Transceiver design for single-cell and multi-cell downlink multiuser MIMO sys...T. E. BOGALE
The document outlines a presentation on transceiver design for single-cell and multi-cell downlink multiuser MIMO systems. It discusses MSE uplink-downlink duality under imperfect CSI, showing that the sum MSE, user MSE, and symbol MSE are dual between the uplink and downlink channels. It demonstrates how to ensure the uplink and downlink MSE values are equal to each other by appropriately setting the transmit covariance matrices. The presentation also covers transceiver design algorithms for coordinated base station systems and generalized duality for multiuser MIMO systems.
R package 'bayesImageS': a case study in Bayesian computation using Rcpp and ...Matt Moores
There are many approaches to Bayesian computation with intractable likelihoods, including the exchange algorithm, approximate Bayesian computation (ABC), thermodynamic integration, and composite likelihood. These approaches vary in accuracy as well as scalability for datasets of significant size. The Potts model is an example where such methods are required, due to its intractable normalising constant. This model is a type of Markov random field, which is commonly used for image segmentation. The dimension of its parameter space increases linearly with the number of pixels in the image, making this a challenging application for scalable Bayesian computation. My talk will introduce various algorithms in the context of the Potts model and describe their implementation in C++, using OpenMP for parallelism. I will also discuss the process of releasing this software as an open source R package on the CRAN repository.
bayesImageS: Bayesian computation for medical Image Segmentation using a hidd...Matt Moores
This document summarizes an R package called bayesImageS that enables Bayesian computation for medical image segmentation using a hidden Potts model. It discusses the statistical model, which involves a hidden Markov random field with a Potts prior on the latent labels. Bayesian computation methods like Gibbs sampling and Metropolis-Hastings using pseudolikelihood approximation are implemented in C++ for efficiency. Experimental results demonstrate the package on a CT electron density phantom and patient radiotherapy data.
The document presents a system model and problem formulation for user scheduling in massive MIMO OFDMA systems with hybrid analog-digital beamforming. The system considers a base station with N antennas but only Na < N RF chains serving multiple single-antenna mobile stations. The objective is to maximize the overall data rate by scheduling Kt mobile stations across subcarriers, subject to a per-subcarrier power constraint. For a single subcarrier, the problem is formulated as maximizing the sum rate of K scheduled users under a total power constraint, assuming Na = K RF chains. Two approaches are discussed: directly constraining the analog beamforming matrix or exploiting the solution from a digital scheduler using a clever decomposition method.
This document summarizes a presentation on graph kernels in chemoinformatics. It discusses using graph kernels to measure similarity between molecular graphs to analyze large families of structural and numerical objects. Specific graph kernels discussed include the treelets kernel, which extracts small labeled subtrees from graphs, and kernels based on cyclic similarity, which analyze relevant cycles in molecules. The treelets kernel is shown to outperform other graph kernels and molecular descriptors in predicting boiling points of molecules.
This document summarizes Rajesh Gandham's PhD thesis defense on high-order numerical methods for ocean modeling applications. The thesis goals are to develop accurate PDE models, leverage many-core hardware architectures, and use efficient algorithm techniques. The document outlines work on two-dimensional shallow water modeling using discontinuous Galerkin methods, a pasiDG simulator implementation, and preliminary work on three-dimensional oceanic modeling. Performance results are shown for the pasiDG simulator running on GPUs and CPUs for the 2004 Indian Ocean tsunami test case.
This document provides an overview of graph edit distance, including its definition, history, and algorithms. It begins by defining an edit path as a sequence of node/edge insertions, deletions, and substitutions that transforms one graph into another. The graph edit distance is the cost of the lowest cost edit path. It describes tree search algorithms used to explore the space of possible edit paths efficiently. It also explains how edit paths can be modeled as assignment problems that are solved using techniques like the Hungarian algorithm to find approximations of the graph edit distance.
This document summarizes quantization design techniques including Lloyd-Max quantizers and variable rate optimum quantizers. It discusses the problem setup for scalar quantization and outlines the local optimality conditions, alternating optimization approach, and dynamic programming approach for designing Lloyd-Max quantizers. It also covers the problem setup for variable rate optimum quantizer design subject to an entropy constraint, and describes analyzing this using a generalized Lloyd-Max algorithm.
Transceiver design for single-cell and multi-cell downlink multiuser MIMO sys...T. E. BOGALE
The document outlines a presentation on transceiver design for single-cell and multi-cell downlink multiuser MIMO systems. It discusses MSE uplink-downlink duality under imperfect CSI, showing that the sum MSE, user MSE, and symbol MSE are dual between the uplink and downlink channels. It demonstrates how to ensure the uplink and downlink MSE values are equal to each other by appropriately setting the transmit covariance matrices. The presentation also covers transceiver design algorithms for coordinated base station systems and generalized duality for multiuser MIMO systems.
