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Scheduling In Wireless Networks With Limited And Imperfect Channel Knowledge
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Book Synopsis Scheduling in Wireless Networks with Limited and Imperfect Channel Knowledge by : Wenzhuo Ouyang
Download or read book Scheduling in Wireless Networks with Limited and Imperfect Channel Knowledge written by Wenzhuo Ouyang and published by . This book was released on 2014 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: We model the scheduling problems as Partially Observable Markov Decision Processes (POMDPs). POMDPs are known to be difficult to solve. We are able to analyze the problems in the framework of Restless Multi-armed Bandit Processes and utilize the Whittle's indexability analysis. Based on our analysis, we propose low-complexity scheduling algorithms that have optimality performance in different wireless networks. Our work reveals that, under limited and imperfect channel state information, exploiting channel memory and ARQ-styled feedback for scheduling can result in significant system-level performance gains and that the proposed polynomial-complexity algorithms have provably optimal performances in various settings.
Book Synopsis Scheduling in Multi-Channel Wireless Networks with Limited Information by :
Download or read book Scheduling in Multi-Channel Wireless Networks with Limited Information written by and published by . This book was released on 2008 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The availability of multiple orthogonal channels in a wireless network can potentially lead to substantial performance improvement by alleviating contention and interference. However, this also gives rise to non-trivial channel coordination issues. The situation is exacerbated by variability in the achievable data-rates across channels and links. Thus, scheduling in such networks may require substantial information-exchange and lead to non-negligible overhead. This provides a strong motivation for the study of scheduling algorithms that can operate with limited information, while still providing acceptable worst-case performance guarantees. In this paper, we make an effort in this direction, by examining the scheduling implications of multiple channels, and heterogeneity in channel-rates. We establish lower bounds on performance of a class of maximal schedulers, and describe a scheduler that require limited information-exchange between nodes. We first demonstrate that when the underlying scheduling mechanism is "imperfect", the presence of multiple orthogonal channels can help alleviate the detrimental impact of the imperfect scheduler, and yield a significantly better efficiency-ratio in a wide range of network topologies. We then establish performance bounds for a scheduler than can achieve good efficiency-ratios in the presence of channels with heterogeneous rates without requiring explicit exchange of queue-information. Our results indicate that it may be possible to achieve a desirable trade-off between performance and information.
Book Synopsis Scheduling in Wireless Networks by : Anna Pantelidou
Download or read book Scheduling in Wireless Networks written by Anna Pantelidou and published by Now Publishers Inc. This book was released on 2011 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews the problem of scheduled channel access in wireless networks with emphasis on ad hoc and sensor networks as opposed to WiFi, cellular, and infrastructure-based networks. It is intended to provide a reference point for the rich set of problems that arise in the allocation of resources in modern and future networks.
Book Synopsis Handbook of Wireless Networks and Mobile Computing by : Ivan Stojmenovic
Download or read book Handbook of Wireless Networks and Mobile Computing written by Ivan Stojmenovic and published by John Wiley & Sons. This book was released on 2003-04-08 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: The huge and growing demand for wireless communication systems has spurred a massive effort on the parts of the computer science and electrical engineering communities to formulate ever-more efficient protocols and algorithms. Written by a respected figure in the field, Handbook of Wireless Networks and Mobile Computing is the first book to cover the subject from a computer scientist's perspective. It provides detailed practical coverage of an array of key topics, including cellular networks, channel assignment, queuing, routing, power optimization, and much more.
Book Synopsis Coordinated Multi-Point under a Constrained Backhaul and Imperfect Channel Knowledge by : Patrick Marsch
Download or read book Coordinated Multi-Point under a Constrained Backhaul and Imperfect Channel Knowledge written by Patrick Marsch and published by Jörg Vogt Verlag. This book was released on 2010 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis On Distributed Scheduling for Wireless Networks with Time-varying Channels by : Akula Aneesh Reddy
Download or read book On Distributed Scheduling for Wireless Networks with Time-varying Channels written by Akula Aneesh Reddy and published by . This book was released on 2013 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless scheduling is a fundamental problem in wireless networks that involves scheduling transmissions of multiple users in order to support data flows with as high rates as possible. This problem was first addressed by Tassuilas and Ephremides, resulting in the celebrated Back-Pressure network scheduling algorithm. This algorithm schedules network links to maximize throughput in an opportunistic fashion using instantaneous network state information (NSI), i.e., queue and channel state knowledge across the entire network. However, the Back-Pressure (BP) algorithm suffers from various drawbacks - (a) it requires knowledge of instantaneous NSI from the whole network, i.e. feedback about time-varying channel and queue states from all links of the network, (b) the algorithm requires solving a global optimization problem at each time to determine the schedule, making it highly centralized. Further, Back-pressure algorithm was originally designed for wireless networks where interference is modeled using protocol interference model. As recent break-throughs in full-duplex communications and interference cancelation techniques provide greatly increased capacity and scheduling flexibility, it is not clear how BP algorithm can be modified to improve the data rates and reduce the delay. In this thesis, we address the drawbacks of Back-Pressure algorithm to some extent. In particular, our first work provides a new scheduling algorithm (similar to BP) that allows users to make individual decisions (distributed) based on heterogeneously delayed network state information (NSI). Regarding the complexity issue, in our second work, we analyze the performance of the greedy version of BP algorithm, known as Greedy Maximal Scheduling (GMS) and understand the effect of channel variations on the performance of GMS. In particular, we characterize the efficiency ratio of GMS in wireless networks with fading. In our third and fourth work, we propose and analyze new scheduling algorithms that can benefit from new advancements in interference cancelation techniques.
