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arXiv 2020年

作者： Wang, Huabin Cheng, Rui Zhou, Jian Tao, Liang Kwan, Hon Keung MOE Key Laboratory of Intelligent Computing and Signal Processing School of Computer Science and Technology Anhui University Hefei Anhui230601 China Department of Electrical and Computer Engineering University of Windsor WindsorONN9B 3P4 Canada

An ability to generalize unconstrained conditions such as severe occlusions and large pose variations remains a challenging goal to achieve in face alignment. In this paper, a multistage model based on deep neural networks is proposed which takes advantage of spatial transformer networks, hourglass networks and exemplar-based shape constraints. First, a spatial transformer - generative adversarial network which consists of convolutional layers and residual units is utilized to solve the initialization issues caused by face detectors, such as rotation and scale variations, to obtain improved face bounding boxes for face alignment. Then, stacked hourglass network is employed to obtain preliminary locations of landmarks as well as their corresponding scores. In addition, an exemplar-based shape dictionary is designed to determine landmarks with low scores based on those with high scores. By incorporating face shape constraints, misaligned landmarks caused by occlusions or cluttered backgrounds can be considerably improved. Extensive experiments based on challenging benchmark datasets are performed to demonstrate the superior performance of the proposed method over other state-of-the-art methods. Copyright © 2020, The Authors. All rights reserved.

关键词： Deep neural networks

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Antenna Array Enabled Space/Air/Ground communications and Networking for 6G

arXiv

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arXiv 2021年

作者： Xiao, Zhenyu Han, Zhu Nallanathan, Arumugam Dobre, Octavia A. Clerckx, Bruno Choi, Jinho He, Chong Tong, Wen The School of Electronic and Information Engineering Beihang University Beijing100191 China The Department of Electrical and Computer Engineering The University of Houston HoustonTX77004 United States The Department of Computer Science and Engineering Kyung Hee University Seoul446-701 Korea Republic of The School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom The Faculty of Engineering and Applied Science Memorial University St. John’sNLA1C 5S7 Canada The Communications and Signal Processing Group Department of Electrical and Electronic Engineering Imperial College London LondonSW7 2AZ United Kingdom The School of Information Technology Deakin University GeelongVIC3220 Australia The Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China The Wireless Advanced System Competency Centre Huawei Technologies Co. Ltd. OttawaONK2K 3J1 Canada

Antenna arrays have a long history of more than 100 years and have evolved closely with the development of electronic and information technologies, playing an indispensable role in wireless communications and radar. With the rapid development of electronic and information technologies, the demand for all-time, all-domain, and full-space network services has exploded, and new communication requirements have been put forward on various space/air/ground platforms. To meet the ever increasing requirements of the future sixth generation (6G) wireless communications, such as high capacity, wide coverage, low latency, and strong robustness, it is promising to employ different types of antenna arrays (e.g., phased arrays, digital arrays, and reconfigurable intelligent surfaces, etc.) with various beamforming technologies (e.g., analog beamforming, digital beamforming, hybrid beamforming, and passive beamforming, etc.) in space/air/ground communication networks, bringing in advantages such as considerable antenna gains, multiplexing gains, and diversity gains. However, enabling antenna array for space/air/ground communication networks poses specific, distinctive and tricky challenges, which has aroused extensive research attention. This paper aims to overview the field of antenna array enabled space/air/ground communications and networking. The technical potentials and challenges of antenna array enabled space/air/ground communications and networking are presented first. Subsequently, the antenna array structures and designs are discussed. We then discuss various emerging technologies facilitated by antenna arrays to meet the new communication requirements of space/air/ground communication systems. Enabled by these emerging technologies, the distinct characteristics, challenges, and solutions for space communications, airborne communications, and ground communications are reviewed. Finally, we present promising directions for future research in antenna array enabled space/ai

关键词： Beamforming

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Codes with Locality for Two Erasures

