Mustapha Djeddou

Adaptive CA-CFAR threshold for non-coherent IR-UWB energy detector receivers

In the present letter, a new adaptive threshold comparison approach for time-of-arrival (TOA) estimation in ultra wideband (UWB) signals is proposed. This approach can be used with non-coherent energy detector receivers in UWB systems. It exploits the idea of cell averaging constant false alarm rate (CA-CFAR) used in radar systems, where the threshold changes every energy block. The performance of several approaches are compared via Monte Carlo simulations using the CM1 channel model of the standard IEEE 802.15.4a. Both simulation results and comparisons are provided highlighting the effectiveness of the proposed approach.

Maximum likelihood angle-frequency estimation in partially known correlated noise for low-elevation targets

In radar applications, the received echo signals reach the array elements via a multiplicity of paths despite the fact that there exists only one target. We address the problem of joint direction of arrival and Doppler frequency estimation using a sensor array in partially known additive noise. We consider a specular reflection model with a radar cross section fluctuating from one pulse repetition interval to another. The proposed model allows the estimation of more paths than sensors. Two approximate maximum likelihood algorithms are proposed. The first approach uses a linear expansion of the noise covariance matrix, whereas the second employs a combination of oblique projections and a zero-forcing solution to alleviate the effect of noise. In contrast to other classical methods, the two approaches are more robust to spatially correlated noise, and they employ more compact cost functions that reduce the dimension of the optimization search. Numerical simulations are provided to assess the basic performance of the two approaches, which are compared to the Crame/spl acute/r-Rao bound.

Security enhancement of the authenticated RFID security mechanism based on chaotic maps

With the fast growth of the automatic authentication and asset tracking usage in a wide variety of applications in different fields, government, logistics, transportation and retail are among the most supportive of the radio-frequency identification (RFID) market. Security is a crucial issue and must be addressed seriously. RFID security must meet the public demand of data protection. Recently, several lightweight RFID authentication protocols conforming to the EPCglobal Class 1 Generation 2 (EPC C1-G2) standard have been proposed. In this paper, we present efficient attacks against the authenticated RFID security mechanism of Chang et al. based on Chebyshev chaotic maps, which is the first solution that adopted the chaos in the RFID authentication process. It turns out that this protocol has fundamental weaknesses that can be used by an adversary to break the system. We will show that this protocol is vulnerable to tracking attack, secret disclosure attack, impersonation attack and desynchronization attack. The proposed attack techniques are in light of two flaws related to the message generation and the shared-secret update process, which are not neatly scrutinized. Then, we propose an improved RFID authentication protocol based on the Chebyshev chaotic map hard problem, conforming to the EPC C1-G2 standard with more flexibility, security and mobility for the RFID application. Copyright

Micro-Doppler classification for ground surveillance radar using speech recognition tools

Among the applications of a radar system, target classification for ground surveillance is one of the most widely used. This paper deals with micro-Doppler Signature (μ-DS) based radar Automatic Target Recognition (ATR). The main goal for performing μ-DS classification using speech processing tools was to investigate whether automatic speech recognition (ASR) techniques are suitable methods for radar ATR. In this work, extracted features from micro-Doppler echoes signal, using MFCC, LPC and LPCC, are used to estimate models for target classification. In classification stage, two parametric models based on Gaussian Mixture Model (GMM) and Greedy GMM were successively investigated for echo target modeling. Maximum a posteriori (MAP) and Majority-voting post-processing (MV) decision schemes are applied. Thus, ASR techniques based on GMM and GMM Greedy classifiers have been successfully used to distinguish different classes of targets echoes (humans, truck, vehicle and clutter) recorded by a low-resolution ground surveillance Doppler radar. Experimental results show that MV post processing improves target recognition and the performances reach to 99,08% correct classification on the testing set.

Design and implementation of a new active RFID authentication protocol based on elliptic curve encryption

RFID (radio frequency identification) is an efficient automatic identification technology used in a wide variety of applications and more recently as a leading authentication technology in many security services. However, the wireless nature of the transmitted data causes various security issues that must be addressed decisively. To solve these issues, numerous solutions and attempts have been proposed in the literature using several cryptographic primitives. Yet, it is still uncertain about the practicability of a significant number of these protocols, as their hardware implementation has not received much attention. In this paper, we deal with an efficient FPGA implementation and validation of an RFID authentication protocol based on elliptic curve (ECC) encryption scheme. As far as we know, this is the first FPGA implementation of an RFID authentication protocol based on ECC-ElGamal encryption. We believe that the proposed design architecture will bring a new clarity to others ECC-based protocols architectures. In addition, we illustrate the effectiveness of the implemented architecture in the car key systems.

