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Author: Si Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
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Book Description
Abstract: We proposed a novel spectrum allocation approach for distributed cognitive radio networks. Cognitive radio systems are capable of sensing the prevailing environmental conditions and automatically adapting its operating parameters in order to enhance system and network performance. Using this technology, our proposed approach optimizes each individual wireless device and its single-hop communication links using the partial operating parameter and environmental information from adjacent devices within the wireless network. Assuming stationary wireless nodes, all wireless communication links employ non-contiguous orthogonal frequency division multiplexing (NC-OFDM) in order to enable dynamic spectrum access (DSA). The proposed approach will attempt to simultaneously minimize the bit error rate, minimize out-of-band (OOB) interference, and maximize overall throughput using a multi-objective fitness function. Without loss in generality, genetic algorithms are employed to perform the actual optimization. Two generic optimization approaches, subcarrier-wise approach and block-wise approach, were proposed to access spectrum. We also proposed and analyzed several approaches implemented via genetic algorithms (GA), such as quantizing variables, using adaptive variable ranges, and Multi-Objective Genetic Algorithms, for increasing the speed and improving the results of combined spectrum utilization/cross-layer optimization approaches proposed, together with several assisting processes and modifications devised to make the optimization to improve efficiency and execution time.
Author: Si Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
Get Book Here
Book Description
Abstract: We proposed a novel spectrum allocation approach for distributed cognitive radio networks. Cognitive radio systems are capable of sensing the prevailing environmental conditions and automatically adapting its operating parameters in order to enhance system and network performance. Using this technology, our proposed approach optimizes each individual wireless device and its single-hop communication links using the partial operating parameter and environmental information from adjacent devices within the wireless network. Assuming stationary wireless nodes, all wireless communication links employ non-contiguous orthogonal frequency division multiplexing (NC-OFDM) in order to enable dynamic spectrum access (DSA). The proposed approach will attempt to simultaneously minimize the bit error rate, minimize out-of-band (OOB) interference, and maximize overall throughput using a multi-objective fitness function. Without loss in generality, genetic algorithms are employed to perform the actual optimization. Two generic optimization approaches, subcarrier-wise approach and block-wise approach, were proposed to access spectrum. We also proposed and analyzed several approaches implemented via genetic algorithms (GA), such as quantizing variables, using adaptive variable ranges, and Multi-Objective Genetic Algorithms, for increasing the speed and improving the results of combined spectrum utilization/cross-layer optimization approaches proposed, together with several assisting processes and modifications devised to make the optimization to improve efficiency and execution time.
Author: Hang Qin
Publisher: Scientific Research Publishing, Inc. USA
ISBN: 1618963988
Category : Computers
Languages : en
Pages : 194
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Book Description
This book is about cognitive radio (CR), a revolution in radio technology and an enabling technology for dynamic spectrum access. Due to the unique characteristics of the wireless networks, it is essential to address the approach of multiple layers (e.g., physical, link, and network) to maximize the network performance. The formulation of this cross-layer problem is usually complicated and challenging, while wireless resource allocation is a vital way to handle the race condition of the limited wireless resources. However, given the intrinsic characteristics of cognitive radio networks (CRN), none of the existing analytical approach could be a direct fit. Therefore, innovative theoretical results, along with the corresponding mathematical techniques, are necessary. In this book, we aim to develop some novel algorithmic design and optimization techniques that provide optimal or near-optimal solutions. Although cross-layer design has been introduced to CRN for many years, there are rarely any books for researchers, engineers, and students, from the engineering perspective. From one hand, most of the existing books primarily focus on the mathematical and economic aspects, which are considerably different from the engineering. On the other hand, all of the books mainly aim to system optimization or control techniques, while the cross-layer algorithm design in the distributed environment is usually ignored. As the result, there is an urgent demand for a reference source, which can provide complete information on how to fully adopt cross-layer resource allocation to the CRN. In this regard, this book not only focuses on the description of the main aspects of cross-layer resource allocation over CRN, but also provides a review of the application solutions. In a nutshell, it provides a specific treatment of cross-layer design in CRN. The topics range from the basic concepts of cross-layer resource allocation, to the state-of-the-art analyses, modelings, and optimizations for CRN.
