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Index assignment-based channel coding

IET COMMUNICATIONS 2012年第2期6卷 172-178页

作者： Oztoprak, H. Villette, S. Kondoz, A. Univ Surrey Ctr Vis Speech & Signal Proc Guildford GU2 7XH Surrey England

A scheme named index assignment-based channel coding (IACC) has been developed for resilience of speech/audio codecs against the bit errors commonly experienced in wireless channels. Although IACC is a type of joint source channel coding, it does not intervene with the source codec design. The proposed scheme takes into account source characteristics and adjusts the amount of coding according to the sensitivity of different values of the source parameters. It is shown that source characteristics play an important role in the performance of IACC. The performance of IACC has been evaluated by applying it to parameters generated by adaptive multi-rate wideband (AMR-WB+) audio codec. A method for perceptual training of IACC codes is also proposed. The results demonstrate that the performance of IACC and IACC concatenated with convolutional coding can be superior to that of conventional convolutional coding at high and moderate bit error rates, respectively.

关键词： combined source-channel coding convolutional codes error statistics source codec design wireless channels concatenated coding adaptive multirate wideband audio codec index assignment-based channel coding speech coding bit error rates Speech and audio coding audio coding adaptive codes concatenated codes speech codecs joint source channel coding Speech processing techniques BER Radio links and equipment convolutional coding Other topics in statistics

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Transmission of Analog Information Over the Multiple Access Relay channel Using Zero-Delay Non-Linear Mappings

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IEEE ACCESS 2019年 7卷 48405-48416页

作者： Fresnedo, Oscar Suarez-Casal, Pedro Castedo, Luis Univ A Coruna Dept Comp Engn La Coruna 15071 Spain

We consider the zero-delay encoding of discrete-time analog information over the Multiple Access Relay channel (MARC) using non-linear mapping functions. On the one hand, zero-delay nonlinear mappings are capable to deal with the multiple access interference (MAI) caused by the simultaneous transmission of the information. On the other, the relaying operation is a Decode-and-Forward (DF) strategy where the decoded messages are merged into a single message using a specific continuous mapping depending on the correlation level of the source information. At the receiver, an approximated Minimum Mean Squared Error (MMSE) decoder is developed to obtain an estimate of the transmitted source symbols which exploits the information received from the relay node in combination with the messages received from the transmitters through the direct links. The resulting system provides better performance than the other alternative encoding strategies for the MARC with similar complexity and delay and also approaches the performance of theoretical strategies which require a significantly higher delay and computational cost.

关键词： combined source-channel coding relay networks multiuser channels network coding

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Information unequal error protection using polar codes

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IET COMMUNICATIONS 2018年第8期12卷 956-961页

作者： Hadi, Ammar Alsusa, Emad Al-Dweik, Arafat Univ Manchester Sch Elect & Elect Engn Manchester M13 9PL Lancs England Khalifa Univ Elect & Comp Engn Dept Abu Dhabi U Arab Emirates

Unequal error protection (UEP) divides the data into different levels of importance in order to ensure that the most important parts of the source information have more protection than the less important parts. In this study, the authors investigate the application of UEP using polar codes and propose a technique that utilises the channel polarisation property of these codes to achieve UEP without any significant modification. They demonstrate the error bounds of the proposed technique particularly within the context of JPEG2000. In addition, they propose a joint source-channel decoding method that is based on iterative decoding. This method takes the advantage of the error resilience tools that already exist in the JPEG2000 decoder. It will be shown that the proposed technique offers better performance than the conventional transmission with equal error protection.

关键词： combined source-channel coding video coding iterative decoding data compression information unequal error protection polar codes UEP source information channel polarisation property joint source-channel decoding method iterative decoding error resilience tools JPEG2000 decoder equal error protection error bounds

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Joint MELP turbo code with unequal error protection

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ELECTRONICS LETTERS 2001年第10期37卷 637-639页

作者： Wang, Q Koh, SN Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore

The mixed excitation linear prediction (MELP) algorithm has been recently selected as the new federal standard for 2.4kbit/s coding of speech signals. The authors exploit the average residual inter-frame correlation and the error sensitivities of the bits in a MELP frame to enhance the robustness of the proposed joint MELP turbo coding schemes for Operations over Rayleigh fading channels.

关键词： BER speech coding mixed excitation linear prediction algorithm error statistics error detection combined source-channel coding turbo codes Codes unequal error protection correlation theory linear predictive coding residual inter-frame correlation Rayleigh channels bit error sensitivities Speech and audio coding Rayleigh fading channels Information theory joint MELP turbo code 2.4 kbit/s error correction MELP algorithm speech signals

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Matched Multiuser Gaussian source channel Communications via Uncoded Schemes

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第7期63卷 4155-4171页

作者： Tian, Chao Chen, Jun Diggavi, Suhas N. Shamai (Shitz), Shlomo Univ Tennessee Dept Elect Engn & Comp Sci Knoxville TN 37996 USA McMater Univ Dept Elect & Comp Engn Hamilton ON L8S 4K1 Canada Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90095 USA Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

We investigate whether uncoded schemes are optimal for Gaussian sources on multiuser Gaussian channels. Particularly, we consider two problems: the first is to send correlated Gaussian sources on a Gaussian broadcast channel where each receiver is interested in reconstructing only one source component (or one specific linear function of the sources) under the mean squared error distortion measure;the second is to send correlated Gaussian sources on a Gaussian multiple-access channel, where each transmitter observes a noisy combination of the sources, and the receiver wishes to reconstruct the individual source components (or individual linear functions) under the mean squared error distortion measure. It is shown that when the channel parameters satisfy certain general conditions, the induced distortion tuples are on the boundary of the achievable distortion region, and thus optimal. Instead of following the conventional approach of attempting to characterize the achievable distortion region, we ask the question whether and how a match can be effectively determined. This decision problem formulation helps to circumvent the difficult optimization problem often embedded in region characterization problems, and it also leads us to focus on the critical conditions in the outer bounds that make the inequalities become equalities, which effectively decouple the overall problem into several simpler sub-problems. Optimality results previously unknown in the literature are obtained using this novel approach. Explicit and novel outer bounds are derived for the two problems as the byproducts of our investigation.

关键词： Broadcast multiple access combined source-channel coding

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Over-the-Air Computation in Correlated channels

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2021年 69卷 5739-5755页

作者： Frey, Matthias Bjelakovic, Igor Stanczak, Slawomir Tech Univ Berlin Network Informat Theory Grp D-10587 Berlin Germany Fraunhofer Heinrich Hertz Inst D-10587 Berlin Germany

Over-the-Air (OTA) computation is the problem of computing functions of distributed data without transmitting the entirety of the data to a central point. By avoiding such costly transmissions, OTA computation schemes can achieve a better-than-linear (depending on the function, often logarithmic or even constant) scaling of the communication cost as the number of transmitters grows. In this work, we propose and analyze an analog OTA computation scheme for a class of functions that contains linear functions as well as some nonlinear functions such as p-norms of vectors. We prove error bounds that are valid for fast-fading channels and all distributions of fading and noise in the class of sub-Gaussian distributions. This class includes Gaussian distributions, but also many other practically relevant cases such as Class A Middleton noise and fading with dominant line-of-sight components. Moreover, there can be correlations in the fading and noise so that the presented results also apply to, for example, block fading channels and channels with bursty interference. There is no assumption that the distributed function arguments follow a particular probability law;in particular, they do not need to be independent or identically distributed. Our analysis is nonasymptotic and therefore provides error bounds that are valid for a finite number of channel uses. OTA computation has a huge potential for reducing communication cost in applications such as Machine Learning (ML)-based distributed anomaly detection in large wireless sensor networks. We illustrate this potential through extensive numerical simulations.

关键词： combined source-channel coding fading channels wireless communication robustness machine learning distributed computing wireless sensor networks boosting

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Sending a Bivariate Gaussian Over a Gaussian MAC

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IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第6期56卷 2714-2752页

作者： Lapidoth, Amos Tinguely, Stephan ETH Dept Informat Technol & Elect Engn CH-8092 Zurich Switzerland

We study the power-versus-distortion tradeoff for the distributed transmission of a memoryless bivariate Gaussian source over a two-to-one average-power limited Gaussian multiple-access channel. In this problem, each of two separate transmitters observes a different component of a memoryless bivariate Gaussian source. The two transmitters then describe their source component to a common receiver via an average-power constrained Gaussian multiple-access channel. From the output of the multiple-access channel, the receiver wishes to reconstruct each source component with the least possible expected squared-error distortion. Our interest is in characterizing the distortion pairs that are simultaneously achievable on the two source components. We focus on the "equal bandwidth" case, where the source rate in source-symbols per second is equal to the channel rate in channel-uses per second. We present sufficient conditions and necessary conditions for the achievability of a distortion pair. These conditions are expressed as a function of the channel signal-to-noise ratio (SNR) and of the source correlation. In several cases, the necessary conditions and sufficient conditions are shown to agree. In particular, we show that if the channel SNR is below a certain threshold, then an uncoded transmission scheme is optimal. Moreover, we introduce a "source-channel vector-quantizer" scheme which is asymptotically optimal as the SNR tends to infinity.

