La croissance rapide des applications interactives et ses demandes en termes de bande passante et de (QoS), a motivé le déploiement de la technologie optique aux réseaux métropolitains. Beaucoup de dispositifs optiques intelligents sont créés pour gérer efficacement la capacité énorme du réseau. L'explosion de la bande passante est principalement attribuable à la croissance du trafic de données dont la nature devient de plus en plus complexe. Actuellement, la plupart des trafics de données sont transportés dans les réseaux qui sont dominées par la technologie de commutation de circuit optique. Néanmoins, cette technique a quelques inconvénients tels que les propriétés inflexibles. Technologie de commutation de paquets optiques (OPS), qui offre des gains significatifs en termes de capacité de passage à l’échelle et d'efficacité de gestion des ressources du réseau, peut surmonter ces limitations. Cela a motivé l'orientation de la commutation de circuit optique à la commutation de paquet optique dans l’infrastructure future du réseau. En réalité, un réseau en anneau à commutation de paquet optique ( OPSR), qui combinent la flexibilité et la mise à l’échelle de la technologie de commutation de paquet avec les avantages de la topologie en anneau tels que la restitution rapide du service en cas de panne et un bon gain de multiplexage statistique du trafic, promettraient une bonne solution pour les réseaux MAN du future. Une nouvelle architecture du réseau OPSR qui se base sur l’infrastructure tout optique a proposé par des équipes de recherche chez Alcatel-Lucent. La nouvelle architecture offre des fonctions intelligentes, avec un coût moins élevé en optimisant le temps de traitement. Elle est envisagée de remplacer les architectures optoélectroniques existantes tels que Resilient Packet Ring. L'élément fondamental du réseau est Packet Optical Add/Drop Multiplexer (POADM) qui est implémenté à l'intérieur des nœuds d’accès, permettant aux nœuds d'exploiter la transparence optique. Cette thèse se concentre donc sur l'évaluation des performances de la nouvelle génération des réseaux optiques métropolitains. Dans cette thèse, nous avons analysé des performances (en termes de délais d’accès et de la distribution du taux de l’occupation au tampon local des nœuds d'accès) d'un bus optique synchrone qui soutient des paquets à taille fixe. Nous avons modélisé chaque nœud d'accès par une chaîne de Markov à temps discret (EDTMC). La solution de l'EDTMC nous permet de calculer la probabilité approximative où les nœuds d'accès dans le bus peuvent "voir" slots libres dans la ligne de transit. En utilisant une technique d'analyse récursive, nous déduisons une formule mesurant le temps moyen d'attente des paquets du client venant de la couche supérieure, ainsi que la distribution du taux de l’occupation au tampon local des nœuds d'accès pour les deux cas: avec et sans garantie QoS). Pour caractériser des performances d'un réseau OPSR asynchrone, nous avons évalué l'impact de la création de containeur optique à taille fixe sur les performances du réseau. L’analyse des performances de ce système nous a permis d'identifier une combinaison raisonnable de certains paramètres (la durée de timeslot, les valeurs d’expiration des temporisateurs, le profil du trafic client, la charge du réseau) qui peuvent améliorer l'utilisation de la bande passante du réseau. Le point le plus important que nous avons mentionné dans la thèse est la comparaison entre deux approches architecturales: le modèle de Variable Length - Optical Packet Format (VL-OPF) versus le modèle de Fixed Length - Optical Packet Format (FL-OPF). En plus de Cos-Upgrade Mécanisme (CUM) qui est proposé d'améliorer le taux de remplissage du conteneur optique, nous avons proposé un nouveau mécanisme appelé Dynamic Upgrade Cos-Mécanisme (DCUM), où les valeurs des temporisateurs sont modifiés dynamiquement en fonction de