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Minh-Quang Nguyen

Bio: Minh-Quang Nguyen is an academic researcher from Université Paris-Saclay. The author has contributed to research in topics: Speech coding & Communication channel. The author has an hindex of 1, co-authored 3 publications receiving 1 citations.

Papers
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Proceedings ArticleDOI
01 Jan 2017
TL;DR: This paper investigates the effect of the analog parts on various outputs of the digital modules in a HDA communication system, and introduces a novel HDA architecture with adaptation for the digital parts that provides robust and graceful performance for a wide range of channel conditions.
Abstract: Hybrid analog digital (HDA) architectures have been widely used in communication systems for analog source over discrete-time memoryless Gaussian channels. They employ a linear coding scheme in the analog parts, while considering separately the design of source and channel codes in the digital parts. To the best of our knowledge, none of the previous HDA schemes exploit the advantages of maintaining a joint source and channel coding design in the digital segment. In this paper, we investigate the effect of the analog parts on various outputs of the digital modules in a HDA communication system, and introduce a novel HDA architecture with adaptation for the digital parts. Such adaptation allows our system to exploit the joint effect of the analog components and the channel noise on outputs of the digital components, while simultaneously taking into consideration the unequal distribution of source code outputs. Our simulations illustrate that the proposed HDA system provides robust and graceful performance (on both bandwidth compression and expansion modes) for a wide range of channel conditions.

1 citations

Proceedings ArticleDOI
27 Jul 2016
TL;DR: A JSCC strategy which takes into account the unequiprobable source output to attain better data quality than traditional methods is proposed and finds significantly improved speech quality after transmission in both cases.
Abstract: According to Shannon's source-channel separation theorem, the source coding and the channel coding operations should be performed independently. However, such a method does not exploit the nature of unequiprobable source output in a finite block regime so that it can not achieve good qualities in several scenarios in practical systems. In this study, we propose a JSCC strategy which takes into account the unequiprobable source output to attain better data quality than traditional methods. An adaptation is performed in order to map source code outputs to appropriate inputs of channel code. We also propose a greedy algorithm to construct parameters for the adaptation in polynomial time. Our simulation is performed on AMR compression to estimate the effect of our approach as compared to the traditional strategy. Using this approach we find significantly improved speech quality after transmission in both cases: transfer of only one AMR codec mode and transfer of all AMR codec modes.
Proceedings ArticleDOI
04 Jun 2017
TL;DR: This work proposes two analog schemes, linear mapping, and non-linear mappings for transmission of digital speech data in PCM format and shows that the proposed systems provide a better performance on a wide range of channel qualities in comparison with traditional purely digital systems.
Abstract: Hybrid digital-analog (HDA) architectures have been widely developed for efficient digital transmission of analog speech, audio or video data. By considering the advantage of both digital and analog components, HDA systems gain better performances than purely analog and digital schemes in a wide range of channel conditions. However, HDA systems described in previous works are mostly designed for continuous-valued sources. In this paper, we address the problem of transmission of discrete sources over noisy channels. In particular, our work focuses on digital speech data in PCM format. We proposed two analog schemes, linear mapping, and non-linear mappings. The linear analog mapping employs an equal error protection scheme while the non-linear mapping takes into account the heterogeneous nature of error values to provide better protection to important values. The experiment results show that our HDA systems provide a better performance on a wide range of channel qualities in comparison with traditional purely digital systems.

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Book ChapterDOI
01 Jan 1993
TL;DR: For a wide class of distortion measures and discrete sources of information there exists a functionR(d) (depending on the particular distortion measure and source) which measures the equivalent rateR of the source (in bits per letter produced) whendis the allowed distortion level.
Abstract: Consider a discrete source producing a sequence of message letters from a finite alphabet. A single-letter distortion measure is given by a non-negative matrix (d ij ). The entryd ij measures the ?cost? or ?distortion? if letteriis reproduced at the receiver as letterj. The average distortion of a communications system (source-coder-noisy channel-decoder) is taken to bed= ? i.j P ij d ij whereP ij is the probability ofibeing reproduced asj. It is shown that there is a functionR(d) that measures the ?equivalent rate? of the source for a given level of distortion. For coding purposes where a leveldof distortion can be tolerated, the source acts like one with information rateR(d). Methods are given for calculatingR(d), and various properties discussed. Finally, generalizations to ergodic sources, to continuous sources, and to distortion measures involving blocks of letters are developed. In this paper a study is made of the problem of coding a discrete source of information, given afidelity criterionor ameasure of the distortionof the final recovered message at the receiving point relative to the actual transmitted message. In a particular case there might be a certain tolerable level of distortion as determined by this measure. It is desired to so encode the information that the maximum possible signaling rate is obtained without exceeding the tolerable distortion level. This work is an expansion and detailed elaboration of ideas presented earlier [1], with particular reference to the discrete case. We shall show that for a wide class of distortion measures and discrete sources of information there exists a functionR(d) (depending on the particular distortion measure and source) which measures, in a sense, the equivalent rateRof the source (in bits per letter produced) whendis the allowed distortion level. Methods will be given for evaluatingR(d) explicitly in certain simple cases and for evaluatingR(d) by a limiting process in more complex cases. The basic results are roughly that it is impossible to signal at a rate faster thanC/R(d) (source letters per second) over a memoryless channel of capacityC(bits per second) with a distortion measure less than or equal tod. On the other hand, by sufficiently long block codes it is possible to approach as closely as desired the rateC/R(d) with distortion leveld. Finally, some particular examples, using error probability per letter of message and other simple distortion measures, are worked out in detail.

658 citations