Tesis sobre el tema "Au-delà des réseaux 5G"
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Guiraud, Maël. "Ordonnancement periodiques de messages pour minimiser la latence dans les réseaux dans un contexte 5G et au delà". Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG034.
Texto completoThis thesis is the result of a collaboration between DAVID Laboratory and Nokia Bell Labs France.The original idea is to find algorithmic solutions to deterministically manage periodic flows in networks in order to control and minimize the transmission time, called latency. One of the objectives of 5G (C-RAN, for Cloud Radio Access Network) is to centralize the calculation units of the radio antennas of telecommunications networks (called Radio Access Network) in the same computer center (the Cloud). The network between the computing center and the antennas must be able to satisfy the latency constraints imposed by the protocols.We define the problem of finding a periodic scheduling for messages so that they never compete for the same resource, and prove that the different variants of the problem studied are NP-complete. We first study the problem for a particular topology in which all the streams share the same link. We first propose polynomial algorithms of increased sophistication, and FPT algorithms that allow us to find a solution when the number of routes is reasonable, which is the case for C-RAN networks.Since the algorithms developed in this first part are not directly adaptable to more general topologies, we then propose a canonical form to the problem which allows us to define an efficient neighborhood notion for local search heuristics (hill climbing, tabu search, simulated annealing). We use this canonical form to define an efficient Branch and Bound algorithm when the number of routes is moderate.We also propose a performance evaluation of the proposed solutions compared to current flow management solutions, and show that our model is feasible in practice thanks to new equipment under development
Khizar, Sadia. "Metrology for 5G edge networks (MEC). Leveraging mobile devices beyond the edge toward task offloading". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS069.
Texto completoThe pervasiveness of mobile devices equipped with internet connectivity and positioning systems leads us to regard them as a valuable resource to leverage. In this thesis, we tackle the use of mobile devices from a new perspective. We consider the extension of the capacity of the MEC by using the available resources of mobile devices beyond the edge of the infrastructure network. The goal is to leverage their untapped resources to process computation on behalf of the MEC in a distributed way. It is fundamental for the MEC to be aware of its operating environment to rely on mobile nodes. In the first part of the thesis, we have focused on the temporal availability of beyond-the-edge resources. We chose to investigate the co-location of terminals and analyze their persistence in a cell. Then, we turn our attention to task allocation. We shift the focus on the spatio-temporal aspect by quantifying the resources that a cell can provide to perform a MEC task. We estimate the potential amount of computational tasks performed by nodes based on the cumulative presence time in a given cell and a given completion delay. Results provide insight into the possibilities of offloading computing tasks on mobile nodes. Furthermore, it allows knowing the locations where it is advisable to offload tasks and the time duration of tasks offloadable
Arora, Sagar. "Cloud Native Network Slice Orchestration in 5G and Beyond". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS278.
Texto completoNetwork Function Virtualization (NFV) is the founding pillar of 5G Service Based Architecture. It has the potential to revolutionize the future mobile communication generations. NFV started long back in 2012 with Virtual-Machine (VM) based Virtual Network Functions (VNFs). The use of VMs raised multiple questions because of the compatibility issues between VM hypervisors and their high resource consumption. This made containers to be an alternative network function packaging technology. The lightweight design of containers improves their instantiation time and resource footprints. Apart from network functions, containerization can be a promising enabler for Multi-access Edge Computing (MEC) applications that provides a home to low-latency demanding services. Edge computing is one of the key technology of the last decade, enabling several emerging services beyond 5G (e.g., autonomous driving, robotic networks, Augmented Reality (AR)) requiring high availability and low latency communications. The resource scarcity at the edge of the network requires technologies that efficiently utilize computational, storage, and networking resources. Containers' low-resource footprints make them suitable for designing MEC applications. Containerization is meant to be used in the framework of cloud-native application design fundamentals, loosely coupled microservices-based architecture, on-demand scalability, and high resilience. The flexibility and agility of containers can certainly benefit 5G Network Slicing that highly relies on NFV and MEC. The concept of Network slicing allows the creation of isolated logical networks on top of the same physical network. A network slice can have dedicated network functions or its network functions can be shared among multiple slices. Indeed, network slice orchestration requires interaction with multiple technological domain orchestrators, access, transport, core network, and edge computing. The paradigm shift of using cloud-native application design principles has created challenges for legacy orchestration systems and the ETSI NFV and MEC standards. They were designed for handling virtual machine-based network functions, restricting them in their approach to managing a cloud-native network function. The thesis examines the existing standards of ETSI NFV, ETSI MEC, and network service/slice orchestrators. Aiming to overcome the challenges around multi-domain cloud-native network slice orchestration. To reach the goal, the thesis first proposes MEC Radio Network Information Service (RNIS) that can provide radio information at the subscriber level in an NFV environment. Second, it provides a Dynamic Resource Allocation and Placement (DRAP) algorithm to place cloud-native network services considering their cost and availability matrix. Third, by combining NFV, MEC, and Network Slicing, the thesis proposes a novel Lightweight edge Slice Orchestration framework to overcome the challenges around edge slice orchestration. Fourth, the proposed framework offers an edge slice deployment template that allows multiple possibilities for designing MEC applications. These possibilities were further studied to understand the impact of the microservice design architecture on application availability and latency. Finally, all this work is combined to propose a novel Cloud-native Lightweight Slice Orchestration (CLiSO) framework extending the previously proposed Lightweight edge Slice Orchestration (LeSO) framework. In addition, the framework offers a technology-agnostic and deployment-oriented network slice template. The framework has been thoroughly evaluated via orchestrating OpenAirInterface container network functions on public and private cloud platforms. The experimental results show that the framework has lower resource footprints than existing orchestrators and takes less time to orchestrate network slices
Sapountzis, Nikolaos. "Optimisation au niveau réseau dans le cadre des réseaux hétérogènes nouvelle génération". Electronic Thesis or Diss., Paris, ENST, 2016. http://www.theses.fr/2016ENST0082.
Texto completoBy 2016, it is well-known that mobile networking has dominated our lives. We use our mobile cell phones for almost everything: from social networking to streaming, finding accommodation or banking. Nevertheless, it seems that operators have not understood yet this domination, since their networks consist of nodes that: (i) suffer from enormous load fluctuations, (ii) waste their resources, and (iii) are blamed to be a major energy-killer worldwide. Such shortcomings hurt: load-balancing, spectral and energy efficiency, respectively. The goal of this dissertation is to carefully study these efficiencies and achieve a good trade-off between them for future mobile 5G heterogeneous networks (HetNets). Towards this direction, we firstly focus on (i) the user and traffic differentiation, emerging from the MTC and IoT applications, and (ii) the RAN. Specifically, we perform appropriate modeling, performance analysis and optimization for a family of objectives, using tools mostly coming from (non) convex optimization, probability and queueing theory. Our initial consideration is on network-layer optimizations (e.g. studying the user association problem). Then, we analytically show that cross-layer optimization is key for the success of future HetNets, as one needs to jointly study other problems coming from the layers below (e.g. the TDD allocation problem from the MAC, or the cross-interference management from the PHY) to avoid performance degradation. Finally, we add the backhaul network into our framework, and consider additional constraints related to the backhaul capacity, backhaul topology, as well as the problem of backhaul TDD allocation
Doanis, Pavlos. "A Deep Reinforcement Learning Framework for Scalable Slice Orchestration in Beyond 5G Networks". Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS100.pdf.
Texto completoThis Thesis introduces a flexible Reinforcement Learning queuing-based framework for dynamic slice orchestration in Beyond 5G networks, supporting multiple concurrent slices that span different technological domains and are governed by diverse end-to-end Service Level Agreements. Different (Deep) Reinforcement Learning methods (single or multi-agent) are investigated to address the state and action complexity hurdles arising in such combinatorial problems, which render the use of "vanilla" Reinforcement Learning algorithms impractical. The performance of the proposed schemes is validated through simulations under both synthetic Markovian traffic and real traffic scenarios
Thomas, Robin. "Stratégies de détection MIMO d'ordre supérieur avec applications au relayage pour les réseaux 4G+ et 5G". Thesis, Paris, ENST, 2016. http://www.theses.fr/2016ENST0081/document.
Texto completoThe evolution of wireless communication networks has always been rapidly progressive partly due to the demands of today’s data hungry users. This dissertation presents two key contributions to the body of knowledge in the evolving area of physical layer 4G+/5G communication technologies, especially in the domain of Higher-order MIMO detection and half-duplex relay network design. The initial part of this research investigates the development of a higher-order MIMO detection strategy for existing and future 4G+/5G receivers, from both a theoretical and practical perspective. A novel pre-processing Block QR decomposition technique has been proposed for an LTE receiver in a single-user interference-limited scenario as well as a point-to-point scenario with the results highlighting the complexity advantages and limitations in performance. The second part of this study involves a practical feasibility study of a novel two-phase three-part-message strategy for a physical layer half-duplex relay network, which features superposition coding and interference-aware successive interference cancellation decoding. A key aim of this study was to analyze the performance of the proposed link adaptation scheme in the non-asymptotic regime (finite block-length and discrete constellation signaling), and evaluate the spectral efficiency (SE) against the theoretical assumptions of asymptotically large block-lengths. An additional SE comparison with a non-cooperative two-hop relay transmission and point-to-point transmission strategy is also presented. The resulting outcomes reveal the SE gains that can be had by exploiting physical layer cooperation between the relay and base station
Thomas, Robin. "Stratégies de détection MIMO d'ordre supérieur avec applications au relayage pour les réseaux 4G+ et 5G". Electronic Thesis or Diss., Paris, ENST, 2016. http://www.theses.fr/2016ENST0081.
Texto completoThe evolution of wireless communication networks has always been rapidly progressive partly due to the demands of today’s data hungry users. This dissertation presents two key contributions to the body of knowledge in the evolving area of physical layer 4G+/5G communication technologies, especially in the domain of Higher-order MIMO detection and half-duplex relay network design. The initial part of this research investigates the development of a higher-order MIMO detection strategy for existing and future 4G+/5G receivers, from both a theoretical and practical perspective. A novel pre-processing Block QR decomposition technique has been proposed for an LTE receiver in a single-user interference-limited scenario as well as a point-to-point scenario with the results highlighting the complexity advantages and limitations in performance. The second part of this study involves a practical feasibility study of a novel two-phase three-part-message strategy for a physical layer half-duplex relay network, which features superposition coding and interference-aware successive interference cancellation decoding. A key aim of this study was to analyze the performance of the proposed link adaptation scheme in the non-asymptotic regime (finite block-length and discrete constellation signaling), and evaluate the spectral efficiency (SE) against the theoretical assumptions of asymptotically large block-lengths. An additional SE comparison with a non-cooperative two-hop relay transmission and point-to-point transmission strategy is also presented. The resulting outcomes reveal the SE gains that can be had by exploiting physical layer cooperation between the relay and base station
Allouis, Alain. "NOMA-MCM strategies in transmission and reception for advanced vehicular communications in 5G and beyond". Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2024. http://www.theses.fr/2024UPHF0003.
Texto completoThe realm of intelligent transportation hinges upon robust vehicular communication infrastructure, vital for traffic management, road monitoring, Internet of Things (IoT) accessibility, and driver/passenger information. While the conventional IEEE802.11p standard has long dominated this domain, the advent of 5G and its successors marks a paradigm shift.This thesis represents a comprehensive exploration of 5G and beyond technologies specifically tailored to the unique demands of Vehicle-to-Everything (V2X) communication. The primary aim is a meticulous analysis of Non-Orthogonal Multiple Access (NOMA) technology and Multi-Carrier Modulation (MCM) schemes within the context of next-generation V2X applications. Central to this exploration is the pursuit of cross-layer PHY/MAC (Physical Layer/Medium Access Control) design strategies aimed at elevating performance benchmarks.The research journey begins with an introductory overview, delving into the historical context and relevance of V2X communications, accompanied by an examination of the diverse requirements across V2X use case groups. This foundational groundwork combines insights from normative organizations and the latest literature, providing a comprehensive overview of the historical landscape of vehicular communication.Subsequently, the thesis navigates the contemporary landscape, emphasizing the application of 5G enabling technologies to various V2X use cases. It maps the relationship between V2X Use Case Groups and Enabling Technologies while exploring the Hierarchical 5G V2X high-level architecture. This exploration bridges current communication requirements and existing standards with open research directions and impending challenges.The core of the thesis revolves around the exploration of NOMA and MCM schemes' implications within next-generation V2X applications. The culmination of this research manifests in a cross-layer design paradigm focusing on the enhancement of performance and adaptability within cellular vehicle-to-everything (C-V2X) communication systems. By dissecting NOMA mechanisms within the Physical/Medium Access Control (PHY/MAC) layers, this study demonstrates substantial throughput performance improvements compared to conventional Orthogonal Multiple Access (OMA) systems.The outcomes of this thesis aspire to contribute advanced solutions for future autonomous and connected transport systems, with a specific emphasis on the enhancement of physical and medium access layer performance within sophisticated V2X scenarios
Hmamouche, Yassine. "Applications of stochastic geometry in the modeling and analysis of wireless networks". Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0212.
