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Improved MPEG-4 High-Efficiency AAC With Variable-Length soft-decision Decoding of the Quantized Spectral Coefficients

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China Communications 2019年第10期16卷 65-82页

作者： Sai Han Hongbing Ma Ping Zhang Tim Fingscheidt China United Network Communications Group Company Limited Beijing 100033China Beijing University of Posts and Telecommunications Beijing 100876China Institute for Communications Technology Technische Universitat BraunschweigBraunschweig 38106Germany

MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variable-length codes (VLCs) are adopted. However, HE-AAC has originally been designed for storage and error-free transmission conditions. For the transmission over bit error-prone channels, error propagation is a serious problem for the VLCs. Therefore, a robust HE-AAC decoder is desired, especially for mobile communications. In contrast to traditional hard-decision decoding, utilizing bit-wise channel reliability information, softdecision (SD) decoding has been known to offer better audio quality. In HE-AAC, the global gain parameter is coded with fixedlength codes (FLCs), while the scale factors and quantized spectral coefficients are coded with VLCs. In this work, we apply FL/SD decoding to the global gain parameter, VL/SD decoding to the parameters scale factors and quantized spectral coefficients. Especially, in order to apply VL/SD decoding to the quantized spectral coefficients, a new modified trellis representation in VL/SD decoding is proposed. An improved HE-AAC performance is clearly observed, with the support of both instrumental measurements and a subjective listening test.

关键词： variable-length soft-decision decoding HE-AAC trellis representation quantization spectral coefficients

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Efficient soft-decision Maximum-Likelihood Decoding of BCH Code in the GNSS

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Journal of Harbin Institute of Technology(New Series) 2015年第1期22卷 54-58页

作者： Jinhai Sun Jinhai Li Haiyang Liu Feng Wang Yuepeng Yan Institute of microelectronics Chinese Academy of Sciences

soft-decision decoding of BCH code in the global navigation satellite system( GNSS) is investigated in order to improve the performance of traditional hard-decision decoding. Using the nice structural properties of BCH code,a soft-decision decoding scheme is proposed. It is theoretically shown that the proposed scheme exactly performs maximum-likelihood( ML) decoding,which means the decoding performance is optimal. Moreover,an efficient implementation method of the proposed scheme is designed based on Viterbi algorithm. Simulation results show that the performance of the proposed soft-decision ML decoding scheme is significantly improved compared with the traditional hard-decision decoding method at the expense of moderate complexity increase.

关键词： GNSS BCH codes soft-decision decoding maximum-like

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Iterative list decoding approach for Reed-Solomon codes

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 8-14,24页

作者： Zhang Zhijun Niu Kai Dong Chao Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications

A novel adaptively iterative list decoding(ILD) approach using for Reed-Solomon(RS) codes was investigated. The proposed scheme is exploited to reduce the complexity of RS Chase algorithm(CA) via an iterative decoding attempt mode. In each decoding attempt process, a test pattern is generated by flipping the bits of the least reliable positions(LRPs) within the received hard-decision(HD) vector. The ILD algorithm continues until a test pattern is successfully decoded by the underlying Berlekamp-Massey algorithm(BMA) of RS codes. Flipping within the same bits, the ILD algorithm provides the same test pattern set as the conventional RS CA, thus there is no degradation in error-rate performance. Without decoding all test patterns, the ILD algorithm can simplify the decoding complexity by its early termination. Simulation results show that the average complexity of the ILD algorithm is much lower than that of the conventional RS CA(and is similar to that of BMA decoding) at high signal-to-noise ratio(SNR) region with no less to the RS CA decoding error-rate performance.

关键词： iterative decoding soft-decision decoding Reed-Solomon codes low-complexity decoding

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Study of LDPC Coded SFH System with Partial-Band Interference

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Communications and Network 2013年第3期5卷 280-285页

作者： Chao Gong Manxi Wang Daoxing Guo Xiaofei Pan College of communications engineering PLA University of Science &Technology China The State Key Laboratory of Complex Electromagnetic Environmental Effects on Electronics&Information System China

The application of Low Density Parity Check (LDPC) code in the anti-interference systems has drawn an increasing attention, due to its admiring performance which is very close to the theory limit. This paper focuses on a LDPC encoded slow frequency hopping (SFH) communication system with partial-band interference. Firstly, a modified soft- decision algorithm based on the utilization of interference information is proposed, and its performance is compared with some other soft-decision methods. Secondly, with numerical simulation, the influence of code rate, code length and the number of symbols per hops on the performance of the system with partial band noise interference is illustrated and examined in detail. Considering the great influence of hops per symbol on the performance, interleaver should be used and its influence on the performance is further examined by simulation. Finally, some constructive advises for the design of LDPC coded SFH system are given. Simulation results show that, with a reasonable design, the SFH system with LDPC code could achieve a desirable performance.

关键词： LDPC SFH soft-decision Partial-band Interference

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