Book Synopsis The Role of Control Information in Wireless Link Scheduling by : Matthew Ryan Johnston
Download or read book The Role of Control Information in Wireless Link Scheduling written by Matthew Ryan Johnston and published by . This book was released on 2015 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: In wireless networks, transmissions must be scheduled to opportunistically exploit the time-varying capacity of the wireless channels to achieve maximum throughput. These opportunistic policies require global knowledge of the current network state to schedule transmissions eciently; however, providing a controller with complete channel state information (CSI) requires signicant bandwidth. In this thesis, we investigate the impact of control information on the ability to effectively schedule transmissions. In particular, we study the tradeoff between the availability and accuracy of CSI at the scheduler and the attainable throughput. Moreover, we investigate strategies for controlling the network with limited CSI. In the first half of the thesis, we consider a multi-channel communication system in which the transmitter chooses one of M channels over which to transmit. We model the channel state using an ON/OFF Markov process. First, we consider channel prob- ing policies, in which the transmitter probes a channel to learn its state, and uses the CSI obtained from channel probes to make a scheduling decision. We investigate the optimal channel probing strategies and characterize the tradeoff between probing frequency and throughput. Furthermore, we characterize a fundamental limit on the rate at which CSI must be conveyed to the transmitter in order to meet a constraint on expected throughput. In particular, we develop a novel formulation of the op- portunistic scheduling problem as a causal rate distortion optimization of a Markov source. The second half of this thesis considers scheduling policies under delayed CSI, re- sulting from the transmission and propagation delays inherent in conveying CSI across the network. By accounting for these delays as they relate to the network topology, we revisit the comparison between centralized and distributed scheduling, showing that there exist conditions under which distributed scheduling outperforms the optimal centralized policy. Additionally, we illustrate that the location of a centralized controller impacts the achievable throughput. We propose a dynamic controller placement framework, in which the controller is repositioned using delayed queue length information (QLI). We characterize the throughput region under all such policies, and propose a throughput-optimal joint controller placement and scheduling policy using delayed CSI and QLI.
Book Synopsis Energy-Efficient Scheduling under Delay Constraints for Wireless Networks by : Randal Berry
Download or read book Energy-Efficient Scheduling under Delay Constraints for Wireless Networks written by Randal Berry and published by Springer Nature. This book was released on 2022-05-31 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Packet delay and energy consumption are important considerations in wireless and sensor networks as these metrics directly affect the quality of service of the application and the resource consumption of the network; especially, for a rapidly growing class of real-time applications that impose strict restrictions on packet delays. Dynamic rate control is a novel technique for adapting the transmission rate of wireless devices, almost in real-time, to opportunistically exploit time-varying channel conditions as well as changing traffic patterns. Since power consumption is not a linear function of the rate and varies significantly with the channel conditions, adapting the rate has significant benefits in minimizing energy consumption. These benefits have prompted significant research in developing algorithms for achieving optimal rate adaptation while satisfying quality of service requirements. In this book, we provide a comprehensive study of dynamic rate control for energy minimization under packet delay constraints. We present several formulations and approaches adopted in the literature ranging from discrete-time formulations and dynamic programming based solutions to continuous-time approaches utilizing ideas from network calculus and stochastic optimal control theory. The goal of this book is to expose the reader to the important problem of wireless data transmission with delay constraints and to the rich set of tools developed in recent years to address it. Table of Contents: Introduction / Transmission Rate Adaptation under Deadline Constraints / Average Delay Constraints
Book Synopsis Information Freshness and Delay Optimization in Unreliable Wireless Systems by : Guidan Yao
