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low-complexity 8-point DCT approximations based on integer functions

SIGNAL PROCESSING 2014年第0期99卷 201-214页

作者： Cintra, R. J. Bayer, F. M. Tablada, C. J. Univ Fed Pernambuco Dept Estat Signal Proc Grp Recife PE Brazil Univ Akron Dept Elect & Comp Engn Akron OH 44325 USA Univ Fed Santa Maria Dept Estat Santa Maria RS Brazil Univ Fed Santa Maria LACESM Santa Maria RS Brazil

The discrete cosine transform (DCT) is a central mathematical operation in several digital signal processing methods and image/video standards. In this paper, we propose a collection of twelve approximations for the 8-point DCT based on integer functions. Considered functions include: the floor, ceiling, truncation, and rounding-off functions. Sought approximations are required to meet the following specific criteria: (i) very low arithmetic complexity, (ii) orthogonality or quasi-orthogonality, and (iii) low-complexity inversion. By varying a scaling parameter, approximations could be systematically obtained and several existing approximations were identified as particular cases of the proposed methodology. Particular cases include the signed DCT and the rounded DCT. Four new quasi-orthogonal approximations were introduced and their practical relevance was demonstrated. All approximations were given fast algorithms based on matrix factorization methods. Proposed approximations are multiplierless;their computation requires only additions and bit-shifting operations. Additive complexity ranged from 18 to 24 additions. Obtained approximations were compared with the exact DCT and assessed in the context of JPEG-like image compression. As quality assessment measures, we considered the peak signal-to-noise ratio and the structural similarity index. Because its low-complexity and good performance properties, the proposed approximations are suitable for hardware implementation in dedicated architectures. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Approximate DCT Image compression Integer functions low-complexity algorithms

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Analog Approximate-FFT 8/16-Beam Algorithm, Architectures and CMOS Circuits for 5G Beamforming MIMO Transceivers

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IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS 2018年第3期8卷 466-479页

作者： Ariyarathna, Viduneth Madanayake, Arjuna Tang, Xinyao Coelho, Diego Cintra, Renato J. Belostotski, Leonid Mandal, Sownyajit Rappaport, Theodore S. Univ Akron Dept Elect & Comp Engn Akron OH 44325 USA Case Western Reserve Univ Dept Elect Engn & Comp Sci Cleveland OH 44106 USA Univ Calgary Dept Elect & Comp Engn Calgary AB T2N 1N4 Canada Univ Fed Pernambuco Signal Proc Grp Dept Estat BR-50740540 Recife PE Brazil NYU Dept Elect & Comp Engn NYU WIRELESS Tandon Sch Engn Brooklyn NY 11201 USA

Emerging millimeter-wave (mmW) wireless systems require beamforming and multiple-input multiple-output (MIMO) approaches in order to mitigate path loss, obstructions, and attenuation of the communication channel. Sharp mmW beams are essential for this purpose and must support baseband bandwidths of at least 1 GHz to facilitate higher system capacity. This paper explores a baseband multi-beamforming method based on the spatial Fourier transform. Approximate computing techniques are used to propose a low-complexity fast algorithm with sparse factorizations that neatly map to integer W/L ratios in CMOS current mirrors. The resulting approximate fast Fourier transform (FFT) can thus be efficiently realized using CMOS analog integrated circuits to generate multiple, parallel mmW beams in both transmit and receive modes. The paper proposes both 8- and 16-point approximate-FFT algorithms together with circuit theory and design information for 65-nm CMOS implementations. Post-layout simulations of the 8-point circuit in Cadence Spectre provide well-defined mmW beam shapes, a baseband bandwidth of 2.7 GHz, a power consumption of 70 mW, and a dynamic range >42.2 dB. Preliminary experimental results confirm the basic functionality of the 8-beam circuit. Schematic-level analysis of the 16-beam I/Q version show worst-case and average side lobe levels of -10.2 dB and -12.2 dB at 1 GHz bandwidth, and -9.1 dB and -11.3 dB at 1.5 GHz bandwidth. The proposed multibeam architectures have the potential to reduce circuit area and power requirements while meeting the bandwidth requirements of emerging 5G baseband systems.