R package 'bayesImageS': a case study in Bayesian computation using Rcpp and ...Matt Moores
There are many approaches to Bayesian computation with intractable likelihoods, including the exchange algorithm, approximate Bayesian computation (ABC), thermodynamic integration, and composite likelihood. These approaches vary in accuracy as well as scalability for datasets of significant size. The Potts model is an example where such methods are required, due to its intractable normalising constant. This model is a type of Markov random field, which is commonly used for image segmentation. The dimension of its parameter space increases linearly with the number of pixels in the image, making this a challenging application for scalable Bayesian computation. My talk will introduce various algorithms in the context of the Potts model and describe their implementation in C++, using OpenMP for parallelism. I will also discuss the process of releasing this software as an open source R package on the CRAN repository.
bayesImageS: Bayesian computation for medical Image Segmentation using a hidd...Matt Moores
This document summarizes an R package called bayesImageS that enables Bayesian computation for medical image segmentation using a hidden Potts model. It discusses the statistical model, which involves a hidden Markov random field with a Potts prior on the latent labels. Bayesian computation methods like Gibbs sampling and Metropolis-Hastings using pseudolikelihood approximation are implemented in C++ for efficiency. Experimental results demonstrate the package on a CT electron density phantom and patient radiotherapy data.
The document presents a system model and problem formulation for user scheduling in massive MIMO OFDMA systems with hybrid analog-digital beamforming. The system considers a base station with N antennas but only Na < N RF chains serving multiple single-antenna mobile stations. The objective is to maximize the overall data rate by scheduling Kt mobile stations across subcarriers, subject to a per-subcarrier power constraint. For a single subcarrier, the problem is formulated as maximizing the sum rate of K scheduled users under a total power constraint, assuming Na = K RF chains. Two approaches are discussed: directly constraining the analog beamforming matrix or exploiting the solution from a digital scheduler using a clever decomposition method.
This document summarizes a presentation on graph kernels in chemoinformatics. It discusses using graph kernels to measure similarity between molecular graphs to analyze large families of structural and numerical objects. Specific graph kernels discussed include the treelets kernel, which extracts small labeled subtrees from graphs, and kernels based on cyclic similarity, which analyze relevant cycles in molecules. The treelets kernel is shown to outperform other graph kernels and molecular descriptors in predicting boiling points of molecules.
This document summarizes Rajesh Gandham's PhD thesis defense on high-order numerical methods for ocean modeling applications. The thesis goals are to develop accurate PDE models, leverage many-core hardware architectures, and use efficient algorithm techniques. The document outlines work on two-dimensional shallow water modeling using discontinuous Galerkin methods, a pasiDG simulator implementation, and preliminary work on three-dimensional oceanic modeling. Performance results are shown for the pasiDG simulator running on GPUs and CPUs for the 2004 Indian Ocean tsunami test case.
This document provides an overview of graph edit distance, including its definition, history, and algorithms. It begins by defining an edit path as a sequence of node/edge insertions, deletions, and substitutions that transforms one graph into another. The graph edit distance is the cost of the lowest cost edit path. It describes tree search algorithms used to explore the space of possible edit paths efficiently. It also explains how edit paths can be modeled as assignment problems that are solved using techniques like the Hungarian algorithm to find approximations of the graph edit distance.
This document summarizes quantization design techniques including Lloyd-Max quantizers and variable rate optimum quantizers. It discusses the problem setup for scalar quantization and outlines the local optimality conditions, alternating optimization approach, and dynamic programming approach for designing Lloyd-Max quantizers. It also covers the problem setup for variable rate optimum quantizer design subject to an entropy constraint, and describes analyzing this using a generalized Lloyd-Max algorithm.
A One-Pass Triclustering Approach: Is There any Room for Big Data?Dmitrii Ignatov
An efficient one-pass online algorithm for triclustering of binary data (triadic formal contexts) is proposed. This algorithm is a modified version of the basic algorithm for OAC-triclustering approach, but it has linear time and memory complexities with respect to the cardinality
of the underlying ternary relation and can be easily parallelized in order to be applied for the analysis of big datasets. The results of computer experiments show the efficiency of the proposed algorithm.
This document outlines material and energy balances for different sections of a distillation column. It provides equations for:
1) Overall, component, and energy balances for the top, enriching, and stripping sections of the column, defining terms like reflux ratio, heat removed, and operating lines on diagrams.
2) Conditions for total reflux, where operating lines become vertical, and minimum reflux ratio, where the minimum length of line a is determined using trials to find where the tie line through F intersects ΔD.
3) Material and energy balances relate flow rates, temperatures, concentrations, and heat of different streams using terms like net heat out per mole and moles of component A out per total
Processing Reachability Queries with Realistic Constraints on Massive Network...BigMine
Massive graphs are ubiquitous in various application domains, such as social networks, road networks, communication networks, biological networks, RDF graphs, and so on. Such graphs are massive (for example, with hundreds of millions of nodes and edges or even more) and contain rich information (for example, node/edge weights, labels and textual contents). In such massive graphs, an important class of problems is to process various graph structure related queries. Graph reachability, as an example, asks whether a node can reach another in a graph. However, the large graph scale presents new challenges for efficient query processing.
In this talk, I will introduce two new yet important types of graph reachability queries: weight constraint reachability that imposes edge weight constraint on the answer path, and k-hop reachability that imposes a length constraint on the answer path. With such realistic constraints, we can find more meaningful and practically feasible answers. These two reachablity queries have wide applications in many real-world problems, such as QoS routing and trip planning.
Presentation of the paper:
Szymon Klarman and Thomas Meyer. Querying Temporal Databases via OWL 2 QL (with appendix). In Proceedings of the 8th International Conference on Web Reasoning and Rule Systems (RR-14), 2014.
