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arXiv 2024年

作者： Bhattacharya, Sayan Costa, Martín Lattanzi, Silvio Parotsidis, Nikos University of Warwick United Kingdom Google Research United States

In this paper, we consider the metric k-center problem in the fully dynamic setting, where we are given a metric space (V, d) evolving via a sequence of point insertions and deletions and our task is to maintain a subset S ⊆ V of at most k points that minimizes the objective maxx∈V miny∈S d(x, y). We want to design our algorithm so that we minimize its approximation ratio, recourse (the number of changes it makes to the solution S) and update time (the time it takes to handle an update). We give a simple algorithm for dynamic k-center that maintains a O(1)-approximate solution with O(1) amortized recourse and Õ(k) amortized update time, obtaining near-optimal approximation, recourse and update time simultaneously. We obtain our result by combining a variant of the dynamic k-center algorithm of Bateni et al. [SODA’23] with the dynamic sparsifier of Bhattacharya et al. [NeurIPS’23]. © 2024, CC BY.

关键词： approximation algorithms

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Joint Beamforming and User Association Design in Active RIS-Aided Cell-Free URLLC System

Joint Beamforming and User Association Design in Active RIS-...

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International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Yuanmeng Song Yu Qian Li Chen Zhiyu Yan Feng Shu Pengcheng Zhu National Mobile Communications Research Laboratory Southeast University Nanjing China Department of Electronic Engineering and Information Science University of Science and Technology of China Hefei China China Academy of Information and Communications Technology Beijing China School of Information and Communication Engineering Hainan University Haikou China

ISBN: (数字)9798350390643

ISBN: (纸本)9798350390650

Reconfigurable intelligent surface (RIS) is considered as a promising technology thanks to its strong ability to reflect incident signals and modify propagation properties of wireless environment. In this paper, we investigate the sum-rate maximization problem for active RIS-aided cell-free multipleinput multiple-output (CF-MIMO) system in ultra-reliable and low-latency communication (URLLC) scenario. Specifically, a two-timescale user-RIS match optimization scheme is proposed to reduce the required channel training and feedback overhead, where beamforming matrices at the remote antenna unit (RAU) and active RIS are jointly optimized under the maximum transmit power constraints. Since the problem formulated is non-convex, an alternating optimization algorithm is proposed, wherein the original optimization problem is decomposed into transmission and association subproblems that can be efficiently solved. For the former subproblem, auxiliary variables are introduced in accordance with the successive convex approximation (SCA) method to overcome the non-convexity, while for the latter subproblem, a penalty-based association scheme is proposed to tackle the non-convex discrete user-RIS match constraints. Simulation results demonstrate that the proposed algorithm outperforms the baseline schemes in terms of spectral efficiency.

关键词： Wireless communication Array signal processing Simulation Transmitting antennas Signal processing algorithms Ultra reliable low latency communication Reconfigurable intelligent surfaces approximation algorithms Matrix decomposition Optimization

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A TDMA Algorithm for Dual-Hop Energy Harvesting Wireless Sensor Networks

A TDMA Algorithm for Dual-Hop Energy Harvesting Wireless Sen...

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Computing and Machine Intelligence (ICMI), International Conference on

作者： Tanner D. Patterson Robert J. Hayek Ahmed Ammar ECCS Dept. Ohio Northern University Ada Ohio USA ECE Dept. Northwestern University Evanston Illinois USA

ISBN: (数字)9798350372977

ISBN: (纸本)9798350372984

In this paper, we propose a time division multiple access (TDMA) algorithm and system for a dual-hop energy harvesting wireless sensor network. We assume that the network is divided into clusters, where each cluster has a cluster head and cluster members. A cluster head collects data from its respective cluster members and then transmits the data in one packet to the base station. The proposed algorithm first synchronizes the network and then enables each node to transmit over its designated time slot. The proposed algorithm allows each node to synchronize not only based on a synchronization packet from the base station, but also based on a data packet from another node that is within its communication range. Moreover, the proposed algorithm synchronizes clusters individually, i.e., if a cluster becomes out-of-sync, the algorithm only synchronizes that cluster while allowing the remaining clusters to continue normal operation. The proposed algorithm works also for single-hop networks, and achieves network synchronization without the need for acknowledgment packets, which reduces the average energy consumption and average delay by approximately 1.36 and 1.46 times, respectively, compared to the most recent single-hop algorithm.

关键词： Time division multiple access Wireless sensor networks Base stations Energy consumption Clustering algorithms approximation algorithms Partitioning algorithms

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Real-Time High-Resolution SAR Imaging Using a Commercial W-Band Radar and Rail System

Real-Time High-Resolution SAR Imaging Using a Commercial W-B...

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International Conference on Control, Automation and Systems ( ICCAS)

作者： Minjun Kim Sungho Kim Department of Electronic Engineering Yeungnam University Gyeongbuk Korea

ISBN: (数字)9788993215380

ISBN: (纸本)9798331517939

This paper proposes a method to combine radar and rail systems to meet SAR data acquisition conditions, minimize oscillations, and easily obtain SAR images. Using a Frequency Modulated Continuous Wave (FMCW) model, the signal is transmitted and the received signal undergoes a dechirp process. The Range Migration Algorithm (RMA) is applied to generate high-resolution images. In practical experiments, a commercial W-band radar was used to acquire data of targets placed approximately 3 meters away. The experimental results show that the shapes of drones and helicopters are captured with high resolution.

关键词： Rails Meters Shape Radar imaging approximation algorithms Radar polarimetry Real-time systems Synthetic aperture radar Signal resolution Oscillators

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Scalable Overspeed Item Detection in Streams

Scalable Overspeed Item Detection in Streams

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International Conference on Data Engineering

作者： Yuhan Wu Hanbo Wu Chengjun Jia Bo Peng Ziyun Zhang Tong Yang Peiqing Chen Kaicheng Yang Bin Cui National Key Laboratory for Multimedia Information Processing School of Computer Science Peking University Beijing China University of Maryland College Park Maryland United States

ISBN: (数字)9798350317152

ISBN: (纸本)9798350317169

In data stream mining, monitoring high-speed users and segregating their excessive use, known as “Overspeed items,” is crucial for preventing system overload and maintaining fairness in messaging and network systems. Current approaches, however, face scalability challenges with large user bases, primarily due to increasing memory requirements proportional to user numbers. We have pinpointed the inefficiency in allocating memory for all users, recognizing that only a small fraction exhibit overspeed behavior at any given time. Addressing this, we employed the sketching technique, a type of approximate algorithm, and designed the first sketch algorithm for finding Overspeed items, named SpeedSketch: (1) Scalability. SpeedSketch can scale user numbers (saving memory space) to a factor of 6430 while maintaining a low average error rate of 0.1% in real-world datasets. (2) Accuracy. In theory, SpeedSketch stands out as the only sketch algorithm offering a per-user relative error bound. (3) Speed. SpeedSketch is implemented on a high-speed programmable switch with a throughput capacity of 4.8 billion items per second. All codes are available on GitHub for reference.

关键词： Codes Scalability Face recognition Memory management Switches Throughput approximation algorithms

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Three Coils, High-Resolution Receiver Positioning System for Wireless Power Transfer

Three Coils, High-Resolution Receiver Positioning System for...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Jiaxing Zhang Jiayang Li Dai Jiang Andreas Demosthenous Department of Electronic and Electrical Engineering University College London Torrington Place London UK

ISBN: (数字)9798350330991

ISBN: (纸本)9798350331004

Wireless power transfer with inductively coupled coils is widely used for powering implantable devices. For a continuously moving receiver coil (Rx), real-time detection of its position is important for the magnetic field distribution control. This paper proposes an Rx positioning system that uses three varying-pitch coils and applies a trilateration algorithm for positioning. It operates at a frequency of 125 kHz. The detection area is approximately 224 cm 2 , when using a 2 cm radius Rx. Experimental results show the position detection system has a 1 cm 2 resolution with an average deviation of 6.8 mm.

关键词： Coils Accuracy Circuits and systems Wireless power transfer Receivers Implants approximation algorithms

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Mutual Coupling Compensation Algorithm for Arrays with Single-Mode Antenna Elements

Mutual Coupling Compensation Algorithm for Arrays with Singl...

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Antennas and Propagation & USNC/URSI National Radio Science Meeting

作者： Isidro Garcia Duncan Madden Kamal Sarabandi The University of Michigan Ann Arbor MI USA

ISBN: (数字)9798350369908

ISBN: (纸本)9798350369915

A novel excitation algorithm to compensate for the effects of mutual coupling in antenna arrays is proposed. By manipulating the array's impedance matrix, the algorithm generates a normalized current excitation for each individual element in the array. This is done by taking advantage of the single mode operation of dipole antennas, often referred to as the single mode approximation, to simplify the analysis of mutual coupling and array synthesis. Simulations of half-wavelength dipole arrays are presented to show the effectiveness of the algorithm when compared to uncompensated excitations. The algorithm produces a far field radiation pattern with increased main beam gain, and decreased side lobes and nulls.

关键词： Phased arrays Couplings Mutual coupling Dipole antennas Conferences approximation algorithms Brain modeling

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Privacy-Preserving Approximate Calculation of Subgraphs in Social Networking Services

Privacy-Preserving Approximate Calculation of Subgraphs in S...