关键词： Analog beamforming multi-beams 5G multi-beam arrays low-complexity algorithms

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Stereophonic acoustic echo cancellation using lattice orthogonalization

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IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING 2002年第7期10卷 517-525页

作者： Mayyas, K Jordan Univ Sci & Technol Dept Elect Engn Irbid 22110 Jordan

Stereophonic teleconferencing provides more natural acoustic perception by virtue of its enhanced sound localization. Of paramount importance is stereo acoustic echo cancellation (SAEC) that poses a difficult challenge to low complexity adaptive algorithms to achieve acceptable AEC due, mainly, to the strong crosscorrelation between the two-channel input signals. This paper proposes a transform domain two-channel lattice algorithm that inherently decorrelates the stereo signals. The algorithm, however, bears a high computational complexity for large filter orders, N. A low complexity 0(4N) algorithm is developed based on employing the functionality of the two-channel lattice cell in the previous algorithm in a weighted subband scheme. The algorithm is capable of producing complete orthogonal subbands of the stereo signals, and also allows for a tradeoff between performance and complexity. The performance of the proposed algorithms is compared with other existing algorithms via simulations and using actual teleconferencing room impulse responses.

关键词： adaptive filters lattice orthogonalization low-complexity algorithms stereo acoustic echo cancellation

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low-complexity JPEG quantization table requiring only bit-shift operations

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IMAGING SCIENCE JOURNAL 2022年第8期70卷 556-563页

作者： Araar, Chaouki Chabbi, Samir Freres Mentouri Constantine 1 Univ Elect Dept POB 325 Ain Bey Way Constantine 25017 Algeria Mohamed Cher Messaadia Univ Souk Ahras Comp Sci Dept Souk Ahras Algeria

In this paper, a low-complexity quantization table is proposed for the baseline JPEG encoder. The proposed scheme does not require any multiplications or additions;only bit-shift operations are involved. The computational complexity should be drastically reduced without almost incurring any significant performance loss. The resulting approximate quantization table has extremely low arithmetic cost and is compared to state-of-the-art schemes in terms of computational complexity. Comparisons showed that our proposal exhibits better or similar results. The proposed low-complexity quantization table is also investigated in image compression context. It could outperforms other related schemes in low and high-compression scenarios. Comparisons with respect to average PSNR and SSIM are conducted. Experiment outcomes show up to 4.03 dB improvement in average PSNR over the state-of-the-art competitor. The proposed quantization table has a considerably lower computational cost while maintaining much higher image quality.

关键词： Image compression JPEG quantization table approximate quantization power-of-two quantization low-complexity algorithms

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low-complexity bit-allocation algorithm for MPEG AAC audio coders

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IEEE SIGNAL PROCESSING LETTERS 2005年第12期12卷 824-826页

作者： Alexandre, E Pena, A Sobreira, M Univ Alcala de Henares Dept Signal Theory & Commun Dept Teor Senal & Comun Escuela Politecn Super Alcala De Henares 28805 Spain Univ Vigo Dept Signal Theory & Commun Dept Teor Senal & Comun ETSE Telecommun Vigo 36310 Spain

This letter presents a method for estimating the quan-. tization noise introduced by a nonuniform quantizer, like those used in the family of MPEG-2/4 AAC audio coders. The method is generalized for the case of estimating the mean squared or the maximum value of the quantization noise. Its use will allow the bit-allocation algorithm to be adapted to different coding scenarios, depending on the available number of bits. Using the proposed method, it is possible to implement a loopless bit-allocation algorithm, without the need for using any kind of iteration loops. This helps to dramatically reduce the computational complexity of the bit-allocation algorithm, making it easier to implement in real-time applications where computational,power is limited.

关键词： audio coding low-complexity algorithms real-time implementations

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Gradient projection decoding of LDPC codes and algorithmic variations

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IET COMMUNICATIONS 2010年第2期4卷 223-233页

作者： Kasparis, C. Beaudonnet, M. Gyftodimos, E. Evans, B. G. Univ Surrey Ctr Commun Syst Res Guildford GU2 5XH Surrey England Univ Aberdeen Dept Comp Sci Aberdeen Scotland

The current study proposes decoding algorithms for low density parity check codes (LDPC), which offer competitive performance-complexity trade-offs relative to some of the most efficient existing decoding techniques. Unlike existing low-complexity algorithms, which are essentially reduced complexity variations of the classical belief propagation algorithm, starting point in the developed algorithms is the gradient projections (GP) decoding technique, proposed by Kasparis and Evans (2007). The first part of this paper is concerned with the GP algorithm itself, and specifically with determining bounds on the step-size parameter, over which convergence is guaranteed. Consequently, the GP algorithm is reformulated as a message passing routine on a Tanner graph and this new formulation allows development of new low-complexity decoding routines. Simulation evaluations, performed mainly for geometry-based LDPC constructions, show that the new variations achieve similar performances and complexities per iteration to the state-of-the-art algorithms. However, the developed algorithms offer the implementation advantages that the memory-storage requirement is significantly reduced, and also that the performance and convergence speed can be finely traded-off by tuning the step-size parameter.

关键词： algorithmic variations performance-complexity tradeoff gradient methods low density parity check codes Interpolation and function approximation (numerical analysis) parity check codes computational complexity low-complexity algorithms classical belief propagation algorithm LDPC codes gradient projection decoding geometry-based LDPC constructions memory-storage requirement decoding Tanner graph Codes

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Protecting the Future of Information: LOCO Coding With Error Detection for DNA Data Storage

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IEEE TRANSACTIONS ON MOLECULAR BIOLOGICAL AND MULTI-SCALE COMMUNICATIONS 2024年第2期10卷 317-333页

作者： Irimagzi, Canberk Uslan, Yusuf Hareedy, Ahmed Middle East Tech Univ Inst Appl Math TR-06800 Ankara Turkiye Middle East Tech Univ Dept Elect & Elect Engn TR-06800 Ankara Turkiye

From the information-theoretic perspective, DNA strands serve as a storage medium for 4-ary data over the alphabet {A, T, G, C} . DNA data storage promises formidable information density, long-term durability, and ease of replicability. However, information in this intriguing storage technology might be corrupted because of error-prone data sequences as well as insertion, deletion, and substitution errors. Experiments have revealed that DNA sequences with long homopolymers and/or with low GC-content are notably more subject to errors upon storage. In order to address this biochemical challenge, constrained codes are proposed for usage in DNA data storage systems, and they are studied in the literature accordingly. This paper investigates the utilization of the recently-introduced method for designing lexicographically-ordered constrained (LOCO) codes in DNA data storage to improve performance. LOCO codes offer capacity-achievability, low complexity, and ease of reconfigurability. This paper introduces novel constrained codes, namely DNA LOCO (D-LOCO) codes, over the alphabet {A, T, G, C} with limited runs of identical symbols. Due to their ordered structure, these codes come with an encoding-decoding rule we derive, which provides simple and affordable encoding-decoding algorithms. In terms of storage overhead, the proposed encoding-decoding algorithms outperform those in the existing literature. Our algorithms are based on small-size adders, and therefore they are readily reconfigurable. D-LOCO codes are intrinsically balanced, which allows us to achieve balanced AT- and GC-content over the entire DNA strand with minimal rate penalty. Moreover, we propose four schemes to bridge consecutive codewords, three of which guarantee single substitution error detection per codeword. We examine the probability of undetecting errors over a presumed symmetric DNA storage channel subject to substitution errors only. We also show that D-LOCO codes are capacity-achieving and that

关键词： Codes DNA Encoding Symbols Memory Table lookup Signal processing algorithms Constrained codes low-complexity algorithms reconfigurable coding LOCO codes homopolymer run balancing error-detection DNA data storage

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Design of Multichannel Spectrum Intelligence Systems Using Approximate Discrete Fourier Transform Algorithm for Antenna Array-Based Spectrum Perception Applications

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algorithms 2024年第8期17卷 338页

作者： Madanayake, Arjuna Lawrance, Keththura Kumarasiri, Bopage Umesha Sivasankar, Sivakumar Gunaratne, Thushara Edussooriya, Chamira U. S. Cintra, Renato J. Florida Int Univ Dept Elect & Comp Engn Miami FL 33174 USA Natl Res Council Canada Herzberg Astron & Astrophys Res Ctr Penticton BC V0H 1K0 Canada Univ Moratuwa Dept Elect & Telecommun Engn Moratuwa 10400 Sri Lanka Univ Fed Pernambuco Dept Technol BR-55015 Caruaru PE Brazil