Texto completoNext generation wireless networks, i.e., fifth generation (5G) and beyond (B5G), are expected to be highly heterogeneous, multilayered, with embedded intelligence at both thecore and edge of the network. In such a context, system-level performance evaluation will be very important to formulate relevant insights into tradeoffs that govern such a complex system and then prevent the need for onerous and timeconsuming computer simulations. Over the past decade, stochastic geometry has emerged as a powerful analytical tool to evaluate system-level performance of wireless networks and capture their tendency towards heterogeneity. This dissertation reviews first novel stochastic geometry models and techniques developed during the last decade in modeling and analysis of modern wireless networks. The discussions are refined enough to be accessible for non-specialist readers and help new, intermediate, or advanced readers familiarize quickly with this field of research. Next, we leverage stochastic geometry frameworks to investigate several aspects of 5G and B5G wireless networks and then illustrate its mathematical flexibility and ability to capture the analysis of the rather unconventional scenarios. Also, new perspectives that will breathe new life into the use of stochastic geometry during this crucial decade are discussed. In a nutshell, extensive discussions were held on broader topics such as free space (FSO) optical communications, visible light communications, unmanned aerial vehicle systems, fog radio access architecture (F-RAN) , artificial intelligence and machine learning, and molecular communications
Li, Ao. "Performances des codes correcteurs d’erreur LDPC appliqués au lien Fronthaul optique haut-débit pour l’architecture C-RAN du réseau 5G : conception et implantation sur FPGA". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0110/document.
Texto completoNowadays, the architecture of the mobile network is in full evolution to ensure the increase in terms of bit rate between the Central (CO) (core networks) and various terminals such as mobiles, computers, tablets in order to satisfy the users. To address these challenges of the future, the C-RAN (Cloud or Centralized-RAN) network is known as a 5G solution. In the C-RAN context, all BBUs (Base Band Units) are centralized in the CO, only the RRH (Remote Radio Head) remain at the head of the base station (BS). A new segment between BBUs and RRHs appears called "fronthaul". It is based on D-ROF (digital radio-overfiber) transmissions and carries the digital radio signal at a high bit rate using the Common Public Radio Interface (CPRI) protocol. Taking into account CAPEX and OPEX, the ANR LAMPION project has proposed the Self-seeded Reflective Semiconductor Optical Amplifier (RSOA) technology in order to make the solution more flexible and overcome the need for colored transmitters / receivers in the context of PON-WDM (Wavelength Division Multiplexing Passive Optical Network). Nevertheless, it is necessary to add a FEC (forward error corrector) in the transmission to ensure the quality of service. So the objective of this thesis is to find the most suitable FEC to apply in the C-RAN context. Our work has focused on the use of LDPC codes, chosen after performance comparisons with other types of codes. We have specified the parameters (code performance, matrix size, cycle, etc.) required for LDPC codes to obtain the best performance. Hard-decision LDPC algorithms were chosen after considering the tradeoff between circuit complexities and performance. Among these hard-decision algorithms, the GDBF (gradient descent bit-flipping) was the best solution. Taking into account a CAN 2-Bit in the channel led us to propose a variant: the BWGDBF (Balanced weighted GDBF). Optimizations have also been made with respect to the convergence of the algorithm and latency. Finally, we managed to implement our own algorithm on the Spartan FPGA 6 xc6slx16. Several methods have been proposed to achieve a latency of 5 μs desired in the C-RAN context. This thesis was supported by the project ANR LAMPION (Lambada-based Access and Metropolitan Passive Optical Networks)
Aissioui, Abdelkader. "Le chemin vers les architectures futures des services mobiles : du Follow Me Cloud (FMC) au Follow Me edge Cloud (FMeC)". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV095.
