Download or read book Cross layer Resource Allocation and Scheduling in Wireless Multicarrier Networks written by Guocong Song and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The current dominate layered networking architecture, in which each layer is designed and operated independently, results in inefficient and inflexible resource use in wireless networks due to the nature of the wireless medium, such as time-varying channel fading, mutual interference, and topology variations. In this thesis, we focus on resource allocation and scheduling in wireless orthogonal frequency division multiplexing (OFDM) networks based on joint physical and medium access control (MAC) layer optimization. To achieve orders of magnitude gains in system performance, we use two major mechanisms in resource management: exploiting the time variance and frequency selectivity of wireless channels through adaptive modulation, coding, as well as packet scheduling and regulating resource allocation through network economics. With the help of utility functions that capture the satisfaction level of users for a given resource assignment, we establish a utility optimization framework for resource allocation in OFDM networks, in which the network utility at the level of applications is maximized subject to the current channel conditions and the modulation and coding techniques employed in the network. Although the nonlinear and combinatorial nature of the cross-layer optimization challenges algorithm development, we propose novel efficient dynamic subcarrier assignment (DSA) and adaptive power allocation (APA) algorithms that are proven to achieve the optimal or near-optimal performance with very low complexity. Based on a holistic design principle, we design max-delay-utility (MDU) scheduling, which senses both channel and queue information. The MDU scheduling can simultaneously improve the spectral efficiency and provide right incentives to ensure that all applications can receive their different required quality of service (QoS). To facilitate the cross-layer design, we also deeply investigate the mechanisms of channel-aware scheduling, such as efficiency, fairness, and stability. First, using extreme value theory, we analyze the impact of multiuser diversity on throughput and packet delay. Second, we reveal a generic relationship between a specific convex utility function and a type of fairness. Third, with rigorous proofs, we provide a method to design cross-layer scheduling algorithms that allow the queueing stability region at the network layer to approach the ergodic capacity region at the physical layer.

Download or read book Cross Layer Resource Allocation in Wireless Communications written by Ana I. Perez-Neira and published by Academic Press. This book was released on 2010-07-28 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross-Layer Resource Allocation in Wireless Communications offers practical techniques and models for the design and optimisation of cross-layer resource allocation – one of the hottest topics in wireless communications. Resource allocation in wireless networks is traditionally approached either through information theory or communications networks. To break down the barriers between these distinct approaches, this book bridges the physical and network layers by providing cross-layer resource allocation techniques, models, and methodologies. Its unique approach allows optimisation of network resources and will enable engineers to improve signal quality, enhance network and spectrum utilization, increase throughput, and solve the problem of shadowing. Topics covered include different views of spectral efficiency, the role of spatial diversity, of delay in resource allocation, and possible extensions to OFDMA systems. This will be an ideal reference on cross-layer resource allocation between the PHY and MAC layers for R&D and network design engineers and researchers in universities dealing with sensor networks and cognitive systems. Gives a full description of the characteristics of the PHY layer that promote efficient resource allocation strategies Gives special emphasis on cross-layer design for spatial diversity schemes Provides a framework for interaction between the PHY and MAC layers, their parameters of performance and their relationship Presents resource allocation as a cross-layer design based on an optimization of MAC layer parameters with an accurate model of the PHY layer

Download or read book Radio Resource Allocation for Multi hop Wireless Networks Using Cross layer Optimization written by Jennifer Catherine Fang and published by . This book was released on 2005 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cross Layer Scheduling and Resource Allocation Algorithms for Cellular Wireless Networks written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis considers the problem of cross layer scheduling and radio resource allocation of multiple users in the downlink of time-slotted and frequency-slotted cellular data networks. For these networks, opportunistic scheduling algorithms improve system performance by exploiting time variations of the radio channel. Within the broader framework of opportunistic scheduling, this thesis solves three distinct problems and proposes efficient and scalable solutions for them. First, we present novel optimal and approximate opportunistic scheduling algorithms that combine channel fluctuation and user mobility information in their decision rules. The algorithms propose the use of dynamic fairness constraints. These fairness constraints adapt according to the user mobility. The optimal algorithm is an off-line algorithm that precomputes constraint values according to a known mobility model. The approximate algorithm is an on-line algorithm that relies on the future prediction of the user mobility locations in time. We show that the use of mobility information increases channel capacity. We also provide analytical bounds on the performance of the approximate algorithm. Second, this thesis presents a new opportunistic scheduling solution that maximizes the aggregate user performance subject to certain minimum and maximum performance constraints. By constraining the performance experienced by individual users, who share a common radio downlink, to some upper bounds, it is possible to provide the system operator with a better control of radio resource allocations and service differentiation among different classes of users. The proposed solution offers better performance than existing solution under practical channel conditions. Finally, we present a dynamic subcarrier allocation solution for fractional frequency reuse in multicell orthogonal frequency division multiple access systems. We formulate the subcarrier allocation as an equivalent set partitioning problem and then p.

