Performance Comparison between Adaptive and Fixed Transmit Power in Underlay Cognitive Radio Networks

In this paper, we compare the performance in terms of symbol error probability, data rate and power consumption of the use of fixed transmit power (FTP) and adaptive transmit power (ATP) in underlay cognitive radio networks. The use of FTP alleviates the signaling requirements of underlay cognitive radio networks compared to the ATP. Nevertheless, the use of FTP influences the performances of the underlay cognitive radio networks. To study this influence, we consider three relay selection schemes using FTP: opportunistic decode and forward with FTP (O-DF with FTP), opportunistic amplify and forward with FTP (O-AF with FTP) and partial relay selection with FTP (PR with FTP). We compare the performances of these schemes in terms of symbol error probability, data rate and power consumption with three relay selection schemes using ATP: opportunistic decode and forward with ATP (O-DF with ATP), opportunistic amplify and forward with ATP (O-AF with ATP) and partial relay selection with ATP (PR with ATP). We provide exact and/or lower bound expressions of the symbol error probabilities of O-DF, O-AF and PR with FTP. The analytical study for the data rate and the power consumption is also provided. Our comparison study shows that FTP has a positive impact on the data rate and power consumption performance while it deteriorates the symbol error probability performance

Minimum Mean Square Error channel estimates for DS-SSS in the presence of ISI

Cet article propose une amélioration de l'estimation de canal lorsque de petits facteurs d'étalements sont utilisés dans les systèmes à étalement de spectre par séquences directes. Nous tenons compte de la structure de l'interférence entre symboles pour construire une estimée optimale selon le critère de minimisation de l'erreur quadratique moyenne. Une amélioration significative des performances est ainsi obtenue pour le récepteur en râteau et l'égaliseur linéaire

Throughput evaluation of HARQ schemes with packet and code combining over multipath fading channels for DS-SSS

Dans cet article, nous évaluons les performances des schémas ARQ et HARQ I, utilisant la stratégie Packet Combining, et HARQ II, utilisant la stratégie Code Combining, en présence d'un canal multi-trajets à évanouissements de Rayleigh. L'analyse est effectuée dans deux scénorios extrêmes où le canal est constant et indépendent durant les différentes retransmissions. Les résultats théoriques obtenus sont ensuite validés par des simulations

Caring Behaviors as Perceived by Emergency Nurses in Tunisia

Patients are dissatisfied due to lack of human and relational aspects in care (Donabedian, 1992 cited in Rafii, 2008). Moreover, caregivers confirmed in a report published in 2013, that the quality of care in emergencies is poor (the Centre for Development of Best Practices in Health, 2013). To resolve this issue, Watson suggested applying treatments based on the Caring in this type of care despite its specific structure (Watson, 2010).Indeed, it would be important to measure the behavior of Caring nursing and emergency nurses from their perceptions. The focus of our research is to improve the quality of care in our emergency departments and consequently the patient satisfaction. The aim of this study is to describe perceptions of Caring for Emergency Nurses at University Hospitals of Greater Tunis and its relationship to socio-demographic characteristics. This is a correlational descriptive study, which was guided by the theory of "Human Caring" of Watson. To measure Caring behavior, the Caring behavior inventory (CBI) developed by Wolf, Giardino, Osborne and Ambrose (1994) was used. It is a questionnaire based on the caratifs factors of Watson's theory (Green, A, 2004). The study included all nurses who were trained in "License applied in Nursing" and working in the Emergency Departments of the university hospitals of Tunis (Charles Nicolle, Rabta, Mongi Slim and Habib Thameur). This survey showed that knowledge and professional skills belonged to the dimension that had the highest perception (m=1.06 +/- 0.37). Tunisians nurses were according more importance to the technical dimension and a less importance for relational dimensions. There is no relationship between the socio-demographic characteristics and the five dimensions of the CBI questionnaire. The results of this study did uncover a reality that has to undergo a serious change to improve the quality of care in Tunisia. Further studies are needed in order to improve quality of care and consequently patient satisfaction. Keywords: Caring Behavior-Nurse-emergency-perception DOI: 10.7176/JHMN/69-03 Publication date: December 31st 201

Récepteur UMTS optimisé

PARIS-Télécom ParisTech (751132302) / SudocSudocFranceF

Optimal Packet Length for Free-Space Optical Communications with Average SNR Feedback Channel

In this article, a method to enhance data rates of free-space optical (FSO) systems using packet length optimization is proposed. The average signal-to-noise ratio (ASNR) is measured at the receiver and sent back to the transmitter to optimize packet length. In addition, the length of packet is optimized to enhance the average throughput. We concluded that packet length can be reduced at low ASNR. However, packet length should be increased at higher values of received ASNR. For each ASNR, we also choose the optimal modulation and coding scheme (MCS) and optimal packet length to maximize the throughput. Different MCSs are investigated such as 4-pulse amplitude modulation (PAM) with and without channel coding, 8-PAM, 16-PAM, and 32-PAM. The proposed method gives 0.8–1.9 dB gain with respect to conventional FSO with adaptive modulation and coding (AMC) and fixed packet length. This is the first paper to deal with packet length optimization for FSO systems

Optimisation Of The Interference Cost Generated By

In this paper, we investigate the optimisation of the Random Access CHannel (RACH) of the UMTS FDD system in terms of generated interference. Conditional on open loop measurements, we search the best initial energy of the RACH in order to reduce the multiple access interference while keeping a reasonable mean access time

Impact of outdated CSI on the secrecy performance of dual-hop networks using cooperative jamming

This paper studies the problem of secure dual-hop AF network in the presence of eavesdropper. We study the secrecy performance of partial relay selection with outdated channel state information (CSI). We propose a system secrecy where two sources and destination simultaneously transmit the legitimate and the jamming signal respectively. The selected relay forwards the combined signal to the legitimate receiver and the eavesdropper. We derive a closed-form expression for lower bound on the ergodic secrecy capacity (ESC) under different assumptions of the eavesdropper channel gains. We verify that the system performance is degraded as the correlation coefficient decreases. Simulation results are considered to verify the exactness of the proposed mathematical analysis. - 2019 IEEE.1This publication was made possible by NPRP grant # 10-0102-170094 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu