Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

THE APPLICATION OF REAL-TIME SOFTWARE IN THE IMPLEMENTATION OF LOW-COST SATELLITE RETURN LINKS

Digital Signal Processors (DSPs) have evolved to a level where it is feasible for digital modems with relatively low data rates to be implemented entirely with software algorithms. With current technology it is still necessary for analogue processing between the RF input and a low frequency IF but, as DSP technology advances, it will become possible to shift the interface between analogue and digital domains ever closer towards the RF input. The software radio concept is a long-term goal which aims to realise software-based digital modems which are completely flexible in terms of operating frequency, bandwidth, modulation format and source coding. The ideal software radio cannot be realised until DSP, Analogue to Digital (A/D) and Digital to Analogue (D/A) technology has advanced sufficiently. Until these advances have been made, it is often necessary to sacrifice optimum performance in order to achieve real-time operation. This Thesis investigates practical real-time algorithms for carrier frequency synchronisation, symbol timing synchronisation, modulation, demodulation and FEC. Included in this work are novel software-based transceivers for continuous-mode transmission, burst-mode transmission, frequency modulation, phase modulation and orthogonal frequency division multiplexing (OFDM). Ideal applications for this work combine the requirement for flexible baseband signal processing and a relatively low data rate. Suitable applications for this work were identified in low-cost satellite return links, and specifically in asymmetric satellite Internet delivery systems. These systems employ a high-speed (>>2Mbps) DVB channel from service provider to customer and a low-cost, low-speed (32-128 kbps) return channel. This Thesis also discusses asymmetric satellite Internet delivery systems, practical considerations for their implementation and the techniques that are required to map TCP/IP traffic to low-cost satellite return links

Multi-core architectures with coarse-grained dynamically reconfigurable processors for broadband wireless access technologies

Broadband Wireless Access technologies have significant market potential, especially the WiMAX protocol which can deliver data rates of tens of Mbps. Strong demand for high performance WiMAX solutions is forcing designers to seek help from multi-core processors that offer competitive advantages in terms of all performance metrics, such as speed, power and area. Through the provision of a degree of flexibility similar to that of a DSP and performance and power consumption advantages approaching that of an ASIC, coarse-grained dynamically reconfigurable processors are proving to be strong candidates for processing cores used in future high performance multi-core processor systems. This thesis investigates multi-core architectures with a newly emerging dynamically reconfigurable processor – RICA, targeting WiMAX physical layer applications. A novel master-slave multi-core architecture is proposed, using RICA processing cores. A SystemC based simulator, called MRPSIM, is devised to model this multi-core architecture. This simulator provides fast simulation speed and timing accuracy, offers flexible architectural options to configure the multi-core architecture, and enables the analysis and investigation of multi-core architectures. Meanwhile a profiling-driven mapping methodology is developed to partition the WiMAX application into multiple tasks as well as schedule and map these tasks onto the multi-core architecture, aiming to reduce the overall system execution time. Both the MRPSIM simulator and the mapping methodology are seamlessly integrated with the existing RICA tool flow. Based on the proposed master-slave multi-core architecture, a series of diverse homogeneous and heterogeneous multi-core solutions are designed for different fixed WiMAX physical layer profiles. Implemented in ANSI C and executed on the MRPSIM simulator, these multi-core solutions contain different numbers of cores, combine various memory architectures and task partitioning schemes, and deliver high throughputs at relatively low area costs. Meanwhile a design space exploration methodology is developed to search the design space for multi-core systems to find suitable solutions under certain system constraints. Finally, laying a foundation for future multithreading exploration on the proposed multi-core architecture, this thesis investigates the porting of a real-time operating system – Micro C/OS-II to a single RICA processor. A multitasking version of WiMAX is implemented on a single RICA processor with the operating system support

Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications

The rapid proliferation of the Internet has been driving communication networks closer and closer to their limits, while available bandwidth is disappearing due to an ever-increasing network load. Over the past decade, optical fiber communication technology has increased per fiber data rate from 10 Tb/s to exceeding 10 Pb/s. The major explosion came after the maturity of coherent detection and advanced digital signal processing (DSP). DSP has played a critical role in accommodating channel impairments mitigation, enabling advanced modulation formats for spectral efficiency transmission and realizing flexible bandwidth. This book aims to explore novel, advanced DSP techniques to enable multi-Tb/s/channel optical transmission to address pressing bandwidth and power-efficiency demands. It provides state-of-the-art advances and future perspectives of DSP as well

Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

Energy Efficient VLSI Circuits for MIMO-WLAN

Mobile communication - anytime, anywhere access to data and communication services - has been continuously increasing since the operation of the first wireless communication link by Guglielmo Marconi. The demand for higher data rates, despite the limited bandwidth, led to the development of multiple-input multiple-output (MIMO) communication which is often combined with orthogonal frequency division multiplexing (OFDM). Together, these two techniques achieve a high bandwidth efficiency. Unfortunately, techniques such as MIMO-OFDM significantly increase the signal processing complexity of transceivers. While fast improvements in the integrated circuit (IC) technology enabled to implement more signal processing complexity per chip, large efforts had and have to be done for novel algorithms as well as for efficient very large scaled integration (VLSI) architectures in order to meet today's and tomorrow's requirements for mobile wireless communication systems. In this thesis, we will present architectures and VLSI implementations of complete physical (PHY) layer application specific integrated circuits (ASICs) under the constraints imposed by an industrial wireless communication standard. Contrary to many other publications, we do not elaborate individual components of a MIMO-OFDM communication system stand-alone, but in the context of the complete PHY layer ASIC. We will investigate the performance of several MIMO detectors and the corresponding preprocessing circuits, being integrated into the entire PHY layer ASIC, in terms of achievable error-rate, power consumption, and area requirement. Finally, we will assemble the results from the proposed PHY layer implementations in order to enhance the energy efficiency of a transceiver. To this end, we propose a cross-layer optimization of PHY layer and medium access control (MAC) layer

Design, implementation and experimental evaluation of a network-slicing aware mobile protocol stack

Mención Internacional en el título de doctorWith the arrival of new generation mobile networks, we currently observe a paradigm shift, where monolithic network functions running on dedicated hardware are now implemented as software pieces that can be virtualized on general purpose hardware platforms. This paradigm shift stands on the softwarization of network functions and the adoption of virtualization techniques. Network Function Virtualization (NFV) comprises softwarization of network elements and virtualization of these components. It brings multiple advantages: (i) Flexibility, allowing an easy management of the virtual network functions (VNFs) (deploy, start, stop or update); (ii) efficiency, resources can be adequately consumed due to the increased flexibility of the network infrastructure; and (iii) reduced costs, due to the ability of sharing hardware resources. To this end, multiple challenges must be addressed to effectively leverage of all these benefits. Network Function Virtualization envisioned the concept of virtual network, resulting in a key enabler of 5G networks flexibility, Network Slicing. This new paradigm represents a new way to operate mobile networks where the underlying infrastructure is "sliced" into logically separated networks that can be customized to the specific needs of the tenant. This approach also enables the ability of instantiate VNFs at different locations of the infrastructure, choosing their optimal placement based on parameters such as the requirements of the service traversing the slice or the available resources. This decision process is called orchestration and involves all the VNFs withing the same network slice. The orchestrator is the entity in charge of managing network slices. Hands-on experiments on network slicing are essential to understand its benefits and limits, and to validate the design and deployment choices. While some network slicing prototypes have been built for Radio Access Networks (RANs), leveraging on the wide availability of radio hardware and open-source software, there is no currently open-source suite for end-to-end network slicing available to the research community. Similarly, orchestration mechanisms must be evaluated as well to properly validate theoretical solutions addressing diverse aspects such as resource assignment or service composition. This thesis contributes on the study of the mobile networks evolution regarding its softwarization and cloudification. We identify software patterns for network function virtualization, including the definition of a novel mobile architecture that squeezes the virtualization architecture by splitting functionality in atomic functions. Then, we effectively design, implement and evaluate of an open-source network slicing implementation. Our results show a per-slice customization without paying the price in terms of performance, also providing a slicing implementation to the research community. Moreover, we propose a framework to flexibly re-orchestrate a virtualized network, allowing on-the-fly re-orchestration without disrupting ongoing services. This framework can greatly improve performance under changing conditions. We evaluate the resulting performance in a realistic network slicing setup, showing the feasibility and advantages of flexible re-orchestration. Lastly and following the required re-design of network functions envisioned during the study of the evolution of mobile networks, we present a novel pipeline architecture specifically engineered for 4G/5G Physical Layers virtualized over clouds. The proposed design follows two objectives, resiliency upon unpredictable computing and parallelization to increase efficiency in multi-core clouds. To this end, we employ techniques such as tight deadline control, jitter-absorbing buffers, predictive Hybrid Automatic Repeat Request, and congestion control. Our experimental results show that our cloud-native approach attains > 95% of the theoretical spectrum efficiency in hostile environments where stateof- the-art architectures collapse.This work has been supported by IMDEA Networks InstitutePrograma de Doctorado en Ingeniería Telemática por la Universidad Carlos III de MadridPresidente: Francisco Valera Pintor.- Secretario: Vincenzo Sciancalepore.- Vocal: Xenofon Fouka

