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23rd IEEE International Conference on Communication Technology, ICCT 2023

作者： Gan, Xu Huang, Chongwen Yang, Zhaohui Zhong, Caijun Chen, Xiaoming He, Jiguang Zhang, Zhaoyang Guo, Qinghua Yuen, Chau Debbah, Merouane College of Information Science and Electronic Engineering Zhejiang University China Xidian University State Key Laboratory of Integrated Service Networks China Technology Innovation Institute Abu Dhabi United Arab Emirates School of Electrical Computer and Telecommunications Engineering University of Wollongong Australia School of Electrical and Electronics Engineering Nanyang Technological University Singapore Khalifa University of Science and Technology United Arab Emirates

ISBN: (纸本)9798350325959

Reconfigurable intelligent surface (RIS) has great potential to improve the performance of integrated sensing and communication (ISAC) systems, especially in scenarios where line-of-sight paths between the base station and users are blocked. However, the spectral efficiency of RIS-aided ISAC uplink transmissions may be drastically reduced by the heavy burden of pilot overhead for realizing sensing capabilities. In this paper, we tackle this bottleneck by proposing a superimposed symbol scheme, which superimposes sensing pilots onto data symbols over the same time-frequency resources. Specifically, a low-complexity simultaneous communication and localization algorithm is proposed, which employs the unitary approximate message passing in the Bayesian learning framework for initial angle estimate, followed by iterative refinements through reduced-dimension matrix calculations. Moreover, the sparse code multiple access technology is incorporated into this iterative framework for accurate data detection which also facilitates localization. Numerical results show that the proposed superimposed symbol-based scheme empowered by the developed algorithm can achieve centimeter-level localization and provide an effective throughput improvement over 143%. © 2023 IEEE.

关键词： Bayesian learning Integrated sensing and communication (ISAC) reconfigurable intelligent surface (RIS) superimposed coding

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Real-Time Observation of Interference between Atomic One-Electron and Two-Electron Excitations

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Physical Review Letters 2012年第12期108卷 123601-123601页

作者： Henning Geiseler Horst Rottke Nickolai Zhavoronkov Wolfgang Sandner Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie Max-Born-Straße 2 A 12489 Berlin Germany

We present results of real-time tracking of atomic two-electron dynamics in an autoionizing transient wave packet in krypton. A coherent superposition of two Fano resonances is excited with a femtosecond extreme-ultraviolet pulse. The evolution of the corresponding wave packet is subsequently probed with a delayed infrared pulse. In our specific case, we get access to the interference between one- and two-electron excitation channels in the launched wave packet, which is superimposed on its decay through autoionization. A simple model is able to account for the observed dynamical evolution of this wave packet.

关键词： ELECTRIC interference ASTRONOMICAL observations WAVE packets AUGER effect superimposed coding KRYPTON

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OPTIMAL SIGNATURE EXTRACTION AND INFORMATION LOSS

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ACM TRANSACTIONS ON DATABASE SYSTEMS 1987年第3期12卷 395-428页

作者： FALOUTSOS, C CHRISTODOULAKIS, S UNIV MARYLAND INST ADV COMP STUDIESCOLLEGE PKMD 20742 UNIV WATERLOO FAC MATHDEPT COMP SCIWATERLOO N2L 3G1ONTARIOCANADA

Signature files seem to be a promising access method for text and attributes. According to this method, the documents (or records) are stored sequentially in one file ("text file"), while abstractions of the documents ("signatures") are stored sequentially in another file ("signature file"). In order to resolve a query, the signature file is scanned first, and many nonqualifying documents are immediately rejected. We develop a framework that includes primary key hashing, multiattribute hashing, and signature files. Our effort is to find the optimal signature extraction *** main contribution of this paper is that we present optimal and efficient suboptimal algorithms for assigning words to signatures in several environments. Another contribution is that we use information theory, and study the relationship of the false drop probability Fd and the information that is lost during signature extraction. We give tight lower bounds on the achievable Fd and show that a simple relationship holds between the two quantities in the case of optimal signature extraction with uniform occurrence and query frequencies. We examine hashing as a method to map words to signatures (instead of the optimal way), and show that the same relationship holds between Fd and loss, indicating that an invariant may exist between these two quantities for every signature extraction method.

