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Approximate Designs for Fast Fourier Transform (FFT) With Application to Speech Recognition

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2019年第12期66卷 4727-4739页

作者： Liu, Weiqiang Liao, Qicong Qiao, Lei Xi, Weijie Wang, Chenghua Lombardi, Fabrizio Nanjing Univ Aeronaut & Astronaut Coll Elect Informat & Engn Nanjing 211106 Jiangsu Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Northeastern Univ Dept Elect & Comp Engn Boston MA 02115 USA

This paper presents different approximate designs for computing the FFT. The tradeoff between accuracy and performance is achieved by adjusting the word length in each computational stage. Two algorithms for word length modification under a specific error margin are proposed. The first algorithm targets an approximate FFT for an area-limited design compared to the conventional fixed design;the second algorithm targets performance so it achieves a higher operating frequency. Both of the proposed algorithms show that an efficient balance between hardware utilization and performance is possible at stage-level. The proposed approximate FFT designs are implemented on FPGA;experimental results show that hardware utilization using the first approximate algorithm are reduced by at least nearly 40. The second algorithm increases performance of the designs by over 20. Fine granularity design is also investigated, where the FPGA resources for a 256-point FFT computation can be further reduced by nearly 10 compared to a coarse design. Finally, the proposed approximate designs are applied to a feature extraction module in an isolated word recognition system;the numbers of LUTs and FFs for the Mel frequency cepstrum coefficients (MFCC) extraction module are decreased by up to 47.2 and 39.0, respectively with a power reduction of up to 27.0 at a loss in accuracy of less than 2.

关键词： Computer architecture approximation algorithms Hardware Program processors Delays Speech recognition Approximate computing Approximate computing pipelined FFT word length 2D FFT speech recognition

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A Sparsity-Assisted Fault Diagnosis Method Based on Nonconvex Sparse Regularization

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IEEE ACCESS 2021年 9卷 59027-59037页

作者： Niu, Yijie Fei, Jiyou Dalian Jiaotong Univ Coll Software Engn Dalian 116028 Peoples R China Dalian Jiaotong Univ Coll Locomot & Rolling Dalian 116028 Peoples R China

Sparse representation theory can be adopted for fault feature extraction and classification. Inspired by these two capabilities of sparse representation theory, this paper proposes a novel collaborative sparsity-assisted fault diagnosis (CSFD) method. Specifically, due to the repeatability and sparsity of fault feature signal in the whole signal, the feature extraction capability of sparse representation is utilized to extract fault features and construct a feature matrix. Subsequently, owing to the sparsity of fault classification problem itself, the classification capability of sparse representation is employed to achieve fault classification. Moreover, fault feature extraction is a key issue for fault diagnosis. Therefore, in order to improve the effectiveness of fault feature extraction, a RC-adjustment strategy with the ability to adaptively adjust regularization parameter is designed to assist the generalized minimax-concave (GMC) penalty for feature extraction. The advantage of the GMC penalty is that it can establish a nonconvex sparse regularization model with convex optimization solution. Finally, the proposed CSFD method is tested and verified by Case Western Reserve University (CWRU) bearing dataset and actual engineering dataset. Especially, the diagnostic accuracy of this method can reach 99.92%, which is nearly 7.68% higher than the traditional method based on L1 norm penalty. Enormous experiment results have thoroughly demonstrated the effectiveness of the proposed CSFD method for fault diagnosis.

关键词： Feature extraction Fault diagnosis Cost function approximation algorithms Vibrations Interference Collaboration Fault diagnosis sparse representation generalized minimax-concave (GMC) penalty fault feature extraction

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Weighted Connected Vertex Cover Based Energy-Efficient Link Monitoring for Wireless Sensor Networks Towards Secure Internet of Things

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IEEE ACCESS 2021年 9卷 10107-10119页

作者： Dagdeviren, Zuleyha Akusta Ege Univ Int Comp Inst TR-35100 Izmir Turkey

Industry 4.0 utilizes the Internet of Things (IoT) to rise the efficiency in manufacturing and automation where wireless sensor networks (WSNs) are crucial technologies for communication layer of IoT. WSNs include hundreds of small sized sensor nodes that have the abilities of wireless transmission and environmental sensing. Wireless transmission is prone to various attacks such as data manipulation since data communication is achieved through transfer of radio packets. A countermeasure of this issue is link monitoring by deploying secure points that can physically capture and inspect radio packets. Graph theory plays a critical role to solve various problems in WSNs. Finding minimum Vertex Cover (VC) is an important NP-Hard graph theoretic problem in which the minimum set of nodes (vertices) is aimed to select in such a way that each link should be incident to at least one node from this set. VC is a significant structure for WSNs where it perfectly fits for link monitoring when nodes in VC are set as secure points (monitors). Since sensor nodes are generally battery-powered and have limited transmission range, energy-efficient multi-hop communication to the sink node is of utmost importance. In weighted connected VC (WCVC) structure, subgraph induced by monitor nodes are connected where monitors are chosen according to their weights. When weights of nodes are assigned as reciprocal of their energies, an energy-efficient virtual backbone can be formed. We propose a novel metaheuristic WCVC algorithm for link monitoring and backbone formation in WSNs modeled as undirected graphs. Our proposed algorithm integrates a genetic search with a greedy heuristic to improve WCVC solution quality and decrease the search time. To evaluate the efficiencies of greedy heuristics, we adopt three different heuristics for WCVC problem. We implement our algorithm with its counterparts and reveal that the algorithm is favorable in terms of solution quality and resource consumption.

关键词： Wireless sensor networks Monitoring Internet of Things Heuristic algorithms approximation algorithms Wireless communication Image edge detection Internet of Things wireless sensor networks link monitoring vertex cover metaheuristic algorithm

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Strategyproof mechanism design for facility location games with weighted agents on a line

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JOURNAL OF COMBINATORIAL OPTIMIZATION 2014年第4期28卷 756-773页

作者： Zhang, Qiang Li, Minming City Univ Hong Kong Dept Comp Sci Hong Kong Hong Kong Peoples R China

approximation mechanism design without money was first studied in Procaccia and Tennenholtz (2009) by considering a facility location game. In general, a facility is being opened and the cost of an agent is measured by its distance to the facility. In order to achieve a good social cost, a mechanism selects the location of the facility based on the locations reported by agents. It motivates agents to strategically report their locations to get good outcomes for themselves. A mechanism is called strategyproof if no agents could manipulate to get a better outcome by telling lies regardless of any configuration of other agents. The main contribution in this paper is to explore the strategyproof mechanisms without money when agents are distinguishable. There are two main variations on the nature of agents. One is that agents prefer getting closer to the facility, while the other is that agents prefer being far away from the facility. We first consider the model that directly extends the model in Procaccia and Tennenholtz (2009). In particular, we consider the strategyproof mechanisms without money when agents are weighted. We show that the strategyproof mechanisms in the case of unweighted agents are still the best in the weighted cases. We establish tight lower and upper bounds for approximation ratios on the optimal social utility and the minimum utility when agents prefer to stay close to the facility. We then provide the lower and upper bounds on the optimal social utility and lower bound on the minimum distance per weight when agents prefer to stay far away from the facility. We also extend our study in a natural direction where two facilities must be built on a real line. Secondly, we propose an novel threshold based model to distinguish agents. In this model, we present a strategyproof mechanism that leads to optimal solutions in terms of social cost.

关键词： Algorithmic mechanism design approximation algorithms Optimization Social choice

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Resource Allocation for Multi-User Downlink MISO OFDMA-URLLC Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2020年第11期68卷 7184-7200页

作者： Ghanem, Walid R. Jamali, Vahid Sun, Yan Schober, Robert Friedrich Alexander Univ Erlangen Nurnberg FAU Inst Digital Commun D-91058 Erlangen Germany

