Visual Communications and Image Processing 2004, 2004
ABSTRACT In this paper we propose an image coding scheme based on Block Turbo Codes (BTC) for pro... more ABSTRACT In this paper we propose an image coding scheme based on Block Turbo Codes (BTC) for protecting SPIHT coded images transmitted over wireless channels. An Unequal Error Protection (UEP) scheme using different product codes is also presented. The optimization of the UEP scheme under a transmission budget constraint is investigated. Performance of the proposed system are first evaluated over Gilbert-Elliott (GE) channels. They are then compared to the well-known system of Sherwood and Zeger, through numerical simulations over a single path Rayleigh fading channel. Then, we present an optimized mobile image transmission framework involving a multiuser asynchronous DS-CDMA transmission system over Rayleigh multipath channels. Simulation results for the 512x512 Lena image, transmitted over the ITU Vehicular A channel, show that a significant gain in PSNR is obtained by using the SIC/RAKE multiuser detector in comparison with a conventional detection by the RAKE receiver. Furthermore, performance are also improved when introducing the UEP scheme.
Sparse code multiple access (SCMA) combined with spectrally efficient frequency division multiple... more Sparse code multiple access (SCMA) combined with spectrally efficient frequency division multiplexing (SEFDM) is a wireless air-interface technology with dual non-orthogonal characteristic which can meet the high spectral efficiency requirement of the future Internet of Things (IoT). In this paper, an iterative multiuser detection/decoder (IMUDD) method for SCMA-SEFDM is proposed, which performs soft information iteration in a turbo style. IMUDD can effectively achieve the multiple-access interference (MAI), inter-symbol interference (ISI) and inter-carrier interference (ICI) cancellation through an external iteration and three internal iterative processes. At each iteration, extrinsic information is extracted from detection and decoding stages, then it is used as a priori information in the next iteration. Furthermore, to reduce the computational complexity of IMUDD scheme, a logarithm domain IMUDD is adopted and analyzed. The simulation results show that IMUDD has a noticeable performance improvement compared to the traditional turbo structured receivers over the multipath fading channel or the additive white Gaussian noise (AWGN) channel.
Turbo D?etection Multi-utilisateur (DS-CDMA) pour la liaison montante du syst`eme UMTS-FDD Ali AL... more Turbo D?etection Multi-utilisateur (DS-CDMA) pour la liaison montante du syst`eme UMTS-FDD Ali AL HOUSSEINI, Samir SAOUDI, Thierry CHONAVEL, Mahmoud AMMAR D?epartement Signal et Communications ENST-Bretagne, BP 832, 29285 BREST Cedex, France ali.husseini, ...
1996 8th European Signal Processing Conference (EUSIPCO 1996), 1996
Before transmission in a narrow band channel, the speech signal has to be compressed. The Code Ex... more Before transmission in a narrow band channel, the speech signal has to be compressed. The Code Excited Linear Prediction Coder (CELP) makes it possible to synthesize good quality speech at low bit rates. Different speech linear predictive coding parameters can be used to design the speech spectral envelope. In our coder the Line Spectrum Pairs (LSP), belonging to the frequency domain, enable us to design the vocal track transfer function. In its first version the coder uses a CLSP (LSP cosine function) scalar quantization leading to a rate of 5.45 kbit/sec. In order to reduce the bit rate to a standard (4.8 kbit/sec), vector quantization was introduced in our coder.
A comparative study of frequency domain HARQ Chase combining schemes for broadband single carrier MIMO CDMA communication
2010 IEEE Globecom Workshops, 2010
In this paper, we consider two turbo packet combining schemes for cyclic prefix (CP)-CDMA MIMO wi... more In this paper, we consider two turbo packet combining schemes for cyclic prefix (CP)-CDMA MIMO with Chase-type ARQ: i) In the first scheme, namely “chip-level turbo packet combining”, minimum-mean-square-error frequency domain equalization (MMSE FDE) and packet combining are jointly performed at the chip-level. ii) In the second scheme, namely “symbol-level turbo packet combining”, chip-level MMSE FDE and despreading are separately
A new Hybrid ARQ scheme based on Blind Separation Sources over MIMO system in multipaths radio fading channel
2009 International Conference on Microelectronics - ICM, 2009
In this paper, we propose a new scheme of Hybrid ARQ (Automatic Repeat reQuest) strategy, based o... more In this paper, we propose a new scheme of Hybrid ARQ (Automatic Repeat reQuest) strategy, based on Blind Separation Sources over Multi Input Multi Output (MIMO) architecture. In the classical HARQ case, when the received packet is erroneous, the system should send a NACK to ask the transmitter to re-send the same packet. Known that in this case, the receiver
Efficient MMSE-Based Space-Time Turbo Equalization in the Presence of Co-Channel Interference
2006 IEEE 63rd Vehicular Technology Conference
... Tarik Ait-Idir*T, and Samir Saoudi* *Signal and Communications Department, ENST-Bretagne, BP ... more ... Tarik Ait-Idir*T, and Samir Saoudi* *Signal and Communications Department, ENST-Bretagne, BP 832, 29285 Brest Cedex, France. ... PIC) and minimum mean square error (MMSE) detection with UCCI have been introduced in [7]. This approach is mainly an extension of the ...