Zero-Forcing Precoding and Generalized InversesDaniel Tai
This document discusses zero-forcing precoding and its relationship to generalized inverses. It examines this technique for multi-input single-output wireless systems under two power constraints: total transmit power and per-antenna power. The paper formulates the optimization problems for maximizing sum rate and fairness under these constraints. It presents the solutions using generalized inverses and simulations to evaluate the performance under different conditions.
Improving initial generations in pso algorithm for transportation network des...ijcsit
Transportation Network Design Problem (TNDP) aims to select the best project sets among a number of new projects. Recently, metaheuristic methods are applied to solve TNDP in the sense of finding better solutions sooner. PSO as a metaheuristic method is based on stochastic optimization and is a parallel revolutionary computation technique. The PSO system initializes with a number of random solutions and seeks for optimal solution by improving generations. This paper studies the behavior of PSO on account of improving initial generation and fitness value domain to find better solutions in comparison with previous attempts.
Joint CSI Estimation, Beamforming and Scheduling Design for Wideband Massive ...T. E. BOGALE
The document presents a new design for joint channel estimation, beamforming, and scheduling for wideband massive MIMO systems. It proposes using non-orthogonal pilots for channel estimation and a two-phase scheduling approach. Simulation results show the proposed design achieves higher total rates than conventional OFDM and performs better in dense multipath environments, especially with larger bandwidths and antenna arrays. An open issue discussed is comparing the proposed non-orthogonal pilot scheme to non-orthogonal multiple access techniques.
Quantitative norm convergence of some ergodic averagesVjekoslavKovac1
The document summarizes quantitative estimates for the convergence of multiple ergodic averages of commuting transformations. Specifically, it presents a theorem that provides an explicit bound on the number of jumps in the Lp norm for double averages over commuting Aω actions on a probability space. The proof transfers the structure of the Cantor group AZ to R+ and establishes norm estimates for bilinear averages of functions on R2+. This allows bounding the variation of the double averages and proving the theorem.
study Streaming Multigrid For Gradient Domain Operations On Large ImagesChiamin Hsu
The document describes a streaming multigrid solver for solving Poisson's equation on large images. It develops a multigrid method using a B-spline finite element basis that can efficiently process images in a streaming fashion using only a small window of image rows in memory at a time. The method achieves accurate solutions to Poisson's equation on gigapixel images in only 2 V-cycles by leveraging the temporal locality of the multigrid algorithm.
1. The document discusses energy-based models (EBMs) and how they can be applied to classifiers. It introduces noise contrastive estimation and flow contrastive estimation as methods to train EBMs.
2. One paper presented trains energy-based models using flow contrastive estimation by passing data through a flow-based generator. This allows implicit modeling with EBMs.
3. Another paper argues that classifiers can be viewed as joint energy-based models over inputs and outputs, and should be treated as such. It introduces a method to train classifiers as EBMs using contrastive divergence.
From planar maps to spatial topology change in 2d gravityTimothy Budd
The document summarizes a talk on generalized causal dynamical triangulations (CDT) in two dimensions. It introduces the generalized CDT model, which allows spatial topology to change in time. It describes how generalized CDT can be solved by viewing causal quadrangulations as labeled trees. It also discusses bijections between labeled quadrangulations and labeled planar maps via Schaeffer's algorithm, which allow counting the numbers of objects in the generalized CDT model.
Operation cost reduction in unit commitment problem using improved quantum bi...IJECEIAES
Unit Commitment (UC) is a nonlinear mixed integer-programming problem. UC used to minimize the operational cost of the generation units in a power system by scheduling some of generators in ON state and the other generators in OFF state according to the total power outputs of generation units, load demand and the constraints of power system. This paper proposes an Improved Quantum Binary Particle Swarm Optimization (IQBPSO) algorithm. The tests have been made on a 10-units simulation system and the results show the improvement in an operation cost reduction after using the proposed algorithm compared with the ordinary Quantum Binary Particle Swarm Optimization (QBPSO) algorithm
The document discusses Wasserstein GANs and improved training methods. It introduces Wasserstein GANs and discusses problems with training GANs using other distances like KL divergence. Wasserstein distance is defined and shown to be continuous and differentiable. The document outlines training Wasserstein GANs using Kantorovich-Rubinstein duality by having the discriminator produce 1-Lipschitz outputs. It then discusses problems with weight clipping and proposes an improved training method by constraining the discriminator's gradient norm to be less than or equal to 1.
Variants of the Christ-Kiselev lemma and an application to the maximal Fourie...VjekoslavKovac1
1. The document discusses variants of the Christ-Kiselev lemma and its application to maximal Fourier restriction estimates.
2. The Christ-Kiselev lemma allows block-diagonal and block-triangular truncations of operators while controlling their operator norms.
3. These lemmas can be used to prove maximal and variational estimates for the restriction of the Fourier transform to surfaces, which has applications in harmonic analysis.
A copy of my slides from the SILO Seminar at UW Madison on our recent developments for the NEO-K-Means methods including new optimization routines and results.
This document describes a course on topics in digital communications from June 2013 to February 2014. The course covers channel estimation techniques for various channel models, including single-tap channels and intersymbol interference channels. It discusses estimating channel coefficients using pilot symbols and maximum likelihood estimation. Channel estimation is applied to tasks such as symbol demodulation, equalization, and echo cancellation.
Short survey for Channel estimation using OFDM systemsMohamed Seif
This document discusses channel estimation techniques for OFDM systems. It begins by introducing OFDM and the need for channel state information at the receiver. It then describes two common pilot arrangements - block and comb type. For block pilots, it examines least squares and minimum mean square error channel estimation. It finds MMSE performs better but with higher complexity. For comb pilots, it presents least squares and LMS estimation as well as interpolation techniques between pilot tones. The document also evaluates channel estimation for MIMO-OFDM and the effects of user mobility.
Orthogonal Faster than Nyquist Transmission for SIMO Wireless SystemsT. E. BOGALE
The document proposes a new Orthogonal Faster than Nyquist (OFTN) transmission scheme for SIMO wireless systems that can transmit more than one symbol per time interval, achieving higher spectral efficiency than existing OFDM. The proposed scheme splits the bandwidth into subbands and transmits symbols across subbands and time intervals. It is shown that up to P symbols can be transmitted in 3P-2 time intervals when there are N receive antennas, an improvement over OFDM. Numerical results demonstrate improved bit error rate and sum rate compared to OFDM, especially at high SNR. Open problems remaining include extending the approach to MISO systems and evaluating performance under different channel and system conditions.
A One-Pass Triclustering Approach: Is There any Room for Big Data?Dmitrii Ignatov
An efficient one-pass online algorithm for triclustering of binary data (triadic formal contexts) is proposed. This algorithm is a modified version of the basic algorithm for OAC-triclustering approach, but it has linear time and memory complexities with respect to the cardinality
of the underlying ternary relation and can be easily parallelized in order to be applied for the analysis of big datasets. The results of computer experiments show the efficiency of the proposed algorithm.
This document outlines material and energy balances for different sections of a distillation column. It provides equations for:
1) Overall, component, and energy balances for the top, enriching, and stripping sections of the column, defining terms like reflux ratio, heat removed, and operating lines on diagrams.
2) Conditions for total reflux, where operating lines become vertical, and minimum reflux ratio, where the minimum length of line a is determined using trials to find where the tie line through F intersects ΔD.
3) Material and energy balances relate flow rates, temperatures, concentrations, and heat of different streams using terms like net heat out per mole and moles of component A out per total
Processing Reachability Queries with Realistic Constraints on Massive Network...BigMine
Massive graphs are ubiquitous in various application domains, such as social networks, road networks, communication networks, biological networks, RDF graphs, and so on. Such graphs are massive (for example, with hundreds of millions of nodes and edges or even more) and contain rich information (for example, node/edge weights, labels and textual contents). In such massive graphs, an important class of problems is to process various graph structure related queries. Graph reachability, as an example, asks whether a node can reach another in a graph. However, the large graph scale presents new challenges for efficient query processing.
In this talk, I will introduce two new yet important types of graph reachability queries: weight constraint reachability that imposes edge weight constraint on the answer path, and k-hop reachability that imposes a length constraint on the answer path. With such realistic constraints, we can find more meaningful and practically feasible answers. These two reachablity queries have wide applications in many real-world problems, such as QoS routing and trip planning.
Presentation of the paper:
Szymon Klarman and Thomas Meyer. Querying Temporal Databases via OWL 2 QL (with appendix). In Proceedings of the 8th International Conference on Web Reasoning and Rule Systems (RR-14), 2014.
Zero-Forcing Precoding and Generalized InversesDaniel Tai
This document discusses zero-forcing precoding and its relationship to generalized inverses. It examines this technique for multi-input single-output wireless systems under two power constraints: total transmit power and per-antenna power. The paper formulates the optimization problems for maximizing sum rate and fairness under these constraints. It presents the solutions using generalized inverses and simulations to evaluate the performance under different conditions.
Improving initial generations in pso algorithm for transportation network des...ijcsit
Transportation Network Design Problem (TNDP) aims to select the best project sets among a number of new projects. Recently, metaheuristic methods are applied to solve TNDP in the sense of finding better solutions sooner. PSO as a metaheuristic method is based on stochastic optimization and is a parallel revolutionary computation technique. The PSO system initializes with a number of random solutions and seeks for optimal solution by improving generations. This paper studies the behavior of PSO on account of improving initial generation and fitness value domain to find better solutions in comparison with previous attempts.
Joint CSI Estimation, Beamforming and Scheduling Design for Wideband Massive ...T. E. BOGALE
The document presents a new design for joint channel estimation, beamforming, and scheduling for wideband massive MIMO systems. It proposes using non-orthogonal pilots for channel estimation and a two-phase scheduling approach. Simulation results show the proposed design achieves higher total rates than conventional OFDM and performs better in dense multipath environments, especially with larger bandwidths and antenna arrays. An open issue discussed is comparing the proposed non-orthogonal pilot scheme to non-orthogonal multiple access techniques.
Quantitative norm convergence of some ergodic averagesVjekoslavKovac1
The document summarizes quantitative estimates for the convergence of multiple ergodic averages of commuting transformations. Specifically, it presents a theorem that provides an explicit bound on the number of jumps in the Lp norm for double averages over commuting Aω actions on a probability space. The proof transfers the structure of the Cantor group AZ to R+ and establishes norm estimates for bilinear averages of functions on R2+. This allows bounding the variation of the double averages and proving the theorem.
study Streaming Multigrid For Gradient Domain Operations On Large ImagesChiamin Hsu
The document describes a streaming multigrid solver for solving Poisson's equation on large images. It develops a multigrid method using a B-spline finite element basis that can efficiently process images in a streaming fashion using only a small window of image rows in memory at a time. The method achieves accurate solutions to Poisson's equation on gigapixel images in only 2 V-cycles by leveraging the temporal locality of the multigrid algorithm.
