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This paper investigates space-frequency (SF) coding for non-coherent (NC) Multiple Input Multiple Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) fading links, where neither the transmitter nor the receiver knows the channel. Our strategy consists in distributing the convolutional encoded and interleaved bits over the different transmit antennas, OFDM tones and OFDM symbols. The combination of the convolutional coding and bit interleaving with the SF coding can exploit the maximum spatial/frequency diversity over frequency-selective channels. In order to reduce the decoding complexity, we divide the OFDM symbol into several groups and apply differential encoding and decoding between adjacent groups. The proposed NC SF matrix is designed as a combination of a differential Cayley code and a systematic NC SF code, which leads to a simple decoding rule over the multipath channel. We show through asymptotic Pairwise Error Probability (PEP) analysis and simulation results that our encoding strategy can provide full diversity gain and achieves better performance in terms of spectrum efficiency and symbol error rate than all three the systematic NC-SF coding, the Cayley differential SF coding and our proposed SF coding without convolutional encoding and bit interleaving.

Cognitive radio is an exciting emerging technology that has the potential of dealing with the stringent requirement and scarcity of the radio spectrum. Such revolutionary and transforming technology represents a paradigm shift in the design of wireless systems as it will offer the ability of radio sensing, self adaptation and dynamic spectrum sharing. In this paper, we are interested in the case where secondary users are allowed to communicate concurrently with primary users provided that they do not create harmful interference to the licensed users. More precisely, the secondary transmission will depend on a variable cost that reliably quantifies the interference power generated by the secondary user at the primary base stations. Here, we aim to improve the unlicensed system performance in terms of throughput. For this aim, we propose to use an adaptive modulation as well as an energy optimization at the unlicensed user in order to maximize its data rate. We show that the system throughput depends on several parameters such as the maximum allowed cost and the number of base stations in the primary network, the secondary user location and its transmission energy.

In this paper, we investigate low complexity numerical optimization, implementation and performance evaluation of biorthogonal pulses for Biorthogonal Frequency Division Multiplexing (BFDM) systems over doubly dispersive channel. In our previous works, we have proposed optimal pulses design based on a numerical maximization of Signal-to-Interference Ratio (SIR) exact expression. In this paper, in order to accelerate the optimization procedure, we undertake the pulse shapes optimization with an approximate expression of the SIR, instead of the exact one. Our approximation of the SIR uses Taylor series of interference and desired signal mean powers. We show through simulations that our new pulses are very close to our previous ones and that they lead to a SIR subtantially equivalent to the exact one. For a performance evaluation of these pulses, we propose to verify if the SIR computed through system level simulation is in conformance with the numerically optimized SIR. More precisely, we simulate a multicarrier transmission system using the optimized pulses. For this aim, we propose an efficient implementation of both the modulator and the demodulator of the system and a simple and efficient method to find out the resulting SIR. Simulations show that the SIR computed through system level simulation matches the maximum achievable SIR obtained through pulses optimization.

This paper deals with the throughput maximization for a new cooperative relaying scheme combined with an adaptive modulation technique. More precisely, we propose a new adaptive Decode-Remodulate-and-Forward (DRF) scheme where the relay decodes and remodulates the received signal with the appropriate modulation scheme before relaying it to the destination. The modulation constellations at the source and relay nodes can be different in order to adapt them to the channels qualities and to maximize the end-to-end throughput. The destination operates a soft-combining, relying on the LLRs (Log Likelihood Ratio) of signals emanating from the source and the relay. Our approach for throughput optimization, applied for DRF scheme in uplink CDMA communications, is carried on while keeping the global multiple-access-interference (MAI) cost constant. This optimization constraint is introduced to ensure throughput maximization with no impairment to the global system performance due to MAI. Simulation results show that the proposed adaptive DRF cooperation protocol provide a significant enhancement, in terms of system throughput, over the direct transmission scheme.

Objectif Le syndrome metabolique (SM) chez les sujets âges apneiques presente des specificites a prendre en compte. L’objectif de notre travail etait de determiner les caracteristiques du SM dans une population de patients âges apneiques. Patients et methodes Etude retrospective ayant concernee 50 patients âges porteurs de syndrome d’apnees hypopnees obstructives du sommeil (SAHOS) suivis au service de pneumologie D a l’hopital Abderrahmane Mami Ariana, Tunisie, entre janvier 2010 et decembre 2014. Nous avons etudie les caracteristiques du SM chez les patients âges apneiques en les comparants au groupe de patients âges sans SM. Resultats La prevalence du SM etait de 76 % (n = 38). L’âge moyen etait comparable dans les deux groupes. Compares aux sujets âges apneiques sans SM, ceux ayant un SM etaient plus frequemment des femmes. Les patients apneiques presentant un SM avaient significativement plus de somnolence diurne (p = 0,016), un score d’Epworth ≥ 10, plus observe (89,4 % vs 77,6 % ; p = 0,034) et un indice de masse corporelle moyen plus eleve (38,34 ± 5,78 kg/m2 vs 34,37 ± 6 kg/m2 ; p = 0,04). En etudiant l’impact de la severite du SAHOS sur la survenue du SM, nous n’avons pas trouve de difference significative (la frequence du SAHOS severe etait de 81,1 % chez les patients avec SM vs 61,5 % chez les patients sans SM). Discussion D’apres notre travail, la prevalence du SM chez les sujets âges apneiques est elevee. Ceci est explique par les modifications physiologiques liees a l’âge en l’occurrence, les modifications hormonales et l’augmentation de la masse grasse.