Download or read book Channel Aware Scheduling and Resource Allocation with Cross Layer Optimization in Wireless Networks written by Sheu-Sheu Tan and published by . This book was released on 2013 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Resource Allocation in Uplink OFDMA Wireless Systems written by Elias Yaacoub and published by John Wiley & Sons. This book was released on 2012-03-13 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tackling problems from the least complicated to the most, Resource Allocation in Uplink OFDMA Wireless Systems provides readers with a comprehensive look at resource allocation and scheduling techniques (for both single and multi-cell deployments) in uplink OFDMA wireless networks relying on convex optimization and game theory to thoroughly analyze performance. Inside, readers will find topics and discussions on: Formulating and solving the uplink ergodic sum-rate maximization problem Proposing suboptimal algorithms that achieve a close performance to the optimal case at a considerably reduced complexity and lead to fairness when the appropriate utility is used Investigating the performance and extensions of the proposed suboptimal algorithms in a distributed base station scenario Studying distributed resource allocation where users take part in the scheduling process, and considering scenarios with and without user collaboration Formulating the sum-rate maximization problem in a multi-cell scenario, and proposing efficient centralized and distributed algorithms for intercell interference mitigation Discussing the applicability of the proposed techniques to state-of-the-art wireless technologies, LTE and WiMAX, and proposing relevant extensions Along with schematics and figures featuring simulation results, Resource Allocation in Uplink OFDMA Wireless Systems is a valuable book for?wireless communications and cellular systems professionals and students.

Download or read book Resource Allocation in Multiuser Multicarrier Wireless Systems written by Ian C. Wong and published by Springer Science & Business Media. This book was released on 2007-11-15 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book proposes a unified algorithmic framework based on dual optimization techniques that have complexities that are linear in the number of subcarriers and users, and that achieve negligible optimality gaps in standards-based numerical simulations. Adaptive algorithms based on stochastic approximation techniques are also proposed, which are shown to achieve similar performance with even much lower complexity. All the algorithms proposed are clearly presented in concise block diagrams allowing the reader to implement these algorithms in the software of their choice. This book is an accessible reference for researchers and industry practitioners alike.

Download or read book Advances in Multi Channel Resource Allocation written by Bo Ji and published by Morgan & Claypool Publishers. This book was released on 2016-11-07 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last decade has seen an unprecedented growth in the demand for wireless services. These services are fueled by applications that often require not only high data rates, but also very low latency to function as desired. However, as wireless networks grow and support increasingly large numbers of users, these control algorithms must also incur only low complexity in order to be implemented in practice. Therefore, there is a pressing need to develop wireless control algorithms that can achieve both high throughput and low delay, but with low-complexity operations. While these three performance metrics, i.e., throughput, delay, and complexity, are widely acknowledged as being among the most important for modern wireless networks, existing approaches often have had to sacrifice a subset of them in order to optimize the others, leading to wireless resource allocation algorithms that either suffer poor performance or are difficult to implement. In contrast, the recent results presented in this book demonstrate that, by cleverly taking advantage of multiple physical or virtual channels, one can develop new low-complexity algorithms that attain both provably high throughput and provably low delay. The book covers both the intra-cell and network-wide settings. In each case, after the pitfalls of existing approaches are examined, new systematic methodologies are provided to develop algorithms that perform provably well in all three dimensions.

Download or read book Dynamic Resource Allocation and Optimization in Wireless Networks written by Yang Song and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fifthly, we analyze the thresholds-based rate adaptation algorithms in IEEE 802.11 WLANs from a reverse engineering perspective and propose a threshold optimization algorithm to enhance the performance of IEEE 802.11 WLANs. Finally, we investigate the stochastic traffic engineering problem in multi-hop cognitive radio networks and derive a distributed algorithm based on the stochastic primal-dual approach for convex scenarios as well as a general solution based on the learning automata techniques for non-convex scenarios.

Download or read book Dynamic Optimized Resource Allocation in Cellular Wireless Networks with Software Interface written by Michel Matta and published by . This book was released on 2015 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past years, there has been a huge advance in the structure and design of wireless networks, and we have seen significant variation form the physical layer algorithm development to the layer protocol design to the system level optimization. Numerous wireless standards have been agreed on to keep up with demand of multiple applications. Over the years researchers came together and realized that for wireless networks, and because of user mobility, fading channel and power resources, and other factors we cannot simply optimize the wireless communication like we used to optimize the wired networks, where they usually concentrate on one layer without paying any attention on the effects it has on other layers. But for wireless networks, interconnection between layers and cross layer optimization is the basic issue to insure high quality performance. One of the most important issues in the cross layer optimization is resource allocation. In Wireless communication there are frequency, time and space diversity as well. If we took advantages of those diversities we can tremendously improve the quality of communication. All those variables contribute to the need of resource allocations. We have seen the advance of resource allocation in the past years with huge progress. As anyone can imagine, because the number of degrees freedom, and multiple parameters, dynamic resource allocation is a broad topic that deals with variety of problems. So the optimization tools and techniques may vary a lot. Aside from the commonly used method which is convex optimization there are non-linear and non-convex methods. When we speak about channel allocation and resource scheduling. Sometimes the problem tends to get more and more complicated. If we took into account the time caring conditions, the problem will evolve to be a dynamic optimization. The cooperation with the distributed and autonomous devices is considered, different mathematical models can be used to find the best strategy and optimal solution. It is only fair to say that there is no single perfect optimization available to solve all the dynamic resource allocation problems.