关键词： Hashing information theory signature files superimposed coding

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Intraframe Scene Capturing and Speed Measurement Based on superimposed Image: New Sensor Concept for Vehicle Speed Measurement

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JOURNAL OF SENSORS 2016年第1-6期2016卷 8696702-8696702页

作者： Nemeth, Mate Zarandy, Akos Hungarian Acad Sci MTA SZTAKI Inst Comp Sci & Control Computat Opt Sensing & Proc Lab H-1111 Budapest Hungary Pazmany Peter Catholic Univ PPKE ITK Fac Informat Technol H-1083 Budapest Hungary

A vision based vehicle speed measurement method is presented in this paper. The proposed intraframe method calculates speed estimates based on a single frame of a single camera. With a special double exposure, a superimposed image can be obtained, where motion blur appears significantly only in the bright regions of the otherwise sharp image. This motion blur contains information of the movement of bright objects during the exposure. Most papers in the field of motion blur are aiming at the removal of this image degradation effect. In this work, we utilize it for a novel speed measurement approach. An applicable sensor structure and exposure-control system are also shown, as well as the applied image processing methods and experimental results.

关键词： Speed measurements superimposed coding Image analysis Information theory Control theory (Mathematics)

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OPTIMAL WEIGHT ASSIGNMENT FOR SIGNATURE GENERATION

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ACM TRANSACTIONS ON DATABASE SYSTEMS 1992年第2期17卷 346-373页

作者： LENG, CWR LEE, DL OHIO STATE UNIV DEPT COMP & INFORMAT SCICOLUMBUSOH 43210

Previous work on superimposed coding has been characterized by two aspects. First, it is generally assumed that signatures are generated from logical text blocks of the same size;that is, each block contains the same number of unique terms after stopword and duplicate removal. We call this approach the fixed-size block (FSB) method, since each text block has the same size, as measured by the number of unique terms contained in it. Second, with only a few exceptions [6, 7, 8, 9, 17], most previous work has assumed that each term in the text contributes the number of ones to the signature (i.e, the weight of the term signatures is fixed). The objective of this paper is to derive an optimal weight assignment that assigns weights to document terms according to their occurrence and query frequencies in order to minimize the false-drop probability The optimal scheme can account for both uniform and nonuniform occurrence and query frequencies, and the signature generation method is still based on hashing rather than on table lookup- Furthermore, a new way of generating signatures, the fixed-weight block (FWB) method, is introduced. FWB controls the weight of every signature to a constant, whereas in FSB, only the expected signature weight is constant. We have shown that FWB has a lower false-drop probability than that of the FSB method, but its storage overhead is slightly higher. Other advantages of FWB are that the optimal weight assignment can be obtained analytically without making unrealistic assumptions and that the formula for computing the term signature weights is simple and efficient.

关键词： DESIGN PERFORMANCE ACCESS METHOD coding METHODS DOCUMENT RETRIEVAL INFORMATION RETRIEVAL OPTIMIZATION SIGNATURE FILE superimposed coding TEXT RETRIEVAL

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ACCESS METHODS FOR TEXT

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COMPUTING SURVEYS 1985年第1期17卷 49-74页

作者： FALOUTSOS, C Univ. of Toronto Toronto Ont. Canada

This paper compares text retrieval methods intended for office systems. The operational requirements of the office environment are discussed, and retrieval methods from database systems and from information retrieval systems are examined. We classify these methods and examine the most interesting representatives of each class. Attempts to speed up retrieval with special purpose hardware are also presented, and issues such as approximate string matching and compression are discussed. A qualitative comparison of the examined methods is presented. The signature file method is discussed in more detail. [ABSTRACT FROM AUTHOR]

关键词： Document retrieval information retrieval office automation office filing signature files special purpose hardware superimposed coding text retrieval