1. The document discusses energy-based models (EBMs) and how they can be applied to classifiers. It introduces noise contrastive estimation and flow contrastive estimation as methods to train EBMs.
2. One paper presented trains energy-based models using flow contrastive estimation by passing data through a flow-based generator. This allows implicit modeling with EBMs.
3. Another paper argues that classifiers can be viewed as joint energy-based models over inputs and outputs, and should be treated as such. It introduces a method to train classifiers as EBMs using contrastive divergence.
From planar maps to spatial topology change in 2d gravityTimothy Budd
The document summarizes a talk on generalized causal dynamical triangulations (CDT) in two dimensions. It introduces the generalized CDT model, which allows spatial topology to change in time. It describes how generalized CDT can be solved by viewing causal quadrangulations as labeled trees. It also discusses bijections between labeled quadrangulations and labeled planar maps via Schaeffer's algorithm, which allow counting the numbers of objects in the generalized CDT model.
Operation cost reduction in unit commitment problem using improved quantum bi...IJECEIAES
Unit Commitment (UC) is a nonlinear mixed integer-programming problem. UC used to minimize the operational cost of the generation units in a power system by scheduling some of generators in ON state and the other generators in OFF state according to the total power outputs of generation units, load demand and the constraints of power system. This paper proposes an Improved Quantum Binary Particle Swarm Optimization (IQBPSO) algorithm. The tests have been made on a 10-units simulation system and the results show the improvement in an operation cost reduction after using the proposed algorithm compared with the ordinary Quantum Binary Particle Swarm Optimization (QBPSO) algorithm
The document discusses Wasserstein GANs and improved training methods. It introduces Wasserstein GANs and discusses problems with training GANs using other distances like KL divergence. Wasserstein distance is defined and shown to be continuous and differentiable. The document outlines training Wasserstein GANs using Kantorovich-Rubinstein duality by having the discriminator produce 1-Lipschitz outputs. It then discusses problems with weight clipping and proposes an improved training method by constraining the discriminator's gradient norm to be less than or equal to 1.
Variants of the Christ-Kiselev lemma and an application to the maximal Fourie...VjekoslavKovac1
1. The document discusses variants of the Christ-Kiselev lemma and its application to maximal Fourier restriction estimates.
2. The Christ-Kiselev lemma allows block-diagonal and block-triangular truncations of operators while controlling their operator norms.
3. These lemmas can be used to prove maximal and variational estimates for the restriction of the Fourier transform to surfaces, which has applications in harmonic analysis.
A copy of my slides from the SILO Seminar at UW Madison on our recent developments for the NEO-K-Means methods including new optimization routines and results.
This document describes a course on topics in digital communications from June 2013 to February 2014. The course covers channel estimation techniques for various channel models, including single-tap channels and intersymbol interference channels. It discusses estimating channel coefficients using pilot symbols and maximum likelihood estimation. Channel estimation is applied to tasks such as symbol demodulation, equalization, and echo cancellation.
Short survey for Channel estimation using OFDM systemsMohamed Seif
This document discusses channel estimation techniques for OFDM systems. It begins by introducing OFDM and the need for channel state information at the receiver. It then describes two common pilot arrangements - block and comb type. For block pilots, it examines least squares and minimum mean square error channel estimation. It finds MMSE performs better but with higher complexity. For comb pilots, it presents least squares and LMS estimation as well as interpolation techniques between pilot tones. The document also evaluates channel estimation for MIMO-OFDM and the effects of user mobility.
Orthogonal Faster than Nyquist Transmission for SIMO Wireless SystemsT. E. BOGALE
The document proposes a new Orthogonal Faster than Nyquist (OFTN) transmission scheme for SIMO wireless systems that can transmit more than one symbol per time interval, achieving higher spectral efficiency than existing OFDM. The proposed scheme splits the bandwidth into subbands and transmits symbols across subbands and time intervals. It is shown that up to P symbols can be transmitted in 3P-2 time intervals when there are N receive antennas, an improvement over OFDM. Numerical results demonstrate improved bit error rate and sum rate compared to OFDM, especially at high SNR. Open problems remaining include extending the approach to MISO systems and evaluating performance under different channel and system conditions.
Pilot Contamination Mitigation for Wideband Massive MIMO: Number of Cells Vs ...T. E. BOGALE
The document presents a pilot contamination mitigation technique for wideband massive MIMO systems. It proposes a three-step approach: 1) Allowing pilot transmission in the time domain, 2) Expressing sub-carrier channel estimates as linear combinations of received signals, and 3) Optimizing the number of cells, pilots, and linear combination terms to ensure unbounded signal-to-interference-plus-noise ratio (SINR). The main results show that the number of cells can be increased to L, where L is the number of multipath taps, allowing cancellation of pilot contamination. Simulation results demonstrate that the proposed approach achieves rates close to perfect channel state information.
This document provides an overview of channel estimation strategies used in orthogonal frequency division multiplexing (OFDM) systems. It describes the basic types of channel estimation methods: block-type pilot channel estimation and comb-type pilot channel estimation. For block-type estimation, pilots are inserted into all subcarriers of OFDM symbols periodically. This allows estimation of the channel conditions between pilot symbols. Estimation can be done with least squares (LS), minimum mean-square error (MMSE), or modified MMSE. For comb-type estimation, pilots are inserted into certain subcarriers of each symbol, requiring interpolation to estimate data subcarriers. The document compares the implementation complexity and performance of different estimation methods.