The radio spectrum is a scarce and extremely valuable resource that demands careful real-time monitoring and dynamic resource allocation. Dynamic spectrum access (DSA) is a new paradigm for managing the radio spectrum, which requires AI/ML-driven algorithms for optimum performance under rapidly changing channel conditions and possible cyber-attacks in the electromagnetic domain. Fast sensing across multiple directions using array processors, with subsequent AI/ML-based algorithms for the sensing and perception of waveforms that are measured from the environment is critical for providing decision support in DSA. As part of directional and wideband spectrum perception, the ability to finely channelize wideband inputs using efficient Fourier analysis is much needed. However, a fine-grain fast Fourier transform (FFT) across a large number of directions is computationally intensive and leads to a high chip area and power consumption. We address this issue by exploiting the recently proposed approximate discrete Fourier transform (ADFT), which has its own sparse factorization for real-time implementation at a low complexity and power consumption. The ADFT is used to create a wideband multibeam RF digital beamformer and temporal spectrum-based attention unit that monitors 32 discrete directions across 32 sub-bands in real-time using a multiplierless algorithm with low computational complexity. The output of this spectral attention unit is applied as a decision variable to an intelligent receiver that adapts its center frequency and frequency resolution via FFT channelizers that are custom-built for real-time monitoring at high resolution. This two-step process allows the fine-gain FFT to be applied only to directions and bands of interest as determined by the ADFT-based low-complexity 2D spacetime attention unit. The fine-grain FFT provides a spectral signature that can find future use cases in neural network engines for achieving modulation recognition, IoT device identif

关键词： approximate discrete Fourier transform wideband spectrum perception wideband multibeam RF digital beamforming low-complexity algorithms

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Optimum low-complexity Decoder for Spatial Modulation

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2019年第9期37卷 2001-2013页

作者： M-Nahhal, Ibrahim Basar, Ertugrul Dobre, Octavia A. Ikki, Salama Mem Univ Fac Engn & Appl Sci St John NF A1B 3X5 Canada Koc Univ Commun Res & Innovat Lab CoreLab Dept Elect & Elect Engn TR-34450 Istanbul Turkey Lakehead Univ Dept Elect Engn Thunder Bay ON P7B 5E1 Canada

In this paper, a novel low-complexity detection algorithm for spatial modulation (SM), referred to as the minimum-distance of maximum-length (m-M) algorithm, is proposed and analyzed. The proposed m-M algorithm is a smart searching method that is applied for the SM tree-search decoders. The behavior of the m-M algorithm is studied for three different scenarios: 1) perfect channel state information at the receiver side (CSIR);2) imperfect CSIR of a fixed channel estimation error variance;and 3) imperfect CSIR of a variable channel estimation error variance. Moreover, the complexity of the m-M algorithm is considered as a random variable, which is carefully analyzed for all scenarios, using probabilistic tools. Based on a combination of the sphere decoder (SD) and ordering concepts, the m-M algorithm guarantees to find the maximum-likelihood (ML) solution with a significant reduction in the decoding complexity compared with SM-ML and existing SM-SD algorithms;it can reduce the complexity up to 94% and 85% in the perfect CSIR and the worst scenario of imperfect CSIR, respectively, compared with the SM-ML decoder. The Monte Carlo simulation results are provided to support our findings as well as the derived analytical complexity reduction expressions.

关键词： Multiple-input multiple-output (MIMO) systems spatial modulation (SM) maximum likelihood (ML) decoder sphere decoder (SD) low-complexity algorithms complexity analysis

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low-complexity Linear Decoupling of Users for Uplink Massive MU-MIMO Detection 99

Low-Complexity Linear Decoupling of Users for Uplink Massive...

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IEEE 99th Vehicular Technology Conference (VTC-Spring)

作者： Sowmya, S. Muthukrishnan, Gokularam Giridhar, K. Indian Inst Technol Madras Dept Elect Engn TelWiSe Grp Chennai 600036 Tamil Nadu India

ISBN: (纸本)9798350387414

Massive MIMO (mMIMO) enables users with different requirements to get connected to the same base station (BS) on the same set of resources. In the uplink of Multiuser massive MIMO (MU-mMIMO), while such heterogeneous users are served, decoupling facilitates the use of user-specific detection schemes. In this paper, we propose a low-complexity linear decoupling scheme called Sequential Decoupler (SD), which aids in the parallel detection of each user's data stream. The proposed algorithm shows significant complexity reduction. Simulations reveal that the complexity of the proposed scheme is only 0.15% of the conventional Singular Value Decomposition (SVD) based decoupling and is about 47% of the pseudo-inverse based decoupling schemes when 80 users with two antennas each are served by the BS. Also, the proposed scheme is scalable when new users are added to the system and requires fewer operations than computing the decoupler all over again. Further numerical analyses indicate that the proposed scheme achieves significant complexity reduction without any degradation in performance and is a promising low-complex alternative to the existing decoupling schemes.

关键词： Massive Multi-User MIMO Decoupled Detection low-complexity algorithms Uplink Communication Left Nullspace Sequential Estimation

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