l'état des tampons locaux aux nœuds d’accès et le trafic circulant dans le réseau / The rapid growth in client application demands, in terms of bandwidth and (QoS), has motivated the deployment of the optical technology at Metro Access and Metro Core Networks. More diverse and more intelligent optic devices are required for efficiently management of huge capacity in the network. The explosion in demand for network bandwidth is mainly due to the growth in data traffic whose nature is also becoming more and more complex. In general, most of service-based traffics are transported in networks which are now being dominated by the optical switching technology. Nevertheless, such technology has some drawbacks such as inflexible and non-scalable properties. (OPS), which offers significant benefits in terms of both network efficiency and control scalability, may overcome these limitations. This has motivated the orientation from optical circuit switching to optical packet switching in the future network infrastructure. In reality, optical packet switching ring (OPSR) networks, which combine the packet switching technology with the well-known advantages of ring topology such as fast service restoration in cases of failure and high gain of statistical traffic multiplexing over the ring, appear to be the technology of choice for the next generation of Metro Area Networks. A new OPSR architecture which is based on the all-optical infrastructure that offers intelligent features with lower cost while maximizing processing time and is now considering being replaced existing opto-electronic architectures such as Resilient Packet Ring, have been presented in the scope of the dissertation. The key element of such network is Packet Optical Add/Drop Multiplexer (POADM) which is implemented inside a ring node, allowing the node to exploit the optical transparency. This dissertation hence focuses on the performance evaluation of the new generation of OPSR network. In this dissertation, we have investigated the performance analysis (in terms of packet delay and queue-length distribution of access nodes) of an optical synchronous bus-based metropolitan network supporting fixed-size packets. We have modeled each access node by an embedded discrete time Markov chain (EDTMC). The solution of the EDTMC allows us to compute the approximate probability that access nodes on the bus “see” free slots in the transit line. Using a recursive analysis technique, we approximately outline the mean waiting time of client packets coming from the upper layer as well as an approximate queue-length distribution of local buffers at access nodes in two cases: with and without QoS guarantees. To characterize the performance of an asynchronous OPSR network, we have evaluated the impact of Optical fixed-Size Packet Creation on the network performance without and with different quality of services (QoS) requirements. Performance analysis of such systems has allowed us to identify a reasonable combination of some parameters (timeslot duration, timer expiration values, profile of client traffic and network load) which may be able to improve the bandwidth utilization of the network for a given traffic matrix. The most important point that we have mentioned in the dissertation is the comparison of two architectural approaches: Variable Length – Optical Packet Format (VL-OPF) model supporting empty packets versus Fixed Length – Optical Packet Format (FL-OPF) model. In addition to CoS-Upgrade Mechanism (CUM) which is proposed to improve the filling ratio of the optical container, we have proposed a novel mechanism named Dynamic CoS-Upgrade Mechanism (DCUM) where timers are dynamically changed according to the state of the local buffer of network nodes and the traffic circulating in the network, in order to create containers with a high filling ratio while limiting the time needed for their creation.

The 5G Radio Access Network (RAN) is a critical system that must be secured against potential attacks, particularly its Base-Band Unit (BBU), which is a common target for intrusions. Ericsson, which is a big provider of such systems, has placed significant emphasis on implementing Intrusion Detection Systems (IDS) to detect threats. However, the attention given to Intrusion Response Systems (IRS) in general is limited, with current challenges including false alarms, response cost, response time and reliability. Also, the hardware limitations of the BBU present difficulties in designing an effective IRS. To address these challenges, a semi-automated IRS was implemented with a dynamic and cost-based response selection approach. Open Source SECurity (OSSEC), which is a free, open-source endpoint detection and response tool, was employed to execute the selected responses. The effectiveness of the IRS was assessed based on Ericsson's requirements, reliability, response time, response cost and false alarms. The results obtained show that the proposed IRS is reliable as it can handle a huge number of intrusions and has negligible performance overhead in less extreme attack cases. These findings offer valuable insights into addressing intrusions within a system with constrained hardware resources.

The increasing demand on user rates in the fifth generation (5G) requires network architectures that can support high data rates with acceptable reliability. In order to increase the data rates in the presence of the current spectrum crisis, shrinking cells and reusing the spectrum is a proposed solution. Conventional implementation of dense cells requires a large number of expensive BSs to locally process and decode users’ signals. Another limiting factor that degrades the performance in a dense network is the inter-cell interference. A cloud radio access network (CRAN) is a promising solution to those cost, complexity, and interference challenges. A typical CRAN architecture consists of simplified low-cost base stations (BSs), termed radio units (RUs), that collect the radio frequency (RF) user equipments’ (UEs) signals and forward them over the fronthaul links to the central office (CO) where signal processing is done over shared resources. Besides the reduced cost and complexity of a CRAN, the joint processing at the CO enables joint interference mitigation techniques. However, the performance of CRANs depends critically on the availability of reliable fronthaul links with large bandwidth that may be expensive. Analog optical fronthaul links provide high data rates at lower cost and complexity since UEs’ signals are optically analog-modulated without digitalization, however, they suffer from other channel impairments and nonlinearities. In this thesis, analog optical fronthaul topologies are considered in which radio signals are forwarded over free-space optical (FSO) links, termed radio-over-free-space optical (RoFSO) links, and optical fiber (OF) links, termed radio-over-fiber (RoF) links. Firstly, a CRAN with mixed RF/RoFSO fronthaul is considered to investigate the performance improvement when RF fronthaul links are replaced one-by-one by RoFSO links. A novel joint optimization problem is introduced for the given architecture in which the weighted sum of UEs’ rates is maximized by jointly designing RF and RoFSO links. The optimization problem is solved over different numbers of RF and RoFSO links and under various weather conditions. Under favorable weather conditions, the replacement of 1 RF link by a RoFSO link is shown to increase the 50th percentile of UEs’ rates by 7 times. Secondly, the reliability of a CRAN with two-hop RoFSO/RoF fronthaul links is derived along with other performance metrics such as the average bit-error rate and the cumulative distribution function of UEs’ rates. For the given architecture, the Gaussian noise model of fiber nonlinearity is applied and an optimal OF average optical power is derived to minimize the outage probability. Using the optimal power, and under favorable weather conditions, the 50th percentile of user rate exceeds 1:5 Gbps. Finally, a CRAN with passive all-optical two-hop fronthaul links is considered where optical signals from the first RoFSO fronthaul hop are passively coupled into the RoF fronthaul link. The fronthaul outage probability is derived in the context of network planning to provide guidance on designing a set of system parameters. Those parameters include coverage area radius, density of RUs, RoFSO gain, RoFSO optical power and RoF length. / Thesis / Doctor of Philosophy (PhD) / The upcoming generation of wireless communications, termed fifth generation (5G), promises faster data rates and lower latency. In order to achieve this, more base stations (BSs) have to be deployed which increases the cost and complexity of the network. A solution to this challenge is to install simple BSs, i.e. radio units (RUs), that collect signals from users and forward them to a central office (CO) for joint processing which is referred to as a cloud radio access network (CRAN). The fronthaul network in a CRAN connects the RUs to the CO and it can be implemented using different kinds of links. While there are several fronthaul media (e.g., radio frequency (RF), free-space optical (FSO) links, copper lines, satellite communications, and optical fiber (OF)), optical links provide high data rates that are promising to achieve the 5G requirements. In this thesis, a novel architecture of a CRAN is considered in which analog optical links, namely FSO links and OF links, are used for fronthauling. Performance improvement in terms of rate and reliability is investigated and optimized through different design tools. In response to the challenges introduced by the proposed architecture, such as the nonlinearities of analog FSO and OF links, various design parameters are proposed in the optimization problems to tackle those challenges. Furthermore, a network planning framework is introduced to provide guidance and insights on designing the network.

Yes / Fifth generation (5G) cellular networks will be comprised of millions of connected devices like wearable devices, Androids, iPhones, tablets and the Internet of Things (IoT) with a plethora of applications generating requests to the network. The 5G cellular networks need to cope with such sky-rocketing tra c requests from these devices to avoid network congestion. As such, cloud radio access networks (C-RAN) has been considered as a paradigm shift for 5G in which requests from mobile devices are processed in the cloud with shared baseband processing. Despite call admission control (CAC) being one of radio resource management techniques to avoid the network congestion, it has recently been overlooked by the community. The CAC technique in 5G C-RAN has a direct impact on the quality of service (QoS) for individual connections and overall system e ciency. In this paper, a novel Fuzzy-Logic based CAC scheme with pre-emption in C-RAN is proposed. In this scheme, cloud bursting technique is proposed to be used during congestion, where some delay tolerant low-priority connections are pre-empted and outsourced to a public cloud with a penalty charge. Simulation results show that the proposed scheme has low blocking probability below 5%, high throughput, low energy consumption and up to 95% of return on revenue.

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada

A utilização, em sistemas de comunicações ópticas, de formatos de modulação digitais é vista, atualmente, como uma forma promissora de aumentar a eficiência espectral, frente aos diversos efeitos de degradação do sinal em fibra óptica, sem alterar a infraestrutura já implantada. É neste contexto que surge a técnica OFDM (orthogonal frequency division multiplexing) que estabelece sobreposição espectral das subportadoras e, desta forma, permite a transmissão dos dados em forma multiplexada com grande eficiência espectral. No presente trabalho, foi proposta a simulação da técnica OFDM com modulação QAM (quadrature amplitude modulation) no software Optisystem, versões 9.0 e 10.0. O objetivo principal da pesquisa é estudar algumas configurações de sistemas OFDM óptico, com detecção direta e coerente, visando avaliar seu desempenho sistêmico frente a efeitos de propagação. Usando as figuras de mérito BER e diagrama de constelação para estabelecer a meta de ótimo desempenho, analisamos a técnica OFDM com detecção coerente em configurações aplicáveis, principalmente, para redes ópticas de acesso com alcance estendido. Para validação dos resultados, são apresentados também estudos que relacionam as degradações do sinal em fibra óptica e a técnica OFDM. Estes resultados foram comparados com os existentes na literatura, apresentando boa concordância. / The development of digital modulation formats in optical communications systems is considered to be a promising way to increase the spectral efficiency and to combat the effects of signal degradation in optical fiber without changing the infrastructure already deployed. In this context, the technique called OFDM (orthogonal frequency division multiplexing) establishes a particular spectral overlap of the subcarriers, which allows data transmission to be multiplexed with high spectral efficiency. The main objective of the research is to study some configurations of optical OFDM systems with direct detection and coherent in order to evaluate their performance against propagation effects. Using the figures of merit BER and constellation diagram to establish the goal of optimal performance, we analyze the OFDM technique with coherent detection in configurations more applicable for optical access networks with extended reach. To validate the results we also present some studies that relate the degradation of the signal in an optical fiber and the OFDM technique. These results were compared with those described in literature, showing good agreement.

More than a billion people access the Internet through residential broadband connections worldwide, and this number is projected to grow further. Surprisingly, little is known about some important properties of these networks: What performance do users obtain from their ISP? What factors affect performance of broadband networks? Are users bottlenecked by their ISP or by their home network? How are applications such as the Web affected by these factors? Answering these questions is difficult; there is tremendous diversity of technologies and applications in home and broadband networks. While a lot of research has tackled these questions piecemeal, the lack of a good vantage point to obtain good measurements from these networks makes it notably difficult to do a holistic characterization of the ﾓlast mileﾔ. In this dissertation we use the home gateway to characterize home and access networks and mitigate performance bottlenecks that are specific to such networks. The home gateway is uniquely situated; it is always on and, as the hub of the network, it can directly observe the home network, the access network, and user traffic. We present one such gateway- based platform, BISmark, that currently has nearly 200 active access points in over 20 countries. We do a holistic characterization of three important components of the last mile using the gateway as the vantage point: the access link that connects the user to the wider Internet, the home network to which devices connect, and Web performance, one of the most commonly used applications in today's Internet. We first describe the design, development, and deployment of the BISmark platform. BISmark uses custom gateways to enable measurements and evaluate performance opti- mizations directly from home networks. We characterize access link performance in the US using measurements from the gateway; we evaluate existing techniques and propose new techniques that help us understand these networks better. We show how access link technology and home networking hardware can affect performance. We then develop a new system that uses passive measurements at the gateway to localize bottlenecks to either the wireless network or the access link. We deploy this system in 64 homes worldwide and characterize the nature of bottlenecks, and the state of the wireless network in these homes - specifically we show how the wireless network is rarely the bottleneck as throughput exceeds 35 Mbits/s. Finally, we characterize bottlenecks that affect Web performance that are specific to the last mile. We show how latency in the last mile results in page load times stagnating at throughput exceeding 16 Mbits/s, and how simple techniques deployed at the gateway can mitigate these bottlenecks.