关键词： Achievable distortion combined source-channel coding correlated sources Gaussian multiple-access channel Gaussian source mean squared-error distortion multiple-access channel uncoded transmission

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Design and analysis of LDPC codes for joint source-channel decoding of two correlated sensors

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IET COMMUNICATIONS 2018年第8期12卷 1003-1010页

作者： Khas, Mohamad Saeedi, Hamid Asvadi, Reza Tarbiat Modares Univ Dept Elect & Comp Engn Tehran Iran Shahid Beheshti Univ Fac Elect Engn Tehran Iran

This study is concerned with the design of ensembles of systematic low-density parity-check (LDPC) codes to increase the lifetime of wireless sensors by taking advantage of the inherent correlation between the transmitted data of the sensors. The authors consider two correlated sensors where the data is encoded independently at each sensor through a systematic LDPC encoder and sent over two independent channels. At the receiver, a joint source-channel decoder consisting of two component LDPC decoders is considered where the encoded bits at the output of each component decoder are used as the a priori information at the other decoder. The authors first perform asymptotic performance analysis using the concept of extrinsic information transfer (EXIT) charts. Then, the developed modified EXIT charts are used to design ensembles for different values of correlation. Our results show that as the average check node degree of the designed ensembles grow, the decoding thresholds corresponding to the designed ensembles approach the theoretical limit. Finite block-length performance evaluation indicates that for larger values of correlation, deploying the designed ensembles through the joint decoder can almost double the sensor's lifetime without increasing the complexity of the encoder.

关键词： parity check codes decoding combined source-channel coding joint source-channel decoding correlated sensors low-density parity-check codes wireless sensors inherent correlation independent channels component LDPC decoders asymptotic performance analysis extrinsic information transfer charts point-to-point communications decoding thresholds

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Non-linear coding and decoding strategies exploiting spatial correlation in wireless sensor networks

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IET COMMUNICATIONS 2012年第14期6卷 2198-2207页

作者： Davoli, F. Marchese, M. Mongelli, M. Univ Genoa DITEN I-16145 Genoa Italy Univ Genoa CNIT Res Unit I-16145 Genoa Italy Natl Res Council Italy CNR IEIIT Inst Elect Comp & Telecommun Engn I-16145 Genoa Italy

The authors consider the acquisition of measurements from a source, representing a physical phenomenon, by means of sensors deployed at different distances, and measuring random variables (r.v.'s) that are correlated with the source output. The acquired values are transmitted over a wireless channel to a sink, where an estimation of the source has to be constructed, according to a given distortion criterion. In the presence of Gaussian random variables (r.v.'s) and a Gaussian vector channel, the authors are seeking optimum real-time joint source-channel encoder-decoder pairs that achieve a distortion sufficiently close to the theoretically optimal one, under a global resource constraint, by activating only a subset of the sensors. The problem is posed in a team decision theoretic framework, and the optimal strategies are approximated by means of neural networks. The analysis investigates the generalisation capabilities of the proposed approach, by showing insights into the structure of the problem. The surprising outcome is that a quasi-static application of the approach reveals to be sufficient to maintain quasi-optimal performance under a dynamic environment (e. g. with respect to nodes' positions).

关键词： real time joint source-channel coding nonlinear coding decoding Gaussian random variables combined source-channel coding Wireless sensor networks neural networks network coding wireless channel distortion criterion nonlinear codes wireless sensor networks spatial correlation Gaussian vector channel Codes

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A sensitivity matched multicarrier modulation

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IEEE COMMUNICATIONS LETTERS 2002年第1期6卷 10-12页

作者： Emami, S Motorola Labs Boynton Beach FL 33426 USA

We develop a multicarrier modulation scheme for transmission of compressed data. The energy allocation among subcarriers is optimized by minimizing a modified symbol error function in either AWGN or Rayleigh fading channels. It is observed that our sensitivity matched multi carrier modulation significantly outperforms the conventional multi carrier modulation. The performance gain in Rayleigh fading channels varies from 0.58 to 3.26 dB depending upon the relative sensitivity of bit groups associated with subchannels.

关键词： combined source-channel coding multicarrier modulation OFDM

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