RFID authentication protocols based on ECC encryption schemes

In this paper, we propose a new RFID authentication protocol based on elliptic curves ElGamal encryption schemes. The proposed protocol needs two passes, requires only scalar point multiplications operation and can resist to various kinds of attacks such as man-in-the-middle attack, simple power analysis, and replay attacks.These features make it very attractive to low cost RFID applications, such as the biometric passport active authentication (AA) for example. The proposed protocol is tested and simulated in c ≠ language for several NIST recommended curves over GF(p) (p = 112; 128; 160; 192 and 256 bits).

Chip Averaging Chaotic ON–OFF Keying: A New Non-Coherent Modulation for Ultra Wide Band Direct Chaotic Communication

This letter proposes a new adaptive threshold modulation scheme, called chip averaging chaotic ON–OFF keying (CA-COOK). This new scheme is applied to non-coherent modulations in ultra-wideband direct chaotic communication. Mainly, the proposed method deals with the “estimation problem” caused by the bit energy variation of the chaotic carrier signal. This is completed by adopting the Cell Averaging Constant False Alarm Rate paradigm used in radar, and each bit period is divided into several chips, where one of those chips is bearing the information. Bit-error-rate performance in additive-white-Gaussian-noise, two-path Rayleigh, and IEEE802.15.4a office NLOS channel models, is analyzed and compared with well-known and challenging chaos-based communication systems. Simulation results show the effectiveness of the proposed CA-COOK.

CA-CFAR threshold selection for IR-UWB TOA estimation

In this paper, we simplify the architecture of the cell averaging constant false alarm rate (CA-CFAR) approach used in time-of-arrival (TOA) estimation for impulse radio ultra wideband (IR-UWB) systems. The CA-CFAR approach uses the received signal samples provided by the non-coherent energy detection (ED) receivers. The modified approach is evaluated by Monte Carlo simulation on the CM1 channel model of the standard IEEE802.15.4a. The effects of the reference cells number and the guard cells duration on the performances of the modified CA-CFAR approach are studied. The simulation demonstrates that the modified approach gives better results than the conventional approaches.

Parameter estimation in low-elevation target tracking

In radar applications, when a target is in close proximity to a reflectory surface, the received echo signal reaches the radar site via two or more paths, even though there exists only one target in the environment. So, it is often relevant to estimate the directions and the relative delays of each path ray. We present two approaches to jointly estimate these parameters based on a 2D ESPRIT-like algorithm Van der Veen et al., (1998) in wireless communications. Numerical simulations are provided to access the performance of the proposed approaches, which are compared to the Cramer-Rao bound and the MUSIC algorithm combined with spatial smoothing.

Security Analysis and Enhancement of the Most Recent RFID Authentication Protocol for Telecare Medicine Information System

Radio frequency identification (RFID) technology has been used in a wide variety of applications, more recently as a leading identification technology in healthcare environments. In the most recent years, this technology is adopted for telecare medicine information system (TMIS) for authentication, safety, security, data confidentiality and patient’s privacy protection over public networks. TMIS is the bridge between patients at home and doctors at healthcare organizations that permits to confirm the correctness of exchanged information between different actors of the system. Recently, several RFID authentication schemes have been presented and suggested for the TMIS in the literature. These schemes try to resolve the security and privacy problems over insecure healthcare networks environments by exploiting different cryptographic primitive’s solutions. In this paper, we analyze in depth the security of the most recent proposed protocol for TMIS in the literature and find out its main vulnerabilities. The proposed attacks are possible due to some weaknesses related to the misuse of the timestamp technique, the calculation of the reader request and tag response messages using the one-way hash function, which are not attentively scrutinized. Furthermore, we propose an efficient and robust improved mobile authentication protocol with high efficiency and security for TMIS. The performance analysis shows that our improved protocol could solve security weaknesses of the studied protocol and provide mobility, efficiency and is well-suited to adoption for TMIS.