically prove that the proposed Cognitive Radio System exhibits improved throughput and sensing capabilities. Finally, simulation results are provided to validate our theoretical analysis.
Stergios Stotas - One of the best experts on this subject based on the ideXlab platform.
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on the throughput and spectrum sensing enhancement of opportunistic spectrum access Cognitive Radio networks
IEEE Transactions on Wireless Communications, 2012Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Cognitive Radio has attracted an increasing amount of interest over the past few years as an effective method of alleviating the spectrum scarcity problem in wireless communications. One of the most promising approaches in Cognitive Radio is the opportunistic spectrum access, which enables unlicensed users to access licensed frequency bands that are detected to be idle. In this paper, we propose a novel Cognitive Radio System that exhibits improved throughput and spectrum sensing capabilities compared to the conventional opportunistic spectrum access Cognitive Radio Systems studied so far. More specifically, we study the average achievable throughput of the proposed Cognitive Radio System under a single high target detection probability constraint, as well as its ergodic throughput under average transmit and interference power constraints, and propose an algorithm that acquires the optimal power allocation strategy and target detection probability, which under the imposed average interference power constraint becomes an additional optimization variable in the ergodic throughput maximization problem. Finally, we provide simulation results, in order to compare the achievable throughput of the proposed Cognitive Radio System with the respective throughput of the conventional Cognitive Radio Systems and discuss the effects of the optimal power allocation and target detection probability on the ergodic throughput of the proposed Cognitive Radio System.
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enhancing the capacity of spectrum sharing Cognitive Radio networks
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Spectrum sharing has attracted a lot of attention in Cognitive Radio recently as an effective method of alleviating the spectrum scarcity problem by allowing unlicensed users to coexist with licensed users under the condition of protecting the latter from harmful interference. In this paper, we focus on the throughput maximization of spectrum sharing Cognitive Radio networks and propose a novel Cognitive Radio System that significantly improves their achievable throughput. More specifically, we introduce a novel receiver and frame structure for spectrum sharing Cognitive Radio networks and study the problem of deriving the optimal power allocation strategy that maximizes the ergodic capacity of the proposed Cognitive Radio System under average transmit and interference power constraints. In addition, we study the outage capacity of the proposed Cognitive Radio System under various constraints that include average transmit and interference power constraints, and peak interference power constraints. Finally, we provide simulation results, in order to demonstrate the improved ergodic and outage throughput achieved by the proposed Cognitive Radio System compared to conventional spectrum sharing Cognitive Radio Systems.
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on the outage capacity of sensing enhanced spectrum sharing Cognitive Radio Systems in fading channels
IEEE Transactions on Communications, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Spectrum sharing has received an increasing amount of attention in Cognitive Radio over the past few years as an effective method of alleviating the spectrum scarcity problem in wireless communications by allowing unlicensed users to use the same spectrum as the licensed users under the condition of protecting the latter from harmful interference using a received interference power constraint at the licensed receivers. In this paper, we study the outage capacity and the truncated channel inversion with fixed rate (TIFR) capacity of a sensing-enhanced spectrum sharing Cognitive Radio System under two different scenarios, namely with and without missed-detection interference power constraints for the protection of the primary users, for both Rayleigh and Nakagami-m fading channels. In our analysis, we consider various constraints on the capacity that include: (i) average transmit power constraints, (ii) peak interference power constraints, (iii) average interference power constraints and (iv) target detection probability constraints, and derive the power allocation strategy, as well as the TIFR and outage capacity for each scenario. Finally, we provide simulation results, which indicate that the sensing-enhanced spectrum sharing Cognitive Radio System can achieve higher outage and TIFR capacity compared to the conventional non-sensing spectrum sharing Cognitive Radio System.
