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Factorised polar-format back-projection algorithm

IET RADAR SONAR AND NAVIGATION 2015年第7期9卷 875-880页

作者： Yang, Zemin Xing, Mengdao Zhang, Yimin D. Sun, Guangcai Bao, Zheng Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Villanova Univ Ctr Adv Commun Villanova PA 19085 USA

The back-projection algorithm (BPA) is a useful technique for synthetic aperture radar (SAR) imaging. The fast factorised BPA (FFBPA) recursively partitions the back-projection integral, thus significantly reducing the overall computation complexity corresponding to the improvement obtained by the FFT algorithm compared with the direct implementation of the discrete Fourier transform. In this study, the authors propose a new fast method, termed as the factorised polar-format BPA (FPFBPA), which combines the polar format algorithm and the factorised back-projection concept. It is demonstrated that, when the first-stage subaperture in the FPFBPA contains more than 3 pulses, the proposed method further reduces the computation complexity comparing with FFBPA, provided that the same interpolation method is used. The proposed algorithm is also capable of processing curved orbit and multi-mode SAR data. The effectiveness of the proposed algorithm is verified by the processed results using measured airborne data.

关键词： synthetic aperture radar radar imaging computational complexity discrete Fourier transforms interpolation airborne radar factorised polar format back-projection algorithm synthetic aperture radar imaging multimode SAR imaging fast factorised BPA FFBPA back-projection integral computation complexity reduction FFT algorithm discrete Fourier transform factorised polar format BPA FPFBPA interpolation method airborne data measurement fast Fourier transform

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Optimal access mode selection and resource allocation for cellular-VANET heterogeneous networks

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IET COMMUNICATIONS 2017年第13期11卷 2012-2019页

作者： Qi, Yanjia Wang, Hongyu Zhang, Lingyan Wang, Bing Dalian Univ Technol Sch Informat & Commun Engn Dalian 116024 Peoples R China State Grid JILIN Maintenance Co Changchun 130000 Jilin Peoples R China

In recent years, the vehicular ad-hoc networks (VANETs) have attracted plenty of attention. However, VANETs can hardly meet surging demands of mobile data. Device-to-device (D2D) communication is regarded as a promising method for providing the reliable connectivity between vehicles. The heterogeneous networks including conventional cellular network and VANETs, where the cellular links and the D2D-based vehicle-to-vehicle communication links coexist by reusing the same spectrum resources, result in a more complicated interference scenario. Thus the access mode switch and resource allocation between cellular and VANETs becomes a challenging issue. In this study, the authors formulate an optimal access mode selection and resource allocation scheme as a user aggregate utility maximisation problem with the joint consideration of various network topologies, transmission delay and power reduction. To reduce the high computation complexity, they provide a distributed algorithm that converges to a near-optimal solution via augmented Lagrangian technique. Numerical results show that remarkable throughput gains are achieved relative to the existing work, especially for large-scale networks. The network throughput can be considerably improved as well due to power reduction.

关键词： vehicular ad hoc networks resource allocation frequency allocation cellular radio radio links radiofrequency interference optimisation telecommunication network topology communication complexity distributed algorithms optimal access mode selection resource allocation cellular-VANET heterogeneous networks vehicular ad-hoc networks mobile data device-to-device communication cellular network cellular links D2D-based vehicle-to-vehicle communication links spectrum resource reuse interference scenario access mode switch user aggregate utility maximisation problem network topologies transmission delay power reduction computation complexity reduction distributed algorithm near-optimal solution augmented Lagrangian technique throughput gains

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Fast mode decision method based on edge feature for HEVC inter-prediction

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IET IMAGE PROCESSING 2018年第5期12卷 644-651页

作者： Tsai, Tsung-Han Su, Sheng-Shuan Lee, Ting-Yu Natl Cent Univ Dept Elect Engn Taoyuan Taiwan

High-efficiency video coding (HEVC) is an international video coding standard. It can reduce bit rate by almost 50% when preceding state-of-the-art standard H.264/advanced video coding (AVC) with the same objective quality but increase about 40% encoding complexity. The computation complexity of HEVC largely relies on the inter-prediction, which consumes about 60-70% of the total encoding time. This study proposes a fast mode decision method for HEVC inter-prediction. Since current coding unit (CU) is the basic coding zone for HEVC encoding process, the authors apply the edge detection method with Sobel operator to extract the edge information inside CU. It is based on the threshold-oriented means to compare those edge values and then predict the best partition mode for this CU. Furthermore, they define a weighting factor to adopt various resolutions of test sequence from wide quarter video graphics array (WQVGA) to 1600p. The experimental results show that the proposed algorithm can reduce computational complexity by 50% on average compared with HEVC reference software, and appear to have almost the same coding performance.

关键词： video coding feature extraction edge detection computational complexity fast mode decision method edge feature HEVC interprediction high-efficiency video coding interprediction international video coding standard H 264 encoding complexity computation complexity reduction total encoding time HEVC encoding process coding unit coding zone edge detection method Sobel operator edge information extraction threshold-oriented means weighting factor test sequence

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Adaptive Extended Min-Sum Algorithm for Nonbinary LDPC Decoding

Adaptive Extended Min-Sum Algorithm for Nonbinary LDPC Decod...