This article considers the resource allocation algorithm design for downlink multiple-input single-output (MISO) orthogonal frequency division multiple access (OFDMA) ultra-reliable low latency communication (URLLC) systems. To meet the stringent delay requirements of URLLC, short packet transmission is adopted and taken into account for resource allocation algorithm design. The resource allocation is optimized for maximization of the weighted system sum throughput subject to quality-of-service (QoS) constraints regarding the URLLC users' number of transmitted bits, packet error probability, and delay. Despite the non-convexity of the resulting optimization problem, the optimal solution is found via monotonic optimization. The corresponding optimal resource allocation policy can serve as a performance upper bound for sub-optimal low-complexity solutions. We develop such a low-complexity sub-optimal resource allocation algorithm based on successive convex approximation and difference of convex programming. Our simulation results reveal the importance of using multiple antennas for reducing the latency and improving the reliability of URLLC systems. Moreover, the proposed sub-optimal algorithm is shown to closely approach the performance of the proposed optimal algorithm and outperforms two baseline schemes by a considerable margin, especially when the users have heterogeneous delay requirements. Finally, conventional resource allocation designs based on Shannon's capacity formula are shown to be not applicable in MISO OFDMA-URLLC systems as they are not able to guarantee the users' delay constraints.

关键词： Resource management Ultra reliable low latency communication Delays MISO communication Downlink Quality of service approximation algorithms Resource allocation orthogonal frequency division multiple access (OFDMA) ultra-reliable low latency communication (URLLC) short packet transmission monotonic optimization

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Approximating the degree-bounded minimum diameter spanning tree problem

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ALGORITHMICA 2005年第2期41卷 117-129页

作者： Könemann, J Levin, A Sinha, A Univ Waterloo Dept Combinator & Optimizat Waterloo ON N2L 3G1 Canada Technion Israel Inst Technol Fac Ind Engn & Management IL-32000 Haifa Israel Univ Michigan Sch Business Ann Arbor MI 48103 USA Carnegie Mellon Univ Tepper Sch Business Pittsburgh PA 15213 USA

We consider the problem of finding a minimum diameter spanning tree with maximum node degree B in a complete undirected edge-weighted graph. We provide an O(rootlog(B) n)-approximation algorithm for the problem. Our a... 详细信息

关键词： approximation algorithms spanning trees bicriteria approximation degree-bounded spanning trees

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Sparse and Low-Rank Constrained Tensor Factorization for Hyperspectral Image Unmixing

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2021年 14卷 1754-1767页

作者： Zheng, Pan Su, Hongjun Du, Qian Hohai Univ Sch Earth Sci & Engn Nanjing 211100 Peoples R China Mississippi State Univ Dept Elect & Comp Engn Starkville MS 39762 USA

Third-order tensors have been widely used in hyperspectral remote sensing because of their ability to maintain the 3-D structure of hyperspectral images. In recent years, hyperspectral unmixing algorithms based on tensor factorization have emerged, but these decomposition processes may be inconsistent with physical mechanism of unmixing. To solve this problem, this article proposes a sparse and low-rank constrained tensor factorization unmixing algorithm based on a matrix-vector nonnegative tensor factorization (MV-NTF) framework. Considering the fact that each component tensor obtained by the image decomposition contains only one endmember and the corresponding abundance matrix has sparse property, a sparse constraint is imposed to ensure the accuracy of abundance maps. Since abundance maps also have low-rank attribute, in order to avoid the strict low-rank constraint in the original MV-NTF framework, a low-rank tensor regularization is introduced to flexibly express the low-rank characteristics of the abundance tensors, making the resulting abundance maps more in line with the actual scene. Then, the optimization problem is solved by using the alternating direction method of multipliers. In experiments, simulated datasets are adopted to demonstrate the effectiveness of the sparse and low-rank constraints of the proposed algorithm, and real datasets from different sensors and different scenarios are used to verify its applicability.

关键词： Tensors Hyperspectral imaging Matrix decomposition Sparse matrices Libraries Estimation approximation algorithms Hyperspectral remote sensing low-rank sparse tensor factorization unmixing

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TRACKING OF UNKNOWN NONSTATIONARY CHIRP SIGNALS USING UNSUPERVISED CLUSTERING IN THE WIGNER DISTRIBUTION SPACE

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 1993年第11期41卷 3085-3101页

作者： COHEN, FS KADAMBE, S BOUDREAUXBARTELS, GF AT&T BELL LABS LANGUAGE IDENTIFICAT PROJECTMURRAY HILLNJ 07974 UNIV RHODE ISL DEPT ELECT ENGNKINGSTONRI 02881

