Download or read book Network Interference Management Via Interference Alignment written by Viveck Ramesh Cadambe and published by . This book was released on 2011 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, we are witnessing a veritable explosion in the number of mobile devices with network connectivity. This explosion in the number of mobile devices which guzzle data is resulting in bandwidth becoming an increasingly scarce resource. The surge in the demand for data calls for new techniques to understand and improve the capacity (data rates) of wireless networks. In this thesis, I will describe and explore the benefits of interference alignment - a recently discovered technique to manage interference, which is the primary bottleneck of rates of communication in wireless communication networks. A primary object of study of this thesis is a communication network with K wireless transmitter-receiver pairs mutually interfering with each other, also known as the K user interference network. In this thesis, we study a high SNR approximation to its capacity known as the degrees of freedom. A widely held belief that influences design of most, if not all wireless networks is the following: in the K user interference network it is optimal from a network degrees of freedom perspective to divide the spectrum among the users like cutting a cake. This cake cutting view of spectrum access also known as orthogonalization enables each user in the interference network to get a fraction of 1/K degrees of freedom, i.e., 1/K of the spectrum free of interference. In this thesis, we will show that, from a degrees of freedom perspective, the belief in the optimality of the cake cutting view of spectrum access (i.e., orthogonalization) is flawed. We show that if the network is frequency-selective or time-varying, then each of the K users of an interference network can essentially get half the degrees of freedom of a single user (i.e., half the spectrum at high signal-to-noise ratios) simultaneously. In other words, each user can get ``half the cake'' rather than merely a fraction 1/K. The key to achieving this is the powerful interference management strategy of interference alignment. The thesis will study and develop various aspects of interference alignment. First, we develop an asymptotic alignment scheme to achieve ``half the cake'' in frequency-selective/time-varying interference channels. We then extend the idea of interference alignment to channels that are not frequency-selective or time-varying (i.e., channels which are constant) via three approaches: asymmetric complex signaling, a deterministic approach, and a distributed (numerical) alignment algorithm. In each of these cases, we will demonstrate degrees of freedom and capacity benefits of interference alignment in wireless interference networks. We also demonstrate practical benefits of the third approach - distributed alignment - in terms of rates at moderate signal-to-noise ratios and distributed implementations. Finally, we show that the impact of interference alignment extends beyond the context of just wireless systems. In particular, we explore an alternate application of the idea of alignment - erasure codes for distributed storage systems.

Download or read book Interference Management Via Interference Alignment in Wireless Networks written by Chenwei Wang and published by . This book was released on 2012 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: In wireless communication networks, competition among users for channel resources can result in severe mutual interference. This is a bottleneck for obtaining higher communication rates. Recent advances in the network information theory, such as the idea of interference alignment, have greatly facilitated our understanding of signal dimensions or even exact capacity of wireless networks and produced a number of new transmission schemes to achieve higher rates. Usually, we are interested in the fundamental questions -- what is the channel capacity of multiuser networks, and how to achieve higher communication rates, attractive for both theoretical researchers and engineers. Since finding the exact capacity of multiuser wireless networks is quite challenging, if not impossible, we are interested in the degrees of freedom (DoF) characterization, i.e., a coarse capacity approximation, of wireless networks. The number of DoF of a communication network is a metric of great significance as it provides a lens into the most essential aspects of the communication problem. DoF investigations have motivated many fundamental ideas such as interference alignment. In this dissertation, we investigate the DoF of a number of multiuser wireless networks using the idea of interference alignment. In particular, we start from the classical interference channels with global channel knowledge at each node. A number of scenarios will be studied, including networks with single antenna or multiple antennas at each node. Next, we consider the interference channel with local cooperation and local connectivity. Then we go beyond one-hop to multihop wireless networks where we find the DoF of multiple unicast for 2-source 2-sink layered networks with arbitrary topologies. Finally, we weaken the global channel knowledge assumption, to study broadcast channels with no channel state information at the transmitter. Several interesting tools, insights and surprising results are obtained in this work -- including phase alignment, asymmetric complex signaling, subspace alignment chains, genie chains, the observation that removing interference-carrying links can reduce the channel capacity, and blind interference alignment.