Cache-Aware Adaptive Video Streaming in 5G networks

Η τεχνολογία προσαρμοστικής ροής video μέσω HTTP έχει επικρατήσει ως ο κυρίαρχος τρόπος μετάδοσης video στο Internet. Η τεχνολογία αυτή βασίζεται στη λήψη μικρών διαδοχικών τμημάτων video από έναν server. Μία πρόκληση που όμως δεν έχει διερευνηθεί επαρκώς είναι η λήψη τμημάτων video από περισσότερους από έναν servers, με τρόπο που να εξυπηρετεί τόσο τις ανάγκες του δικτύου όσο και τη βελτίωση της Ποιότητας Εμπειρίας του χρήστη (Quality of Experience, QoE). Η συγκεκριμένη διπλωματική εργασία θα διερευνήσει αυτό το πρόβλημα, προσομοιώνοντας ένα δίκτυο με πολλαπλούς video servers και διάφορους video clients. Στη συνέχεια, θα υλοποιήσει τόσο την δυνατότητα επικοινωνίας peer-to-many στα πλαίσια της προσαρμοστικής ροής video όσο και τον αλγόριθμο επιλογής video server. Όλα αυτά θα διερευνηθούν στο περιβάλλον του Mininet, που είναι ένας δικτυακός εξομοιωτής, για να προσομοιωθεί η τεχνολογία DASH με τη βοήθεια των κόμβων του δικτύου του εξομοιωτή. Αρχικά, το βίντεο χωρίστηκε σε μικρά κομμάτια με τη βοήθεια του εργαλείου ffmpeg και στη συνέχεια, υλοποιήθηκαν πειράματα που ένας πελάτης ζητούσε το βίντεο από έναν server προσωρινής αποθήκευσης (cache server). Αν το συγκεκριμένο τμήμα του βίντεο δεν υπήρχε εκεί, τότε στελνόταν αίτημα από τον server προσωρινής αποθήκευσης σε έναν διακομιστή που περιείχε όλα τα τμήματα του βίντεο (main server). Στα πειράματα αυτά εξετάστηκε και η προστιθέμενη δικτυακή κίνηση, με τελικό συμπέρασμα ότι το περιβάλλον του Mininet προκαλεί αναπόφευκτους περιορισμούς στη περίπτωση της δικτυακής κίνησης, καθώς παρατηρήσαμε πως το κανάλι του server βάσης δεδομένων παρέμενε ανενεργό καθ’ όλη τη διάρκεια αιτημάτων από τον server προσωρινής αποθήκευσης, με αποτέλεσμα να δημιουργούνται συνθήκες μη-ρεαλιστικού δικτύου. Γι’ αυτόν τον λόγο, προβήκαμε στην υλοποίηση μιας νέας προσέγγισης, εξαλείφοντας το Mininet περιβάλλον και δουλεύοντας πάνω σε νέες τεχνικές προσθήκης δικτυακής κίνησης και τροποποιώντας την επικοινωνία των διακομιστών μεταξύ τους. Με αυτόν τον τρόπο, καταφέραμε να δείξουμε σαφέστερα τους περιορισμούς της προηγούμενης προσέγγισης αλλά και να συμπεράνουμε ότι η ύπαρξη servers προσωρινής αποθήκευσης είναι ένα χρήσιμο εργαλείο υπό όρους αύξησης της ποιότητας εμπειρίας ενός χρήστη. Η γενική τάση που παρατηρήθηκε ήταν ότι με την αύξηση του διαθέσιμου χώρου αποθήκευσης, η ποιότητα αναπαραγωγής του βίντεο ανέβαινε σε κάποιο βαθμό. Ταυτόχρονα όμως, το ποσοστό βελτίωσης αυτό, είναι άρρηκτα δεμένο με τον αλγόριθμο επιλογής κομματιών βίντεο που χρησιμοποιείται. Για ακόμα καλύτερα αποτελέσματα λοιπόν, θεωρείται αναγκαία η εύρεση της χρυσής τομής μεταξύ χωρητικότητας του χώρου προσωρινής αποθήκευσης και αλγορίθμου επιλογής κομματιών. Στην παρούσα διπλωματική παρουσιάζονται τα εξής κεφάλαια: Στο κεφάλαιο 1 αναφέρεται η ιστορική αναδρομή της τεχνολογίας των δικτύων. Στο κεφάλαιο 2 αναλύεται η τεχνολογία προσαρμοστικής ροής βίντεο μέσω HTTP. Στο κεφάλαιο 3 αναλύονται οι διαφορετικές τεχνικές προσωρινής αποθήκευσης. Στο κεφάλαιο 4 παρουσιάζεται η έννοια της Ποιότητας Εμπειρίας του χρήστη και η συσχέτισή της με πολλούς άλλους παράγοντες. Το κεφάλαιο 5 περιγράφεται αναλυτικά η διαδικασία στησίματος του περιβάλλοντος και τα διάφορα απαραίτητα εργαλεία για την υλοποίησή μας. Το κεφάλαιο 6 αναφέρει τα πειράματα μέσω Mininet, την τοπολογία και όλο το στήσιμο, καθώς και τους λόγους που μας οδήγησαν στην πορεία μιας διαφορετικής προσέγγισης. Στο κεφάλαιο 7 προτείνεται η διαφορετική προσέγγιση και παρουσιάζεται η μεθοδολογία