Hybrid automatic repeat request (HARQ) is used in high-speed uplink packet access (HSUPA) to incr... more Hybrid automatic repeat request (HARQ) is used in high-speed uplink packet access (HSUPA) to increase the data rate. Chase combining is the simplest of HARQ algorithms. It provides a time diversity and requires a small memory. In this paper, we propose a technique to increase the chase combining efficiency. In this method, HARQ transmissions are seen as additional receive antennas which are jointly combined at chip-level using a space-time linear minimum square error (LMMSE). We demonstrate that the chase combining diversity gain is considerably increased especially for high-order modulation.
Chip-Level LMMSE Based HARQ Chase Combining for HSUPA
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
Hybrid automatic repeat request (HARQ) is one of the main technologies used in HSUPA system to in... more Hybrid automatic repeat request (HARQ) is one of the main technologies used in HSUPA system to increase the uplink data throughput. Chase combining (CC) and incremental redundancy (IR) are the most known HARQ algorithms. The first provides a time diversity, while the second offers a coding gain. In this paper, we propose a method to increase the chase combining efficiency.
This paper investigates resource allocation and scheduling schemes based on utility theory in a m... more This paper investigates resource allocation and scheduling schemes based on utility theory in a multiuser OFDM home power line communication (PLC) network since utility can evaluate network performance in terms of the level of users' satisfaction from network resource provision. The proposed cross-layer scheme consists of two phases: subcarrier allocation at the physical (PHY) layer and scheduling scheme at the medium access control (MAC) layer, which dynamically integrates channel conditions and queue characteristics to ensure leveled quality-of-service (QoS) requirements. Moreover, a lowcomplexity algorithm is proposed to solve the allocation problem. Simulation results demonstrate that the proposed scheme can greatly improve system performance on the basis of satisfying the QoS requirements of delay-sensitive services.
This paper addresses the issue of efficient turbo packet combining techniques for coded transmiss... more This paper addresses the issue of efficient turbo packet combining techniques for coded transmission with a Chase-type automatic repeat request (ARQ) protocol operating over a multiple-input-multiple-output (MIMO) channel with intersymbol interference (ISI). First of all, we investigate the outage probability and the outage-based power loss of the MIMO-ISI ARQ channel when optimal maximum a posteriori (MAP) turbo packet combining is used at the receiver. We show that the ARQ delay (i.e., the maximum number of ARQ rounds) does not completely translate into a diversity gain. We then introduce two efficient turbo packet combining algorithms that are inspired by minimum mean square error (MMSE)-based turbo equalization techniques. Both schemes can be viewed as low-complexity versions of the optimal MAP turbo combiner. The first scheme is called signal-level turbo combining and performs packet combining and multiple transmission ISI cancellation jointly at the signal-level. The second scheme, called symbol-level turbo combining, allows ARQ rounds to be separately turbo equalized, while combining is performed at the filter output. We conduct a complexity analysis where we demonstrate that both algorithms have almost the same computational cost as the conventional log-likelihood ratio (LLR)-level combiner. Simulation results show that both proposed techniques outperform LLR-level combining, while for some representative MIMO configurations, signal-level combining has better ISI cancellation capability and achievable diversity order than that of symbol-level combining. Index Terms-Automatic repeat request (ARQ) mechanisms, multiple-input-multiple-output (MIMO), intersymbol interference (ISI), outage probability, turbo equalization, minimum mean square error (MMSE). I. INTRODUCTION A. Research Motivation H YBRID-AUTOMATIC repeat request (ARQ) protocols and multiple-input-multiple-output (MIMO) play a key role in the evolution of current wireless systems toward high data rate wireless broadband standards [1]. While MIMO techniques allow the space and time diversities of the multiantenna channel to be translated into diversity and/or multiplexing gains [2], hybrid-ARQ mechanisms exploit the ARQ delay, i.e., the maximum number of ARQ transmission rounds,
EURASIP Journal on Advances in Signal Processing, 2008
The plug-in method enables optimization of the bandwidth of the kernel density estimator in order... more The plug-in method enables optimization of the bandwidth of the kernel density estimator in order to estimate probability density functions (pdfs). Here, a faster procedure than that of the common plug-in method is proposed. The mean integrated square error (MISE) depends directly upon J(f) which is linked to the second-order derivative of the pdf. As we intend to introduce an analytical approximation of J(f), the pdf is estimated only once, at the end of iterations. These two kinds of algorithm are tested on different random variables having distributions known for their difficult estimation. Finally, they are applied to genetic data in order to provide a better characterisation in the mean of neutrality of Tunisian Berber populations.
Une nouvelle méthode de codage des signaux audio génériques est présentée, à un débit de 64 kbit/... more Une nouvelle méthode de codage des signaux audio génériques est présentée, à un débit de 64 kbit/s dans la bande de fréquence 20-15000 Hz, avec un faible délai. Cette méthode se base sur un codage en sous-bandes associé au LD-CELP ainsi qu'à des bancs de filtres cascadés. Des travaux initiaux [1] montrent que, lorsqu'un débit de 16 kbit/s est alloué à chaque sous-bande, la qualité audio n'est pas satisfaisante. Nous proposons un nouvel algorithme basé sur la quantification en réseau de points afin de pallier la complexité de la quantification vectorielle statistique. La souplesse du système permet d'effectuer une allocation binaire dynamique dans chaque sous-bande. Des résultats expérimentaux sont présentés et évaluent la validité de la méthode proposée.
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Papers by S. Saoudi