Download or read book Interference Alignment written by Syed A. Jafar and published by Now Publishers Inc. This book was released on 2011 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference Alignment: A New Look at Signal Dimensions in a Communication Network provides both a tutorial and a survey of the state-of-art on the topic.

Download or read book Interference Management in Wireless Networks written by Venugopal V. Veeravalli and published by Cambridge University Press. This book was released on 2018-02-22 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about a new, information-theoretic approach to minimizing interference in 5G wireless networks.

Download or read book Interference and Resource Management in Heterogeneous Wireless Networks written by Jiandong Li and published by Artech House. This book was released on 2017-11-30 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: This authoritative resource offers a comprehensive overview of heterogeneous wireless networks, small cells, and device-to-device (D2D) communications. The book provides insight into network modeling and performance analysis of heterogeneous wireless networks. Interference management framework and design issues are covered as well as details about resource mobility, channel models, and typical and statistical interference modeling. This resource explains leveraging resource heterogeneity in interference mitigation and presents the challenges and feasible solutions for concurrent transmission. Moreover, complete coverage of interference alignment in MIMO heterogeneous networks for both downlink and uplink is presented. This book provides performance results for an ideal partially connected interference network as well as a practical heterogeneous network. Readers find practical guidance for LTE and LTE-Advanced as well as 5G in this resource. New techniques and designs for heterogeneous wireless networks are included.

Download or read book Cognitive Radio Communications and Networks written by Alexander M. Wyglinski and published by Academic Press. This book was released on 2009-11-13 with total page 737 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cognitive Radio Communications and Networks gives comprehensive and balanced coverage of the principles of cognitive radio communications, cognitive networks, and details of their implementation, including the latest developments in the standards and spectrum policy. Case studies, end-of-chapter questions, and descriptions of various platforms and test beds, together with sample code, give hands-on knowledge of how cognitive radio systems can be implemented in practice. Extensive treatment is given to several standards, including IEEE 802.22 for TV White Spaces and IEEE SCC41 Written by leading people in the field, both at universities and major industrial research laboratories, this tutorial text gives communications engineers, R&D engineers, researchers, undergraduate and post graduate students a complete reference on the application of wireless communications and network theory for the design and implementation of cognitive radio systems and networks Each chapter is written by internationally renowned experts, giving complete and balanced treatment of the fundamentals of both cognitive radio communications and cognitive networks, together with implementation details Extensive treatment of the latest standards and spectrum policy developments enables the development of compliant cognitive systems Strong practical orientation – through case studies and descriptions of cognitive radio platforms and testbeds – shows how real world cognitive radio systems and network architectures have been built Alexander M. Wyglinski is an Assistant Professor of Electrical and Computer Engineering at Worcester Polytechnic Institute (WPI), Director of the WPI Limerick Project Center, and Director of the Wireless Innovation Laboratory (WI Lab) Each chapter is written by internationally renowned experts, giving complete and balanced treatment of the fundamentals of both cognitive radio communications and cognitive networks, together with implementation details Extensive treatment of the latest standards and spectrum policy developments enables the development of compliant cognitive systems Strong practical orientation – through case studies and descriptions of cognitive radio platforms and testbeds – shows how "real world" cognitive radio systems and network architectures have been built

