The Experts below are selected from a list of 17610 Experts worldwide ranked by ideXlab platform
Hanchieh Chao - One of the best experts on this subject based on the ideXlab platform.
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a cross layer protocol of Spectrum Mobility and handover in cognitive lte networks
Simulation Modelling Practice and Theory, 2011Co-Authors: Yuhshyan Chen, Chinghsiung Cho, Ilsun You, Hanchieh ChaoAbstract:Abstract Cognitive radio technique is the next step toward efficient wireless bandwidth utilization. While some of the Spectrum bands (unlicensed band) have been increasingly used, most of the other Spectrum resources (licensed band) are underutilized. This drives the challenges of open Spectrum and dynamic Spectrum access concepts, which allows unlicensed users (or called secondary users, SUs) equipped with cognitive radios to opportunistically access the Spectrum not used by licensed users (or called primary users, PUs). Most existing results mainly focus on designing the lower-layer cognitive radio problems. In the literature, this is the first result to investigate the higher-layer solution for cognitive radio networks. In this paper, we present a cross-layer protocol of Spectrum Mobility (layer-2) and handover (layer-3) in cognitive LTE networks. With the consideration of the Poisson distribution model of Spectrum resources, a cross-layer handoff protocol with the minimum expected transmission time is developed in cognitive LTE networks. Performance analysis of the proposed handoff protocol is investigated. Finally, simulation results illustrates the proposed handoff protocol significantly reduces the expected transmission time and the Spectrum Mobility ratio.
Ian F. Akyildiz - One of the best experts on this subject based on the ideXlab platform.
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Spectrum-Aware Mobility Management in Cognitive Radio Cellular Networks
IEEE Transactions on Mobile Computing, 2012Co-Authors: Ian F. AkyildizAbstract:Cognitive radio (CR) networks have been proposed as a solution to both Spectrum inefficiency and Spectrum scarcity problems. However, they face several challenges based on the fluctuating nature of the available Spectrum, making it more difficult to support seamless communications, especially in CR cellular networks. In this paper, a Spectrum-aware Mobility management scheme is proposed for CR cellular networks. First, a novel network architecture is introduced to mitigate heterogeneous Spectrum availability. Based on this architecture, a unified Mobility management framework is developed to support diverse Mobility events in CR networks, which consists of Spectrum Mobility management, user Mobility management, and intercell resource allocation. The Spectrum Mobility management scheme determines a target cell and Spectrum band for CR users adaptively dependent on time-varying Spectrum opportunities, leading to increase in cell capacity. In the user Mobility management scheme, a mobile user selects a proper handoff mechanism so as to minimize a switching latency at the cell boundary by considering spatially heterogeneous Spectrum availability. Intercell resource allocation helps to improve the performance of both Mobility management schemes by efficiently sharing Spectrum resources with multiple cells. Simulation results show that the proposed method can achieve better performance than conventional handoff schemes in terms of both cell capacity as well as Mobility support in communications.
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crahns cognitive radio ad hoc networks
Ad Hoc Networks, 2009Co-Authors: Ian F. Akyildiz, Wonyeol Lee, Kaushik R ChowdhuryAbstract:Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available Spectrum and the inefficiency in the Spectrum usage by exploiting the existing wireless Spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate Spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available Spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying Spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel Spectrum management functionalities such as Spectrum sensing, Spectrum sharing, and Spectrum decision, and Spectrum Mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided Spectrum etiquette.
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a survey on Spectrum management in cognitive radio networks
IEEE Communications Magazine, 2008Co-Authors: Ian F. Akyildiz, Wonyeol Lee, Mehmet C Vuran, S MohantyAbstract:Cognitive radio networks will provide high bandwidth to mobile users via heterogeneous wireless architectures and dynamic Spectrum access techniques. However, CR networks impose challenges due to the fluctuating nature of the available Spectrum, as well as the diverse QoS requirements of various applications. Spectrum management functions can address these challenges for the realization of this new network paradigm. To provide a better understanding of CR networks, this article presents recent developments and open research issues in Spectrum management in CR networks. More specifically, the discussion is focused on the development of CR networks that require no modification of existing networks. First, a brief overview of cognitive radio and the CR network architecture is provided. Then four main challenges of Spectrum management are discussed: Spectrum sensing, Spectrum decision, Spectrum sharing, and Spectrum Mobility.