και οι μετρικές. Επίσης, αναλύονται διαγράμματα που εξάχθηκαν από την ανάλυση τω μετρικών. Τέλος, το κεφάλαιο 8 αφορά τα συμπεράσματα και θέματα μελλοντικής έρευνας για βελτίωση της Ποιότητας Εμπειρίας του χρήστη περαιτέρω.Dynamic Adaptive Streaming over HTTP (DASH) has prevailed as the dominant way of video transmission over the Internet. This technology is based on receiving small sequential video segments from a server. However, one challenge that has not been adequately examined, is the obtainment of video segments from more than one server, in a way that serves both the needs of the network and the improvement of the Quality of Experience (QoE). This thesis will investigate this problem by simulating a network with multiple video servers and a video client. It will then implement both the peer-to-many communication in the context of adaptive video streaming and the video server caching algorithm based on proposed criteria that will improve the status of the network and/or the user. All of this will be explored in the environment of Mininet, which is a network emulator, in order to simulate the DASH technology with the help of the emulator network nodes. Initially, the video was split into small segments using the ffmpeg tool, and then experiments were conducted in which a client requested the video from a cache server. If the segment could not be found in the cache server, then a request was sent from the cache server to a server that contained all segments of the video (main server). In these experiments, the added traffic was also examined, by concluded to the fact that the Mininet environment causes unavoidable limitations in the case of the traffic. What we observed was that the main server channel remained inactive throughout the requests of the cache server, resulting in unrealistic network conditions. For this reason, we have explored a new approach, eliminating the Mininet environment and working on new techniques for adding web traffic and modifying the communication of the servers, regarding the requests they receive. In this way, we were able to clearly show the limitations of the previous approach but also to conclude that the existence of caching servers is a useful tool in terms of increasing the quality of experience. The general tendency was that, as the available buffer size increased, the video playback quality increased to some extent. However, at the same time this improvement is linked to the random selection algorithm. For even better results, it is considered necessary to find an appropriate caching selection algorithm in order to take full advantage of the caching technology. The following chapters presented in this thesis are: Chapter 1 mentions the historical background of the networks. Chapter 2 analyzes the Dynamic Adaptive Streaming over HTTP. Chapter 3 analyzes the caching techniques. Chapter 4 presents the concept of Quality of Experience and its correlation with many other factors. Chapter 5 describes in detail the process of setting up the environment and the various necessary tools for our implementation. Chapter 6 refers to the Mininet experiments, the topology, and the set-up, as well as the reasons that led us to a different approach. Chapter 7 proposes the different approach and presents the methodology and the metrics. Also, diagrams extracted from the analysis of the metrics are analyzed in Chapter 7. Finally, Chapter 8 summarizes the conclusions and issues of future research to improve the Quality of Experience even further