Objectifs Evaluer la qualite de vie (Qdv) d’un groupe de patients diabetiques et identifier les facteurs associes a sa deterioration. Patients et methodes Etude transversale sur 60 patients diabetiques de type 1 ou 2, âges de 15 a 65 ans, sous insuline, hospitalises pour diabete mal equilibre (HbA1c > 8 %). Pour evaluer la Qdv de nos patients, nous avons utilise une echelle specifique au diabete : Audit of Diabetes Dependet Quality of Life (ADDQOL). Ce questionnaire comprend trois scores. Le premier concerne la Qdv generale. Le deuxieme interroge le patient sur sa Qdv s’il n’etait pas diabetique. Le dernier est un score compose de 19 items concernant differents domaines de la vie. L’ADDQoL a ete traduit en arabe facile. Le score varie de −9 : impact negatif maximal a +3 : impact positif maximal. Resultats L’âge moyen etait de 43 ans. L’HbA1c moyenne etait de 11,5 ± 1,8 %. Le score moyen de « Qdv generale » etait de −0,23. Le score de « Qdv sans diabete » etait de −2,01. Le score composite moyen etait de −3,4. Les trois scores etaient comparables dans les deux types de diabete et dans les deux sexes. La presence de retinopathie diabetique etait associee a une deterioration de la Qdv (p = 0,008). L’utilisation d’analogues d’insuline et le niveau d’instruction eleve etaient associes a une meilleure Qdv (p = 0,004). Discussion La Qdv des patients interroges etait mauvaise. La presence de complications et le niveau d’instruction sont deux facteurs qui ont influence significativement la Qdv. L’evaluation de la Qdv devrait s’integrer dans la prise en charge des patients diabetiques afin de depister precocement les multiples problemes lies a cette maladie chronique.

Introduction L’objectif de notre etude etait de rapporter les modalites de l’insulinotherapie fonctionnelle (IF) utilisees dans notre service et d’evaluer l’impact metabolique de cette methode. Methodes Etude retrospective sur 36 patients diabetiques type 1 (dont 13 hommes) hospitalises pour IF. Nous avons releve les caracteristiques de ces patients avant l’IF, les modalites pratiques de l’IF et l’impact metabolique de cette methode. Resultats L’âge moyen etait de 20,33 ± 8,22 ans (7–40 ans). Le diabete evoluait depuis 6,9 ± 5,41 ans (6 mois–27 ans). Durant l’annee precedant l’IF, une hypoglycemie severe etait rapportee par 3 patients et une decompensation cetosique est survenue chez 3 malades. Apres l’epreuve de jeune glucidique, la dose moyenne d’insuline basale etait significativement reduite (0,34 UI/kg/j vs 0,44 UI/kg/j ; p = 0,023). Les ratios moyens etaient de 1,8 UI/10 g au petit dejeuner, 1 UI/10 g au dejeuner et 1,4 UI/10 g au diner. La sensibilite moyenne a l’insuline etait de 0,48 g/L/1 UI d’insuline. La sensibilite moyenne au resucrage etait de 0,38 g/L/10 g de sucre. La duree moyenne d’hospitalisation etait de 6,88 jours. Apres un suivi moyen de 2,6 ans ± 1,7 (3 mois–5 ans), 15 patients (41 %) etaient toujours adherents a l’IF. Chez ce groupe, l’HbA1c est passee de 10,07 % avant IF a 9,2 % a 1 an de suivi ( p = 0,022) et elle est restee stable a 2 ans (8,91 % ; p = ns). Un cas d’hypoglycemie severe et un cas de cetose diabetique sont survenus au cours du suivi sous IF. Conclusions Notre etude a montre des modalites pratiques conformes aux recommandations internationales, avec reduction significative de la dose d’insuline basale et de l’HbA1c grâce a l’IF.

Objectif La physiopathologie du syndrome des ovaires polykystiques (SOPK) reste mal elucidee. La presence d’antecedents familiaux de premier degre d’HTA ou de diabete type 2 (DT2) serait associee a une aggravation du phenotype. L’objectif de notre travail etait de chercher un lien entre les antecedents familiaux et le phenotype du SOPK. Methodes Etude retrospective sur 50 patientes porteuses de SOPK partagees en 2 groupes : groupe 1 (avec antecedents familiaux de DT2 ou HTA ; n = 23) et groupe 2 (sans antecedents familiaux ; n = 27). Nous avons compare le phenotype du SOPK dans les deux groupes. Resultats Les patientes du groupe 1 etaient significativement plus âgees (27,3 ± 6,17 vs 23,15 ± 5,1 ans, p = 0,012) avec un âge de menarche significativement plus jeune (11,77 ± 1,3 vs 12,59 ± 1,64 ans, p = 0,05). Le phenotype le plus frequent etait celui associant la spaniomenorrhee, l’hyper-androgenie et les signes echographiques, avec des frequences comparables dans les deux groupes. Les troubles menstruels etaient plus frequents dans le groupe 1 (87 % vs 77,8 %) mais sans difference significative. Malgre que la frequence de l’obesite etait comparable dans les 2 groupes (56,5 % vs 44,4 %, p = ns), le diabete type 2 et la baisse du HDL cholesterol etaient significativement plus frequents dans la groupe 1 (p respectifs : 0,05 et 0,022). Discussion Les patientes ayant un SOPK avec une histoire familiale de DT2 ou d’HTA auraient un risque metabolique plus eleve que les autres.

