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Bayesian Equalization for ldpc Channel Decoding

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2012年第5期60卷 2672-2676页

作者： Salamanca, Luis Jose Murillo-Fuentes, Juan Perez-Cruz, Fernando Univ Seville Escuela Super Ingn Dept Teoria Senal & Comunicaciones Seville 41092 Spain Univ Carlos III Madrid Dept Teoria Senal & Comunicaciones Madrid 28911 Spain

We describe the channel equalization problem, and its prior estimate of the channel state information (CSI), as a joint Bayesian estimation problem to improve each symbol posterior estimates at the input of the channel decoder. Our approach takes into consideration not only the uncertainty due to the noise in the channel, but also the uncertainty in the CSI estimate. However, this solution cannot be computed in linear time, because it depends on all the transmitted symbols. Hence, we also put forward an approximation for each symbol's posterior, using the expectation propagation algorithm, which is optimal from the Kullback-Leibler divergence viewpoint and yields an equalization with a complexity identical to the BCJR algorithm. We also use a graphical model representation of the full posterior, in which the proposed approximation can be readily understood. The proposed posterior estimates are more accurate than those computed using the ML estimate for the CSI. In order to illustrate this point, we measure the error rate at the output of a low-density parity-check decoder, which needs the exact posterior for each symbol to detect the incoming word and it is sensitive to a mismatch in those posterior estimates. For example, for QPSK modulation and a channel with three taps, we can expect gains over 0.5 dB with same computational complexity as the ML receiver.

关键词： Bayesian inference BCJR (Bahl-Cocke-Jelinek-Raviv) algorithm channel equalization expectation propagation fading channels intersymbol interference ldpc coding

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ldpc Decoding With Low Complexity for OFDM Index Modulation

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IEEE ACCESS 2021年 9卷 68435-68444页

作者： Yoon, Eunchul Kwon, Soonbum Yun, Unil Kim, Sun-Yong Konkuk Univ Dept Elect & Elect Engn Seoul 05029 South Korea Sejong Univ Dept Comp Engn Seoul 05006 South Korea

In this paper, the posterior probabilities of the low-density parity check (ldpc) coded bits are derived for the orthogonal frequency division multiplexing index modulation (OFDM-IM) system to reduce the implementation complexity of ldpc decoding without performance loss. Specifically, the complexity of ldpc decoding is reduced by decomposing the posterior probability of the coded bit into multiple likelihood probabilities, each of which is obtained for each subcarrier of the corresponding OFDM-IM subblock. The results of the complexity analysis indicate that the proposed approach significantly reduces the implementation complexity of ldpc decoding for OFDM-IM compared to the conventional approach. Furthermore, the simulation results confirm that the proposed approach provides the same bit error rate performance as the conventional approach.

关键词： Communication systems Simulation OFDM Bit error rate Modulation Parity check codes Encoding Communication system signaling OFDM decoding index modulation ldpc coding

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Subchannel Ordering Scheme for ldpc-Coded OFDM Transmission Over Selective Channels

Subchannel Ordering Scheme for LDPC-Coded OFDM Transmission ...

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36th International Conference on Telecommunications and Signal Processing (TSP)

作者： Dziwoki, Grzegorz Sulek, Wojciech Silesian Tech Univ Inst Elect Fac Automat Control Elect & Comp Sci Gliwice Poland

ISBN: (纸本)9781479904020;9781479904037

OFDM modulation seems to be a good choice to deal with highly distorted transmission channels, and ldpc error correction codes allow the system performance to get close to the Shannon capacity. Performance improvement of the ldpc-coded OFDM system can be accomplished by use of irregular binary ldpc codes along with an appropriate match between the bits of the codeword and the OFDM subchannels. Non-binary ldpc codes over high order finite fields GF(q) are an additional booster in case of short to moderate codeword lengths. In this paper, a simple practical method of the subchannel ordering for OFDM modulation with non-binary ldpc codes is proposed. The method exploits some special structural properties of the ldpc code parity check matrix generated based on the PEG (Progressive-Edge-Growth) algorithm. A noticeable improvement was achieved for regular codes when the column weights of the parity check matrix is equal to 2.

关键词： Interleaving ldpc coding OFDM modulation wireless transmission

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ldpc-coded HARQ throughput performance of MC-CDMA using ICI cancellation

LDPC-coded HARQ throughput performance of MC-CDMA using ICI ...

