Dissertations / Theses on the topic 'Network management'

Community networks (in South Africa and Africa) are often serviced by limited bandwidth network backhauls. Relative to the basic needs of the community, this is an expensive ongoing concern. In many cases the Internet connection is shared among multiple sites. Community networks may also have a lack of technical personnel to maintain a network of this nature. Hence, there is a demand for a system which will monitor and manage bandwidth use, as well as network use. The proposed solution for community networks and the focus within this dissertation, is a system of two parts. A Community Access Point (CAP) is located at each site within the community network. This provides the hosts and servers at that site with access to services on the community network and the Internet, it is the site's router. The CAP provides a web based interface (CAPgui) which allows configuration of the device and viewing of simple monitoring statistics. The Access Concentrator (AC) is the default router for the CAPs and the gateway to the Internet. It provides authenticated and encrypted communication between the network sites. The AC performs several monitoring functions, both for the individual sites and for the upstream Internet connection. The AC provides a means for centrally managing and effectively allocating Internet bandwidth by using the web based interface (ACgui). Bandwidth use can be allocated per user, per host and per site. The system is maintainable, extendable and customisable for different network architectures. The system was deployed successfully to two community networks. The Centre of Excellence (CoE) testbed network is a peri-urban network deployment whereas the Siyakhula Living Lab (SLL) network is a rural deployment. The results gathered conclude that the project was successful as the deployed system is more robust and more manageable than the previous systems.

Renewable energy generation is becoming a major part of energy supply, often in the form of distributed generation (DG) connected to distribution networks. While growth has been rapid, there is awareness that limitations on spare capacity within distribution (and transmission) networks is holding back development. Developments are being shelved until new network reinforcements can be built, which may make some projects non-viable. Reinforcements are costly and often underutilised, typically only loaded to their limits for a few occasions during the year. In order to accommodate new DG without the high costs or delays, active network management (ANM) is being promoted in which generation and other network assets are controlled within the limits of the existing network. There is a great deal of complexity and uncertainty associated with developing ANM and devising coherent plans to accommodate new DG is challenging for Distribution Network Operators (DNOs). As such, there is a need for robust network planning tools that can explicitly handle ANM and which can be trusted and implemented easily. This thesis describes the need for and the development of a new distribution expansion planning framework that provides DNOs with a better understanding of the impacts created by renewable DG and the value of ANM. This revolves around a heuristic planning framework which schedules necessary upgrades in power lines and transformers associated with changes in demand as well as those driven by the connection of DG. Within this framework a form of decentralised, adaptive control of DG output has been introduced to allow estimation of the impact of managing voltage and power flow constraints on the timing and need for network upgrades. The framework is initially deployed using simple scenarios but a further advance is the explicit use of time series to provide substantially improved estimates of the levels of curtailment implied by ANM. In addition, a simplified approach to incorporating demand side management has been deployed to facilitate understanding of the scope and role this may play in facilitating DG connections.

Thesis (M.S. in Information Technology Management) Naval Postgraduate School, September 1999.
"September 1999". Thesis advisor(s): Geoffrey Xie, Gilbert Lundy. Includes bibliographical references (p. 215-224). Also available online.

Two research topics in next-generation optical networks with wavelength-division multiplexing (WDM) technologies were investigated: (1) scalability of network management and control, and (2) resilience/reliability of networks upon faults and attacks. In scalable network management, the scalability of management information for inter-domain light-path assessment was studied. The light-path assessment was formulated as a decision problem based on decision theory and probabilistic graphical models. It was found that partial information available can provide the desired performance, i.e., a small percentage of erroneous decisions can be traded off to achieve a large saving in the amount of management information. In network resilience under malicious attacks, the resilience of all-optical networks under in-band crosstalk attacks was investigated with probabilistic graphical models. Graphical models provide an explicit view of the spatial dependencies in attack propagation, as well as computationally efficient approaches, e.g., sum-product algorithm, for studying network resilience. With the proposed cross-layer model of attack propagation, key factors that affect the resilience of the network from the physical layer and the network layer were identified. In addition, analytical results on network resilience were obtained for typical topologies including ring, star, and mesh-torus networks. In network performance upon failures, traffic-based network reliability was systematically studied. First a uniform deterministic traffic at the network layer was adopted to analyze the impacts of network topology, failure dependency, and failure protection on network reliability. Then a random network layer traffic model with Poisson arrivals was applied to further investigate the effect of network layer traffic distributions on network reliability. Finally, asymptotic results of network reliability metrics with respect to arrival rate were obtained for typical network topologies under heavy load regime. The main contributions of the thesis include: (1) fundamental understandings of scalable management and resilience of next-generation optical networks with WDM technologies; and (2) the innovative application of probabilistic graphical models, an emerging approach in machine learning, to the research of communication networks.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, September 2009.
Thesis Advisor(s): Bordetsky, Alex. "September 2009." Description based on title screen as viewed on November 9, 2009. Author(s) subject terms: IP, tactical sensor network, TNT, Internet Protocol Version 6, network management, quality of service, DiffServ, information management. Includes bibliographical references (p. 197-202). Also available in print.

Some companies today are using sub-optimal and nearly obsolete management systems for their networks. Given the large number of different services that are demanded by users, there is a need to adapt the network structure to support the current and potential future demands. As a result, there is a need for new Network Management Solutions (NMSs). The aim of this thesis project is to help a company who uses a NMS called Local Area Network (LAN) Management Solution (LMS). LMS was designed by Cisco for managing LAN networks. However, the company’s demands are growing and they need to expand their network more than expected. Moreover, LMS is designed to only support devices by Cisco, whereas the company wants a universal solution with wide device support from many manufacturers. This thesis presents an analysis of their current system and suggests potential solutions for an upgrade that will meet all of the company’s demands and will have a long operating life. To help find reasonable solutions a thorough evaluation of their existing NMS and network monitoring and management needs was made.  This evaluation gave good insights into different aspects of their system. A reasonable solution was found by following a three-step approach, beginning with 82 possible solutions, filtering out and breaking down with each step, until only the most suitable NMS was left. Two NMSs has been proposed as equally suitable replacements: IBM Tivoli Netcool/OMNIbus and ManageEngine OpManager. Regardless of which one is chosen, they both have the following advantages over the company’s existing NMS: they are very stable solutions which can handle a large number of managed devices; they are universal solutions with wide device support, and the company can add custom support if needed; they are user-friendly with the ability to add custom interfaces; and they both have a professional first-line technical support department locally located.
Vissa företag använder idag suboptimala och föråldrade övervakningsssystem för sina nätverk. Med tanke på det stora antalet olika tjänster som efterfrågas av användare finns det ett stort behov av att anpassa nätverksstrukturen för att stödja de nuvarande och potentiellt framtida kraven. Som ett resultat finns det ett behov av nya övervakningssystem (Network Management Solutions (NMSs)) för nätverken. Syftet med detta examensarbete är att hjälpa ett företag som använder NMS:en Local Area Network (LAN) Management Solution (LMS). LMS utecklades av Cisco för att hantera lokala nätverk (LANs). Men med tiden har företagets krav förändrats och de har därför behövt expandera sitt nätverk mer än väntat.  Dessutom är LMS endast utformad för att hantera enheter tillverkade av Cisco, medan företaget vill ha en universal lösning med stöd för enheter från många olika tillverkare. Denna rapport presenterar en analys av deras nuvarande system, samt föreslår möjliga lösningar som kan ersätta detta. Den nya lösningen ska vara långvarig samt ska uppfylla alla krav företaget ställt. För att hitta lämpliga lösningar har en grundlig utvärdering av den befintliga NMS:en samt en analys av de ställda kraven utförts. Denna analys gav goda insikter i olika aspekter av deras nuvarande system. En lämplig lösning hittades genom att följa en trestegsmetod. Metoden utgick från 82 möjliga lösningar, som efter flera steg av filtrering resulterade i de mest lämpade ersättningssystemen. Två NMS:er har föreslagits som lika lämpliga ersättare: IBM Tivoli Netcool/OMNIbus och ManageEngine OpManager. Oavsett vilken som väljs, har de båda följande fördelar jämfört med den nuvarande NMS:en: de är båda väldigt stabila lösningar som klarar av en stor mängd hanterade enheter; de är universella lösningar med stöd för en stor mängd olika enheter, dessutom går det även att lägga till eget stöd för enheter vid behov; de är användarvänliga och har möjlighet till att anpassa egna gränssnitt; samt att de båda har en professionell first-line teknisk support placerad lokalt i landet.<p>

In distribution networks, the traditional way to eliminate network stresses caused by increasing generation and demand is to reinforce the primary network assets. A cheaper alternative is active network management (ANM) which refers to real-time network control to resolve power flow, voltage, fault current and security issues. However, there are two limitations in ANM. First, previous ANM strategies investigated generation side and demand side management separately. The generation side management evaluates the value from ANM in terms of economic generation curtailment. It does not consider the potential benefits from integrating demand side response such as economically shifting flexible load over time. Second, enhancing generation side management with load shifting requires the prediction of network stress whose accuracy will decrease as the lead time increases. The uncertain prediction implies the potential failure of reaching expected operational benefits. However, there is very limited investigation into the trade-offs between operational benefit and its potential risk. In order to tackle the challenges, there are two aspects of research work in this thesis. 1) Enhanced ANM. It proposes the use of electric vehicles (EVs) as responsive demand to complement generation curtailment strategies in relieving network stress. This is achieved by shifting flexible EV charging demand over time to absorb excessive wind generation when they cannot be exported to the supply network. 2) Uncertainty management. It adopts Sharpe Ratio and Risk Adjust Return On Capital concepts from financial risk management to help the enhanced ANM make operational decisions when both operational benefit and its associated risk are considered. Copula theory is applied to further integrate correlations of forecasting errors between nodal power injections (caused by wind and load forecasting) into uncertainty management. The enhanced ANM can further improve network efficiency of the existing distribution networks to accommodate increasing renewable generation. The cost-benefit assessment informs distribution network operators of the trade-off between investment in ANM strategy and in the primary network assets, thus helping them to make cost-effective investment decisions. The uncertainty management allows the impact of risks that arise from network stress prediction on the expected operational benefits to be properly assessed, thus extending the traditional deterministic cost-benefit assessment to cost-benefit-risk assessment. Moreover, it is scalable to other systems in any size with low computational burden, which is the major contribution of this thesis.

This research focuses on developing a secure, SNMP-based network management system specifically tailored for deployment in internetworks that rely on low-bandwidth backbone networks. The network management system developed uses a two-level hierarchy of network management applications consisting of one top-level management application communicating with several mid-level management applications strategically distributed throughout the internetwork. Mid-level management applications conduct routine monitoring chores on behalf of the top-level management application and report results in a way that makes intelligent use of the limited bandwidth available on the backbone network. The security framework is based on using SNMPv2c over IPSec. This research shows that the other security alternative considered, SNMPv3, consumes as much as 24 percent more network capacity than SNMPv2c over IPSec. The management framework is based on the Management by Delegation (MbD) model and is implemented using the IETF DISMAN Script MIB. This research demonstrates that the MbD-based management framework consumes only 2 percent of the network capacity required by the traditional, centralized management scheme.
Master of Science

Since 2004, when the Long Term Evolution (LTE) was first proposed to be publicly available in the year 2009, a plethora of new characteristics, techniques and applications have been constantly enhancing it since its first release, over the past decade. As a result, the research aims for LTE-Advanced (LTE-A) have been released to create a ubiquitous and supportive network for mobile users. The incorporation of heterogeneous networks (HetNets) has been proposed as one of the main enhancements of LTE-A systems over the existing LTE releases, by proposing the deployment of small-cell applications, such as femtocells, to provide more coverage and quality of service (QoS) within the network, whilst also reducing capital expenditure. These principal advantages can be obtained at the cost of new challenges such as inter-cell interference, which occurs when different network applications share the same frequency channel in the network. In this thesis, the main challenges of HetNets in LTE-A platform have been addressed and novel solutions are proposed by using self-organising network (SON) management approaches, which allows the cooperative cellular systems to observe, decide and amend their ongoing operation based on network conditions. The novel SON algorithms are modelled and simulated in OPNET modeler simulation software for the three processes of resource allocation, mobility management and interference coordination in multi-tier macro-femto networks. Different channel allocation methods based on cooperative transmission, frequency reuse and dynamic spectrum access are investigated and a novel SON sub-channel allocation method is proposed based on hybrid fractional frequency reuse (HFFR) scheme to provide dynamic resource allocation between macrocells and femtocells, while avoiding co-tier and cross-tier interference. Mobility management is also addressed as another important issue in HetNets, especially in hand-ins from macrocell to femtocell base stations. The existing research considers a limited number of methods for handover optimisation, such as signal strength and call admission control (CAC) to avoid unnecessary handovers, while our novel SON handover management method implements a comprehensive algorithm that performs sensing process, as well as resource availability and user residence checks to initiate the handover process at the optimal time. In addition to this, the novel femto over macro priority (FoMP) check in this process also gives the femtocell target nodes priority over the congested macrocells in order to improve the QoS at both the network tiers. Inter-cell interference, as the key challenge of HetNets, is also investigated by research on the existing time-domain, frequency-domain and power control methods. A novel SON interference mitigation algorithm is proposed, which is based on enhanced inter-cell interference coordination (eICIC) with power control process. The 3-phase power control algorithm contains signal to interference plus noise ratio (SINR) measurements, channel quality indicator (CQI) mapping and transmission power amendments to avoid the occurrence of interference due to the effects of high transmission power. The results of this research confirm that if heterogeneous systems are backed-up with SON management strategies, not only can improve the network capacity and QoS, but also the new network challenges such as inter-cell interference can also be mitigated in new releases of LTE-A network.

Wireless Sensor Networks (WSNs) have been widely studied in the last decade because of the large set of applications that can be potentially enabled by this novel network paradigm, as environmental monitoring, home automation, localization and tracking of mobile users, seamless and ubiquitous data exchange. However, the severe constraints in terms of energy, processing, memory and reliability of the low--cost sensor devices left a number of unresolved problems, open to research. This thesis tackles two of the most interesting problems concerning WSNs, namely localization and traffic management. Accurate sensor localization is crucial for a wide variety of WSN applications and protocols, including monitoring, routing, scheduling, data fusion and so on. Typically, localization algorithms are based on an infrastructure of nodes which are aware of their geographical positions, called beacons. These nodes broadcast their coordinates in order to let the other nodes in the network, referred to as stray nodes, infer their own position by means of some estimation technique. The topic has been widely investigated, both in simulation and, more recently, in experimental testbeds. Nonetheless, the performance obtained by most of the proposed algorithms is still unsatisfactory, in particular in indoor environments. Therefore, further research is needed. In this thesis, the problem has been tackled from different perspectives, in order to gain a deep and clear understanding of the several facets that characterize this interesting domain. As a consequence, we collected a rather wide set of results that apparently may not seem to be strongly correlated, though they all fit within the same research project. As a first step, we compare well known localization algorithms in indoor environments for static networks, based on a Received Signal Strength Indicator (RSSI) ranging estimation technique. Results shed light on the actual potentialities and limits of common localization algorithms in indoor environments in a real testbed. In particular, we observed the strong impact of the shadowing random attenuation of the power of the received signal on the performance of the localization algorithms. Therefore, research has been addressed to the reduction of the shadowing term in the RSSI measures. To this end, we investigated the effect of the carrier frequency and of the antenna anisotropy on the randomness of the shadowing component, again using real measurements collected in different testbeds. Successively, our attention turned to the problem of beacon positioning that we observed may strongly affect the localization performance. We analyzed the optimal beacons placement both using an exhaustive but very complex approach and a heuristic scheme that provides close to optimal solutions while maintaining a linear complexity with the number of beacons. Looking at the localization performance separating the different effects of localization algorithms, channel parameters and beacon positioning, has been important to understand the contribution of each one of these aspects to the localization error and how much is it possible to improve the localization accuracy by means of a single technique, that usually is chosen depending on the particular scenario and available resources. Then nodes mobility has been included into the framework. We first considered an Autonomous Mobile Robot (AMR) that can interact with sensors, but is also capable to self--localize using onboard odometry. Leveraging on the complementarities of WSN and AMR, we considered the Simultaneous Localization and Mapping (SLAM) problem that consists in creating the map of an area without any a priori knowledge of the environment, while localizing the nodes in the WSN by combining the information provided by the WSN and by the AMR odometry. Second, we considered a completely mobile wireless networks in which heterogeneous nodes with different self--localization capabilities can interact one another on an opportunistic basis, exchanging localization information with other nodes that occasionally happen to be in geographical proximity. The performance of this scheme has been analyzed through a mathematical framework. We considered a Maximum Likelihood (ML) approach, a Linear Matrix Inequality (LMI) system and a simple heuristic strategy to define opportunistic localization algorithms. The validity of the mathematical model has been confirmed through experimental measures. We considered two main settings, one in which a node can rely on a single opportunistic interaction and one in which multiple contacts can be set while the node remains in the same position. We analyzed the different techniques, finding that in the first scenario, if the channel is not very noisy and the self--localization of the cooperative node quite accurate, the heuristic algorithm performs very well, in some case slightly better than ML, while the ML approach is very robust and improves localization accuracy even in difficult scenarios. If multiple interactions are available, then the heuristic technique is quite poor and it is better to rely on the LMI technique. Moreover LMI is quite flexible, because it does not require an initial guess of the position by the stray node and it can be used both with and without ranging information. The static scenario analysis was very useful to focus on the mobile localization. The design of the proposed algorithms and scenarios, the simulation parameters and limits, are strictly related to the knowledge of the channel behavior and localization performance gained from the previous studies. The opportunistic idea raises from two main considerations: the limited accuracy of the beacon based RSSI localization in a real scenario and the quite good ranging accuracy of RSSI when limiting the distance. Alongside the main research line concerning localization in WSN, during the Ph.D. we also investigated other research topics, namely traffic management and underwater sensor network, which are not directly related to the previous ones but still of great scientific and educational interest. The most significant achievements obtained in these areas have also been collected in the thesis for two reasons. First, these topics still belong to the context of wireless sensor networks, sharing some basic characteristics such as the assumptions of simplicity and energy constraints. Second, the excursion on different but correlated fields may potentially open new perspectives to well known problems, thus contributing to the innovation and the progress of the research. As mentioned, the second problem addressed in this thesis regards the traffic management in WSN. Usually all the nodes in a WSN send packets to a common node, called sink. This traffic pattern, under a certain load, can lead to congestion problems, causing packet losses, high delays and waste of energy. The proposed solutions in literature usually aim at detecting the occurence of congestion by involving in this task many nodes, sometimes the entire network. We propose a different protocol, called Efficient Packet Converge Casting (EPC$^2$), that mitigates the congestion at the sink involving only a fixed number of nodes, namely the sink's neighbors. Another scenario we look into was that of underwater wireless sensor networks (UWSNs), which enable a number of applications as for radio WSNs, fostering interest in this research field. Similarly to radio networks, the energy efficiency remains a main issue. Nodes are powered by battery and it is very important to extend the network lifetime as much as possible. The different characteristics of the environment in which nodes are deployed raise new research challenges that require novel protocol design. We addressed the energy efficiency problem in UWSN with two different approaches. First, we investigated the effect of duty--cycle and node density on the energy consumption of the network, assuming that nodes can use different power levels to transmit. Second, we proposed a channel management scheme to optimize the energy consumption, considering the strong relationship between distance, frequency and channel attenuation. Both solutions are very simple and suitable for the low--complexity underwater sensor devices and do not need any central unit to coordinate, but they work asyncronously and distributely.
Negli ultimi anni, le reti wireless di sensori (WSN) sono state molto studiate a causa delle numerose applicazioni in cui possono essere usate, come il monitoraggio ambientale, la domotica, la localizzazione e il tracking di utenti mobili. Le forti limitazioni dei nodi sensori in termini di energia, processamento, memoria e affidabilita', lasciano ancora aperti molti problemi per la ricerca. Questa tesi affronta due problemi molto importanti relativi alle reti wireless di sensori: la localizzazione e la gestione del traffico. Un'accurata localizzazione dei sensori e' importante per molte applicazioni per WSN, come monitoraggio, routing, scheduling, data fusion e molte altre. Tipicamente, gli algoritmi di localizzazione si basano su una infrastruttra di nodi, detti nodi ancora che conoscono la loro posizione geografica. Questi nodi trasmettono in broadcast le loro coordinate agli altri nodi della rete, che da queste informazioni ricavano la loro posizione tramite tecniche di stima. L'argomento e' stato largamente studiato, sia con simulazioni sia, piu' recentemente, con testbed sperimentali. Ciononostante, l'accuratezza ottenuta dalla maggior parte degli algoritmi proposti e' ancora insufficiente, soprattutto in ambienti interni. E' quindi necessario cercare nuove metodologie e nuovi approcci. In questa tesi, il problema e' stato affrontato da diversi punti di vista, in modo da capire in maniera piu' chiara e accurata i diversi aspetti che lo caratterizzano. Come conseguenza, abbiamo raccolto una vasta quantita' di dati che potrebbero apparire come non molto legati uno all'altro, ma che in realta' rientrano tutti nello stesso progetto di ricerca. Come primo passo, abbiamo confrontato algoritmi di localizzazione proposti in letteratura in uno scenario indoor e con nodi statici, stimando la distanza tra i nodi utilizzando la potenza del segnale ricevuto (RSSI). I risultati ci hanno permesso di capire le potenzialita' e i limiti dei piu' diffusi algoritmi di localizzazione in ambiente indoor e in un testbed reale. In particolare, abbiamo osservato il grande impatto che ha sulle prestazioni di localizzazione l'aleatorieta', data dal termine di shadowing, della misura di potenza ricevuta. Abbiamo quindi cercato delle strategie per ridurre la varianza di questo termine aleatorio. A questo scopo, abbiamo studiato l'effetto della frequenza della portante, utilizzando una stima della potenza ricevuta multi--canale, e l'impatto dell'anisotropia dell'antenna sulle oscillazioni dei valori di potenza ricevuta. Entrambi glil studi sono stati fatti con misure reali raccolte in diversi testbed. Successivamente, abbiamo analizzato il problema del posizionamento dei nodi ancora, dopo aver osservato l'incidenza che questo ha sull'accuratezza della localizzazione. Abbiamo confrontato il posizionamento ottimo dei nodi ancora usando sia una tecnica esaustiva, ma computazionalmente molto complessa, sia uno schema euristico che raggiunge prestazioni molto vicine all'ottimo pur mantenendo una complessita' lineare con il numero di ancore. Guardare alle prestazioni di localizzazione separando i diversi effetti degli algoritmi, dei parametri di canale e del posizionamento dei nodi ancora e' stato importante per capire il contributo dei diversi aspetti all'interno dell'errore di localizzazione e quanto sia possibile migliorare la precisione della localizzazione ottimizzando uno di questi aspetti, che solitamente viene scelto in base allo scenario e alle risorse disponibili. Quindi, abbiamo incluso nel nostro scenario anche nodi mobili. All'inizio abbiamo considerato un robot mobile (AMR) che poteva interagire con i sensori, ma anche capace di localizzarsi grazie all'odometria. Facendo leva sulla complementarieta' della rete di sensori e del