Download or read book Information Freshness and Delay Optimization in Unreliable Wireless Systems written by Guidan Yao and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the rapid development of time-critical applications in wireless networks like video streaming and augmented reality, there have been significant efforts been made to deliver time-efficient services in terms of different time-related metrics, i.e., delay and the age. However, the problems become increasingly challenging in the wireless environment because of the inherent unreliability of the wireless channel. In this dissertation, we investigate optimal transmission scheduling policies in terms of either delay or the age in variety of unreliable wireless systems. We take into account heterogenous transmission choices in terms of transmission delay and error probability, and transmission with energy constraints. We show that making optimal transmission decisions can greatly improve latency in terms of delay and age. We develop an integrated mmWave-sub-6 GHz architecture, where packets can be delivered via either mmWave or sub-6 GHz interface. Our goal is to combat the intermittency of the mmWave and thus reduce the resultant delay with aid of scheduling design and usage of the sub-6 GHz. To this end, we show that the delay- optimal policy for the system is of threshold-type, i.e., packets should always be routed to the mmWave interface as long as the number of packets in the system is smaller than the state-dependent threshold. Moreover, numerical results demonstrate that under heavy traffic, integrating sub-6 GHz with mmWave can reduce the average delay by over 70%. We also study age minimization with heterogenous transmission choices. In particular, we consider a status update system, in which update packets are sent to the destination via a wireless medium that allows for multiple rates, where a higher rate also naturally corresponds to a higher error probability. We design a low-complexity optimal scheduler that selects between two different transmission rate and error prob- ability pairs to be used at each transmission epoch. To this end, we show that there exists a threshold-type policy that is age-optimal, and that the objective function is quasi-convex or non-decreasing in the threshold. In wireless sensor networks or IoT systems, devices are usually energy limited. Further, different knowledge of channel state information (CSI) may require differ- ent policies to minimize the age under energy constraints. To get some insights on transmission scheduling with imperfect CSI, we consider a system, where updates are periodically generated and transmitted to the destination over a time-correlated fading channel. And we consider two practical ways to obtain the CSI: (i) CSI is revealed by the feedback on transmissions, (ii) CSI is available via delayed channel sensing. Our goal is to find transmission control (transmission or suspension) policy that minimizes the long-term average age under a constraint on the average energy. For either case, we prove that the optimal policy is a randomized mixture of no more than two stationary deterministic threshold-type policies. With the properties, we design low-complexity structure-aware algorithms. Finally, we consider both energy and distortion requirements and consider a status update system, where an access point collects samples from multiple sensors and transmits the collected samples to the destination over error-prone channels. Our goal is to minimize the long-term average age under constraints on the long-term average energy and distortion of each update, where the distortion is determined by the number of collected samples. Under the assumption that the distortion requirement is a non-decreasing function of the age, we show that the optimal policy is a mixture of two stationary deterministic policies, each of which is optimal for a parameterized average cost problem and is of a threshold-type, i.e., transmission is conducted when the age exceeds a threshold and the distortion requirement is met. We derive the average cost as a piecewise function of threshold, and obtain the optimal threshold in the last interval. With these, we develop a low-complexity algorithm for the original problem. Moreover, we provide a closed-form solution to the parameterized problem with constant distortion function.
Book Synopsis Optimization in Electrical Engineering by : Mohammad Fathi
Download or read book Optimization in Electrical Engineering written by Mohammad Fathi and published by Springer. This book was released on 2019-03-01 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides students, researchers, and engineers in the area of electrical engineering with advanced mathematical optimization methods. Presented in a readable format, this book highlights fundamental concepts of advanced optimization used in electrical engineering. Chapters provide a collection that ranges from simple yet important concepts such as unconstrained optimization to highly advanced topics such as linear matrix inequalities and artificial intelligence-based optimization methodologies. The reader is motivated to engage with the content via numerous application examples of optimization in the area of electrical engineering. The book begins with an extended review of linear algebra that is a prerequisite to mathematical optimization. It then precedes with unconstrained optimization, convex programming, duality, linear matrix inequality, and intelligent optimization methods. This book can be used as the main text in courses such as Engineering Optimization, Convex Engineering Optimization, Advanced Engineering Mathematics and Robust Optimization and will be useful for practicing design engineers in electrical engineering fields. Author provided cases studies and worked examples are included for student and instructor use.