Codes with Locality for Two Erasures

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作者： Prakash, N. Lalitha, V. Balaji, S.B. Vijay Kumar, P. Indian Institute of Science Bengaluru560 012 India Signal Processing and Communications Research Centre International Institute of Information Technology Hyderabad500 032 India Department of Electrical Communication Engineering Indian Institute of Science Bengaluru560 012 India Department of Electrical Communication Engineering Indian Institute of Science Bengaluru560 012 India Intel Labs HillsboroOR97124 United States Department of Electrical and Computer Engineering University of Southern California Los AngelesCA United States

Codes with locality are a class of codes introduced by Gopalan et al. to efficiently repair a failed node, by minimizing the number of nodes contacted during repair. An [n,k] systematic code is said to have information locality r , if each message symbol can be recovered by accessing ≤q r other symbols. An [n,k] code is said to have all-symbol locality r , if each code symbol can be recovered by accessing ≤ r other symbols. In this paper, we consider a generalization of codes with all-symbol locality to the case of handling two erasures. We study codes with locality that can recover from two erasures via a sequence of two local, parity-check computations. We refer to these codes as sequential-recovery locally repairable codes (denoted by 2-seq LR codes). Earlier approaches to handling multiple erasures considered recovery in parallel;the sequential approach allows us to potentially construct codes with improved minimum distance. We derive an upper bound on the rate of 2-seq LR codes. We provide constructions based on regular graphs which are rate-optimal with respect to the derived bound. We also characterize the structure of any rate-optimal code. By studying the Generalized Hamming Weights of the dual code, we derive a recursive upper bound on the minimum distance of 2-seq LR codes. We also provide constructions of a family of codes based on Turán graphs, that are optimal with respect to this bound. We also present explicit distance-optimal Turán graph based constructions of 2-seq LR codes for certain parameters. Our approach also leads to a new bound on the minimum distance of codes with all-symbol locality for the single-erasure case. © 1963-2012 IEEE.

关键词： Recovery

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Locality in index coding for large min-rank

arXiv

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arXiv 2019年

作者： Natarajan, Lakshmi Dau, Hoang Krishnan, Prasad Lalitha, V. Department of Electrical Engineering Indian Institute of Technology Hyderabad Department of Electrical and Computer Systems Engineering Monash University Melbourne Australia Signal Processing & Communications Research Center International Institute of Information Technology Hyderabad India

An index code is said to be locally decodable if each receiver can decode its demand using its side information and by querying only a subset of the transmitted codeword symbols instead of observing the entire codeword. Local decodability can be a beneficial feature in some communication scenarios, such as when the receivers can afford to listen to only a part of the transmissions because of limited availability of power. The locality of an index code is the ratio of the maximum number of codeword symbols queried by a receiver to the message length. In this paper we analyze the optimum locality of linear codes for the family of index coding problems whose min-rank is one less than the number of receivers in the network. We first derive the optimal trade-off between the index coding rate and locality with vector linear coding when the side information graph is a directed cycle. We then provide the optimal trade-off achieved by scalar linear coding for a larger family of problems, viz., problems where the min-rank is only one less than the number of receivers. While the arguments used for achievability are based on known coding techniques, the converse arguments rely on new results on the structure of locally decodable index codes. Copyright © 2019, The Authors. All rights reserved.

关键词： Decoding

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Information Transmission Through Solids Using Ultrasound Invited Paper

Information Transmission Through Solids Using Ultrasound Inv...

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2018 IEEE International Ultrasonics Symposium, IUS 2018

作者： Saniie, Jafar Wang, Boyang Huang, Xin Department of Electrical and Computer Engineering Illinois Institute of Technology Embedded Computing and Signal Processing Research Laboratory ChicagoIL United States

ISBN: (纸本)9781538634257

Ultrasonic signals can be utilized as a viable communication method to transmit information through gas, liquid, and solid channels or a mixed media consisting of a solid interfaced with liquid and/or gas. Underwater communication channels using sound waves cause many challenges, often unforeseen, due to absorption, scattering, refractions, reverberations, multipaths, doppler shifts, temperature, salinity, and acoustic scintillation. Ultrasonic communication through the air is less prone to the environmental challenges that are often encountered in the underwater communications. Ultrasonic communication in solid channels is also adversely affected by absorption, scattering, refractions, reverberations, beam skewing, dispersion, mode conversation, multipaths, and above all these challenges are compounded by the geometrical structure of solids and type of ultrasonic waves. With solid structures many different ultrasonic wave types can be generated including Longitudinal (Compressional), Shear (Transverse), Surface-Rayleigh, Plate-Lamb (Symmetrical or Extensional Mode and Asymmetric or Flexural Mode), Plate-Love, and Stoneley (Leaky Rayleigh). The type of waves is governed by the frequency and angle of the incident waves on a solid structure where the quality of the signal for communication is limited by the composition and geometrical shape of the solids. For this study we have developed a testbed platform using the ZYNQ SoC (System-on-Chip) FPGA by Xilinx which offers reconfigurability and high-performance computational capability, high speed signal converters, power amplifiers for excitation of transducers, low noise receiving amplifiers and high frequency ultrasonic transducers for transmitting and receiving information. Theoretically, ASK (amplitude shift keying) or any form of digital modulation can be realized with the system using the concept of the software-defined ultrasonic communications (SDUC). In practice, the received signal is very complex, primarily ca

关键词： Underwater acoustics

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Automatic flower and visitor detection system 26

Automatic flower and visitor detection system

引用

26th European signal processing Conference, EUSIPCO 2018

作者： Tran, Dat Thanh Høye, Toke Thomas Gabbouj, Moncef Iosifidis, Alexandros Laboratory of Signal Processing Tampere University of Technology Finland Department of Bioscience Aarhus University Aarhus Denmark Department of Engineering Electrical and Computer Engineering Aarhus University Denmark

ISBN: (纸本)9789082797015

The visit patterns of insects to specific flowers at specific times during the diurnal cycle and across the season play important roles in pollination biology. Thus, the ability to automatically detect flowers and visitors occurring in video sequences greatly reduces the manual human efforts needed to collect such data. Data-dependent approaches, such as supervised machine learning algorithms, have become the core component in several automation systems. In this paper, we describe a flower and visitor detection system using deep Convolutional Neural Networks (CNN). Experiments conducted in image sequences collected during field work in Greenland during June-July 2017 indicate that the system is robust to different shading and illumination conditions, inherent in the images collected in the outdoor environments. © EURASIP 2018.

关键词： Deep neural networks

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Secure Edge Caching Placement and Delivery for Ultra-Reliable and Low-Latency Vehicular Networks

Secure Edge Caching Placement and Delivery for Ultra-Reliabl...

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IEEE Globecom Workshops

作者： Haojun Yang Kuan Zhang Kan Zheng Yi Qian Intelligent Computing and Communications (IC) Lab Wireless Signal Processing and Networks (WSPN) Lab Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing China Department of Electrical and Computer Engineering University of Nebraska-Lincoln Omaha NE USA

ISBN: (数字)9781728109602

ISBN: (纸本)9781728109619

To meet the urgent requirements of ultra-reliable and low-latency communications (URLLCs) in vehicular networks, vehicular edge caching (VEC) becomes a promising solution to reduce backhaul costs and mitigate network congestion. However, the data requested by vehicular users may be maliciously tampered by attackers during the caching delivery phase. In this paper, we investigate the problem of secure caching placement and delivery for a VEC URLLC system. Specifically, we first analyze the lower bound of spectral efficiency for URLLCs and security metric, i.e., vulnerability. Then, an optimization problem of minimizing the maximum vulnerability among all vehicular users is formulated based on the analysis. Subsequently, we propose a secure caching placement and delivery algorithm to obtain the solutions of our formulated problem by reasonable complexity. Simulation results show that the proposed algorithm can significantly improve the performance of security for the VEC URLLC system.

