Ammar Bouallegue

Performance evaluation of an acoustic indoor localization system based on a fingerprinting technique

We present an acoustic location system that adopts the time of arrival of the path of maximum amplitude as a signature and estimates the target position through nonparametric kernel regression. The system was evaluated in experiments for two main configurations: a privacy-oriented configuration with code division multiple access operation and a centralized configuration with time division multiple access operation. The effects of the number and positions of sources on the performance of the privacy-oriented system was studied. Moreover, the effect of the number of fingerprint positions on the performance of both systems was investigated. Results showed that our privacy-oriented scheme provides an accuracy of 8.5 cm with 87% precision, whereas our centralized system provides an accuracy of 2.7 cm for 93% of measurements. A comparison between our privacy-oriented system and another acoustic location system based on code division multiple access operation and lateration was conducted on our test bench and revealed that the cumulative error distribution function of the fingerprint-based system is better than that of the lateration-based system. This result is similar to that found for Wi-Fi radio-based localization. However, our experiments are the first to demonstrate the detrimental effect that reverberation has on naive acoustic localization approaches.

Wavelet domain watermark embedding strategy using TTCQ quantization

Invisible digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyright material. Due to its characteristics, one of the problems in image watermarking is to decide how to hide in an image as many bits of information as possible while ensuring that the information can be correctly retrieved at the detecting stage, even after various attacks. Several approaches based on discrete wavelet transform (DWT) have been proposed to address the problem of image watermarking. The advantage of DWT relative to the DCT is that it allows for localized watermarking of the image. The central contribution of this paper is to develop a watermarking algorithm, resilient to like lossy compression attack, by exploring the use of turbo trellis-coded quantization techniques (turbo TCQ) on the wavelet domain. Our results indicate that the proposed approach performs well against lossy wavelet-based compression attacks such as JPEG2000 and SPIHT.

On the optimization of CAPEX and OPEX for the design of island-based translucent optical backbone networks

Abstract The transmission reach of signals in optical transmission systems is limited. To go beyond these transparent reach limits, signal regeneration is necessary to re-amplify, re-shape, and re-time the optical signals. Translucent optical networks use a set of sparsely but strategically placed regenerators for the purpose of signal regeneration. These networks are emerged as a promising solution achieving both opaque-networks Quality-of-Transmission (QoT) requirements and transparent-networks cost-effectiveness. Despite massive progress, there are many outstanding issues regarding the design of translucent networks. Mainly, two approaches have been proposed in the literature to deal with the design of such networks, namely, island-of-transparency and sparse-regeneration. In our present work, we adopted the island-based approach which suits much better the operator׳s expectations especially in terms of network scalability and operational expenses, to address the problem of designing translucent WDM backbone networks. Based on such an approach, we present an original two-phase heuristic which locates the regeneration-sites and determines the number of electronic regenerators to be installed in, according to an efficient strategy that aims at minimizing both Capital Expenditures (CAPEX) and Operational Expenditures (OPEX) inherent to regeneration while ensuring QoT requirements. Compared to previously presented island-based approaches, our algorithm is, to the best of our knowledge, the first island-based algorithm that aims at minimizing simultaneously CAPEX and OPEX while using an accurate QoT estimator incorporating all major linear and nonlinear physical-layer impairment effects during the design and dimensioning process. The performances of the proposed heuristic are evaluated through multiple simulations and compared to those of previously presented approaches in order to highlight the main improvements.

Improved QIM-based watermarking integrated to JPEG2000 coding scheme

In recent years it has been recognized that embedding information in wavelet transform domain leads to more robust blind watermarks. A major difficulty, however, in watermarking in transform domain lies in the fact that constraints on the allowable distortion at any pixel are specified in the spatial domain. In order to insert an invisible watermark, the current trend has been to model the Human Visual System and specify a masking function which yields the allowable distortion. However, this method is highly suboptimal since it leads to irreversible losses at the embedding stage because the watermark is being adjusted in the spatial domain with no care for the consequences in the transform domain. The central contribution of this work is the proposal of integrated wavelet-based non-linear scaling QIM (NLS–QIM) watermark design to reduce fidelity problem. We consider the watermarking process in conjunction with lossy JPEG2000 compression engine. Experimental results have shown that the proposed watermarking strategy exhibits high robustness to compression attacks with respect to the reconstruction quality. Moreover, it provides a significant capacity improvement compared to other hybrid watermarking coding methods in the literature.