Texto completoThis Ph.D. thesis aims to deal with the future delivery architectures of mobile cloud-based services, through network infrastructures evolving from Mobile Cloud Computing (MCC) to Mobile Edge Computing (MEC). We mainly focused on Follow Me Cloud (FMC) concept as a new service delivery strategy for improved user experience and efficient resource utilization. That enables cloud-based services to follow their mobile users during their movement across access network technologies and by delivering the cloud-service via the optimal service point inside the cloud infrastructure. Several contributions are proposed in this thesis and evaluated in both theoretical analysis and scientific simulation.First, we proposed an alternative FMC architecture that allows: (i) to open the FMC design on non-3GPP mobile network access technologies (ii) to provide interoperability among different PMIPv6 domains permitting MNs inter-PMIPv6 domain roaming with seamless IP mobility and service session continuity (iii) to offer a tunnel-free architecture in MNs roaming situation, avoiding any additional overhead associated with tunneling in mobility management. This proposed scheme leverage SDN/OpenFlow technology and PMIPv6 mobility management protocol by integrating them within a framework permitting to realize the FMC vision.Second, to address the scalability and resiliency concerns in centralized SDN/OpenFlow control plane architecture, we introduced a new design of an elastic distributed SDN controller tailored for Mobile Cloud Computing (MCC) and more notably for Follow Me Cloud (FMC) management systems. We illustrated how the new control plane scheme is distributed on two-level hierarchical architecture, a first level with a single global SDN controller and a second level with several local SDN controllers. Then, we presented the building blocks of our novel control plane framework, the system Key Performance Indicator (KPI) computation and set the key objective of our design aiming to keep the system KPI value within a predefined threshold window. Last, we proved how this goal is achieved by adapting the number of local SDN controllers and their locations in an elastic manner and deploying them as VNF instances on the cloud thanks to NFV technology.Third, we introduced FMeC concept, leveraging the intertwining of MEC and FMC architectures with the aim of sustaining requirements of the 5G automotive systems. We began by defining FMeC key concept elements permitting to provide FMC technology at the edge of mobile networks. Then, we presented an automated driving use case projection of our FMeC solution integrating automotive with Telco infrastructures towards the future 5G automotive vision. Focusing on the V2I/N communications types, we introduced our FMeC design architecture based on SDN/OpenFlow technologies and MEC infrastructure entities whose resources are pooled together to provide a federated edge clouds. Finally, we presented our mobility-aware framework for edge-cloud service placement based on a set of basic algorithms that permit achieving the automated driving QoS requirements in terms of ultra-short latency within 5G network
Robichaud, Daniel. "Au delà de l'action et de la structure, traduction, réseaux d'actants et narrativité dans un processus de discussion publique". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0014/NQ35633.pdf.
Texto completoBarthomeuf, Sylvain. "Augmentation de la capacité des interfaces PONs TDMA au-delà de 10Gbit/s dans les réseaux d’accès en fibres optiques". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT052.
Texto completoThe optical access network is booming, especially with the massive deployment of FTTH connecting clients’ home and antenna sites for the incoming 5G. The fiber’s popularization and the transformation of data consumption drive the bitrate growth. Many solutions are proposed. In this thesis, the passive optical network’s (PON) bitrate growth will be studied along three axes :• PAM4 to reuse 10GHz optoelectronical components to reach 25Gbit/s. This four levels modulation format is more bandwidth efficient than NRZ and it allows to transmit two bitratesas the same time on a PON tree. Within the first chapter, optical amplification is studied to enhance the optical budget for a PAM4 transmission. Last part of the chapter presents asimulation based on the real-time experiment to simulate PAM8.• Three vendors’ solutions for the throughput growth. The first prototype is based on theNG-PON2 standard and its PtP WDM option. The second prototype demonstrates how to transmit 25Gbit/s with duobinary and vestigial side band modulation. The last prototype illustrates a youthful solution for 5G fronthauling with a PtP WDM system transmitting at 25Gbit/s.• Equalization in PON’s context. Signal processing and equalization are common in optical transport links. With the throughput rising, equalization in access network seems indispensable. In the chapter, an implementation of equalization is proposed congruently with point-to-multipoints PON application and compliantly with access network’s cost needs and topology
Attencourt, Boris. "Les intellectuels à l’épreuve de la visibilité : faire carrière au-delà de l’université (1970-2015)". Thesis, Paris, EHESS, 2021. http://www.theses.fr/2021EHES0009.
Texto completoThis thesis focuses on the channels through which a fraction of intellectuals become visible (quality press, intellectual journals, think tanks, conference venues, cultural radio and television broadcasts, publishing houses, etc.). Combining reference to legitimate culture, accessibility and action, such circuits developed at the end of the 1970s until they established themselves as the space for the public value of ideas and their carriers.The thesis therefore focused on the issues of visibility for intellectuals during the period from the 1970s to the mid-2010s and shows that careers in external recognition do not take place after or outside the university but rather at the same time. In order to explain this configuration of intellectual notoriety, we have resorted here to a sociohistorical and multilevel approach of the circuits of visibility where it is a question of apprehending their institutions, producers and audiences. However, the places of scholarly conferences intended for a large public because they occupy a cardinal place within the circuits of intellectual visibility have proven to be a particularly effective entry point for empirically reconstituting the channels that have been woven between the margins. academia, senior administration and the media. A multisite ethnography of the conferences (N = 15) which resulted in a large body of observations (N = 97) thus paved the way for a whole set of explorations of these circuits at the micro and macro scales. Through long-term immersions and a participant observation which made it possible to collect substantial empirical material (observations, interviews and archives), we endeavored to reconstruct the genesis and then the trajectory of exemplary institutions (Beaubourg, the International College of Philosophy and the University of all knowledge). We conducted interviews with producers (N = 18) and, in connection with this category of interviewees, cultural intermediaries and their back-up staff (N = 9). In the qualitative register, we also carried out analyzes of controversies (Billeter / Jullien and Badiou / Finkielkraut). In addition, many quantitative treatments, including factorial and network analyzes, were carried out based on a prosopography of producers divided between natural sciences (N = 64) and human and social sciences (N = 195) following a sampling representative of speakers. With regard to reception, the focus was placed on conference listeners by diversifying the investigation methods: to the observations collected from the public during all phases of the conferences, interviews were added (N = 27) and several questionnaire surveys conducted by us within the International College of Philosophy (N = 330) and the University of All Knowledge (N = 285, 157 and 183).On the basis of these various surveys, the thesis takes account of the monopoly exercised by these circuits of cultural celebration in the access to public notoriety of intellectuals which led to the formation of a heteronomous space where social capital takes precedence over autonomous species. cultural capital. Consequently, this space and the elite of the spirit which is devoted to it participate in the renewal of the modes of domination of the dominant class since the 1980s. If this work is a contribution to the sociology of intellectuals and sciences, to that of the elites and the media, to that of cultural taste and consumption and to methodological reflections around the articulation of levels, he would also like to contribute to the analysis of ideological and academic forms of intellectual doxa
Hamza, Anis Amazigh. "Improving cooperative non-orthogonal multiple access (CNOMA) and enhancing the physical layer security (PLS) for beyond 5G (B5G) and future eHealth wireless networks". Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0006.
Texto completoThe fifth generation of cellular networks (5G) was a real revolution in radio access technologies and mobile networks, presenting itself as the breakthrough generation that allowed the coexistence of extremely diversified applications and usage scenarios, unified under the same standard. Nevertheless, 5G is just the beginning: new scenarios and challenges are emerging. Therefore, the research community is pushing the research ahead and preparing the ground for beyond 5G (B5G) cellular systems. In this regard, several enabling technologies are investigated. In addition to the cognitive radio (CR), mmWave, massive MIMO, or even the use of full-duplex (FD), non-orthogonal multiple access (NOMA) emerged as a promising technology that allows multiple users to share the same resource block and hence, optimizes resource allocation, reduces the end-to-end latency, and improves both spectrum and energy efficiencies. Those advantages make NOMA a serious candidate as a multiple access scheme for future B5G networks, especially for the demanding eHealth applications. Furthermore, NOMA can be flexibly combined with any wireless technology such as cooperative communication, FD, mmWave, and multicarrier modulation (MCM).Motivated by this treatise, this thesis provides a comprehensive and intensive examination of this emerging technology, particularly, cooperative NOMA (CNOMA) which is considered a promising enabling technology for future B5G eHealth networks, from the basic principles to its combination with the full-duplex technology, MCM transmission, to deep learning as well as enhancing the physical layer security (PLS).First, this thesis investigates the error rate performance of FD-CNOMA systems over wireless fading channels. New closed-form expressions of the exact bit error rates (BER) are derived. Moreover, high-SNR analyses are conducted, which reveals that FD-CNOMA has an error floor due to the successive interference cancellation (SIC) imperfections