Objectifs Evaluer l’observance therapeutique chez un groupe de patients diabetiques et identifier les facteurs lies a une mauvaise observance. Methodes Etude transversale sur 60 patients (37 femmes) diabetiques de type 1 ou 2, âges de 15 a 65 ans, sous insuline, hospitalises pour diabete mal equilibre (HbA1c > 8 %). L’adhesion au traitement etait evaluee par un auto-questionnaire derive du Medication Adherence Questionnaire (MAQR) de Morisky-Green. Ce questionnaire etait traduit et valide en langue arabe. Il comporte 6 items de type oui/non. Cette echelle permet de definir trois profils d’observance : bonne observance si la reponse est « non » pour les 6 items, observance moyenne si 1 ou 2 reponses « oui », mauvaise observance si 3 ou plus reponses « oui ». Resultats L’âge moyen etait de 43 ans. L’anciennete moyenne de diabete etait de 12 ± 6,27 annees. L’HbA1c moyenne etait de 11,5 ± 1,8 %. La majorite de nos patients (95 %) avaient un probleme d’observance (45 % : mauvaise observance et 50 % : observance moyenne). L’observance etait plus mauvaise chez les diabetiques de type 1 (p = 0,02), chez les hommes (p = 0,09) et chez les patients sous schema basal bolus (p = 0,01). L’utilisation des analogues d’insuline et le niveau d’instruction eleve etaient associes a une meilleure observance (p = 0,003). Conclusions L’observance therapeutique etait mediocre dans notre etude. L’adhesion au traitement est un parametre sous-estime dans la prise en charge du diabetique. Tout doit etre mis en œuvre pour la depister, evaluer son importance et y porter remede.

Les crises febriles (CF) se definissent comme des crises declenchees par la fievre, en l’absence d’infection du systeme nerveux chez l’enfant d’âge inferieur a 6 ans. Frequentes, leur prevalence est de 2 a 5 %. Le risque de recurrence ou d’epilepsie ulterieure est eleve et depend de plusieurs facteurs [1] , [2] . La realisation, dans ce contexte, d’un electroencephalogramme (EEG) a visee pronostique est un sujet controverse. Nous avons mene une etude retrospective colligeant les EEG de 34 enfants d’âge moyen 23,5 mois (sex-ratio de 1,6) ayant eu au moins une CF. Les patients ayant des antecedents personnels d’epilepsie, d’affection neurologique ou d’infection du systeme nerveux central ont ete exclus. Ainsi, quatre patients avaient des CF simples et 30 des CF complexes (12 crises focales, 12 crises prolongees et 6 crises recurrentes). L’EEG etait depourvu d’anomalies paroxystiques (AP) chez 20 patients (4 CF simples et 16 CF complexes). 14 EEG comportaient des AP focales. Ces anomalies etaient de topographie frontale dans 4 cas, occipitale dans 5 cas et autre dans 5 cas. Les AP etaient plus frequentes en cas de presence de facteurs connus predictifs d’epilepsie ulterieure a savoir en cas de crise prolongee (7/12 patients), de crise focale (5/12) de crises recurrentes (2/6), d’enfant de sexe masculin et d’enfant de plus de 3 ans (6/7). Ces donnees rejoignent celles de la litterature. Par ailleurs, la focalisation frontale des AP retrouvee dans 28 % des cas serait egalement fortement predictive d’epilepsie ulterieure alors que la focalisation occipitale ne serait pas significativement associee a un risque superieur d’epilepsie. L’EEG pourrait jouer le role d’outil d’evaluation pronostique des CF pour predire l’evolution vers l’epilepsie. Un suivi de cohorte serait d’un grand apport pour evaluer la valeur predictive des anomalies EEG dans les CF.

L’epilepsie absence de l’enfant (EAE) est definie par des crises epileptiques faites d’une alteration de la conscience a debut et fin brusque, de duree breve concomitante a une decharge generalisee de pointe-ondes (PO) rythmiques a 3 Hz avec une activite de fond normale a l’electroencephalogramme (EEG). Des aspects electriques moins typiques critiques et intercritques ont ete decrits [1] , [2] , [3] . Nous rapportons les observations de 3 enfants d’un âge moyen de 6 ans ayant des crises d’absences typiques. A l’EEG de veille intercritique, le rythme de fond etait normal mais des anomalies intercritiques a type de pointes frontales unilaterales et de bouffees de PO frontales bilaterales a bascule ont ete objectivees chez les 3 patients. L’EEG critique a montre chez deux enfants des decharges generalisees de PO a 3 Hz precedees de PO frontales. Chez le troisieme patient, les decharges debutaient en frontal puis se generalisaient et comportaient des PO et des polypointe-ondes a 3 Hz. Une mauvaise synchronisation durant la decharge a egalement ete observee. Ces crises etaient resistantes a l’acide valproique en monotherapie chez les trois patients et ont necessite l’association de zarontin ou lamictal avec une evolution favorable. Ainsi, la presence de 2 voire 3 pointes par complexe, d’anomalies focales intercritiques, d’un debut focal et d’une mauvaise synchronisation de la decharge ne doivent pas remettre en cause le diagnostic de l’EAE.