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SEARCHING LINEAR FILES ONLINE

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ONLINE REVIEW 1977年第1期1卷 53-58页

作者： HICKEY, T UNIV ILLINOIS COORDINATED SCI LABINFORMAT RETRIEVAL RES LABURBANAIL 61801

Two types of linear on‐line search have been implemented on a data base of 100,000 INSPEC records, and compared with an inverted search program on the same file. It was found that the linear search which does a character‐by‐character scan of the whole file was too slow to be useful as an on‐line search, but that the second linear search, which uses a linear file of keys to select records for full scanning, was useable on‐line. An algorithm suitable for the on‐line searching of the linear file of keys is presented with run time nearly independent of the number of terms in the search query. Neither of the linear searches can compete with an inverted search in terms of user convenience, but they do not require as complex file‐maintenance software, they use less processing time to build indexes, and they have lower storage requirements than inverted files.

关键词： On‐line searching On‐line interaction Linear files Sequential files Inverted files superimposed coding Microstructure of words

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ESTIMATING ACCESSES IN PARTITIONED SIGNATURE FILE ORGANIZATIONS

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ACM TRANSACTIONS ON INFORMATION SYSTEMS 1993年第2期11卷 133-142页

作者： CIACCIA, P ZEZULA, P TECH UNIV BRNO CS-60200 BRNOCZECHOSLOVAKIA

We show that performance of some basic methods for the partitioning of signature files, namely Quick Filter and Fixed Prefix, can be easily evaluated by means of a closed formula. The approximation is based on well-known results from probability theory, and, as shown by simulations, introduces no appreciable errors when compared with the exact, cumbersome formulas used so far. Furthermore, we prove that the exact formulas for the two methods coincide. Although this does not imply that the two methods behave in the same way, it sheds light on the way they could be compared.

关键词： ACCESS METHOD INFORMATION RETRIEVAL PERFORMANCE EVALUATION superimposed coding

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A spatial filter for similarity retrieval

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INTERNATIONAL JOURNAL OF PATTERN RECOGNITION AND ARTIFICIAL INTELLIGENCE 1996年第6期10卷 711-730页

作者： Chang, CC Jiang, JH NATL CHUNG CHENG UNIV INST COMP SCI & INFORMAT ENGNCHIAYI 62107TAIWAN

Recently, Yang and Lee(13) proposed a powerful data structure, the 2D B-string, to express the spatial knowledge embedded in iconic images. The data structure can be used to describe images with partly- or completely- overlapping objects without the need for partitioning the objects. We propose a signature file method for similarity retrieval of symbolic images described in 2D B-strings. The signatures of images are extracted by the disjoint coding and the superimposed coding techniques. A linear hashing function is adopted to organise the signature file. The experimental results show that the method has better performance than the one proposed by Lee, Yang and Chen.(11)

关键词： similarity retrieval 2D-string 2D B-string two-level signature disjoint coding superimposed coding

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Information Retrieval: PEEKABIT, computer offspring of punched card PEEKABOO, for natural language searching

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Communications of the ACM 1968年第9期11卷 595-598页

作者： Hutton, Fred C. Union Carbide Corp. Oak Ridge TN United States

The “peekaboo” idea from punched card information retrieval methods has been mated with the idea of superimposed punching to produce a programming technique which cuts computer run time in half on a test search of 33,000 subject index entries. A search program using the device has been operational since late 1963. As an item is entered in the store, an 18-byte mask is created from the item's meaningful words using the inclusive OR operation. If, at search time, the logical product (using the AND operation) of this mask and a similarly constructed question mask is not equal to the question mask, then one or more question words are not present in the store item. An equality is inconclusive;the words of the store item must be unpacked and compared with question words. The present store is made up of over 600,000 subject index entries estimated to average 60 characters each. Longer texts, such as abstracts, could be handled by multiple masks. © 1968, ACM. All rights reserved.

关键词： computer search technique information compaction natural language searching peekaboo superimposed coding text searching

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