Download or read book Interference Management for Wireless Networks written by Chia-Chi Huang and published by . This book was released on 2009 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference is a key property of wireless communications due to the broadcasting nature of wireless links. The design of wireless networks needs to put interference management into consideration. Traditionally, interference management is done by partitioning the whole network into orthogonal non-interfering channels via time- or frequency-division multiplexing. While orthogonalization significantly reduces the complexity of the design and implementation of wireless networks, it also introduces artificial restriction and leads to suboptimal performance. This thesis is devoted to the design and analysis of interference management from a cross-layer perspective. The key to increase spectrum efficiency of a wireless network is to treat the entire network as a channel rather than viewing them as a set of separate links. Based on this idea, we propose three interference management schemes and evaluate the fundamental limits associated with them. We use the notions of both conventional and generalized degrees of freedom (DOF), which are two widely-used approximations of channel capacity, as merits to evaluate and compare the performance improvement brought by the interference management schemes. The thesis consists of four main results. First, we consider a multiple-input-multiple-output (MIMO) 2-suer cognitive radio system in an information theoretic setting where some messages are made available, by a genie, to some nodes (other than the intended nodes) non-causally, noiselessly, and for free. We find the DOF region of this system and show that this region is larger than the one without cognitive message sharing. Our results also show that in general it may be more beneficial, in terms of sum DOF, for a user to have a cognitive transmitter than to have cognitive receiver. Second, we consider a MIMO Gaussian interference channel with user cooperation, including cooperation at transmitters only, at receivers only, and at transmitters as well as receivers. We find the DOF region of this system and obtain a negative result that allowing users to cooperate does not enlarge the DOF region of this channel. Third, we explore the capacity and generalized degrees of freedom (GDOF) of a 2-user Gaussian X channel, i.e. a generalization of the 2-user interference channel where there is an independent message from each transmitter to each receiver. We provide the GDOF characterization of the channel under a symmetric setting. We also identify the regime where interference alignment is helpful so that the X channel has a higher capacity than the underlying symmetric interference channel. We further extend the noisy interference capacity characterization previously obtained for the interference channel to the X channel. Lastly, we study the effect of the absence of channel knowledge for MIMO networks. In particular, we assume perfect channel state information at the receivers and no channel state information at the transmitter(s). We provide the characterization of the DOF region for a 2-user MIMO broadcast channel. We then use the result of the broadcast channel to find the DOF region for some special cases of a 2-user MIMO interference channel.

Download or read book Interference Management in Wireless Networks written by Venugopal V. Veeravalli and published by Cambridge University Press. This book was released on 2018-02-22 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about an information-theoretic approach to managing interference in future generation wireless networks. Focusing on cooperative schemes motivated by Coordinated Multi-Point (CoMP) technology, the book develops a robust theoretical framework for interference management that uses recent advancements in backhaul design, and practical pre-coding schemes based on local cooperation, to deliver the increased speed and reliability promised by interference alignment. Gain insight into how simple, zero-forcing pre-coding schemes are optimal in locally connected interference networks, and discover how significant rate gains can be obtained by making cell association decisions and allocating backhaul resources based on centralized (cloud) processing and knowledge of network topology. Providing a link between information-theoretic analyses and interference management schemes that are easy to implement, this is an invaluable resource for researchers, graduate students and practicing engineers in wireless communications.