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next generation dynamic Spectrum access cognitive radio wireless networks a survey
Computer Networks, 2006Co-Authors: Ian F. Akyildiz, Wonyeol Lee, Mehmet C Vuran, S MohantyAbstract:Today's wireless networks are characterized by a fixed Spectrum assignment policy. However, a large portion of the assigned Spectrum is used sporadically and geographical variations in the utilization of assigned Spectrum ranges from 15% to 85% with a high variance in time. The limited available Spectrum and the inefficiency in the Spectrum usage necessitate a new communication paradigm to exploit the existing wireless Spectrum opportunistically. This new networking paradigm is referred to as NeXt Generation (xG) Networks as well as Dynamic Spectrum Access (DSA) and cognitive radio networks. The term xG networks is used throughout the paper. The novel functionalities and current research challenges of the xG networks are explained in detail. More specifically, a brief overview of the cognitive radio technology is provided and the xG network architecture is introduced. Moreover, the xG network functions such as Spectrum management, Spectrum Mobility and Spectrum sharing are explained in detail. The influence of these functions on the performance of the upper layer protocols such as routing and transport are investigated and open research issues in these areas are also outlined. Finally, the cross-layer design challenges in xG networks are discussed.
Abhirup Das Barman - One of the best experts on this subject based on the ideXlab platform.
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q learning based co operative Spectrum Mobility in cognitive radio networks
Local Computer Networks, 2017Co-Authors: Avirup Das, Sasthi C Ghosh, Nabanita Das, Abhirup Das BarmanAbstract:In cognitive radio systems, fast and efficient Spectrum selection is a vital task to minimize the overhead of Spectrum scanning, and hence to improve the response time of the system. So, the choice of channel sensing sequence plays an important role for better performance of the system. This paper proposes a co-operative Q-learning based Spectrum sensing technique for the secondary users of an ad hoc network to access the primary channels. By the proposed technique, every secondary user (SU) maintains a dynamic priority list of channels based on Q-learning from its own action-observation history, as well as from spatial channel information exchange among its local neighbors. Whenever there is a demand an SU scans the Spectrum according to the order in the priority list until there is a success. Simulation studies show that with significantly less computing and scanning overhead, our proposed Q-learning based approach improves the response time and call block / drop rate to offer better performance compared to other contemporary reinforcement learning based approaches.
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cooperative Spectrum Mobility in heterogeneous opportunistic networks using cognitive radio
Local Computer Networks, 2015Co-Authors: Avirup Das, Sasthi C Ghosh, Nabanita Das, Abhirup Das BarmanAbstract:With the advent of smarter technologies in cellular networks, often the bands used for lower versions remain unoccupied. To utilize that, in this paper, a new paradigm of cognitive radio has been proposed, where the nodes of a self-organized opportunistic ad hoc network act as the secondary users (SU) to use the white spaces of the existing cellular network. Each SU can freely move around, and in a self-organized fashion may collaborate with other neighboring SUs to gather information on the channels assigned to the cells of the primary network for cognitive use of the licensed Spectrum with reduced Spectrum latency. Simulation studies show that our proposed cooperative approach significantly improves the call drop/ block rate, and also results better QoS compared to the non-cooperative approach at the cost of negligible additional message overhead.
Yuhshyan Chen - One of the best experts on this subject based on the ideXlab platform.