Efficient and fast multi-modal foreground-background segmentation using RGBD data

Abstract This paper addresses the problem of foreground and background segmentation. Multi-modal data specifically RGBD data has gain many tasks in computer vision recently. However, techniques for background subtraction based only on single-modality still report state-of-the-art results in many benchmarks. Succeeding the fusion of depth and color data for this task requires a robust formalization allowing at the same time higher precision and faster processing. To this end, we propose to make use of kernel density estimation technique to adapt multi-modal data. To speed up kernel density estimation, we explore the fast Gauss transform which allows the summation of a mixture of M kernel at N evaluation points in O(M+N) time as opposed to O(MN) time for a direct evaluation. Extensive experiments have been carried out on four publicly available RGBD foreground/background datasets. Results demonstrate that our proposal outperforms state-of-the-art methods for almost all of the sequences acquired in challenging indoor and outdoor contexts with a fast and non-parametric operation.

Joint network coding and OFDMA based MAC-layer in PLC networks

Due to the existing frequency-selectivity in PLC channels, data transmission over long distance can exhibit serious difficulties in PLC systems. In order to reduce the attenuation effect for long transmission distances between two nodes (a transmitter and a receiver), we use a relay in PLC systems. Many considerations are taken into account in this system such as the variation of the distances between the transmitter and the relay and between the relay and the receiver. We highlight in this paper how the use of network coding makes it possible to increase the transmitted data rate in an OFDMA based MAC layer. In order to maximize the total data rate, we propose low-complexity subcarrier assignment algorithms for the uplink and downlink of OFDMA based PLC networks. Simulation results are given to support our claims and highlight the performance gain that can be obtained for PLC systems in terms in enhancement of the transmission rate.

JP3D compressed-domain watermarking of still and volumetric medical images

Digital watermarking can be used as data hiding technique to interleave medical images with patient information before transmitting and storing applications. While digital image watermarking and lossy compression methods have been widely studied, much less attention has been paid to their application in medical imaging situations, due partially to speculations on loss in viewer performance caused by degradation of image information. This article describes an hybrid data hiding/compression system, adapted to medical imaging. The central contribution is to integrate blind watermarking, based on turbo trellis-coded quantization, to JP3D encoder. The latter meets conformity condition, with respect to its antecedents JPEG2000 coders. Thus, the watermark embedding can be applied on two-dimensional as well as volumetric images. Results of our method applied to magnetic resonance and computed tomography medical images have shown that our watermarking scheme is robust to JP3D compression attacks and can provide relative high data embedding rate whereas keep a relative lower distortion.

Hidden Field Equations Cryptosystem Performances

It is pointed out in (1) that HFE is faster than RSA, but it has larger key storage. In this paper, we will outline some of its advantages and disadvantages. We will also study the fact of the extension field degree and the private key degree on the speed of key generation, encryption and decryption.

An iterative partial path protection-based approach for routing static D-connections in WDM transparent networks with SRLG constraints

In this paper, we present an iterative heuristic algorithm that tackles the network survivability problem, in all-optical WDM backbone networks, under SRLG considerations. Based on the Partial Path Protection (PPP) recovery technique, our approach aims at minimizing the total bandwidth consumption when providing shared SRLG protection for a given set of static connections with fault-tolerant requirements (referred to as dependable connections (D-connections)) so that the overall network throughput is maximized. The main originality brought by the proposed heuristic consists essentially in its attempt to incorporate another network resource sharing technique called primary-backup multiplexing besides the use of the traditional backup multiplexing in order to further improve resource utilization. To the best of our knowledge, this is the first SRLG protection scheme which uses the primary-backup multiplexing concept without compromising the 100% fault-recovery guarantee when dealing with static traffic. The performance of the presented algorithm is demonstrated to be promising through illustrative numerical examples.

Collision Avoidance in a Power Controller and Reactive Routing Protocol in Wireless Mobile Network

This paper introduces a power controller method for Ad Hoc On-Demand Distance Vector (AODV) reactive routing protocol. The proposed algorithm uses adaptive HELLO messages where their transmit periods are adapted according to the instantaneous energy level of the battery. By transmitting HELLO messages at calculated instant, each node stores its neighborhood energy information. The valid(safest) path between sources and destinations is calculated using route request messages. Indeed, the safest path is defined as the route with the maximum energy levels. However, the collision probability occurred by two nodes having very close energy levels is very hight. Then, we investigate, firstly, the collision occurrence probability using Markov Chain modelling of the battery discharge process. After, we introduce a collision avoidance process to a Power Controller and Reactive Routing Protocol (PC-AODV). The performance of the proposed protocol is theoretically canalised and validated by simulation.