Download or read book Feedback and Interference Alignment in Networks written by Changho Suh and published by . This book was released on 2011 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing complexity of communication networks in size and density provides us enormous opportunities to exploit interaction among multiple nodes, thus enabling higher date rate of data streams. On the flip side, however, this complexity comes with challenges in managing interference that multiple source-destination pairs in the network may cause to each other. In this dissertation, we make progress on how we exploit the opportunities, as well as how we overcome the challenges. In the first part, we find that feedback - one of the common ways to enable interaction in networks - has a promising role in improving the capacity performance of networks. Earlier results on feedback capacity were somewhat discouraging. This is mainly due to Shannon's original result on feedback capacity where he showed that in point-to-point communication, feedback does not increase capacity. Hence, traditionally it is believed that feedback has had little impact on increasing capacity of communication links. Therefore, the use of feedback has been limited to improving the reliability of communications, usually in the form of ARQ. In this dissertation, we show that in stark contrast to the point-to-point case, feedback can improve the capacity of interference-limited network. In fact, the improvement can be unbounded. This result shows that feedback can have a potentially significant role to play in mitigating interference. Also in the process of deriving this conclusion, we characterize the feedback capacity of the two-user Gaussian interference channel to within 2 bits, one of the longstanding open problems in network information theory. In the second part, we propose a new interference management technique for widely deployed cellular networks. Inspired by a recent breakthrough, the concept of interference alignment, we develop an interference alignment technique for cellular networks. Our technique promises almost interference-free communication with the increase of the number of clients in cellular networks. It shows substantial gain (around 30% to 60%) as compared to one of the interference management techniques in current cellular systems. In addition, it comes with implementation benefits: it can actually be implemented with small changes to emerging 4G cellular standards and architectures at the base-stations and clients. In particular, the required signal-processing circuitry, software control, and channel-state feedback mechanisms are extensions of existing implementations and standards. Lastly, we extend the interference alignment principle, developed in the context of wireless networks, into other fields of network research such as storage networks. In an effort to protect information against node failures, storage networks employ coding techniques, such as maximum distance separable (MDS) erasure codes, known as optimal codes in reliability with respect to redundancy. However, these MDS codes come with prohibitive maintenance cost when it comes to repairing failed storage nodes. While only partial information stored in the failed node needs to be recovered, the conventional MDS codes focus on the complete data recovery (including unwanted data, corresponding to interference) by downloading too much information from survivor storage encoded nodes, thus causing the high repair cost. Building on the connection between wireless and wireline networks, we leverage the interference alignment principle to develop a new class of MDS codes that significantly reduces the repair cost over the conventional MDS codes and also achieves information-theoretic optimal bound on the repair cost for all admissible code parameters.

Download or read book Interference Management with Limited Channel State Information in Wireless Networks written by Namyoon Lee and published by . This book was released on 2014 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference creates a fundamental barrier in attempting to improve throughput in wireless networks, especially when multiple concurrent transmissions share the wireless medium. In recent years, significant progress has been made on characterizing the capacity limits of wireless networks under the premise of global and instantaneous channel state information at transmitter (CSIT). In practice, however, the acquisition of such instantaneous and global CSIT as a means toward cooperation is highly challenging due to the distributed nature of transmitters and dynamic wireless propagation environments. In many limited CSIT scenarios, the promising gains from interference management strategies using instantaneous and global CSIT disappear, often providing the same result as cases where there is no CSIT. Is it possible to obtain substantial performance gains with limited CSIT in wireless networks, given previous evidence that there is marginal or no gain over the case with no CSIT? To shed light on the answer to this question, in this dissertation, I present several achievable sum of degrees of freedom (sum-DoF) characterizations of wireless networks. The sum-DoF is a coarse sum-capacity approximation of the networks, deemphasizing noise effects. These characterizations rely on a set of proposed and existing interference management strategies that exploit limited CSIT. I begin with the classical multi-user multiple-input-single-output (MISO) broadcast channel with delayed CSIT and show how CSI feedback delays change sum-capacity scaling law by proposing an innovative interference alignment technique called space-time interference alignment. Next, I consider interference networks with distributed and delayed CSIT and show how to optimally use distributed and moderately-delayed CSIT to yield the same sum-DoF as instantaneous and global CSIT using the idea of distributed space-time interference alignment. I also consider a two-hop layered multiple-input-multiple-output (MIMO) interference channel, where I show that two cascaded interfering links can be decomposed into two independent parallel relay channels without using CSIT at source nodes through the proposed interference-free relaying technique. Then I go beyond one-way and layered to multi-way and fully-connected wireless networks where I characterize the achievable sum-DoF of networks where no CSIT is available at source nodes using the proposed space-time physical-layer network coding. Lastly, I characterize analytical expressions for the sum spectral efficiency in a large-scale single-input-multiple- output (SIMO) interference network where the spatial locations of nodes are modeled by means of stochastic geometry. I derive analytical expressions for the ergodic sum spectral efficiency and the scaling laws as functions of relevant system parameters depending on different channel knowledge assumptions at receivers.