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optimal sensing and power allocation strategy for an efficient Cognitive Radio System
International Conference on Communications, 2011Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:Cognitive Radio has attracted a lot of attention recently as an effective method of alleviating the spectrum scarcity problem in wireless communications. However, the constraints imposed on Cognitive Radio networks as secondary networks restrict their achievable throughput and highlight the importance of efficient spectrum sensing and power allocation. In this paper, we focus on maximizing the ergodic throughput of the opportunistic spectrum access Cognitive Radio System proposed in [1] under both average transmit and interference power constraints. More specifically, we propose an algorithm that obtains the optimal power allocation strategy and target detection probability, which under the imposed average interference power constraint becomes an additional optimization variable in the ergodic throughput maximization of the Cognitive Radio System. Finally, we provide simulation results and discuss the effects of the power allocation and target detection probability on the achievable ergodic throughput of the Cognitive Radio System.
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overcoming the sensing throughput tradeoff in Cognitive Radio networks
International Conference on Communications, 2010Co-Authors: Stergios Stotas, Arumugam NallanathanAbstract:In a Cognitive Radio network that employs opportunistic spectrum access, the users are allowed to access a frequency band only when it is not being used by licensed users. Hence, spectrum sensing is of utmost importance, in order to efficiently exploit the unused spectrum and effectively protect the quality of service of licensed networks. For this reason, a time slot has been allocated for spectrum sensing at the beginning of each frame in the Systems proposed so far. During this slot, data transmission is prohibited, which results in the sensing-throughput tradeoff problem. In this paper, we propose a novel Cognitive Radio System that overcomes the sensing-throughput tradeoff by performing spectrum sensing and data transmission at the same time, which maximizes both the sensing time and the throughput of the Cognitive Radio network. We introduce a novel receiver and frame structure for Cognitive Radio and analytically prove that the proposed Cognitive Radio System exhibits improved throughput and sensing capabilities. Finally, simulation results are provided to validate our theoretical analysis.
Erik G. Larsson - One of the best experts on this subject based on the ideXlab platform.
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Intelligent Reflecting Surface-Assisted Cognitive Radio System
IEEE Transactions on Communications, 2021Co-Authors: Jie Yuan, Ying-chang Liang, Jingon Joung, Gang Feng, Erik G. LarssonAbstract:Cognitive Radio (CR) is an effective solution to improve the spectral efficiency (SE) of wireless communications by allowing the secondary users (SUs) to share spectrum with primary users (PUs). Meanwhile, intelligent reflecting surface (IRS), also known as reconfigurable intelligent surface (RIS), has been recently proposed as a promising approach to enhance energy efficiency (EE) of wireless communication Systems through intelligently reconfiguring the channel environment. To improve both SE and EE, in this paper, we introduce multiple IRSs to a downlink multiple-input single-output (MISO) CR System, in which a single SU coexists with a primary network with multiple PU receivers (PU-RXs). Our design objective is to maximize the achievable rate of SU subject to a total transmit power constraint on the SU transmitter (SU-TX) and interference temperature constraints on the PU-RXs, by jointly optimizing the beamforming at SU-TX and the reflecting coefficients at each IRS. Both perfect and imperfect channel state information (CSI) cases are considered in the optimization. Numerical results demonstrate that IRS can significantly improve the achievable rate of SU under both perfect and imperfect CSI cases.
Mohamedslim Alouini - One of the best experts on this subject based on the ideXlab platform.
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extended delivery time analysis for secondary packet transmission with adaptive modulation under interweave Cognitive implementation
IEEE Transactions on Cognitive Communications and Networking, 2017Co-Authors: Wenjing Wang, Muneer Usman, Hongchuan Yang, Mohamedslim AlouiniAbstract:Cognitive Radio communication can opportunistically access underutilized spectrum for emerging wireless applications. With interweave Cognitive implementation, a secondary user (SU) transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission periods and waiting periods. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary System. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay analysis of such Cognitive Radio System. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length SU transmission and waiting periods. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.
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service time analysis for secondary packet transmission with adaptive modulation
Wireless Communications and Networking Conference, 2017Co-Authors: Wenjing Wang, Muneer Usman, Hongchuan Yang, Mohamedslim AlouiniAbstract:Cognitive Radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave Cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary System. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such Cognitive Radio System. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.
