Browsing by Author "Ajgou Riadh"

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Accès Multiple Non Orthogonal dans le Domaine de Puissance (NOMA) dans les Futurs Systèmes Mobiles
(University Of Eloued جامعة الوادي, 2020-02-23) Azzouz Mourad; Ajgou Riadh
L'accès multiple non orthogonal (NOMA) est l'une des techniques d'accès radio prometteuses pour l'amélioration des performances dans les communications cellulaires de prochaine génération. Par rapport à l'accès multiple par répartition en fréquence orthogonale (OFDMA), qui est une technique bien connue d'accès multiple orthogonal à haute capacité (OMA), NOMA offre un ensemble d'avantages souhaitables, y compris une plus grande efficacité spectrale. Il existe différents types de techniques NOMA, y compris le domaine de puissance et le domaine de code. Cet article se concentre principalement sur le NOMA du domaine de puissance qui utilise le codage de superposition (SC) à l'émetteur et l'annulation d'interférence successive (SIC) au niveau du récepteur. Divers chercheurs ont démontré que NOMA peut être utilisé efficacement pour répondre aux exigences des technologies de cinquième génération (5G). De ce point de vue, notre travail examine de manière les progrès récents de NOMA dans les systèmes 5G, en examinant l'analyse de capacité de pointe, les stratégies d'allocations de puissance. De plus, nous discutons les performances de NOMA peuvent être encore améliorées en le combinant avec la technologie multi-entrées multisorties (MIMO), la formation de faisceaux, le codage spatio-temporel, les ondes millimétrique. Cette thèse aborde plusieurs problèmes liés à l'allocation des ressources basée sur NOMA afin d'améliorer les performances du réseau en termes d'efficacité spectrale, de débit et …. En ce sens, des solutions théoriques et algorithmiques doivent être proposées et des résultats numériques doivent être obtenus afin de valider les solutions et vérifier la capacité des algorithmes développés à atteindre des performances optimales
Hybrid Beamforming-Based Massive MIMO systems
(University Of Eloued جامعة الوادي, 2020-02-23) Bezzahi Abdelhakim; Ajgou Riadh
In the context of “smart City”, a very large number of sensors will be deployed everywhere in the cities. These sensors constitute several networks working in parallel in the same geographical area. In order to a massive deployment of sensors, a very low price per sensor is needed. Furthermore, in many applications the sensors should work on battery. We are interested in proposing the ways to decrease the transmitted power of sensors without adding complexity to them. In fact, all the complexity will be in the gateway level, which is supposed to be connected to the outlet. Decreasing the transmitted power will contribute indirectly in the overall interference diminution. One solution is to increase the number of antennas at the gateway in order to point the individual sensors. Because of the great number of sensors, a great number of antennas (massive MIMO) should be used, which increases exponentially the complexity with the number of antennas. In order to do beamforming for the important number of antennas, the hybrid methods are proposed. That is because a totally digital beam-former requires too many RF front-ends. On the other side, allanalogic beam-former does not allow a multi-stream transmitter, therefore not interesting for a multiuser network. Therefore, the beam-former is divided into two parts, analogic and digital, which is called “hybrid beamforming”. In fact, the analog part add complex coefficients at each signal path. Many sub-optimal analog parts have been proposed to simplify the analog structure. We will use LabVIEW as the programming environment because we will implement the developed programs into a USRP that can be programmed by LabVIEW. This thesis should give us a good insight about hybrid beamforming in sub-optimal beam-former case. We should simulate the transmitter with many antennas, including the digital and analog beam formers. The channels should be modeled and the received should be designed and simulated.
Spectral Efficiency Performance Analysis of UL Linear Precoding in Massive MIMO Systems with S-MMSE and MMMSE
(University Of Eloued جامعة الوادي, 2020-02-23) Soualah Badr Eddine; Ajgou Riadh
The 5G network encompasses a set of technologies corresponding to the fifth generation of the standard for mobile telephony. It is validated by the ITU, the International Telecommunication Union. Among these technologies is massive MIMO. The most important concern is improving spectral efficiency. Massive MIMO systems use large arrays of antennas at the base station to transmit multiple users on the same time-frequency resource. The goal of this paper is to maximize the spectral efficiency with linear precoding. In this work, we analyzed the performance and the effect of the minimum mean square error (MMSE), which is a technique of linear precoding on the massive MIMO uplink spectral efficiency in two scenarios: single-cell and multi-cell. We have focused the multi-cell for the reason that it suffers from pilot contamination problems. Orthogonal pilot sequences have to be reused among cells; this leading to estimation errors of channel state information in both the transmitter and the receiver, The MMSE technique is used to overcome the interference that limits the spectral efficiency for massive MIMO system. We apply two MMSE algorithms explicitly S-MMSE and M-MMSE.