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66th IEEE Vehicular Technology Conference

作者： Fukuda, Kaoru Nakajima, Akinori Adachi, Fumiyuki Tohoku Univ Grad Sch Engn Dept Elect & Commun Engn Sendai Miyagi 980 Japan

ISBN: (纸本)9781424402632

Broadband packet data services are demanded in the next generation mobile communications systems. Multi-carrier CDMA (MC-CDMA) is considered to be a promising wireless technique. Hybrid ARQ (HARQ) is a powerful error control technique. It is known that the HARQ throughput performance of MC-CDMA degrades due to the residual inter-code interference (ICI) after frequency-domain equalization (FDE). The use of frequency-domain soft interference cancellation (FDSIC) technique can reduce the residual ICI and improve the throughput performance. An important technical problem is the generation of accurate residual ICI replica for FDSIC. In this paper, we consider low-density parity-check coded (ldpc-coded) MC-CDMA HARQ and generate the residual ICI replica from a-posteriori log-likelihood ratio (LLR) obtained by the ldpc decoder. We evaluate, by computer simulation, the throughput performance in a frequency-selective Rayleigh fading channel. We show that if the residual ICI is removed, MC- CDMA can provide better throughput performance than orthogonal frequency division multiplexing (OFDM).

关键词： MC-CDMA ICI cancellation ldpc coding

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Studying the GOP size impact on the performance of a feedback channel-based Wyner-Ziv video codec

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2nd IEEE Pacific Rim Symposium on Video and Technology

作者： Pereira, Fernando Ascenso, Joao Brites, Catarina Univ Tecn Lisboa Inst Telecommun Inst Super Tecn P-1049001 Lisbon Portugal Inst Telecommun Inst Super Tecn P-1950062 Lisbon Portugal

ISBN: (纸本)9783540771289

Wyner-Ziv video coding has become one of the hottest research topics in the video coding community due to the conceptual, theoretical and functional novelties it brings. Among the many practical architectures already available, feedback channel-based with channel coding, e.g. ldpc and turbo codes, solutions are rather popular. These solutions rely on decoder motion estimation based on periodic Intra coded key frames, setting the so-called GOP size, very much like in conventional video coding. This paper targets the rate-distortion and complexity performance study of this type of Wyner-Ziv coding solution as a function of the GOP size, considering both LPDC and turbo codes.

关键词： distributed video coding Wyner-Ziv video coding GOP size ldpc coding turbo coding RD performance complexity performance

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Wyner-Ziv Scheme Based Multiple Description coding for Robust Video Transmission over Path Diversity Networks 12

Wyner-Ziv Scheme Based Multiple Description Coding for Robus...

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12th International Conference on Advanced Technologies for Communications (ATC)

作者： Dinh Trieu Duong Univ Engn & Technol VNU Fac Elect & Telecommun Hanoi Vietnam

ISBN: (纸本)9781728123929

In this paper, we propose a novel multiple description coding method based on the Wyner-Ziv scheme for robust video transmission. In the proposed method, the motion vector (MV) field is encoded into two descriptions, which are transmitted over different paths to the decoder. Unlike the conventional methods, the correlation between descriptions in the proposed method is generated without using any additional redundant data since it can be estimated based on the high spatial correlation of MVs themselves in the MV field. At the decoder, this correlation is then employed as the side information in the Wyner-Ziv scheme to effectively improve the performance of the proposed method. Experimental results show that the proposed method can achieve a wide range of tradeoffs between coding efficiency and error resilience, and provide much better objective and subjective performance than other conventional MDC methods.

关键词： Multiple description coding error resilience ldpc coding

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A new method for detection of ldpc coded GMSK modulated signals

A new method for detection of LDPC coded GMSK modulated sign...

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2nd IEEE International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM 2006)

作者： Taki, Mehrdad Nezafati, Mohdmmad B.

ISBN: (纸本)9781424405169

In this paper a new method for detection of ldpc coded, GMSK modulated signals will be proposed. Detection technique is based on Laurent decomposition of CPM signal into PAM pulses. At the receiver, the signal is passed through a filter matched to a PAM pulse with highest energy. Thereafter to eliminate effect of other pulses, a linear equalizer and a Turbo like equalizer combined with ldpc decoder will be used. The performance of designed receiver is shown that is very close to optimum Maximum Likelihood receiver but its complexity is much smaller.