Download or read book Interference Management for Multiuser Mimo Wireless Networks written by Tiangao Gou and published by . This book was released on 2012 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the primary goals of designing communication systems is to achieve high data rates. Due to limited spectrum, users need to share the common resource, which causes interference with each other. Interference in turn creates a bottleneck on the communication rate. Recently two breakthroughs have been made to relieve this bottleneck. One is using multiple antennas known as multiple input multiple output (MIMO) technology and the other is an interference management technique called interference alignment. While much progress has been made on understanding of each individually, relatively little is known about how to use both techniques together to deal with interference. This thesis presents the progress we have made towards determining the capacity benefits of multiple antennas and interference alignment in different network settings and under various assumptions about the channel state information known at the transmitters. The thesis consists of five main results. First, we characterize the optimal degrees of freedom (DoF) of the K user MIMO Gaussian interference channel with M transmit and N receive antennas for each user when the ratio of the maximum to the minimum of M and N is equal to an integer. Second, we study the N+1 user single input multiple output (SIMO) Gaussian interference channel with one transmit and N receive antennas for each user. We characterize the generalized degrees of freedom (GDoF) of the network, which directly leads to a capacity approximation within a bounded gap which is independent of the signal strength. We also derive outer bounds which identify a strong interference regime where the capacity region is established. Third, we characterize the optimal DoF of two classes of finite state compound wireless networks including the multiple-input single-output (MISO) finite state compound broadcast channel (BC) with arbitrary number of users and antennas at the transmitter and the finite state scalar (single antenna nodes) compound X networks with arbitrary number of users. Fourth, we propose a blind interference alignment scheme through staggered antenna switching, i.e., we seek to align interference without any knowledge of the channel coefficient values at the transmitters. This scheme achieves the optimal DoF of the vector broadcast channel where the transmitter is equipped with M antennas and there are K receivers, each equipped with a reconfigurable antenna capable of switching among M preset modes. Fifth, we go beyond the single hop wireless networks to multihop interference networks and characterize the DoF of the 2-source 2-destination 2-hop interference network formed by concatenation of two 2-user interference channels. The key to this result is a new idea, called aligned interference neutralization, that provides a way to align interference terms over each hop in a manner that allows them to be cancelled over the air at the last hop.

Download or read book Interference Management in a Class of Multi User Networks written by Seyyed Hassan Mahboubi and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectrum sharing is known as a key solution to accommodate the increasing number of users and the growing demand for throughput in wireless networks. Interference is the primary barrier to enhancing the overall throughput of the network, especially in the medium and high signal to noise ratios (SNRs). Managing interference to overcome this barrier has emerged as a crucial step in developing efficient wireless networks. An interference management strategy, named interference Alignment, is investigated. It is observed that a single strategy is not able to achieve the maximum throughput in all possible scenarios, and in fact, a careful design is required to fully exploit all available resources in each realization of the system. In this dissertation, the impact of interference on the capacity of X networks with multiple antennas is investigated. Degrees of freedom (DoF) are used as a figure of merit to evaluate the performance improvement due to the interference management schemes. A new interference alignment technique called layered interference alignment, which enjoys the combined benefits of both vector and real alignment is introduced in this thesis. This technique, which uses a type of Diophantine approximation theorems first introduced by the author, is deployed and was proved to enable the possibility of joint decoding among the antennas of a receiver. With a careful transmitter signal design, this method characterizes the total DoF of multiple-input multiple-output (MIMO) X channels. Then, this result is used to determine the total DoF of two families of MIMO X channels. The Diophantine approximation theorem is also extended to the field of complex numbers to accommodate the complex channel realizations as well.