Download or read book Mobile WiMAX written by Yan Zhang and published by CRC Press. This book was released on 2007-12-10 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Wireless Metropolitan Area Network (WirelessMAN) is a promising Broadband Wireless Access (BWA) technology that provides high-speed, high-bandwidth efficiency and high-capacity multimedia services for both residential and enterprise applications. Mobile WiMAX: Toward Broadband Wireless Metropolitan Area Networks examines the basic concepts, rec

Download or read book Scheduling and Resource Allocation in Multi user Wireless Systems written by Xuan Wang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we discuss various aspects of scheduling and resource allocation in multi-user wireless systems. This work starts from how to utilize advanced physical-layer technology to improve the system performance in a multi-user environment. We show that by using superposition coding (SPC) and successive interference cancellation, the system performance can be greatly improved with utility-based scheduling. Several observations are made as the design guideline for such system. Scheduling algorithms are designed for a system with hierarchical modulation which is a practical implementation of SPC. However, when the utility-based scheduling is designed, it is based on the assumption that the system is saturated, {\em i.e.}, users in the system always have data to transmit. It is pointed out in the literature that in a system with stochastic traffic, even if the arrival rate lies inside the capacity region, the system in terms of queue might not be stable with the utility-based scheduling. Motivated by this, we have studied the stability region of a general utility-based scheduling in a multi-user system with stochastic traffic. We show that the stability region is generally less than the capacity region, depends on how to interpret an intermediate control variable, and the resultant stability region may be even non-convex and exhibits undesirable properties which should be avoided. As the utility-based scheduling cannot achieve throughput-optimal, we turn our attentions to the throughput-optimal scheduling algorithms, whose stability region is identical to the capacity region. The limiting properties of an overloaded wireless system with throughput-optimal scheduling algorithms are studied. The results show that the queue length is unstable however the scheduling function of the queue length is stable, and the average throughput of the system converges. Finally we study how to schedule users in a multi-user wireless system with information-theoretic security support, which is focused on the secrecy outage probability. The problem is essentially about how to schedule users, and allocate resources to stabilize the system and minimize the secrecy outage probability. We show that there is a tradeoff between the arrival rate of the traffic and the secrecy outage probability. The relative channel condition of the eavesdropper also plays an important role to the secrecy outage probability. In summary, we showed utility-based scheduling using SPC can improve the system performance greatly, but the utility-based scheduling has limitations: the stability region might not have desired properties. On the contrary throughput-optimal scheduling has its own drawbacks: the traffic cannot be handled properly if the system is overloaded. The further study on the secrecy outage probability gives guideline on how to design a scheduler in a system with information-theoretic security support.

Download or read book Multi carrier Techniques For Broadband Wireless Communications A Signal Processing Perspective written by C-c Jay Kuo and published by World Scientific. This book was released on 2007-12-10 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-Carrier Techniques for Broadband Wireless Communications provides an accessible introduction to OFDM-based systems from a signal processing perspective. The first part presents a concise treatment of some fundamental concepts related to wireless communications and multicarrier systems, while the second offers a comprehensive survey of recent developments on a variety of critical design issues. These include synchronization techniques, channel estimation methods, adaptive resource allocation and practical schemes for reducing the peak-to-average power ratio of the transmitted waveform./a

Download or read book Cross layer Optimization for Resource Allocation in Multihop Wireless Networks written by Jian Tang and published by . This book was released on 2006 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Cross layer Design Framework for Resource Allocation in Wireless Data Networks written by Ming Hu and published by . This book was released on 2004 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cooperation and Optimal Cross layer Resource Allocation in Wireless Networks written by Chris T. K. Ng and published by . This book was released on 2007 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: In wireless networks, we can improve system performance by exploiting cooperative communications, where neighbor nodes may interact to jointly encode, decode, or relay information. In this thesis, we show that cooperation can improve capacity, but only when the right cooperation strategy is chosen based on the network topology, signal-to-noise ratio (SNR), channel state information (CSI), and power allocation assumptions. In particular, when we consider the deployment of relay nodes in a wireless network, CSI at the transmitter is necessary for effective transmitter cooperation, while transmission power allocation between the cooperating nodes is crucial for receiver cooperation. The benefits of cooperation are further studied when the relay and receiver can iterate to exchange information over orthogonal, finite-capacity channels known as conference links. We show that a two-round iterative decoding scheme can achieve a higher capacity over non-iterative cooperation.

Download or read book Cross layer Resource Allocation Algorithms in Wireless Networks with Antenna Arrays written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: