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17th Symposium on Integrated Circuits and Systems Design (SBCCI 2004)

作者： Vogt, T Wehn, N Alves, P Univ Kaiserslautern D-67663 Kaiserslautern Germany

ISBN: (纸本)1581139470

In this paper, a VLSI implementation of a multi-standard channel-decoder for EDGE, WCDMA, and CDMA2k convolutional-codes is presented. The new architecture employs the MAP algorithm for convolutional decoding to support soft-outputs. The decoder is designed for base-station applications. The maximum throughput of the decoder is 16 Mbps for WCDMA and CDMA2k, and 70 Mbps for EDGE, at a clock frequency of 200 MHz.

关键词： convolutional decoder MAP hardware sharing configurable wireless W-CDMA CDMA2k

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Handwritten Mathematical Expression Recognition via Paired Adversarial Learning

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INTERNATIONAL JOURNAL OF COMPUTER VISION 2020年第1-11期128卷 2386-2401页

作者： Wu, Jin-Wen Yin, Fei Zhang, Yan-Ming Zhang, Xu-Yao Liu, Cheng-Lin Chinese Acad Sci Inst Automat Natl Lab Pattern Recognit Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Artificial Intelligence Beijing 100049 Peoples R China CAS Ctr Excellence Brain Sci & Intelligence Techn Beijing 100190 Peoples R China

Recognition of handwritten mathematical expressions (MEs) is an important problem that has wide applications in practice. Handwritten ME recognition is challenging due to the variety of writing styles and ME formats. As a result, recognizers trained by optimizing the traditional supervision loss do not perform satisfactorily. To improve the robustness of the recognizer with respect to writing styles, in this work, we propose a novel paired adversarial learning method to learn semantic-invariant features. Specifically, our proposed model, named PAL-v2, consists of an attention-based recognizer and a discriminator. During training, handwritten MEs and their printed templates are fed into PAL-v2 simultaneously. The attention-based recognizer is trained to learn semantic-invariant features with the guide of the discriminator. Moreover, we adopt a convolutional decoder to alleviate the vanishing and exploding gradient problems of RNN-based decoder, and further, improve the coverage of decoding with a novel attention method. We conducted extensive experiments on the CROHME dataset to demonstrate the effectiveness of each part of the method and achieved state-of-the-art performance.

关键词： Handwritten ME recognition Paired adversarial learning Semantic-invariant features convolutional decoder Coverage of decoding

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Iterative receiver for the triple differential PSK modulation in the time-varying underwater acoustic communications

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IET COMMUNICATIONS 2020年第16期14卷 2813-2819页

作者： Cui, Hongyu Liu, Changxin Si, Boyu Wu, Jie Sun, Dajun Harbin Engn Univ Acoust Sci & Techol Lab Harbin 150001 Peoples R China Harbin Engn Univ Coll Underwater Acoust Engn Harbin 150001 Peoples R China Shanghai Univ Med & Hlth Sci Coll Med Instrument Shanghai 201318 Peoples R China

Due to the time-varying property of the underwater acoustic (UWA) channel, the significant Doppler spread will severely degrade the performance of direct-sequence spread-spectrum (DSSS) communications. The relative velocity variation between the transmitter and the receiver will cause both the phase rotation and the magnitude loss of correlation peak, during the long transmission of the DSSS packet. To solve this problem, the authors propose a novel transceiver design for the UWA DSSS communications. At the transmitter, the triple differential phase shift keying (D3PSK) modulation is adopted to overcome the phase rotation, whereas the phase noise will be amplified resulting in the signal-to-noise ratio (SNR) loss. At the receiver, the improved bit-interleaved coded modulation with iterative decoding algorithm for D3PSK is used to recover the SNR loss, in which the D3PSK demodulator is treated as the convolutional decoder, and the linear prediction is adopted to track the channel variation. Furthermore, an adaptive selection of local reference signal is also applied to recover the correlation loss. Theoretical simulation shows that the proposed transceiver can effectively mitigate the performance loss caused by the motion acceleration, and the performance gain is significant over the conventional.