Introduction Le syndrome du canal carpien (SCC) est la plus frequente des neuropathies canalaires. Le diabete est associe a une prevalence et une incidence plus elevees de SCC. Objectifs Identifier les caracteristiques cliniques et les donnees electriques du SCC des patients diabetiques par rapport aux patients n’ayant pas d’antecedents de pathologies endocriniennes ni metaboliques. Patients et methodes Il s’agit d’une etude retrospective de type cas-temoin menee au service d’explorations fonctionnelles du CHU Habib Bourguiba de Sfax durant l’annee 2013 colligeant 324 patients (34 diabetiques et 290 temoins n’ayant pas d’antecedents de pathologies endocriniennes ni metaboliques) dont l’electroneuromyogramme a objective un SCC uni- ou bilateral. La severite de l’atteinte electrique a ete classee selon l’echelle electrophysiologique de l’Association americaine des pathologies neuromusculaires et de l’electrodiagnostic. Resultats L’âge moyen etait plus avance chez le groupe des diabetiques (55,8 ± 11,9 vs 49,5 ± 9,7 ans) (p Discussion Le diabete est considere comme un facteur de risque du SCC. Ceci peut etre explique par l’augmentation de la pression osmotique resultant de l’accumulation de sorbitol en intracellulaire, entrainant un œdeme et une degenerescence hydropique. Le pourcentage eleve des SCC bilateraux renforce cette hypothese. L’âge avance et la duree d’evolution du diabete peuvent expliquer la frequence elevee des SCC severes. Conclusion Le SCC associe au diabete presente certaines caracteristiques cliniques et electriques particulieres (âge plus avance, frequence elevee des formes severes avec atteinte axonale sensitive et/ou motrice).

A family of space-time codes suited for noncoherent multi-input multi-output (MIMO) systems is presented. These codes use all the complex degrees of freedom of the system, i.e. M/spl times/(1-(M/T)) symbols per channel use. They are constructed as codes on the Grassmann manifold G/sub T,M/(/spl Copf/) where T is the temporal codelength and M is the number of transmit antennas.

In this paper, we define a multi-access interference (MAI) cost that can assess the extra interference, inherent to relaying use and perceived by the whole cellular network. This MAI cost shadows an implicit and smart power control for CDMA uplink communications. In fact, this cost takes into account not only the reception quality required at the serving base station but also the global interference generated to all others base stations in the cellular system. Here, the optimization goal aims to enhance the system performance, in terms of Packet-Error-Rate (PER), for a required quality of service (QoS). The optimization approach is achieved for both Decode-and-Forward (DF) and Incremental DF relaying schemes, carried out on packet-by-packet basis. A variety of simulation results are obtained using the analytical expressions of Packet-Error-Probability (PEP) that we derive for both DF and IDF schemes. By way of an example, for a target PER of 10−2, our optimized IDF scheme could afford more than 13 dB gain, in terms of MAI cost reduction, over the direct transmission scheme. Furthermore, simulation results underline that the optimized IDF relaying is more powerful than the optimized DF scheme and provides as much as 3 dB gain for some relay positions.

In this paper, we investigate limited feedback precoding for two single-user MIMO systems. The first one employs spatial diversity at the transmitter and Maximum Ratio Combining at the receiver. The second one uses spatial multiplexing at the transmitter and V-BLAST signal processing at the receiver. For both systems, the precoder is selected at the receiver among a codebook and its index is conveyed to the transmitter through an error free feedback channel. For the first system, we consider two Grassmannian precoding codebooks and show through simulation results that a small number of feedback bits can reach the theoretical performance. For the case of a single-user system based on spatial multiplexing, we propose a novel criterion for selecting among codebook matrices the optimum precoding matrix at the receiver which maximizes the minimum signal to interference and noise ratio over the transmitted substreams. Simulation results show that our proposed selection criterion outperforms three other criteria introduced in the literature for the spatial muliplexing MIMO system. They also show a significant enhancement over the unprecoded spatial multiplexing system.

In this paper, we conceive and develop a prototype of a car parking management system. The system gives a real-time snapshot of the monitored parking equipped by a Wireless Sensor Network (WSN). The developed application consists of two parts; one embedded in sensor nodes and another one executed at the pc containing interfaces. Moreover, this system enables to develop a Web application which allows the driver to reserve a free place in the parking or to guide him to localize a place using the parking map with all details of the way to reach it.

Resistance to thyroid hormone (RTH) is a rare disorder characterized by variable tissue hyporesponsiveness to thyroid hormone, usually caused by mutations in the thyroid hormone receptor beta (TRβ). It has been reported that the serum of patients with RTH is free of auto-antibodies against thyroglobulin (Tg) and thyroid peroxidase (TPO), except in rare cases where coincidental autoimmune thyroiditis is also present. We describe a 13-year-old girl with chronic thyroiditis and RTH. This patient had increased plasma free T3, free T4 at the upper limits with unsuppressed TSH. She had peripheral manifestations of thyroid hormone excess, hypertension and growth acceleration. Anti-TPO antibodies were positive. Sequence analysis of the TRβgene was performed and revealed a novel mutation I54V in exon 4. The same mutation was also found in the mother and two asymptomatic sisters. The clinical presentation of our patient is not habitual in RTH because growth retardation is frequently reported in this syndrome. The association between RTH and thyroiditis complicate the management of the hypothyroidism.