From the first generation, 1G, to the fourth generation, 4G, the development and technological advancements in telecommunications network systems have been remarkable. Faster and better connections have opened up for new markets, ideas and possibilities, to that extent that there now is a demand that surpasses the supply. Despite all these advancements made in the mobile communications field most of the concept of how the technology works and its infrastructure has remained the same. This however, is about to change with the introduction of the fifth generation (5G) mobile communication. With the introduction of 5G much of the technology introduced will be different from that of previous generations. This change extends to include the entire infrastructure of the mobile communications system. With these major changes, many of the tools available today for telecommunications network evaluation do not really suffice to include the 5G network standard. For this reason, there is a need to develop a new kind of tool that will be able to include the changes brought by this new network standard. In this thesis a simulation framework adapted for the next generation telecommunication standard 5G is set to be developed. This framework should include many of the characteristics that set 5G aside from previous generations.

A utilização, em sistemas de comunicações ópticas, de formatos de modulação digitais é vista, atualmente, como uma forma promissora de aumentar a eficiência espectral, frente aos diversos efeitos de degradação do sinal em fibra óptica, sem alterar a infraestrutura já implantada. É neste contexto que surge a técnica OFDM (orthogonal frequency division multiplexing) que estabelece sobreposição espectral das subportadoras e, desta forma, permite a transmissão dos dados em forma multiplexada com grande eficiência espectral. No presente trabalho, foi proposta a simulação da técnica OFDM com modulação QAM (quadrature amplitude modulation) no software Optisystem, versões 9.0 e 10.0. O objetivo principal da pesquisa é estudar algumas configurações de sistemas OFDM óptico, com detecção direta e coerente, visando avaliar seu desempenho sistêmico frente a efeitos de propagação. Usando as figuras de mérito BER e diagrama de constelação para estabelecer a meta de ótimo desempenho, analisamos a técnica OFDM com detecção coerente em configurações aplicáveis, principalmente, para redes ópticas de acesso com alcance estendido. Para validação dos resultados, são apresentados também estudos que relacionam as degradações do sinal em fibra óptica e a técnica OFDM. Estes resultados foram comparados com os existentes na literatura, apresentando boa concordância. / The development of digital modulation formats in optical communications systems is considered to be a promising way to increase the spectral efficiency and to combat the effects of signal degradation in optical fiber without changing the infrastructure already deployed. In this context, the technique called OFDM (orthogonal frequency division multiplexing) establishes a particular spectral overlap of the subcarriers, which allows data transmission to be multiplexed with high spectral efficiency. The main objective of the research is to study some configurations of optical OFDM systems with direct detection and coherent in order to evaluate their performance against propagation effects. Using the figures of merit BER and constellation diagram to establish the goal of optimal performance, we analyze the OFDM technique with coherent detection in configurations more applicable for optical access networks with extended reach. To validate the results we also present some studies that relate the degradation of the signal in an optical fiber and the OFDM technique. These results were compared with those described in literature, showing good agreement.

Die Verfügbarkeit von Breitbandnetzen wird für die Sicherung und Weiterentwicklung des Wirtschafts-, Technologie- und Tourismusstandortes Sachsen immer wichtiger. Eine gute Nachricht gleich zu Beginn: Das Land Sachsen stellt seit Ende letzten Jahres Fördermittel für den Aufbau von Breitbandnetzen auch für die zukunftsfähigen Next-Generation-Access-Netze (NGA) zur Verfügung. Zuwendungsempfänger sind neben Gemeinden, Landkreisen, Verwaltungsgemeinschaften und Gemeindeverbände auch Eigenbetriebe und Zweckverbände. Das ließ viele Zuhörer auf der Informationsveranstaltung „Breitband und Straßen als kommunale Herausforderung“ am 26. März 2015 in Leipzig aufhorchen.