Author: Danda B. Rawat
Publisher: Springer
ISBN: 3319152998
Category : Computers
Languages : en
Pages : 83
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Book Description
This SpringerBrief presents adaptive resource allocation schemes for secondary users for dynamic spectrum access (DSA) in cognitive radio networks (CRNs) by considering Quality-of-Service requirements, admission control, power/rate control, interference constraints, and the impact of spectrum sensing or primary user interruptions. It presents the challenges, motivations, and applications of the different schemes. The authors discuss cloud-assisted geolocation-aware adaptive resource allocation in CRNs by outsourcing computationally intensive processing to the cloud. Game theoretic approaches are presented to solve resource allocation problems in CRNs. Numerical results are presented to evaluate the performance of the proposed methods. Adaptive Resource Allocation in Cognitive Radio Networks is designed for professionals and researchers working in the area of wireless networks. Advanced-level students in electrical engineering and computer science, especially those focused on wireless networks, will find this information helpful.
Author: Sheu-Sheu Tan
Publisher:
ISBN: 9781267995414
Category :
Languages : en
Pages : 160
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Book Description
We develop channel aware scheduling and resource allocation schemes with cross-layer optimization for several problems in multiuser wireless networks. We consider problems of distributed opportunistic scheduling, where multiple users contend to access the same set of channels. Instead of scheduling users to the earliest available idle channels, we also take the instantaneous channel quality into consideration and schedule the users only when the channel quality is sufficiently high. This can lead to significant gains in throughput compared to system where PHY and MAC layers are designed separately and the wireless fading channels are abstracted as time invariant, fixed rate channels for scheduling purposes. We first consider opportunistic spectrum access in a cognitive radio network, where a secondary user (SU) share the spectrum opportunistically with incumbent primary users (PUs). Similar to earlier works on distributed opportunistic scheduling (DOS), we maximize the throughput of SU by formulating the channel access problem as a maximum rate-of-return problem in the optimal stopping theory framework. We show that the optimal channel access strategy is a pure threshold policy, namely the SU decides to use or skip transmission opportunities by comparing the channel qualities to a fixed threshold. We further increase the spectrum utilization by interleaving SU's packets with periodic sensing to detect PU's return. We jointly optimize the rate threshold and the packet transmission time to maximize the average throughput of SU, while limiting interference to PU. Next, we develop channel-aware opportunistic spectrum access strategies in a more general cognitive radio network with multiple SUs. Here, we additionally take into account the collisions and complex interaction between SUs and sharing of resources between them. We derive strategies for both cooperative settings where SUs maximize their sum total of throughputs, as well as non-cooperative game theoretic settings, where each SU tries to maximize its own throughput. We show that the optimal schemes for both scenarios are pure threshold policies. In the non-cooperative case, we establish the existence of Nash equilibrium and develop best response strategies that can converge to equilibria, with SUs relying only on their local observations. We study the trade-off between maximal throughput in the cooperative setting and fairness in the non-cooperative setting, and schemes based on utility functions and pricing that mitigate this tradeoff. In addition to maximizing throughput and fair sharing of resources, it is important to consider network/scheduling delays for QoS performance of delay-sensitive applications. We study DOS under both network-wide and user-specific average delay constraints. We take a stochastic Lagrangian approach and characterize the corresponding optimal scheduling policies accordingly, and show that they have a pure threshold structure. Next, we consider the use of different types of channel quality information, i.e., channel state information (CSI) and channel distribution information (CDI) in the opportunistic scheduling design for MIMO ad hoc networks. CSI is highly dynamic in nature and provides time diversity in the wireless channel, but is difficult to track. CDI offers temporal stability, but is incapable of capturing the instantaneous channel conditions. We design a new class of cross-layer opportunistic channel access scheduling framework for MIMO networks where CDI is used in the network context to group the simultaneous transmission links for spatial channel access and CSI is used in the link context to decide when and which link group should transmit based on a pre designed threshold. We thereby reap the benefits of both the temporal stability of CDI and the time diversity of CSI. Finally, we consider a novel application of cross layer optimization for communication of progressive coded images over OFDM wireless fading channels. We first consider adaptive modulation based on the instantaneous channel state information. An algorithm is proposed to allocate power and constellation size at each subchannel by maximizing the throughput. We next consider both the variance and the average of the throughput when deciding the constellation size for adaptive modulation. Simulation results confirm that cross-layer optimization with adaptive modulation enhances system performance.