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54th Annual IEEE Global Telecommunications Conference (GLOBECOM)

作者： Guan, Xuan Fei, Yunsi Freescale Semiconductor United States Electrical and Computer Engineering University of Connecticut United States

ISBN: (纸本)9781424492688

Low Density Parity Check (LDPC) codes over a Galois Field GF(q) can provide significantly better error-correcting quality than binary LDPC codes with moderate code length. However, the computational complexity and memory requirement of nonbinary codes are much higher, limiting the application of non-binary LDPC codes. In this paper, we propose an adaptive message truncation algorithm for non-binary LDPC decoding, guided by the estimated code error rates. Compared to the previous fixed message truncation method, it can cut the messages adaptively, and therefore provide better decoding quality and computation complexity reduction. To further reduce the computation, we propose another adaptive check node update algorithm, simplifying the decoding by reducing the number of check nodes updating. Our simulation results demonstrate that by combining these two algorithms together, the average message size can be reduced greatly and good decoding quality is achieved, at a little cost of iterations. Compared to the existing truncation algorithms, our approach can reduce the order of complexity to O(n(a)log(2)(n(a))) (where n(a) is messages size), with less performance degradation.

关键词： complexity theory Decoding Error analysis Galois field Galois fields Iterative decoding Peer to peer computing Signal to noise ratio adaptive extended min-sum algorithm computation complexity reduction computational complexity decoding quality error correction codes error-correcting quality low density parity check codes nonbinary LDPC decoding parity check codes

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DOA Estimation by Synthetic Aperture Measurement with Compressed Sensing and Neural Network

DOA Estimation by Synthetic Aperture Measurement with Compre...

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International Symposium on Antennas and Propagation (ISAP)

作者： Ikeda, Tomonori Fujimoto, Mitoshi Tomimoto, Kazuma Yamaguchi, Ryo Univ Fukui Grad Sch Engn 3-9-1 Bunkyo Fukui 9108507 Japan SoftBank Corp Tokyo Japan

ISBN: (纸本)9781665431132

This paper proposes a DOA estimation method by synthetic aperture measurement with neural network and compressed sensing. The proposed method enables to simplify the synthetic aperture measurement by high-resolution of compressed sensing. Additionally, preprocessing technique using synthetic aperture and neural network realizes to reduce computational complexity of compressed sensing. Thus, proposed method is suitable for radio wave environment survey.

关键词： Synthetic Aperture Compressed Sensing Neural Network DOA estimation computation complexity reduction

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Optimum Delay-Rate Tradeoff in Ergodic Interference Alignment 7

Optimum Delay-Rate Tradeoff in Ergodic Interference Alignmen...

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7th International Symposium on Telecommunications (IST)

作者： Khamesi, Atieh R. Lahouti, Farshad Zorzi, Michele Univ Tehran Coll Engn Sch Elect & Comp Engn Tehran Iran Univ Padua Dept Informat Engn Padua Italy

ISBN: (纸本)9781479953592

In this paper, we consider one of the main disadvantages of Ergodic Interference Alignment, i.e., delay. We propose two methods to solve the open problem of finding the best choice of user sets in order to minimize the delay. With these methods we are able to find the best JAP-B scheme which aims to trade off rate for delay in Ergodic Interference Alignment. First, we provide the solution based on the trellis structure and Viterbi algorithm. Observation and analysis of the result of this method for the different networks lead to the second proposed solution. With this method, the computation complexity reduces to the substitution of the network's parameters in a closed form equation and is independent of the network size. The local optimality of this solution is also proved.

关键词： MIMO communication maximum likelihood estimation radiofrequency interference trellis codes wireless channels JAP-B scheme Viterbi algorithm closed form equation computation complexity reduction ergodic interference alignment multiple input multiple output channel optimum delay-rate tradeoff trellis structure Benchmark testing Delays Educational institutions Equations Interference Receivers Vectors Benchmark testing Viterbi algorithm Trellis codes MIMO communication Radiofrequency interference wireless channels Educational institutions maximum likelihood estimation Receivers delay closed forms interference interference

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A Generalized Modified Split-Radix FFT Algorithm For N=q×2~m And Its Applications

A Generalized Modified Split-Radix FFT Algorithm For N=q×2~...

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International Congress on Image and Signal Processing

作者： Jiasong Wu Longyu Jiang Yang Chen Lotfi Senhadji Huazhong Shu Key Lab. of Comput. Network & Inf. Integration Southeast Univ. Nanjing China

ISBN: (纸本)9781479958368

This paper presents a generalized odd factor modified split-radix-2/4 Fast Fourier transform (FFT) algorithm for computing the DFT of length-N = q×2~m, where q is a positive odd integer. Compared with former algorithms for N = q×2~m, the proposed algorithm reduces the computation complexity of DFT from O(4 N log_2(N/q)) to O((34/9)Nlog_2(N/q)) for complex input. The proposed algorithm can be applied to some international wireless standards where the length of DFT is not a power of two, and to some international speech and audio standards where the modified discrete cosine transform (MDCT) with length-N = q×2~m, q = 5,15 is used.

关键词： audio signal processing computational complexity digital arithmetic discrete cosine transforms fast Fourier transforms speech processing DFT computation computation complexity reduction generalized modified split-Radix FFT algorithm generalized odd factor modified split-radix-2/4 fast Fourier transform algorithm international audio standards international speech standards international wireless standards modified discrete cosine transform positive odd integer signal processing Algorithm design and analysis Bismuth computational complexity Discrete Fourier transforms Signal processing algorithms Standards DFT FFT international standard split-radix

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