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a relay assisted protocol for Spectrum Mobility and handover in cognitive lte networks
IEEE Systems Journal, 2013Co-Authors: Yuhshyan Chen, Jiashiang HongAbstract:Most of the licensed and license-exempt bands are underused while usage in some unlicensed bands is increasing. This trend has driven unlicensed users, equipped with cognitive radios, to opportunistically and dynamically access the Spectrum not used by licensed users. Relaying techniques are an important issue for coverage and capacity extension. In this paper, we describe a relay-assisted protocol for Spectrum Mobility and handover with minimum expected transmission times in cognitive long-term evolution networks, which allows unlicensed users access to not only the previous base stations but also the next base station, with the assistance of relay nodes. Performance analysis of the proposed handover protocol is investigated, and simulation results of the proposed handover protocol are presented, which illustrate a significant reduction in total transmission time and Spectrum Mobility ratio, and increases in throughput.
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a cross layer protocol of Spectrum Mobility and handover in cognitive lte networks
Simulation Modelling Practice and Theory, 2011Co-Authors: Yuhshyan Chen, Chinghsiung Cho, Ilsun You, Hanchieh ChaoAbstract:Abstract Cognitive radio technique is the next step toward efficient wireless bandwidth utilization. While some of the Spectrum bands (unlicensed band) have been increasingly used, most of the other Spectrum resources (licensed band) are underutilized. This drives the challenges of open Spectrum and dynamic Spectrum access concepts, which allows unlicensed users (or called secondary users, SUs) equipped with cognitive radios to opportunistically access the Spectrum not used by licensed users (or called primary users, PUs). Most existing results mainly focus on designing the lower-layer cognitive radio problems. In the literature, this is the first result to investigate the higher-layer solution for cognitive radio networks. In this paper, we present a cross-layer protocol of Spectrum Mobility (layer-2) and handover (layer-3) in cognitive LTE networks. With the consideration of the Poisson distribution model of Spectrum resources, a cross-layer handoff protocol with the minimum expected transmission time is developed in cognitive LTE networks. Performance analysis of the proposed handoff protocol is investigated. Finally, simulation results illustrates the proposed handoff protocol significantly reduces the expected transmission time and the Spectrum Mobility ratio.
Xiuzhen Cheng - One of the best experts on this subject based on the ideXlab platform.
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big data routing in d2d communications with cognitive radio capability
IEEE Wireless Communications, 2016Co-Authors: Jianhui Huang, Xiuzhen Cheng, Shengling Wang, Jingping BiAbstract:In D2D communications, random contacts can be utilized to exchange data among nodes without the support from infrastructures or central control units. Because of the huge quantity and high Mobility of the nodes, the scarcity of the available Spectrum severely limits the data delivery capacity in D2D communications. CR technology gives D2D the ability to use idle licensed radio spectra from licensed networks to improve data delivery capacity. The advantages of opportunistic data delivery and CR technology make D2D communications an alternative that provides a complementary technology for big data applications. However, efficient routing algorithm design in D2D communications with CRD2D is nontrivial due to the spatial, temporal, and Spectrum limitations introduced by node Mobility and the available Spectrum bands. This article investigates and analyzes the latest routing algorithms for D2D communications and CR networks. Taking advantage of the integration of D2D and CR techniques, a routing framework with social awareness for big data applications is proposed, which employs the regularities of nodes' Mobility and Spectrum Mobility to improve the performance of data delivery. Open research issues for big data routing in CRD2D networks are also addressed.
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Spectrum prediction in cognitive radio networks
IEEE Wireless Communications, 2013Co-Authors: Xiaoshuang Xing, Tao Jing, Wei Cheng, Xiuzhen ChengAbstract:Spectrum sensing, Spectrum decision, Spectrum sharing, and Spectrum Mobility are four major functions of cognitive radio systems. Spectrum sensing is utilized to observe the Spectrum occupancy status and recognize the channel availability, while CR users dynamically access the available channels through the regulation processes of Spectrum decision, Spectrum sharing, and Spectrum Mobility. To alleviate the processing delays involved in these four functions and to improve the efficiency of Spectrum utilization, Spectrum prediction for cognitive radio networks has been extensively studied in the literature. This article surveys the state of the art of Spectrum prediction in cognitive radio networks. We summarize the major Spectrum prediction techniques, illustrate their applications, and present the relevant open research challenges.