This paper is concerned with the problems of 1) detecting the presence of one or more FM chirp signals embedded in noise, and 2) tracking or estimating the unknown, time-varying instantaneous frequency of each chirp component. No prior knowledge is assumed about the number of chirp signals present, the parameters of each chirp, or how the parameters change with time. A detection/estimation algorithm is proposed that uses the Wigner distribution transform to find the best piecewise cubic approximation to each chirp's phase function. The first step of the WD based algorithm consists of properly thresholding the WD of the received signal to produce contours in the time-frequency plane that approximate the instantaneous frequency of each chirp component. These contours can then be approximated as generalized lines in the (omega, t, t2) space. The number of chirp signals (or equivalently, generalized lines) present is determined using maximum likelihood segmentation. Minimum mean square estimation techniques are used to estimate the unknown phase parameters of each chirp component. We demonstrate that for the cases of i) nonoverlapping linear or nonlinear FM chirp signals embedded in noise or ii) over-lapping linear FM chirp signals embedded in noise, the approach is very robust, highly reliable, and can operate efficiently in low signal-to-noise environments where it is hard for even trained operators to detect the presence of chirps while looking at the WD plots of the overall signal. For multicomponent signals, the proposed technique is able to suppress noise as well as the troublesome cross WD components that arise due to the bilinear nature of the WD.

关键词： Chirp Phase estimation Working environment noise Frequency estimation Change detection algorithms Phase detection approximation algorithms Time frequency analysis Maximum likelihood detection Maximum likelihood estimation

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Cooperative Approaches to Construction and Maintenance of Networks' Virtual Backbones for Extreme Wireless Sensor Applications

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IEEE SENSORS JOURNAL 2014年第11期14卷 3782-3790页

作者： Al-Nabhan, Najla Al-Rodhaan, Mznah Al-Dhelaan, Abdullah King Saud Univ Dept Comp Sci Coll Comp & Informat Sci Riyadh 11682 Saudi Arabia

Wireless sensing technology is becoming a new scientific instrument for environmental monitoring under extreme conditions. This class of applications requires reliable, energy-efficient, and self-organizing approaches. Connected dominating sets (CDSs) have been widely used for virtual backbone construction in unstructured wireless sensor networks to control topology, facilitate routing, and extend network lifetime. This paper proposes two distributed algorithms for CDS construction and maintenance in extreme wireless sensor networks. The proposed approaches efficiently construct and maintain a small CDS for challenging environments. Simulation shows that our proposed approaches provide significant energy efficiency without introducing any performance degradation in terms of CDS size.

关键词： Distributed algorithms approximation algorithms connected dominating set space and extreme environments wireless sensor networks energy efficiency virtual backbone unstructured networks

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Rounding Algorithm of Minimizing Executing and Transmitting Time in Multiple CRANs

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IEEE ACCESS 2021年 9卷 166804-166814页

作者： Hu, Chia-Cheng Liu, Wen-Wu Pan, Jeng-Shyang Yango Univ Coll Artificial Intelligence Fuzhou 350015 Peoples R China Ningbo Univ Fac Elect Engn & Comp Sci Ningbo 315000 Zhejiang Peoples R China Shandong Univ Sci & Technol Coll Comp Sci & Engn Qingdao 266590 Peoples R China

Recently, Cloud Radio Access Network (CRAN) is a technology for reducing communication load and improving the performance of user tasks. In a CRAN, remote radio heads (RRHs) are densely set up to enable users to connect to the network nearby, and baseband unit (BBU) pools are used to store and execute user contents and tasks. In this paper, our goal is to perform joint optimization when scheduling user tasks and assigning RRH to users in a multiple CRAN infrastructure. The joint problem is NP-hard and modeled as a 0/1 integer linear programming (ILP) with the objective of minimizing the total time of executing user tasks and transmitting user output contents under the constraints of RRH linked capacities and BBU pool computing resources. Then, an algorithm is designed by adopting the rounding technology to solve the 0/1 ILP. We will prove its approximation ratio competitively. The conducted simulations further show that the difference between its solution and the optimal one of the 0/1 ILP is very small, and its approximation ratio is between 1.09 and 1.17. In the conducted experiments, the results demonstrate that the proposed algorithm is indeed practical to be implemented in a multiple CRAN infrastructure.

关键词： Task analysis Costs approximation algorithms Optimization Resource management Wireless communication Servers Cloud radio access network (CRAN) resource allocation task scheduling

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