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IEEE International Conference on Web Services (ICWS)

作者： Guixun Luo Yonghan Lin Huilin Ai Zhiyun Zhang Naiyue Chen Li Duan School of Computer Science and Technology Beijing Jiaotong University Beijing China School of Mathematics University of Birmingham Birmingham England School of Electronic and Information Engineering Beijing Jiaotong University Beijing China

ISBN: (数字)9798350368550

ISBN: (纸本)9798350368567

Social Networking Services (SNS) are one of the most widely used web applications and have a profound influence on the real world. Network structure analysis plays a crucial role in the optimization of the functionalities of SNS. In particular, subgraph statistics is widely used as a fundamental method to reveal the basic features and patterns of networks. However, one of the main challenges in data collection is how to perform effective analysis without violating users’ privacy. Existing privacy-preserving subgraph statistics methods mainly rely on enumeration, which are often inefficient or require multiple rounds of interactions. It is difficult to meet the needs of rapidly evolving social network services. To address this problem, we propose a set of new algorithms that aim to improve the efficiency and accuracy of subgraph counting under privacy preservation. By focusing on two typical network structures, the Random network and Barabási-Albert network, our approach is able to efficiently analyse the network structure while ensuring individual privacy. These algorithms perform with high accuracy in experiments, especially in evaluating triangles in BA networks, when compared with the state-of-the-art algorithm.

关键词： Privacy Data privacy Accuracy Social networking (online) Web services Estimation Focusing Complex networks approximation algorithms Optimization

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QUETZAL: Vector Acceleration Framework for Modern Genome Sequence Analysis algorithms

QUETZAL: Vector Acceleration Framework for Modern Genome Seq...

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Annual International Symposium on Computer Architecture, ISCA

作者： Julian Pavon Ivan Vargas Valdivieso Carlos Rojas Cesar Hernandez Mehmet Aslan Roger Figueras Yichao Yuan Joël Lindegger Mohammed Alser Francesc Moll Santiago Marco-Sola Oguz Ergin Nishil Talati Onur Mutlu Osman Unsal Mateo Valero Adrian Cristal Barcelona Supercomputing Center Universitat Politècnica de Catalunya TOBB ETÜ University of Economics & Technology University of Michigan ETH Zurich

ISBN: (数字)9798350326581

ISBN: (纸本)9798350326598

Genome sequence analysis is fundamental to medical breakthroughs such as developing vaccines, enabling genome editing, and facilitating personalized medicine. The exponentially expanding sequencing datasets and complexity of sequencing algorithms necessitate performance enhancements. While the performance of software solutions is constrained by their underlying hardware platforms, the utility of fixed-function accelerators is restricted to only certain sequencing *** paper presents QUETZAL, the first general-purpose vector acceleration framework designed for high efficiency and broad applicability across a diverse set of genomics algorithms. While a commercial CPU’s vector datapath is a promising candidate to exploit the data-level parallelism in genomics algorithms, our analysis finds that its performance is often limited due to long-latency scatter/gather memory instructions. QUETZAL introduces a hardware-software co-design comprising an accelerator microarchitecture closely integrated with the CPU’s vector datapath, alongside novel vector instructions to fully capitalize on the proposed hardware. QUETZAL integrates a set of scratchpad-style buffers meticulously designed to minimize latency associated with scatter/gather instructions during the retrieval of input genome sequences data. QUETZAL supports both short and long reads, and different types of sequencing data formats. A combination of hardware and software techniques enables QUETZAL to reduce the latency of memory instructions, perform complex computation using a single instruction, and transform data representations at runtime, resulting in overall efficiency gain. QUETZAL significantly accelerates a vectorized CPU baseline on modern genome sequence analysis algorithms by 5.7×, while incurring a small area overhead of 1.4% post place-and-route at the 7nm technology node compared to an HPC ARM CPU.

关键词： Sequential analysis Sequences Software algorithms Genomics approximation algorithms Vectors Hardware

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An Energy Efficient CMA Equalizer based on Approximate Computing

An Energy Efficient CMA Equalizer based on Approximate Compu...

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IEEE International Conference on Electronic Information and Communication Technology (ICEICT)

作者： Junjie Zhou Ke Chen College of Integrated Circuits Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (数字)9798350384437

ISBN: (纸本)9798350384444

Constant Modulus Algorithm (CMA) has found extensive application within digital communication systems. Unlike traditional adaptive equalizers, the CMA equalizer leverages its own statistical properties to recover signals from channel interference, obviating the need for training sequences. However, the significant number of multiplier units required by the CMA algorithm can lead to excessive circuit overhead. Approximate computing offers a promising approach to achieving high performance while mitigating circuit complexity. In this study, we propose an approximation scheme tailored specifically for the CMA equalizer. We introduce two approximate multipliers, strategically integrated into different computational modules to ensure mutual compensation for accuracy. Implementation results demonstrate that the proposed approximate CMA system achieves reductions of 40.10% in area and 18.13% in power consumption compared to the precise system.

关键词： Training Electric potential Accuracy Power demand Approximate computing Interference approximation algorithms

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