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reduced dimension power allocation over clustered channels in Cognitive Radios System under co channel interference
Modeling and Optimization in Mobile Ad-Hoc and Wireless Networks, 2014Co-Authors: Mahdi Ben Ghorbel, Mamoun Guenach, Mohamedslim AlouiniAbstract:The objective of this paper is to propose a reduceddimension resource allocation scheme in the context of Cognitive Radio System in presence of co-channel interference between users. We assume a multicarrier transmission for both the primary and secondary Systems. Instead of optimizing the powers over all sub-carriers, the sub-carriers are grouped into clusters of sub-carriers, where the power of each sub-carrier is directly related to the power of the correspondent cluster. The power optimization is done only over the set of clusters instead of all sub-carriers which can significantly reduce the complexity of the resource allocation problem. The performance loss of the reduced dimension solution with respect to the optimal solution, where the optimization is carried over all active sub-carriers, allows trading-off complexity versus performance. Numerical evaluation indeed revealed that a limited performance loss occurs by optimizing over a reduced set of clusters instead of the full optimization in the context of Cognitive Radio Systems.
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optimal transmit power allocation for mimo two way Cognitive relay networks with multiple relays using af strategy
IEEE Wireless Communications Letters, 2014Co-Authors: Ahmad Alsharoa, Hakim Ghazzai, Mohamedslim AlouiniAbstract:In this letter, we consider a multiple-input multiple-output two-way Cognitive Radio System under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary terminals aims to exchange different messages with each other using multiple relays where each relay employs an amplify-and-forward strategy. The main objective of our work is to maximize the secondary sum rate allowed to share the spectrum with the primary users by respecting a primary user tolerated interference threshold. In this context, we derive an analytical expression of the optimal power allocated to each antenna of the terminals. We then discuss the impact of some System parameters on the performance in the numerical result section.
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optimal transmit power allocation for mimo two way Cognitive relay networks with multiple relays
arXiv: Information Theory, 2013Co-Authors: Ahmad Alsharoa, Hakim Ghazzai, Mohamedslim AlouiniAbstract:In this letter, we consider a multiple-input multiple-output two-way Cognitive Radio System under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary terminals aims to exchange different messages with each other using multiple relays where each relay employs an amplify-and-forward strategy. The main objective of our work is to maximize the secondary sum rate allowed to share the spectrum with the primary users by respecting a primary user tolerated interference threshold. In this context, we derive a closed-form expression of the optimal power allocated to each antenna of the terminals. We then discuss the impact of some System parameters on the performance in the numerical result section.
Jie Yuan - One of the best experts on this subject based on the ideXlab platform.
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Intelligent Reflecting Surface-Assisted Cognitive Radio System
IEEE Transactions on Communications, 2021Co-Authors: Jie Yuan, Ying-chang Liang, Jingon Joung, Gang Feng, Erik G. LarssonAbstract:Cognitive Radio (CR) is an effective solution to improve the spectral efficiency (SE) of wireless communications by allowing the secondary users (SUs) to share spectrum with primary users (PUs). Meanwhile, intelligent reflecting surface (IRS), also known as reconfigurable intelligent surface (RIS), has been recently proposed as a promising approach to enhance energy efficiency (EE) of wireless communication Systems through intelligently reconfiguring the channel environment. To improve both SE and EE, in this paper, we introduce multiple IRSs to a downlink multiple-input single-output (MISO) CR System, in which a single SU coexists with a primary network with multiple PU receivers (PU-RXs). Our design objective is to maximize the achievable rate of SU subject to a total transmit power constraint on the SU transmitter (SU-TX) and interference temperature constraints on the PU-RXs, by jointly optimizing the beamforming at SU-TX and the reflecting coefficients at each IRS. Both perfect and imperfect channel state information (CSI) cases are considered in the optimization. Numerical results demonstrate that IRS can significantly improve the achievable rate of SU under both perfect and imperfect CSI cases.