In this paper, we propose a novel approach for cooperative systems performance optimization. We are interested on the uplink CDMA communications, known to be both intra-cell and inter-cell interference limited. More precisely, we define a multi-access interference (MAI) cost that reliably quantifies the additional interference generated by a relayed communication to the whole cellular system. For CDMA uplink communications, this MAI cost hides an implicit and smart power control that takes into account not only the reception quality required at the serving base station but also the interference generated to the whole network. Here, the optimization process aims to improve the system performance, in terms of Packet-Error-Rate (PER) for a certain required quality of service (QoS). The optimization process is carried for both Selective Relaying (SR) and Incremental Selective Relaying (ISR) schemes, on packet-by-packet basis. A variety of simulation results are carried using analytical expressions of Packet-Error-Probability that are derived for SR and ISR schemes. We show that, for a target PER of 10−2, our optimized ISR scheme could provide up to 14 dB gain, in terms of MAI cost reduction, over the direct transmission scheme. Additionally, results highlight that our optimized ISR relaying is always more powerful than the optimized SR scheme and provides as much as 4 dB gain in the most favorable cases.

In this paper, we investigate fast time-varying channel estimation for two orthogonal space–time block-coded systems with either two or three transmit antennas and with one receive antenna. We propose an iterative expectation–maximisation-based maximum a posteriori (MAP) semi-blind algorithm for the estimation of the discrete propagation channels seen from the transmit antennas. This algorithm requires a convenient representation of the channel using a discrete version of the Karhunen-Loeve expansion theorem. It incorporates the coded structure of each block in a turbo-processing fashion and uses the MAP training-based channel estimation algorithm for its optimum initialisation. The transmit antennas are assumed to be spatially correlated for the system with two transmit antennas and spatially uncorrelated for the three-antenna system. The validity of the proposed algorithm is highlighted by simulation results. The performance of the proposed receivers, based on MAP channel estimation, for the two systems approaches that of the perfect channel state information receiver, even for very time selective fading channels. Copyright © 2011 John Wiley & Sons, Ltd.

In this paper, an efficient procedure for collision resolution in slotted ALOHA MIMO systems is proposed. We have proved in a previous work that packet collision resolution with spatial successive interference cancellation (SSIC) is a promising approach to improve the performance of slotted ALOHA protocol, when the colliding users' powers are different. However, it is not efficient for very close powers of collided packets. In this paper, we propose to solve this problem with a preliminary linear processing for its initialization. We evaluate the bit error rate and the throughput of the system using the proposed procedure. The simulation results show that we obtain an efficient random access method with high throughput for wireless transmission.

Offset QAM orthogonal frequency division multiplexing (OFDM/OQAM) is a promising technique for high data rate next generation cellular systems, operating on highly time-frequency dispersive channels. To combat dispersive channel interference, OFDM/OQAM systems allow very well time and frequency localized prototype functions. The good localization of the prototype function results from the separation of the transmission of the in-phase and quadrature phase components. Unfortunately, this separation introduces a crosstalk between these components when imperfect channel estimation is used to demodulate transmitted data. The main goal of this paper is the enhancement of channel estimation quality for OFDM/OQAM systems through the minimization of this crosstalk. Our approach consists in introducing a number of optimum linear constraints on neighbors of pilot symbols used to estimate the channel. The optimality of these components is related to a minimization of the residual interference mean power. In our study, for the representation of the signal space of our OFDM/OQAM system, we consider both square and hexagonal lattices in the time-frequency plane.

In this paper, we propose a novel optimization approach for Amplify-and-Forward (AF) relaying schemes. In previous works, we have optimized the AF relaying scheme carried on a symbol-by-symbol basis. Here, we focus on AF and Incremental AF (IAF) schemes, operating on a packet-by-packet basis. The optimization is carried out while keeping the additional multiple access interference cost, inherent to relaying, constant. For CDMA uplink communications, this cost can reliably quantify the capacity loss incurred by the use of relaying in the transmission process. We define an optimization cost constraint and propose an approach to optimize AF and IAF relaying performance in terms of Block-Error-Rate (BLER). In order to assess the performance enhancement over direct transmission of optimized relaying schemes and compare AF and IAF, we have carried numerous simulations results.

In cooperative networks, different single-antenna terminals cooperate in order to provide better signal quality over Rayleigh fading channels. The main drawback of cooperative diversity is the throughput loss due to the extra resources needed for relaying. Therefore, we propose to use adaptive modulation in cooperative networks in order to compensate the throughput loss due to the relaying. In this paper, we analyze the performance of different cooperative schemes using adaptive modulation. For cooperative schemes, we consider amplify and forward (AF) protocol with one relay, AF protocol with two relays and AF protocol based on the Alamouti space-time code. For the adaptive modulation, we propose a novel criterion for the determination of the decision table for the modulation choice. Simulation results show that, in bad channel conditions, these adaptive protocols have better performance compared with the classical system with direct transmission.

This paper considers the problem of maximum a posteriori (MAP) sequence equalization over a frequency selective channel when the channel is not perfectly known at the receiver. The imperfect channel estimate is provided by a least squares estimator using a training sequence (TS). The derivation of the MAP criterion taking into account the channel estimation error exists in the literature but no direct practical implementation has been proposed. In this paper, we propose an approximate solution to the problem by using an iterative burst-by-burst equalizer based on the Expectation Maximisation (EM) algorithm. Simulation results show that the performance of our iterative equalizer is significantly better than the performance of the non-iterative equalizer which does not take into account the channel estimation error. Copyright © 2010 John Wiley & Sons, Ltd.

We propose in this paper a turbo channel estimation algorithm for Alamouti's space-time coded system over fast time varying channels. This algorithm performs an iterative estimation of the multiplicative fading channel according to the maximum a posteriori (MAP) criterion. It requires a convenient representation of the fast varying channel based on the Karhunen-Loeve expansion theorem. It takes into account the coded structure of data symbols in the estimation process thanks to the BCJR algorithm. The validity of the proposed structure is highlighted by simulation results.