关键词： iterative decoding differential phase shift keying transceivers underwater acoustic communication spread spectrum communication interleaved codes modulation coding signal detection demodulation wireless channels time-varying channels phase noise convolutional codes channel coding iterative receiver triple differential PSK modulation time-varying underwater acoustic communications time-varying property underwater acoustic channel Doppler spread direct-sequence spread-spectrum communications relative velocity variation transmitter phase rotation magnitude loss DSSS packet novel transceiver design UWA DSSS communications phase noise signal-to-noise ratio loss iterative decoding algorithm SNR loss channel variation local reference signal performance gain UWA channel receiver triple differential phase shift keying modulation D3PSK modulation improved bit-interleaved coded modulation D3PSK demodulator convolutional decoder linear prediction adaptive selection correlation loss recovery performance loss mitigation motion acceleration

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Driven Stability of Nonlinear Feedback Shift Registers With Inputs

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IEEE TRANSACTIONS ON COMMUNICATIONS 2016年第6期64卷 2274-2284页

作者： Zhong, Jianghua Lin, Dongdai Chinese Acad Sci Inst Informat Engn State Key Lab Informat Secur Beijing 100093 Peoples R China

Driven stable nonlinear feedback shift registers (NFSRs) with inputs are not only able to limit error propagations in convolutional decoders, but also helpful to analyze the period properties of sequences generated by a cascade connection of NFSRs in stream ciphers. An NFSR is driven stable if and only if the reachable set is a subset of the basin. Due to lack of efficient algebraic tools, the driven stability of NFSRs with inputs has been much less studied. This paper continues to address this research using a Boolean control network approach. Viewing an NFSR with input as a Boolean control network, we first give its Boolean control network representation, which is characterized with a state transition matrix. Some properties of the state transition matrix are then provided. Based on these, explicit forms are given for the reachable set and the set of basin. Two algorithms for obtaining both the sets are provided as well. Compared with the exhaustive search and the existing state operator method, the Boolean control network approach requires lower computational complexity for those NFSRs with their stages greater than 1.

关键词： Shift register stability convolutional decoder computational complexity state transition matrix

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Concatenated convolutional and differential codes in interference-suppressed DS-CDMA systems

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IEE PROCEEDINGS-COMMUNICATIONS 2002年第2期149卷 99-104页

作者： Li, Y Li, KH Natl Univ Singapore Ctr Wireless Commun Singapore 117674 Singapore Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore

A serial concatenated convolutional and differential coding scheme is employed in a multi-user direct-sequence code-division multiple-access (DS-CDMA) system. The system consists of single-user detectors (SUDs), which are used to suppress multiple-access interference (MAI) with no requirement of other users' spreading codes, timing, or phase information. The differential code, treated as a convolutional code of code rate I and memory 1, does not sacrifice the coding efficiency and has the least number of states. The iterative process exchanges information between the differential decoder and the convolutional decoder. Both component decoders adopt the a posteriori probability (APP) algorithm. Numerical results in additive white Gaussian noise (AWGN) channels show that this concatenated coding scheme provides better performance and more flexibility than conventional convolutional codes in DS-CDMA systems, even in the sense of similar complexity. Further study shows that the performance of this coding scheme applied to DS-CDMA systems with SUDs improves by increasing the processing gain or the number of taps of the interference suppression filter. and degrades for higher near-far interfering power or additional near-far interfering users.

关键词： serial concatenated convolutional code probability concatenated codes multi-user system additive white Gaussian noise channels Electromagnetic compatibility and interference coding efficiency phase information spreading codes processing gain iterative process near-far interfering power component decoders differential codes near-far interfering users code rate a posteriori probability algorithm iterative decoding single-user detectors Other topics in statistics convolutional codes differential decoder interference suppression filter multiuser channels spread spectrum communication interference-suppressed DS-CDMA systems AWGN channels multiple-access interference suppression Codes interference suppression timing information convolutional decoder Radio links and equipment memory

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A new linearization method for nonlinear feedback shift registers

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JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2015年第4期81卷 783-796页

作者： Zhong, Jianghua Lin, Dongdai Chinese Acad Sci Inst Informat Engn State Key Lab Informat Secur Beijing 100093 Peoples R China Qingdao Univ Inst Complex Sci Qingdao 266071 Peoples R China

Nonlinear feedback shift registers (NFSRs) have been used as the main building blocks in many stream ciphers and convolutional decoders. The linearization of NFSRs is to find their state transition matrices. This paper uses a Boolean network approach to facilitate the linearization of NFSRs. A new state transition matrix is found for an NFSR, which can be simply computed from the truth table of its feedback function. Compared to the existing results, the new state transition matrix is easier to compute and is more explicit. Some properties of the matrix are provided, which are helpful to theoretically analyze NFSRs. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Shift register Automaton State transition matrix Boolean function Stream cipher convolutional decoder Boolean network

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Iterative decoding of GMSK modulated convolutional code

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ELECTRONICS LETTERS 1999年第10期35卷 810-811页

作者： Qin, GF Zhou, SD Yao, Y Tsing Hua Univ Dept Elect Engn State Key Lab Microwave & Digital Commun Beijing 100084 Peoples R China

An iterative decoding scheme for the serial concatenation of a convolutional code and a GMSK modulator is presented. The maximum aposteriori probability (MAP) algorithm accepting a priori information and providing a soft-output is applied to a GMSK differential phase detector (DPD). An iteration scheme is devised to act between the demodulation and the subsequent. convolutional decoder.: Compared with the traditional decoding method, simulation results of the new scheme show an evident improvement in overcoming the severe intersymbol interference of GMSK signals.