This document announces a call for papers for the IEEE PIMRC 2015 conference in Hong Kong from August 30 to September 2, 2015. It will include technical sessions, tutorials, workshops, and panels on wireless communications, networks, services, and applications. The deadline for paper submissions is April 30, 2015. It also provides details on one of the tutorials that will be presented on advanced air interface techniques for 5G networks. The tutorial will discuss key 5G technologies including distributed antenna systems, massive MIMO, millimeter wave communications, and small cell networks. It will analyze the technical aspects and challenges of 5G and present emerging research opportunities in this area. The tutorial presenters and their brief biographies are also included.
The document proposes a new method for frame synchronization in OFDMA mode of wireless networks. The method uses a timing metric based on the preamble structure specified for OFDMA, which consists of real BPSK symbols on every third subcarrier. In an ideal scenario with a DFT size of 2046, the timing metric results in four significant peaks, with the true frame boundary indicated by one of the peaks. Thresholding and detection strategies are discussed to identify the frame boundary in noisy channels. Simulations show the proposed method performs better than existing techniques, especially in fading channels.
VTC-location based channel estimation for massive full-dimensional MIMO systemsQian Han
This document proposes a two-dimensional location-based channel estimation method for massive full-dimensional MIMO systems. It uses an intra-cell pilot reuse scheme where users with the same pilots can be distinguished by their unique azimuth and elevation angles of arrival. The method applies a 2D FFT to the pilot-aided channel estimates followed by a 2D window function in the angle domain to isolate the different users. Simulation results show the proposed method outperforms conventional pilot-aided estimation and that 3D MIMO can improve sum capacity and serve more users compared to traditional MIMO systems.
This document discusses synchronization and MIMO capabilities of USRP devices from Ettus Research. It provides details on:
1) How the USRP N200/N210 support plug-and-play 2x2 MIMO systems using a shared reference cable.
2) External references can be used to synchronize larger MIMO arrays, though additional equipment is required.
3) While other USRP models can be synchronized, some do not meet all requirements for MIMO without additional considerations.
USRP Implementation of Max-Min SNR Signal Energy based Spectrum Sensing Algor...T. E. BOGALE
This poster presents the USRP experimental results of the Max-Min signal
SNR Signal Energy based Spectrum Sensing Algorithms for Cognitive Radio
Networks. The full detail of the poster has been published in ICC 2014.
Transportation of MIMO Radio Signals over RoF-Distributed Antenna System and ...奈良先端大 情報科学研究科
Radio on Fiber-Distributed Antenna System (RoF- DAS) is known to improve coverage and performance of wireless communications. Currently, various multiplexing schemes in RoF-DAS for transport Multiple Input Multiple Output (MIMO) signals in a fiber link are studied. The RoF-DAS over Wave- length Division Multiplexing - Passive Optical Network (WDM- PON) with optical Time Division Multiplexing (TDM) is actively researched. This system uses optical switcher to multiplex a set of MIMO radio signals in a fiber and transfer to the Remote Antenna Unit (RAU). Since a pair of switches multiplex and demultiplex MIMO radio signals, two switches are required to synchronize completely. Therefore, there is a problem that high performance switches are required to perform the clock extraction. This paper proposes asynchronous optical TDM. In this proposal, synchronization mismatch is compensated by estimating the amount of drifting and cancel it out at the RAU. The bit error ratio (BER) performance is evaluated by using computer simulation.
This document summarizes an OFDM channel estimation project. It discusses the objective to maximize OFDM system capacity through channel estimation and adaptive transmission. It outlines the system architecture, including the transmitter, channel, receiver, and channel estimation. It also lists the work completed, such as programs for channel impulse response, Rayleigh fading, and adding noise.
The document summarizes key aspects of channel estimation for wireless OFDM communications. It discusses the history and development of OFDM, including how the use of IFFT/FFT allows for practical implementation. It also describes how cyclic prefixes maintain orthogonality over multipath channels by converting linear convolution to circular convolution. The document then provides the continuous-time model for an OFDM transceiver system, showing how information symbols are modulated onto orthogonal subcarriers within an OFDM symbol structure that includes a cyclic prefix.
ABSTRACT The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm-wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fifth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm-wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices.
INDEX TERMS 28GHz, 38GHz, millimeter wave propagation measurements, directional antennas, channel models, 5G, cellular, mobile communications, MIMO.
OFDM allows tightly packed carriers to convey information orthogonally and with high bandwidth efficiency
Objectives Description:
Concepts
Basic idea
Introduction to OFDM
Implementation
Advantages and Drawbacks.
FDMA
Beamforming for Multiuser Massive MIMO Systems: Digital versus Hybrid Analog-...T. E. BOGALE
The document compares digital and hybrid analog-digital beamforming for multiuser massive MIMO systems. It describes the system model and problem formulation. Digital beamforming requires many RF chains and ADCs which is expensive for massive MIMO. Hybrid beamforming uses limited RF chains by employing analog beamforming at the transmitter with phase shifters. The document proposes a hybrid beamforming algorithm that minimizes the mean square error between the estimated signals of digital and hybrid beamforming. Simulation results show the proposed hybrid approach achieves similar performance as digital beamforming using fewer RF chains and phase shifters. It concludes hybrid beamforming provides significant savings in hardware complexity over digital beamforming for multiuser massive MIMO systems.
orthogonal frequency division multiplexing(OFDM)
its orthogonal frequency multiplexing topic basicallly in digital signal processing , network signal and system , it also helpful in engineering course either electrical or electronics and communication engineering.
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and the derivation of the PLA from the underlying LGT has
been pursued by various methods. The relative
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the derivative of the PLA in any direction in the space of
Polyakov line holonomies.1 Given some ansatz for the PLA,
depending on some set of parameters, we can use the relative
weights method to determine those parameters. Then, given
the PLA at some fixed temperature T, we can apply a mean
field method to search for phase transitions at finite chemical
potential m. This is the strategy which we have outlined
in some detail in, where some preliminary results for finite
densities were presented. The relative weights method
has strengths and weaknesses; on the positive side the approach
is not tied to either a strong coupling or hopping parameter
expansion, and the non-holomorphic character of the
fermion action is irrelevant. The main weakness is that the validity
of the results depends on a good choice of ansatz for the
PLA. We have suggested, for exploratory work, an ansatz for
the PLA inspired first by the success of the relative weights
method applied to pure gauge theories, and secondly by
the form of the PLA obtained for heavy-dense quarks.
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Pilot Optimization and Channel Estimation for Multiuser Massive MIMO Systems
1. Pilot Optimization and Channel Estimation for
Multiuser Massive MIMO Systems
Tadilo Endeshaw Bogale
Institute National de la Recherche Scientifique (INRS),
Canada
March 20, 2014
2. Presentation outline
Presentation outline
1 Multiuser Block Diagram
2 Problem Statement
3 Proposed Solution
4 Simulation Results
5 Conclusions
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 2 / 12
3. Multiuser Block Diagram
Communication Scenario and Objective
BS
a1 · · · aM
MS1
MS2
MSK
h
1
h2
hK
Scenario
• MS1, MS2, MSK are separated in space
and no coordination between them
⇒ Downlink Multiuser system
• MS1, MS2, MSK have single antennas
⇒ Downlink Multiuser MISO system
• Channel between Tx and Rx is flat fading
• Transmission is TDD
• M >> K (i.e., Massive MIMO system)
General Objective
• To estimate channels H = [h1, h2, · · · hk ]
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 3 / 12
4. Multiuser Block Diagram
Conventional Channel Estimation (Orthogonal)
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
h3
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 4 / 12
5. Multiuser Block Diagram
Conventional Channel Estimation (Orthogonal)
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
h3
x1
x2
x3
⋄ y1 = h1x11 + h2x21 + h3x31 + n1
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 5 / 12
8. Multiuser Block Diagram
Conventional Channel Estimation (Orthogonal)
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
h3
x1
x2
x3
⋄ y1 = h1x11 + h2x21 + h3x31 + n1
y2 = h1x12 + h2x22 + h3x32 + n2
y3 = h1x13 + h2x23 + h3x33 + n3
⇒ Y = HX + N
where X = [x1 x2 x3]
N = [n1 n2 n3]
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 5 / 12
9. Multiuser Block Diagram
Conventional Channel Estimation (Orthogonal)
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
h3
x1
x2
x3
⋄ y1 = h1x11 + h2x21 + h3x31 + n1
y2 = h1x12 + h2x22 + h3x32 + n2
y3 = h1x13 + h2x23 + h3x33 + n3
⇒ Y = HX + N
where X = [x1 x2 x3]
N = [n1 n2 n3]
⇒ YXH
= H + NXH
ˆhk = hk + NxH
k
⇒ Requires N ≥ K
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 5 / 12
10. Problem Statement
Problem Statement
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Objective : Optimize pilots xk
Estimate channels hk , ∀N, M, K
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 6 / 12
11. Problem Statement
Problem Statement
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Objective : Optimize pilots xk
Estimate channels hk , ∀N, M, K
⋄ Assumptions : hk =
√
gk
˜hk
˜hk ∼ CN(0, 1)
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 6 / 12
12. Problem Statement
Problem Statement
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Objective : Optimize pilots xk
Estimate channels hk , ∀N, M, K
⋄ Assumptions : hk =
√
gk
˜hk
˜hk ∼ CN(0, 1)
⋄ Problem : Y = HXH
+ N
where H = [h1, · · · , hK ]
X = [x1, · · · , xN ]
N = [n1, · · · , nN]
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 6 / 12
13. Problem Statement
Problem Statement
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Objective : Optimize pilots xk
Estimate channels hk , ∀N, M, K
⋄ Assumptions : hk =
√
gk
˜hk
˜hk ∼ CN(0, 1)
⋄ Problem : Y = HXH
+ N
where H = [h1, · · · , hK ]
X = [x1, · · · , xN ]
N = [n1, · · · , nN]
⋄ Represent : hk = WH
k Yuk
ξk = tr{E{|hk − hk |2
}}
= uH
k (
K
i=1 gi xi xH
i + σ2
IN)uk tr{(WH
k Wk )}
+gk IM − (gk xH
k uk )tr{WH
k } − (gk uH
k xk )tr{Wk }
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 6 / 12
14. Proposed Solution
Proposed Solution
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Represent : hk = WH
k Yuk
ξk = tr{E{|hk − hk |2
}}
= uH
k (
K
i=1 gi xi xH
i + σ2
IN)uk tr{(WH
k Wk )}
+gk IM − (gk xH
k uk )tr{WH
k } − (gk uH
k xk )tr{Wk }
⋄ ξk depends on gk ⇒ higher gk higher ξk
⇒ To incorporate fairness
minxk ,uk ,Wk
K
k=1
1
gk
ξk
s.t xH
k xk ≤ Pk
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 7 / 12
15. Proposed Solution
Proposed Solution
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Represent : hk = WH
k Yuk
ξk = tr{E{|hk − hk |2
}}
= uH
k (
K
i=1 gi xi xH
i + σ2
IN)uk tr{(WH
k Wk )}
+gk IM − (gk xH
k uk )tr{WH
k } − (gk uH
k xk )tr{Wk }
⋄ ξk depends on gk ⇒ higher gk higher ξk
⇒ To incorporate fairness
minxk ,uk ,Wk
K
k=1
1
gk
ξk
s.t xH
k xk ≤ Pk
⋄ Wk =
gk xH
k uk
K
i=1 gi xH
i
uk uH
k
xi +σ2uH
k
uk
IM .