This paper exhibits a methodology to achieve a system level design for Cognitive Radio (CR) receiver supporting IEEE 802.22 Standard. Based on superheterodyne receiver supporting Sub-Band Sensing, the overall radio system characteristics depicted from the IEEE 802.22 Standard specifications are dispatched through the different receiver blocks. Moreover, we developed the theoretical calculation and different techniques of system level design. Each of Radio Frequency (RF) characteristics such as noise figure (NF), gain and linearity (third order intercept point, (IIP3)) is simulated taking in account the analog-to-digital converter (ADC) full scale power constraint. On the one hand, our system level simulation results proved that the receiver architecture is capable to perform spectrum sensing and to allow communication processing. The receiver performs a total gain of 51 dB and an IIP3 of −19.8 dBm for low gain mode. It achieves 105dB as gain and 9.9 dB for noise figure for high gain mode.

In radio mobile cellular networks, the users located at the cell border are suffering from a bad quality of service (QoS). Cooperative communications is a promising technique that can overcome this weakness by allowing the users to profit from powerful benefits of the spatial diversity. Nevertheless, abstraction is usually made on the impact of the additional multiple access interference inherent to relaying. In this paper, we propose a novel approach that optimizes the system performance of an amplify-and-forward (AF) relaying scheme subject to a constant multiple access interference cost for the uplink CDMA (Code Division Multiple Access) communications. We present a variety of simulation results illustrating the cellular system performance enhancement in term of BER (Bit Error Rate) over direct transmission.

In radio mobile cellular networks, the users located at the cell border suffer from a bad quality of service (QoS). Cooperative communication is a promising technique that can overcome this weakness by allowing these users to profit from powerful benefits of spatial diversity. Nevertheless, abstraction is usually made on the impact of the additional multiple access interference inherent to relaying. In a previous work, we have optimized amplify-and-forward (AF) relaying scheme subject to a constant multiple access interference cost for CDMA (Code Division Multiple Access) uplink communications. Here, we extend this work by dealing with performance optimization for decode-and-forward (DF) relaying subject to the same cost constraint for the same framework. We compare the performance of both optimized AF and DF schemes for different scenarii. A variety of simulation results reveals that DF relaying provides cellular performance enhancement in terms of BER (Bit Error Rate) over both direct transmission and AF relaying schemes.

This paper deals with the problem of code design for non-coherent frequency-selective Multiple Input Multiple Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) fading links, where neither the transmitter nor the receiver knows the channel. A simple and classical approach for non coherent (NC) coding for MIMO-OFDM system consists of coding across antennas and time slots on each OFDM subcarrier. Only, this approach does not permit to exploit the diversity of frequency-selective channels. In our aim to exploit this diversity, we propose in this paper a strategy that consists of coding across antennas and OFDM subcarriers (space-frequency coding) within a single OFDM symbol. Our space-frequency (SF) codes are based on NC Grassmann space-time (ST) codes obtained via an exponential map from coherent ST codes. We determine the asymptotic Pairwise Error Probability (PEP) for each scheme in order to evaluate the diversity and the coding gains. Simulations show that compared with the classical approach, our NC-SF codes can get more diversity gain and better symbol error performance.

In this paper, we consider joint iterative equalization and channel estimation for TDMA systems over a frequency selective, quasi-static fading channel. We assume a slowly varying channel impulse response from one burst to the following one. We modify the maximum a posteriori (MAP) criterion by taking into account an a priori channel estimate obtained from the burst preceding the one processed. Assuming that the receiver knows the channel statistics, we propose to use the EM (Expectation-Maximization) algorithm for a joint iterative equalization and channel estimation. During each iteration of the receiver, the EM algorithm reestimates the channel by using the a posteriori probabilities (APP) available at the output of the equalizer. The algorithm we propose has linear-time complexity per iteration. Simulations show that our MAP receiver reaches the performance of the MAP equalizer with perfect channel knowledge after a few iterations, for high SNR and for small values of normalized Doppler spread. They show also that our receiver outperforms the MAP equalizer that uses a channel estimate obtained by using a training sequence.

In this paper, we consider a cooperative network with one source, one destination and two relays to bring cooperative diversity. We assume the link between the source and the destination is so bad that we do not consider it. We propose a decode-and-forward (DAF) strategy based on the Alamouti space-time (ST) code. The two relays must recover the transmitted sequence and forward it to the destination. We consider fast time varying channels between the cooperative users and the destination and our objective is to estimate these two channels in order to recover the information sequence at the destination. We propose a data-aided decision-directed Maximum A Posteriori (MAP) iterative channel estimation algorithm. It can profit from an optimum initialization by means of the MAP data-aided channel estimation. Besides, we adapt this iterative receiver to the case where the destination is equipped with two receive antennas to bring more diversity. The validity of the proposed algorithms is highlighted by simulation results.

This paper studies the throughput enhancement in a wireless slotted ALOHA system via multi-user detection. For this aim, we focus on uplink access and propose an iterative receiver algorithm that can jointly detect the colliding packets for different users that share the same physical channel. This algorithm performs a spatial successive interference cancellation. We show that its performance can be improved with a good initialization. We evaluate the throughput of the system when we apply the iterative receiver for the detection of two and three colliding user packets. We show that our approach improves considerably the performance of the slotted ALOHA system since a packet can be received correctly, even if it collides with one or two other user packets.