关键词： GMSK modulation ldpc coding laurent representation iterative decoding turbo equalization

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UTW-OFDM-based 5G New Radio with Low Out-of-band Emission 22

UTW-OFDM-based 5G New Radio with Low Out-of-band Emission

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22nd International Symposium on Wireless Personal Multimedia Communications (WPMC)

作者： Yokoyama, Riichi Mizutani, Keiichi Matsumura, Takeshi Harada, Hiroshi Kyoto Univ Grad Sch Informat Sakyo Ku Yoshida Honmachi Kyoto 6068501 Japan

ISBN: (数字)9781728154190

ISBN: (纸本)9781728154190

For the 5G and beyond, the UTW-OFDM has been proposed as one of the new-waveforms which can strongly suppress out-of-band emission (OOBE) and has high compatibility with the CP-OFDM-based system currently used for the LTE. In the UTW-OFDM system, interference generated by windowing is suppressed by using channel coding, and the practicality of UTW-OFDM has been shown for the IEEE 802.11af system using the convolutional coding and the LTE system using the turbo coding Meanwhile, to our best knowledge, the UTW-OFDM-based 5G system using low-density parity-check (ldpc) coding has not been presented. In this paper, the authors describe how the UTW-OFDM can be applied to 5G new radio (NR). Firstly, the authors point out that common calculation methods of the log-likelihood ratio (LLR) in the decoding process of the ldpc coding degrade the communication quality, especially in a high SNR environment. Then, an adjustment method of the LLR is proposed to mitigate the degradation of the communication quality and demonstrate that the proposed method strongly suppresses OOBE with maintaining the communication quality when applying the UTW-OFDM to the 5G NR.

关键词： CP-OFDM UTW-OFDM Out-of-band emission LTE 5G Beyond 5G ldpc coding LLR

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Real-Time Adaptive ldpc Coded APSK for Aeronautical Telemetry 13

Real-Time Adaptive LDPC Coded APSK for Aeronautical Telemetr...

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13th International Conference on Advanced Technologies, Systems and Services in Telecommunications (TELSIKS)

作者： Zou, Ding Djordjevic, Ivan. B. Univ Arizona Dept Elect & Comp Engn 1230 E Speedway Blvd Tucson AZ 85719 USA

ISBN: (纸本)9781538618004

In this paper, we consider the design of capacity-approaching forward error correction (FEC) coded amplitude phase shift keying (APSK) modulation schemes for use in the aeronautical telemetry. By maximizing the mutual information, we first investigate the designs of APSK modulations suitable for communication over nonlinear wireless channels. Then we propose a unified FPGA-based hardware-efficient architecture which combines the capacity-approaching ldpc decoders with four APSK modulation formats, including Gray-mapping-based 8-APSK, 16-APSK, 32-APSK, and 64-APSK. The proposed architecture allows the flexibility of the FEC-encoded signal to be received by legacy test-range systems. The emulation results show that such an ldpc-coded modulation scheme can adapt to wide range of received signal-to-noise ratios, ranging from 9.4 dB to 21.4 dB, by using different ldpc codes and/or modulation formats.

关键词： Aeronautical telemetry ldpc coding APSK FPGA coded modulation adaptive coding

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Beyond 100 Tb/s Serial Optical Transport Networks based on Hybrid Multidimensional ldpc-Coded Modulation

Beyond 100 Tb/s Serial Optical Transport Networks based on H...

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11th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services (TELSIKS)

作者： Djordjevic, Ivan B. Univ Arizona Dept Elect & Comp Engn 1230 E Speedway Blvd Tucson AZ 85721 USA Tech Univ Darmstadt Darmstadt Germany

ISBN: (纸本)9781479909025

As a solution to limited bandwidth and high energy consumption of information infrastructure as well as heterogeneity of optical networks, a hybrid multidimensional coded modulation scheme is proposed employing all available electrical and optical degrees of freedom. Electrical basis functions are based on either modified orthogonal polynomials or prolate spheroidal wave functions, while optical ones on polarization and spatial mode states. The proposed scheme is both multi-Tb/s and beyond 100 Tb/s enabling technology. Additionally, the proposed scheme provides the adaptive, software-defined, and dynamic allocation of bandwidth with fine granularity. Finally, the proposed scheme significantly outperforms the conventional polarization-division multiplexed QAM.

关键词： Terabit optical Ethernet Advanced FEC ldpc coding Coded-modulation Multidimensional signaling

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