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 7 / 12
16. Proposed Solution
Proposed Solution
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Represent : hk = WH
k Yuk
ξk = tr{E{|hk − hk |2
}}
= uH
k (
K
i=1 gi xi xH
i + σ2
IN)uk tr{(WH
k Wk )}
+gk IM − (gk xH
k uk )tr{WH
k } − (gk uH
k xk )tr{Wk }
⋄ ξk depends on gk ⇒ higher gk higher ξk
⇒ To incorporate fairness
minxk ,uk ,Wk
K
k=1
1
gk
ξk
s.t xH
k xk ≤ Pk
⋄ Wk =
gk xH
k uk
K
i=1 gi xH
i
uk uH
k
xi +σ2uH
k
uk
IM .
⋄ ˜ξk = M gk −
uH
k (g2
k xk xH
k )uk
uH
k
( K
i=1 gi xi xH
i
+σ2IN )uk
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 7 / 12
17. Proposed Solution
Proposed Solution
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Wk =
gk xH
k uk
K
i=1 gi xH
i
uk uH
k
xi +σ2uH
k
uk
IM .
⋄ ˜ξk = M gk −
uH
k (g2
k xk xH
k )uk
uH
k
( K
i=1 gi xi xH
i
+σ2IN )uk
⋄ ˜˜ξk = Mgk − Mg2
k xH
k A−1
xk
where A =
K
i=1 gi xi xH
i + σ2
I
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 8 / 12
18. Proposed Solution
Proposed Solution
BS
a1 · · · aM
MS1
MS2
MS3
h
1
h2
hK
x1
x2
xK
⋄ Wk =
gk xH
k uk
K
i=1 gi xH
i
uk uH
k
xi +σ2uH
k
uk
IM .
⋄ ˜ξk = M gk −
uH
k (g2
k xk xH
k )uk
uH
k
( K
i=1 gi xi xH
i
+σ2IN )uk
⋄ ˜˜ξk = Mgk − Mg2
k xH
k A−1
xk
where A =
K
i=1 gi xi xH
i + σ2
I
⋄ minxk
tr{Q−1
k } −
gk xH
k Q−2
k
xk
1+gk xH
k
Q−1
k
xk
s.t xH
k xk ≤ Pk
where Qk =
K
i=1,i=k gi xi xH
i + σ2
IN
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 8 / 12
20. Simulation Results
Effect of Number of pilots (N)
Parameters: M = 128, K = 32, Pk = 1mw, SNR = Pav
σ2
16 18 20 22 24 26 28 30 32
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Number of pilot symbols (N)
NormalizedWSMSE
Existing (Orange) and proposed (Blue) algorithms
SNR = 18dB
SNR = 12dB
SNR = 6dB
g =
0.04 0.74 0.81 0.26
0.70 0.29 0.08 0.87
0.07 0.74 0.12 0.44
0.59 0.63 0.53 0.20
0.67 0.24 0.72 0.40
0.39 0.41 0.14 0.87
0.02 0.92 0.63 0.06
0.63 0.75 0.76 0.06
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 10 / 12
21. Simulation Results
Convergence speed and effect of initialization
Parameters: M = 128, N = 16, K = 32, Pk = 1mw, SNR = Pav
σ2
5 10 15 20 25 30 35 40
0.75
0.755
0.76
0.765
0.77
0.775
0.78
0.785
0.79
0.795
0.8
Iteration number
NormalizedWSMSE
SNR = 0dB
DFT matrix with pilot reuse
Truncated DFT matrix
Random matrix
5 10 15 20 25 30 35 40
0.67
0.68
0.69
0.7
0.71
0.72
0.73
SNR = 3dB
Iteration number
NormalizedWSMSE
DFT matrix with pilot reuse
Truncated DFT matrix
Random matrix
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 11 / 12
22. Conclusions
Conclusions
In this work, we accomplish the following main tasks.
We propose new pilot assignment and channel estimation
algorithm (especially for Massive MIMO system)
The proposed algorithm employs WSMSE as an objective function
To solve the problem, we apply MMSE and Rayleigh quotient
methods
The proposed algorithm achieves the optimal pilot and estimated
channel when K = N
Tadilo (CISS, Princeton, NJ, USA, Mar. 2014) Channel estimation March 20, 2014 12 / 12