Orthogonal frequency division multiplexing (OFDM) has been used in various wireless communication systems. For these OFDM systems, the elementary pulse has to guarantee orthogonality with its time-frequency shifted versions. However, the time and frequency dispersion of the wireless channel leads to the loss of this orthogonality, producing inter-symbol and inter-channel interference. In order to reduce these interferences, a good localization of the pulse shape is required. In this paper, we investigate the optimization of the OFDM pulse shape for time and frequency dispersive channels. We consider the same envelope functions in transmission and reception. The proposed pulse shape is expressed as a linear combination of the most localized Hermite functions. The optimization, with respect to the signal-to-interference ratio (SIR), is carried out using the Arrow-Hurwicz algorithm. Simulations show that OFDM optimized systems can be outperform conventional OFDM systems.

In this paper, we consider the problem of maximum a posteriori (MAP) equalization of the received signal over a frequency selective channel when the channel is not perfectly known at the receiver. The derivation of the MAP criterion in this case leads to an expression for which no exact implementation exists in the literature. In this paper, we propose to solve the problem by using the expectation-maximization (EM) algorithm. The algorithm we propose has linear-time complexity per iteration. Simulations show that few iterations are required to reach the performance of the MAP equalizer with perfect channel knowledge.

In this paper, we propose an optimal biorthogonal pulses design for a biorthogonal frequency division multiplexing (BFDM) systems operating on a time-frequency dispersive additive white Gaussian noise (AWGN) channel. The proposed transmit and receive pulse shapes which are expressed as a linear combination of the most localized Hermite waveforms and are therefore well time-frequency localized. We propose a method for designing biorthogonal pulse shapes that maximize the signal-to-interference-and-noise ratio (SINR). We demonstrate that the SINR of the BFDM systems operating over dispersive channels with additive white Gaussian noise converges to the value of signal-to-noise ratio (SNR).

Electroencephalography (EEG) and magnetic resonance imaging (MRI) are noninvasive neuroimag- ing modalities. They are widely used and could be complementary. The fusion of these modalities may enhance some emerging research fields targeting the exploration better brain activities. Such research attracted various scientific investigators especially to provide a convivial and helpful advanced clinical-aid tool enabling better neurological explorations. Our present research was, in fact, in the context of EEG inverse problem resolution and investigated an advanced estimation methodology for the localization of the cerebral activity. Our focus was, therefore, on the integration of temporal priors to low-resolution brain electromagnetic tomography (LORETA) formalism and to solve the inverse problem in the EEG. The main idea behind our proposed method was in the integration of a temporal projection matrix within the LORETA weighting matrix. A hyperparameter is the principal fact for such a temporal integration, and its importance would be obvious when obtaining a regularized smooth- ness solution. Our experimental results clearly confirmed the impact of such an optimization procedure adopted for the temporal regularization parameter comparatively to the LORETA method. © 2015 SPIE and IS&T (DOI: 10

Resume Introduction Le syndrome des pointes-ondes continues du sommeil (POCS) represente une forme rare d’epilepsie qui peut se manifester par des troubles neurocognitifs et/ou psychiatriques. Les troubles autistiques sont frequemment associes. Observation Un garcon de 5 ans, issu d’un mariage consanguin lointain ne a terme par cesarienne sans notion de souffrance neonatale, a presente, a l’âge de 18 mois, une epilepsie focale a semiologie centrale confirmee par un electroencephalogramme (EEG) de veille et de sommeil. Il a ete mis sous valproate de sodium (Depakine ® ). Le bilan neuropsychologique a permit d’etablir le diagnostic d’autisme typique (CIM10). Dans le cadre du bilan du retard du langage et des troubles du comportement, un EEG de sommeil realise a l’âge de 3 ans et demi, a objective un pattern de POCS. L’evolution electrique a ete initialement favorable sous valproate de sodium (Depakine ® ) et Clobazam (Urbanyl ® ) avec disparitions des anomalies a l’EEG de sommeil pratique apres un mois et demi de traitement. L’evolution a ensuite ete marquee par la reapparition du pattern de POCS aux EEG ulterieurs ayant necessite l’association aux traitements anterieurs d’ethosuximide (Zarontin ® ). L’evolution electroclinique a ete partiellement favorable grâce a un traitement multidisciplinaire (medicamenteux, reeducation orthophonique et psychomotricite) Discussion L’association autisme et POCS peut etre meconnue ; les POCS ne se manifestant que par une aggravation des troubles neurocognitifs. Nous attirons l’attention sur cette entite clinique, afin de pouvoir la traiter efficacement. L’EEG de sommeil est indispensable pour une meilleure prise en charge. La disparition du pattern de POCS sous traitement s’accompagne habituellement d’une amelioration neuropsychologique significative bien que partielle. Conclusion Cette observation d’un enfant presentant des troubles du comportement et du langage, revelant un POCS, souligne l’interet dans ces situations cliniques frequentes de pratiquer un EEG de sommeil. Informations complementaires Pas de financement.

We propose an approximated Generalized Likelihood Ratio Test (GLRT) for noncoherent systems which use constellations over the Grassmannian generated by the exponential map. By means of this approximation we succeeded in coping with the strong non-linearity introduced by the exponential map. The new simplified decoder, which implements the approximated GLRT, is in fact quasi-optimal with respect to the GLRT. We analyze the performance of the new decoder in terms of structure, complexity and error probability for uncoded and coded noncoherent constellations.