关键词： Security Optimization Roads Reliability Fading channels signal to noise ratio Antennas

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Transferring the Full-Duplex Radio Technology from Wireless Networking to Defense and Security 52

Transferring the Full-Duplex Radio Technology from Wireless ...

引用

52nd Asilomar Conference on signals, Systems and computers, ACSSC 2018

作者： Parlin, Karel Riihonen, Taneli Wichman, Risto Korpi, Dani Rantelon Tallinn Estonia Laboratory of Electronics and Communications Engineering Tampere University of Technology Tampere Finland Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering Helsinki Finland

ISBN: (纸本)9781538692189

Classically, the in-band full-duplex (IBFD) radio technology that has recently been revolutionizing modern wireless communications was used in the form of same-frequency simultaneous transmit and receive (SF-STAR) operation in continuous-wave radars. Thus far, the main motivation for IBFD operation in commercial wireless communication systems has been to improve their spectral efficiency. In this invited paper, we suggest that IBFD/SF-STAR radios could bring about a paradigm shift in defense applications in the form of a multifunction military full-duplex radio (MFDR) by integrating tactical communications, signals intelligence, and electronic warfare as well as investigate the prospects of transferring the concept to civilian/commercial security and privacy applications in the form of a radio shield. © 2018 IEEE.

关键词： Electronic warfare

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Deep CNN for Extraction of Sidelobes from SAR Imagery in Spectrally Restricted Environment

Deep CNN for Extraction of Sidelobes from SAR Imagery in Spe...

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Asilomar Conference on signals, Systems & computers

作者： Lam H. Nguyen Trac D. Tran RF Signal Processing and Modeling Branch CCDC Army Research Laboratory Adelphi MD USA Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD USA

ISBN: (数字)9781728143002

ISBN: (纸本)9781728143019

This paper explores the critical problem of spectral estimation and recovery via deep convolutional neural networks (CNNs). This problem often arises in ultra-wideband (UWB) synthetic aperture radar (SAR) applications where the wide available bandwidth dictates the final SAR image resolution and quality. Our simple robust solution here also complements well the recently developed stepped-frequency radars built by the U.S. Army Research laboratory, allowing the system to bypass prohibited frequency bands specified by local frequency management agencies and congested frequency bands that are deemed to contain too much interference. Extensive experimental results confirm the validity as well as the promising prospect of the proposed approach - our CNN-based generative network can still robustly recover SAR images when up to 90% of the operating spectrum is missing.

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Straggler mitigation with tiered gradient codes

arXiv

引用

arXiv 2019年

作者： Sasi, Shanuja Lalitha, V. Aggarwal, Vaneet Sundar Rajan, B. Department of Electrical Communication Engineering Indian Institute of Science Bangalore 560012 India Purdue University Signal Processing and Communications Research Center IIIT Hyderabad School of Industrial Engineering School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States

Coding theoretic techniques have been proposed for synchronous Gradient Descent (GD) on multiple servers to mitigate stragglers. These techniques provide the flexibility that the job is complete when any k out of n servers finish their assigned tasks. The task size on each server is found based on the values of k and n. However, it is assumed that all the n jobs are started when the job is requested. In contrast, we assume a tiered system, where we start with n1≥k tasks, and on completion of c tasks, we start n2-n1more tasks. The aim is that as long as k servers can execute their tasks, the job gets completed. This paper exploits the flexibility that not all servers are started at the request time to obtain the achievable task sizes on each server. The task sizes are in general lower than starting all n2tasks at the request times thus helping achieve lower task sizes which helps to reduce both the job completion time and the total server utilization. Copyright © 2019, The Authors. All rights reserved.

关键词： Gradient methods

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