关键词： convolutional decoder serial concatenation iteration scheme concatenated codes phase detectors soft-output minimum shift keying maximum a posteriori probability iterative decoding Codes convolutional codes intersymbol interference Other topics in statistics probability differential phase detector GMSK modulated convolutional code demodulation

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Bit-interleaved coded modulation with iterative decoding using soft feedback

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ELECTRONICS LETTERS 1998年第10期34卷 942-943页

作者： Li, XD Ritcey, JA Univ Washington Dept Elect Engn Seattle WA 98195 USA

A new iterative decoding (ID) scheme is suggested for bit-interleaved coded modulation (BICM). The bit-metric generation at the demodulator is optimised with the soft-output feedback from the convolutional decoder. Computer simulation results indicate that BICM-ID, with a few iterations, significantly outperforms conventional trellis coded modulation and is therefore another promising technique to achieve large coding gain without bandwidth expansion.

关键词： bit-metric generation convolutional decoder iterative methods Codes iterative decoding soft feedback bit-interleaved coded modulation feedback Interpolation and function approximation (numerical analysis) modulation coding decoding

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Iterative demapping for QPSK modulation

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ELECTRONICS LETTERS 1998年第15期34卷 1459-1460页

作者： ten Brink, S Speidel, J Yan, RH Univ Stuttgart Inst Telecommun Dept 0408 D-70569 Stuttgart Germany Lucent Technol Bell Labs Swindon SN5 6PP Wilts England

The authors present an iterative decoding scheme which is particularly suited for quadrature phase shift keying (QPSK) modulation with anti-Gray mapping. Al the receiver, a soft demapper accepting a priori information and a convolutional decoder are applied in a serial concatenation. Numerical results are presented for QPSK in additive white Gaussian noise and Rayleigh-fading channels. The iterated system applying anti-Gray mapping outperforms the conventional system using Gray mapping after only one iteration.

关键词： anti-Gray mapping Rayleigh-fading channels Interpolation and function approximation (numerical analysis) soft demapper QPSK modulation Codes quadrature phase shift keying additive white Gaussian noise decoding serial concatenation convolutional decoder white noise iterative demapping convolutional codes Rayleigh channels decoding scheme iterative methods a priori information fading Gaussian noise

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IRA Code Design for Iterative Detection and Decoding: A Setpoint-based Approach 79

IRA Code Design for Iterative Detection and Decoding: A Setp...

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IEEE 79th Vehicular Technology Conference (VTC-Spring)

作者： Lenkeit, F. Bockelmann, C. Wuebben, D. Dekorsy, A. Univ Bremen Dept Commun Engn D-28359 Bremen Germany

ISBN: (纸本)9781479944828

In this paper, a novel setpoint-based design approach for Irregular Repeat Accumulate (IRA) codes in iterative detection and decoding structures is presented. In contrast to conventional IRA code design in which the convolutional decoder is combined with the detector, the goal behind this approach is to keep the IRA decoding structure consisting of convolutional decoder and repetition decoder intact, i.e. to consider it as an inner loop of the overall detection structure. The outer loop is then composed of the IRA decoder and the system specific detector. This approach requires to adapt the irregular repetition code jointly to the convolutional decoder as well as to the detector which is achieved by formulating setpoints for the inner and outer code characteristic. As will be shown, the presented code design approach, although starting from a completely different viewpoint as the conventional approach, leads to an irregular repetition code with a very similar transfer characteristic and code rate than the conventional approach.

关键词： convolutional codes iterative decoding IRA code design convolutional decoder irregular repeat accumulate codes irregular repetition code iterative detection repetition decoder setpoint based design convolutional codes Decoding Detectors Iterative decoding Iterative methods MIMO Turbo codes Iterative decoding convolutional coding DECODING turbo codes iterative methods multiple input multiple output systems detector repetition coding decoders Codes

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