We consider single-input multiple-output non-coherent communication over the flat fading Rayleigh channel. At the transmitter we propose an architecture based on the unitary space-time codes obtained via exponential mapping (Kammoun, I and Belfiore, J, 2003). At the receiver we implemented a simple low-complexity decoding algorithm inspired from the optimal GLRT decoder. The performance of the sub-optimal decoder is very close to the optimal GLRT decoder. The unitary non-coherent codes are considered as points over the Grassmann manifold G/sub T, M/ (/spl Copf/).

In this paper we investigate single-input multiple-output non-coherent space-time schemes over the flat fading Rayleigh channel. First, we propose a simplified decoding algorithm for a unitary space-time code obtained via the exponential mapping. We analyze the performance of this scheme in terms of complexity and error probability. We compare this scheme to training-based schemes since they are one of the best available propositions in the literature.

We consider multiple-antenna non-coherent communications over Rayleigh flat fading channels and single-antenna non-coherent systems with unknown channel phase. For both systems, we propose some sub-optimal simplified decodings for the class of unitary space-time codes obtained via the exponential map (I. Kammoun and J.-C. Belfiore, Nov. 2003). To this aim, we use the geometrical interpretation of these codes as sets of points over the Grassmann manifold G/sub TM/. We compare these codes with other propositions in the literature, for which a simplified decoder exists.

We propose, in this paper, the construction of noncoherent spherical constellations, both uncoded and coded, by mapping a T-1 dimensional constellation carved from /spl Zopf/[i]/sup T-1/ onto the unit T dimensional sphere. The chosen mapping corresponds to the parametrization of the Grassmann manifold G/sub T,1/ where T is the code-length. The advantage of the spherical codes that we propose here is that the GLRT detector can be slightly simplified. The coding and decoding principles are derived from Galliou et al. (2002).

We propose the construction and the decoding of noncoherent space-time codes which use all the complex degrees of freedom of the system (M/spl times/(1-M/T)). They extend the construction of codes for differential reception for which the number of real degrees of freedom per channel use is M. They are derived from codes on the Grassmann manifold G(T, M) where T is the code length and M is the number of transmit antennas.

Objectif Nos objectifs etaient d’etudier les habitudes alimentaires, le niveau des connaissances et de correler les deux resultats chez des jeunes diabetiques de type 1. Patients et methodes Cette etude transversale a porte sur 30 patients diabetiques de type 1, depuis plus de 6mois. Le recueil des donnees a ete fait au moyen d’un questionnaire qui comprend 5 sections (caracteristiques socio demographiques, caracteristiques du diabete, les habitudes alimentaires, evaluation des connaissances). L’analyse des donnees a ete fait par un logiciel de statistique SPSS 11. et l’enquete alimentaire par le logiciel « Bilnut ». Resultats L’apport calorique moyen etait de 2104 ± 478 cal/j. Cet apport se repartissait en 51,8 ± 4,5% pour les glucides, 15 ± 1,4% pour les proteines et 33,21% ± 4,7 pour les lipides. Le score moyen des connaissances etait 11,13 ± 4,59 sur 20, le deficit des connaissances portait surtout sur toutes les complications aigues du diabete, y compris la cetose (rapporte dans 13% des cas) et certaines complications chroniques, telle que l’infarctus du myocarde (rapportee dans 40% des cas) et la neuropathie rapportee dans 3,3% des cas. Nous avons trouve une correlation significative entre le niveau de connaissances, l’apport calorique (p = 0,05), l’apport en glucides (p = 0,015) et l’apport en acides gras poly insatures (p = 0,052). Par ailleurs, le score de connaissance s’eleve avec le niveau d’instruction et l’âge. Discussion L’insuffisance des connaissances de nos diabetiques de type 1 sur leur maladie pourrait s’expliquer, d’une part, par la periode qui precede l’apparition des complications degeneratives et d’autre part, par un deficit d’information de la part du systeme educatif. Il faut donc elaborer des programmes d’education specifiques a l’enfant et a l’adolescent, tout en engageant leur familles dans le processus educatif, moyennant un support sous forme de videos, de loisirs et de jeux attractifs pour les enfants.

Introduction La maladie de Cushing (MC) est souvent due a un microadenome hypophysaire. Nous rapportons le cas de trois patientes avec une MC due a un macroadenome corticotrope (MAC). Observations La premiere est âgee de 42 ans, consultant pour baisse de l’acuite visuelle (BAV), l’examen clinique a trouve des signes specifiques du syndrome de Cushing (SC), l’examen ophtalmologique a trouve une hemianopsie bilaterale et une paleur papillaire, le bilan hormonal etait en faveur d’une MC et l’IRM hypophysaire a montre un macroadenome comprimant le chiasma optique (CO). La malade a ete operee avec amelioration de la vision, une cortisolemie a j7 postoperatoire (pop) a 90 nmol/l et absence de reliquat tumoral a l’IRM. La deuxieme est âgee de 58 ans consultant pour cephalees et BAV. L’examen physique etait normal, le FO a montre une pâleur papillaire. L’IRM a montre un macroadenome refoulant le CO, le bilan hypophysaire etait en faveur d’une MC. La malade a ete operee, avec amelioration de la vision mais la cortisolemie en pop etait a 900 nmol/l et a l’IRM un reliquat tumoral. La troisieme malade est âgee de 27 ans consultant pour hirsutisme et sterilite primaire, le bilan hormonal etait en faveur d’une MC et l’IRM a montre un macroadenome sans compression chiasmatique. La patiente a ete operee avec persistance de la MC. Conclusion Les MAC ont une expression clinique differente, la guerison de notre malade est une modalite evolutive rare.