Desenho da camada DLL para sistemas de comunicação por luz visível

Mestrado em Engenharia Electrónica e TelecomunicaçõesWith the advent of the Information Age, communication systems have become the backbone of our society. The modern society strives to nd instant access to speci c sources of information to make time-constrained decisions. Therefore, the twenty- rst century is marked by a growing demand for bandwidth in wireless communications, as it allows users to communicate and access daily applications even from remote areas. Up to the present time, numerous breakthroughs in wireless communications were accomplished but mainly using the radio portion of the electromagnetic spectrum, which made RF to take the central role in today's communication systems. However, RF technology is a victim of its own success. Due to the tremendous increase in the number of mobile devices, RF technology cannot cope much longer with this market demand and will eventually reach a saturation point. VLC is a recently appealing technique in the eld of wireless communications that intends to complement RF technologies and is sought by many researchers as a viable alternative. VLC based on Light Emitting Diode (LED) takes advantage of these solid-state devices superior modulation capability to transmit data while assuring their lighting functionality. This work addresses the problem of achieving high bandwidth in a DLL design for OFDM based VLC broadcast systems and is inserted in a funded project called VLCLighting. The main objective of this dissertation work is to implement an e cient DLL in a Microblaze soft processor in a FPGA and to study its usage in a broadcast VLC system for lighting systems. Since two value added services were identi ed in the VLCLighting project, the proposed DLL aims at furnishing the adequate means to fragment and route those services requests while maintaining a continuous transmission ow that assures lighting and transceiver functionality. This work proposes a DLL design that was inspired in DVB and project OMEGA systems, able to describe the required amendments to full ll VLCLighting goals.Com a chegada da era da Informação, os sistemas de comunicação tornaram-se na espinha dorsal da nossa sociedade. A Sociedade Moderna esforça-se por ter acesso instantâneo a fontes de informação específicas para tomar decisões limitadas pelo tempo. Portanto, o século XXI está marcado pela crescente exigência da largura de banda nas comunicações sem fios, pois tal permite aos utilizadores comunicarem e acederem as aplicações a partir de áreas longínquas. Até ao momento, foram alcançados diversos avanços/descobertas na largura de banda das comunicações sem fos, mas tal tem sido conseguido usando o intervalo de radiofrequências (RF) do espectro eletromagnético e que fez com que o RF ficasse com o papel principal nos sistemas de comunicação de hoje. Contudo, a Tecnologia RF e vitima do seu próprio sucesso. Devido ao tremendo aumento do número de aparelhos de comunicação móveis, a tecnologia RF não pode lidar muito mais tempo com a exigência dos mercados e atingirá o seu ponto de saturação. VLC (Comunicação através de luz visivel) é uma tecnica recente muito apelativa no campo das comunicações sem-fios e que pretende ser um complemento à tecnologia RF, sendo considerada por muitos investigadores como uma alternativa viável. Esta dissertação discute o problema de se alcançar uma grande taxa de transmissão com a implementação de uma Data Link Layer (DLL) direccionada para sistemas VLC com modulação OFDM e está inserida num projecto financiado intitulado VLCLighting. O objectivo principal desta dissertação consiste na implementação de um DLL eficiente num processador Microblaze numa Field-Programmable Gate Array (FPGA) e no estudo da sua utilização em sistemas VLC para uso combinado em sistemas de iluminação. Uma vez que foram identificados dois serviços com valor acrescentado para serem incluídos no projecto VLCLighting, a proposta DLL pretende fornecer os meios necessários á fragmentação e encaminhamento das exigências dos serviços, enquanto se mantêm um fluxo contínuo de transmissão capaz de assegurar as funcionalidades de iluminação e comunicação. A presente dissertação propõe um desenho inspirado nos sistemas DVB e do projeto OMEGA, e descrevendo as alterações exigidas para satisfazer os objectivos do projecto VLCLighting