Rachida Touhami

Analysis of the Mixed Coupling in Bilateral Microwave Circuits Including Anisotropy for Mics and Mmics Applications

Higher integration and smaller layout size, two major trends in today’s industry, lead to more prominent electromagnetic coupling with direct applications in the RF/microwave area such as directional couplers, filters, multiplexers, shifters, delay lines, etc. In the present work, an efficient hybrid-mode method is presented for a rigorous characterization of the coupling in multilayer bilateral microwave circuits including anisotropy effects. Various types of planar configurations were considered including microstrip, finline and coplanar structures, but the proposed approach can easily be extended to any form of coupled lines. To fully characterize bilateral multilayer circuits in millimetre wave region with an arbitrary number of conductors, closed forms of dyadic Green’s functions were determined in the spectral domain, with use of the Galerkin technique. The computed results show good agreement with data available in the literature. Furthermore, two original configurations based on three line bilateral couplers were computed and validated using neural network models.

Generic Spectral Immittance Approach for Fast Design of Multilayered Bilateral Structures Including Anisotropic Media

In this letter, the spectral domain immittance-based approach is generalized for a fast and efficient design of bilateral microwave structures with multilayered anisotropic layers. This technique is based on the derivation of dyadic Greens functions by introducing, for the first time, a new conjoint admittance parameter. An original configuration based on three-line bilateral couplers is computed and validated using neural network models. Furthermore, numerical examples are presented and close agreement is obtained between simulated results and published data. The CPU time is also investigated

60-GHz Statistical Channel Characterization for Wireless Data Centers

This letter presents 60-GHz radio channel measurements and characterization in a productivity data center. Path loss and delay spread are statistically modeled for possible use-cases corresponding to potential deployment scenarios in a wireless data center (WDC). Models behaviors are then used to highlight the propagation differences across use-cases. It was found that most use-cases are characterized by a rich scattering channel and sub-free-space path loss exponent values. Compared to common indoor environments, delay spread and path loss values suggest a better link budget at higher distances and possibly higher interference in dense deployment scenarios. The reported models and key propagation behaviors are useful for practical system design and evaluation of WDC millimeter-wave links.

Performance analysis of basic tree protocols and ALOHA-based anti-collision algorithms used in RFID systems

Radio Frequency Identification (RFID) is a popular automatic identification and an emerging wireless technology with highly promising applications. In an RFID system, the anti-collision algorithm is one of the primary mechanisms to address the issue of multi-object identification. This paper focused on a detailed study of the ALOHA anti-collision problem and a comparative study with the basic binary tree protocols. Two tag estimation methods were investigated and a performance analysis was successfully achieved based on various key design parameters such as the probability of a successful transmission, the collision ratio, the offered load, the system efficiency, the system throughput and the estimation accuracy of successful transmission.

A comparative study of various microstrip bandpass filters topologies for UWB applications

Because of their large spectrum, Ultra-Wide Band (UWB) systems are requested to maintain a very low power spectral density, making them vulnerable to higher power narrowband signals. To mitigate any in-band narrowband interference (NBI), which may degrade the overall UWB system performance, filtering is an inescapable solution. The aim of this paper is to compare the performance of various microstrip planar filters which are designed based on a specific electric model in order to provide UWB filter designers with key design tools to efficiently select the most suitable filter based on their particular needs.

A comparative performance evaluation study of the basic binary tree and aloha based anti-collision protocols for passive RFID system

RFID (Radio Frequency Identification) technology is one of the most important branches of the automatic identification technology which achieves the identification of targets by contactless communications. One of the major challenges for RFID systems is to avoid or solve collisions due to interference that might occur between tags which decrease the efficiency of RFID system. This paper focused on a detailed comparative performance evaluation study and an adoption of certain algorithms of anti-collision for passive RFID system, for the two families of solving collision: deterministic (according to the: QTA, CTTA, BS-QTA, BS-CTTA) and stochastic (ALOHA, SLOTTED ALOHA, np-CSMA). The simulation results for the two families that we get with protocols evaluation are based on their own proper evaluation parameters. Thus, for evaluating the simulation of the stochastic family, we have proposed a new performance metric which judges and correctly evaluates this anti-collision protocol; which is: the number of identified tags versus to the time. This metric provides a direct measure of the time taken to read a group of tags.

Simulation of the anti-collision process of RFID systems based on multiple access protocol modeling

In this paper, the authors targeted multiple access protocols to analyze the problem of collision and collision avoidance in RFID systems. By considering user terminals as tags and access point as reader, the authors efficiently modelled the wireless communication channel by considering the capture effect. Otherwise, if the capture effect is not considered, the system is modelled under wired communication.

A new full-wave modal technique for fast modeling of isotropic/anisotropic asymmetric CPW

In this paper, an original dispersive numerical modal approach combining accuracy and speediness is presented as promising tool for fast analysis of asymmetric coplanar waveguide on isotropic/anisotropic substrates. For this purpose, a quasi-symmetric model was introduced using C and π mode trial functions along with the formalism of operators to efficiently study the dispersion effect of coplanar structures. Comparisons with published and asymmetric model data are presented to further confirm the adequate choice of trial functions used in this quasisymmetric approach.

Evaluation performance of anti collision circuit based BSS method for RFID system

For Radio Frequency Identification (RFID) system, this paper presents an anti collision circuit design for fast of multi tags identification system. Principally, the authors use the Blind Signal Separation (BSS) method by the Independent Component Analysis (ICA) algorithm based computation of anti-collision circuit for speedily extracting the hidden factor of signal independence in neural network learning. Then, to reach the separation performance of BSS method, the design of the anti-collision circuit in the reader is based on the processing for more inputs of signal samples by one neuron hardware model of neural network through one multiplexer, which by means of a control circuit the original signal are estimated through one decoder. Thus, the performance results of the proposed approach is estimated since the speed rate of the anti-collision circuit provides numerical results, which evaluates the performance of an anti-collision circuit through the number of identified tags of RFID system.

ICA-based blind symbol detection for compound system MIMO-OFDM in CDMA context

Independent Component Analysis (ICA) based method for detection in the compound system MIMO-OFDM and in the context of CDMA is proposed. ICA algorithm is used as a post processor attached to a subspace based CDMA receiver. The proposed architecture of receiver reduces the bias caused by the channel noise and further decreases the noise by dimensionality reduction. A downlink CDMA based MIMO-OFDM channel is investigated given that only the code of the wanted mobile user is known. So, the blind symbol separation is then performed with the proposed receiver. We compare the proposed receiver and the ICA ability to the conventional matched filter, the well-known linear MMSE receiver, the ZF detector. The obtained simulation results for the Additive White Gaussian Noise (AWGN) channel demonstrate that the proposed scheme achieves significant Bit Error Rate (BER) performance and is suitable for CDMA based MIMO-OFDM system.