Book Synopsis Online Learning for Scheduling in Wireless Networks by : Isfar Tariq
Download or read book Online Learning for Scheduling in Wireless Networks written by Isfar Tariq and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last few years, online learning has grown in importance as it allows us to build systems that can interact with the environment while continuously learning from past interactions to improve future decisions to maximize some objective. While online learning is used in several areas like recommendation systems, however, due to the complexity of wireless scheduling it is unclear how to utilize online learning. For instance, MU-MIMO scheduling involves the selection of a user subset and associated rate selection each time-slot for varying channel states (the vector of quantized channels matrices for each of the users) — a complex integer optimization problem that is different for each channel state. We propose that a low-dimensional structure is present in the wireless systems which can be exploited through online learning. For instance, channel-states "near" each other will likely have the same optimal solution. In our first problem, we present a framework through which we formulate the wireless scheduling problem as a multi-armed bandit problem. We then propose an online algorithm that can cluster the channel-states and learn the capacity region of these clusters. We show that our algorithms can significantly reduce the complexity of online learning for wireless settings and provide regret guarantees for our algorithm. In the second problem, we expand on our previous work and present (1) a framework that further exploits the low-dimensional structure present in the system by clustering users and (2) an online algorithm that utilizes the parameters learned by our previous algorithms to optimize the subset of users to be scheduled for given channel-state. We show that our algorithms can not only converge faster but also improve the overall throughput of the system. We also provide regret guarantees for the user clustering algorithm
Book Synopsis Theoretical Foundations of Channel Scheduling in Wireless Networks by : Amrinder Arora
Download or read book Theoretical Foundations of Channel Scheduling in Wireless Networks written by Amrinder Arora and published by . This book was released on 2006 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Feedback Strategies for Wireless Communication by : Berna Özbek
Download or read book Feedback Strategies for Wireless Communication written by Berna Özbek and published by Springer Science & Business Media. This book was released on 2013-10-19 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the different strategies regarding limited feedback information. The book analyzes the impact of quantization and the delay of CSI on the performance. The author shows the effect of the reduced feedback information and gives an overview about the feedback strategies in the standards. This volume presents theoretical analysis as well as practical algorithms for the required feedback information at the base stations to perform adaptive resource algorithms efficiently and mitigate interference coming from other cells.
Book Synopsis 5G and Beyond Wireless Systems by : Manish Mandloi
Download or read book 5G and Beyond Wireless Systems written by Manish Mandloi and published by Springer Nature. This book was released on 2020-08-11 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the fundamental concepts, recent advancements, and opportunities for future research in various key enabling technologies in next-generation wireless communications. The book serves as a comprehensive source of information in all areas of wireless communications with a particular emphasis on physical (PHY) layer techniques related to 5G wireless systems and beyond. In particular, this book focuses on different emerging techniques that can be adopted in 5G wireless networks. Some of those techniques include massive-MIMO, mm-Wave communications, spectrum sharing, device-to-device (D2D) and vehicular to anything (V2X) communications, radio-frequency (RF) based energy harvesting, and NOMA. Subsequent chapters cover the fundamentals and PHY layer design aspects of different techniques that can be useful for the readers to get familiar with the emerging technologies and their applications.
Book Synopsis Multi-Carrier Techniques for Broadband Wireless Communications by : Man-On Pun
Download or read book Multi-Carrier Techniques for Broadband Wireless Communications written by Man-On Pun and published by Imperial College Press. This book was released on 2007 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.
Book Synopsis Integrated Data and Energy Transfer in Wireless Networks by : Jie Hu
Download or read book Integrated Data and Energy Transfer in Wireless Networks written by Jie Hu and published by Springer Nature. This book was released on with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Opportunistic Scheduling with Limited Feedback in Wireless Communication Networks by : Mohammed E. Eltayeb
Download or read book Opportunistic Scheduling with Limited Feedback in Wireless Communication Networks written by Mohammed E. Eltayeb and published by . This book was released on 2014 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: In multiuser networks, the base stations (BSs) rely on the channel state information (CSI) of the users to perform user scheduling and downlink transmissions. While the downlink channels can be easily estimated at all user terminals via a single broadcast, several key challenges are faced during uplink (feedback) transmissions. Firstly, the amount of air-time consumed during feedback transmission grows linearly with the number of users. This domination of the network resources by feedback traffic leads to increased scheduling delay and outdated CSI at the BS. Secondly , the fed back CSI is generally corrupted by the fading and noisy feedback channel. This could lead to transmission outages if the network scheduler bases its scheduling decisions on inaccurate CSI. These challenges make CSI acquisition arduous, if not impossible, in practice. In this research, we develop efficient scheduling algorithms that account for the feedback channel impairments of multiuser wireless networks. The proposed algorithms encompass both single and dual-hop wireless networks, and; permit the BS to obtain CSI with acceptable recovery guarantees under substantially reduced feedback overhead. More specifically, we consider feedback reduction for i) multiuser networks with single antenna base stations, ii) multiuser user networks with multi-antenna base stations, and iii) cooperative multiuser networks. Analytical and simulations results show that the proposed algorithms, together with the proposed feedback noise mitigation techniques, drastically reduce the feedback overhead, and achieve a rate close to that obtained by scheduling algorithms that require noiseless dedicated feedback from all users.