Download or read book Interference Management in Wireless Networks written by Leonard Henry Grokop and published by . This book was released on 2008 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interference Management in Non cooperative Networks written by Abolfazl Sayed Motahari and published by . This book was released on 2009 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectrum sharing is known as a key solution to accommodate the increasing number of users and the growing demand for throughput in wireless networks. While spectrum sharing improves the data rate in sparse networks, it suffers from interference of concurrent links in dense networks. In fact, interference is the primary barrier to enhance the overall throughput of the network, especially in the medium and high signal-to-noise ratios (SNR's). Managing interference to overcome this barrier has emerged as a crucial step in developing efficient wireless networks. This thesis deals with optimum and sub-optimum interference management-cancelation in non-cooperative networks. Several techniques for interference management including novel strategies such as interference alignment and structural coding are investigated. These methods are applied to obtain optimum and sub-optimum coding strategies in such networks. It is shown that a single strategy is not able to achieve the maximum throughput in all possible scenarios and in fact a careful design is required to fully exploit all available resources in each realization of the system.

Download or read book Designing MIMO Interference Alignment Networks written by Behrang Nosrat Makouei and published by . This book was released on 2012 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks are increasingly interference-limited, which motivates the development of sophisticated interference management techniques. One recently discovered approach is interference alignment, which attains the maximum sum rate scaling (with signal-to-noise ratio) in many network configurations. Interference alignment is not yet well understood from an engineering perspective. Such design considerations include (i) partial rather than complete knowledge of channel state information, (ii) correlated channels, (iii) bursty packet-based network traffic that requires the frequent setup and tear down of sessions, and (iv) the spatial distribution and interaction of transmit/receive pairs. This dissertation aims to establish the benefits and limitations of interference alignment under these four considerations. The first contribution of this dissertation considers an isolated group of transmit/receiver pairs (a cluster) cooperating through interference alignment and derives the signal-to-interference-plus-noise ratio distribution at each receiver for each stream. This distribution is used to compare interference alignment to beamforming and spatial multiplexing (as examples of common transmission techniques) in terms of sum rate to identify potential switching points between them. This dissertation identifies such switching points and provides design recommendations based on severity of the correlation or the channel state information uncertainty. The second contribution considers transmitters that are not associated with any interference alignment cooperating group but want to use the channel. The goal is to retain the benefits of interference alignment amid interference from the out-of-cluster transmitters. This dissertation shows that when the out-of-cluster transmitters have enough antennas, they can access the channel without changing the performance of the interference alignment receivers. Furthermore, optimum transmit filters maximizing the sum rate of the out-of-cluster transmit/receive pairs are derived. When insufficient antennas exist at the out-of-cluster transmitters, several transmit filters that trade off complexity and sum rate performance are presented. The last contribution, in contrast to the first two, takes into account the impact of large scale fading and the spatial distribution of the transmit/receive pairs on interference alignment by deriving the transmission capacity in a decentralized clustered interference alignment network. Channel state information uncertainty and feedback overhead are considered and the optimum training period is derived. Transmission capacity of interference alignment is compared to spatial multiplexing to highlight the tradeoff between channel estimation accuracy and the inter-cluster interference; the closer the nodes to each other, the higher the channel estimation accuracy and the inter-cluster interference.

Download or read book Interference Alignment in Cellular Networks written by Gokul Sridharan and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interference Management in Wireless Networks written by Venugopal V. Veeravalli and published by Cambridge University Press. This book was released on 2018-02-22 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about an information-theoretic approach to managing interference in future generation wireless networks. Focusing on cooperative schemes motivated by Coordinated Multi-Point (CoMP) technology, the book develops a robust theoretical framework for interference management that uses recent advancements in backhaul design, and practical pre-coding schemes based on local cooperation, to deliver the increased speed and reliability promised by interference alignment. Gain insight into how simple, zero-forcing pre-coding schemes are optimal in locally connected interference networks, and discover how significant rate gains can be obtained by making cell association decisions and allocating backhaul resources based on centralized (cloud) processing and knowledge of network topology. Providing a link between information-theoretic analyses and interference management schemes that are easy to implement, this is an invaluable resource for researchers, graduate students and practicing engineers in wireless communications.