and residual self-interference (RSI). Based on the derived expressions, a novel selective relaying scheme is proposed to opportunistically improve the system performance using the minimal channel state information (CSI) overhead.Second, the MCM-based CNOMA is examined under doubly selective channels encountered in vehicular and railway wireless communications. In the eHealth context, this can be projected to ambulance emergency healthcare use cases. More importantly, this thesis presents a performance improvement method for cell-edge users of MCM-NOMA systems with imperfect SIC and imperfect CSI under doubly selective wireless channels. Two efficient iterative interference cancellation schemes are proposed to enable user relaying for MCM-based CNOMA. The proposed schemes are robust for high mobility scenarios with a relatively low computational complexity.Third and last, advances in machine learning based on deep neural networks (DNNs) attracted great attention in the wireless communication community (WCS). It is regarded as a key component of B5G networks. Deep learning has found a broad range of applications in wireless systems, e.g., spectrum sensing, waveform design, SIC, and channel estimation. However, DNNs are known to be highly susceptible to adversarial attacks. Many robust over-the-air adversarial attacks against DNN-based WCS have been proposed in the literature. This is becoming a major challenge facing the physical layer security (PLS) of DNN-based WCS. To overcome this vulnerability, this thesis proposes a novel robust defense approach. The objective of our defense is to protect the victim without significantly degrading the accuracy of its baseline model in the absence of the attack. The obtained results are very promising and confirm that the proposed defense technique can enhance significantly the PLS of future DNN-based WCS
Bemani, Ali. "Affine Frequency Division Multiplexing (AFDM) for Wireless Communications". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS610.pdf.
Texto completoIn the realm of next-generation wireless systems (beyond 5G/6G), the vision is clear: to support a broad range of services and applications. This includes ensuring reliable communications in environments marked by high mobility, such as high-speed railway systems and various vehicular communications. Despite the deployment of various multicarrier techniques like orthogonal frequency division multiplexing (OFDM) and single-carrier frequency division multiple access (SC-FDMA) in standardized communication systems, the challenge persists. These techniques, while effective in time-invariant frequency selective channels, face performance degradation in high mobility scenarios due to the destruction of orthogonality among subcarriers caused by significant Doppler frequency shifts. Addressing this, the search for new, robust modulation techniques is paramount. It stands as a key area of investigation aiming to resolve the reliable communications issue for next-generation wireless networks within doubly-selective wireless channels. In this thesis, a novel solution, affine frequency division multiplexing (AFDM), is proposed. This new chirp-based multicarrier waveform is based on the discrete affine Fourier transform (DAFT), a variant of the discrete Fourier transform characterized with two parameters that can be adapted to better cope with doubly dispersive channels. This thesis provides a comprehensive investigation into the principles of AFDM within high mobility communications. It provides insight into the explicit input-output relation in the DAFT domain, unveiling the consequential impact of AFDM parameters. The manuscript details the precise setting of DAFT parameters, ensuring a full delay-Doppler representation of the channel. Through analytical demonstrations, it asserts that AFDM optimally achieves the diversity order in doubly dispersive channels due to its full delay-Doppler representation. The thesis also proposes two low-complexity detection algorithms for AFDM, taking advantage of its inherent channel sparsity. The first is a low complexity MMSE detector based on LDL factorization. The second is a low complexity iterative decision feedback equalizer (DFE) based on weighted maximal ratio combining (MRC) of the channel impaired input symbols received from different paths. Additionally, the thesis presents an embedded channel estimation strategy for AFDM systems, leveraging AFDM's ability to achieve full delay-Doppler representation of the channel. In this approach, an AFDM frame contains a pilot symbol and data symbols, with zero-padded symbols employed as guard intervals to prevent interference. A practical channel estimation algorithm based on an approximate maximum likelihood (ML) approach and compatible with this pilot scheme is also provided. The thesis concludes by delving into the expanded applications of AFDM, specifically in integrated sensing and communication (ISAC) and extremely high frequency (EHF) band communications. It is demonstrated that to identify all delay and Doppler components linked with the propagation medium, one can use either the full AFDM signal or only its pilot part consisting of one DAFT domain symbol and its guard interval. Furthermore, the chirp nature of AFDM allows for unique and simple self-interference cancellation with a single pilot, eliminating the need for costly full-duplex methods. The thesis also highlights AFDM's efficient performance in high-frequency bands (with or without mobility), where the maximal spreading of its signal in time and frequency ensures a coverage gain. Unlike other waveforms, AFDM not only provides maximal time-frequency spreading but also ensures robust and efficient detection, characterized by one-tap equalization and resilience to carrier frequency offset (CFO) and phase noise