Author: Christina Comaniciu
Publisher: Springer Science & Business Media
ISBN: 0387277501
Category : Technology & Engineering
Languages : en
Pages : 214
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Book Description
Cross-layer design seeks to enhance the capacity of wireless networks significantly through the joint optimization of multiple layers in the network, primarily the physical (PHY) and medium access control (MAC) layers. Although there are advantages of such design in wireline networks as well, this approach is particularly advantageous for wireless networks due to the properties (such as mobility and interference) that strongly affect performance and design of higher layer protocols. This unique monograph is concerned with the issue of cross-layer design in wireless networks, and more particularly with the impact of node-level multiuser detection on such design. It provides an introduction to this vibrant and active research area insufficiently covered in existing literature, presenting some of the principal methods developed and results obtained to date. Accompanied by numerous illustrations, the text is an excellent reference for engineers, researchers and students working in communication networks.
Author: Leonidas Georgiadis
Publisher: Now Publishers Inc
ISBN: 1933019263
Category : Technology & Engineering
Languages : en
Pages : 161
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Book Description
Information flow in a telecommunication network is accomplished through the interaction of mechanisms at various design layers with the end goal of supporting the information exchange needs of the applications. In wireless networks in particular, the different layers interact in a nontrivial manner in order to support information transfer. In this text we will present abstract models that capture the cross-layer interaction from the physical to transport layer in wireless network architectures including cellular, ad-hoc and sensor networks as well as hybrid wireless-wireline. The model allows for arbitrary network topologies as well as traffic forwarding modes, including datagrams and virtual circuits. Furthermore the time varying nature of a wireless network, due either to fading channels or to changing connectivity due to mobility, is adequately captured in our model to allow for state dependent network control policies. Quantitative performance measures that capture the quality of service requirements in these systems depending on the supported applications are discussed, including throughput maximization, energy consumption minimization, rate utility function maximization as well as general performance functionals. Cross-layer control algorithms with optimal or suboptimal performance with respect to the above measures are presented and analyzed. A detailed exposition of the related analysis and design techniques is provided.
Author: George F. Elmasry
Publisher: John Wiley & Sons
ISBN: 1119573777
Category : Technology & Engineering
Languages : en
Pages : 752
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Book Description
Optimize your dynamic spectrum access approach using the latest applications and techniques Dynamic Spectrum Access Decisions: Local, Distributed, Centralized and Hybrid Designs prepares engineers to build optimum communications systems by describing at the outset what type of spectrum sensing capabilities are needed. Meant for anyone who has a basic understanding of wireless communications and networks and an interest in the physical and MAC layers of communication systems, this book has a tremendous range of civilian and military applications. Dynamic Spectrum Access Decisions provides fulsome discussions of cognitive radios and networks, but also DSA technologies that operate outside the context of cognitive radios. DSA has applications in: Licensed spectrum bands Unlicensed spectrum bands Civilian communications Military communications Consisting of a set of techniques derived from network information theory and game theory, DSA improves the performance of communications networks. This book addresses advanced topics in this area and assumes basic knowledge of wireless communications.
Author: Haibo Zhou
Publisher: Springer
ISBN: 3319450778
Category : Technology & Engineering
Languages : en
Pages : 121
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Book Description
This book focuses on the current research on the dynamic spectrum sharing for efficient spectrum resource utilization, which covers the overlay spectrum sharing, underlay spectrum sharing and database-assisted spectrum sharing related research issues. Followed by a comprehensive review and in-depth discussion of the current state-of-the-art research literature and industry standardization, this book first presents a novel overlay spectrum sharing framework for dynamic utilization of available cellular frequency bands, formulates the dynamic spectrum sharing problem as a dynamic resource demand-supply matching problem, and accordingly develops a distributed fast spectrum sharing algorithm to solve the resource matching problem. A self-awareness power control approach for multi-hop routing selection is proposed, which can establish an effective and practical routing selection optimization in secondary access networks and minimize the interference to primary users. Finally, this book offers dynamic secondary access scheme for database-assisted spectrum sharing networks, which is targeted to support the prosperous wireless multimedia networking applications by leveraging the TV white spaces of geolocation databases while satisfying QoS guarantees of secondary users. The overlay spectrum sharing, underlay spectrum sharing, and database-assisted white spaces spectrum sharing research results that are presented in this book provide useful insights for the design of next generation wireless access networks. This book motivates a new line of thinking for efficient spectrum resource utilization and performance enhancements of future wireless access applications.
Author: Tianqi Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 470
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Book Description
"Short-range wireless networks, such as wireless sensor networks, have become an integral part of our modern lives and have been broadly applied in many fields such as industry, military and research to facilitate the gathering and distribution of information. Compared with traditional wireless networks, such as cellular networks, short-range wireless networks have the following unique characteristics. (i) Dense deployment: the network devices are often densely deployed to achieve better monitoring of the environment. (ii) Circuit power consumption: due to the short communication distances, the network devices communicate with each other using low transmit power that is comparable to the devices' circuit power consumption. Thus, circuit power consumption is a major contributor to the energy drain of the network devices. (iii) Battery powered: the network devices are usually battery powered and may be deployed in remote areas. Thus, it is difficult or even impossible to replace the energy supplies of many of the network devices in a short-range wireless network. Therefore, maximizing the energy efficiency of short-range wireless networks is of paramount importance. In this dissertation, I explore the cross-layer design principle to improve the energy efficiency of energy constrained short-range wireless networks, while fully considering their unique characteristics as outlined above. In order to maximize energy efficiency, my research focuses on the cross-layer optimization of the physical layer, the data link layer, the multiple access layer, the network layer, and the application layer. In this dissertation, I (i) develop an energy efficient cross-layer design of the physical layer and the data link layer in a typical narrowband system over an additive white Gaussian noise (AWGN) channel and a Rayleigh fading channel, as well as in a typical Impulse Radio Ultra Wideband (IR-UWB) system over a frequency selective channel; (ii) optimize the energy efficiency of a clustered wireless network by choosing the optimal transmit power, selecting the optimal cluster head, and deciding whether or not to use multi-hop routing within a cluster; and (iii) optimize the energy efficiency of a short-range wireless network with distributed source coding (DSC) and adaptive transmission, as well as with DSC over Gaussian multiple access channels. Compared with existing work in the literature, I make unique contributions in this dissertation in the following aspects. First, the unique characteristics of short-range wireless networks, such as dense deployment and circuit power consumption, are considered in all of my cross-layer optimizations. Second, I focus on achieving a balance between cost and performance during the development of the cross-layer optimization schemes, due to the limited computational capacity of the network devices in short-range wireless networks. Third, throughout this dissertation, I develop universal optimal solutions that are highly parameterized and directly applicable in general scenarios. My research results in a large improvement in the energy efficiency of devices for short-range wireless networks"--Leaves v-vi.
Author: Guowang Miao
Publisher: Cambridge University Press
ISBN: 1107039886
Category : Computers
Languages : en
Pages : 387
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Book Description
Provides the fundamental principles and practical tools needed to design next-generation wireless networks that are both energy- and spectrum-efficient.