robot mobile, abbiamo studiato e implementato un algoritmo di localizzazione e mappatura simultanea (SLAM), problema che consiste nel creare la mappa di un'area senza nessuna conoscenza a priori dell'ambiente e in contemporanea localizzare i nodi sensore confrontando le informazioni provenienti dai sensori e quelle ricavate dall'odometria del robot. Poi abbiamo considerato uno scenario piu' generale composto da nodi mobili ed eterogenei, con diverse capacita' di autolocalizzazione, che possono interagire uno con l'altro in modo opportunistico, scambiandosi informazioni di localizzazione con altri nodi che occasionalmente si trovano in prossimita'. Le prestazioni di questo schema sono state analizzate in un modello matematico. Abbiamo studiato un approccio a Massima Verosimiglianza (ML), uno basato su Linear Matrix Inequalities (LMI) e una semplice strategia euristica per definire gli algoritmi di localizzazione opportunistica. La validita' del modello matematico e' stata confermata attraverso misure sperimentali. Abbiamo considerato due scenari principali, uno in cui un nodo puo' contare su una sola interazione opportunistica e uno dove possono essere fatti contatti multipli mentre il nodo resta nella stessa posizione. Abbiamo analizzato le diverse tecniche, trovando che nel primo caso, se le informazioni di autolocalizzazione del nodo cooperatore e di ranging sono buone, l'algoritmo euristico ha buone prestazioni, a volte addirittura meglio della Massima Verosimiglianza, che invece e' estremamente robusto e riesce a migliorare la stima di localizzazione anche in scenari molto difficili. Se invece sono disponibili numerose interazioni, allora l'algoritmo euristico porta prestazioni scarse ed e' meglio utilizzare la tecnica LMI, specialmente utilizzando l'informazione di ranging. Inoltre l'LMI non richiede una conoscenza della posizione iniziale del nodo incognito. Lo scenario statico e' stato molto utile per studiare in maniera efficace la localizzazione mobile. La scelta degli algoritmi proposti e dello scenario, i parametri di simulazione e i limiti, sono strettamente legati a quello che abbiamo studiato riguardo al canale wireless e alle prestazioni di localizzazione nei lavori precedenti. L'idea dello scenario opportunistico infatti e' venuta a partire da due considerazioni: la limitata precisione della localizzazione con ancore basata su RSSI in uno scenario reale e la buona precisione nella stima di distanza con RSSI quando la distanza e' limitata. Affianco al principale filone di ricerca riguardante la localizzazione nelle WSN, durante il dottorato di ricerca abbiamo approfondito anche altri argomenti, come la gestione del traffico e le reti di sensori sottomarine, che non sono direttamente collegate con il tema principale, ma sono comunque di grande interesse scientifico. I risultati piu' significativi ottenuti in questi temi sono stati inseriti all'interno della tesi per due motivi. Innanzitutto, questi argomenti appartengono al contesto delle reti di sensori wireless, condividendo alcune caratteristiche di base quali l'assunzione di semplicita' e le limitazioni energetiche. Inoltre, il trattare campi diversi ma correlati, puo' aprire nuove prospettive a problemi noti, contribuendo cosi' all'innovazione della ricerca. Il secondo problema affrontato in questa tesi e' stato la gestione del traffico in reti di sensori wireless. Spesso, i nodi di una rete di sensori mandano i pacchetti ad un nodo comune, chiamato sink. Questo modello di traffico, quando il carico cresce, puo' portare a problemi di congestione, causando perdita di pacchetti, ritardi e spreco di energia. Le soluzioni proposte in letteratura solitamente cercando di individuare l'inizio di una congestione, utilizzando in questo compito molti nodi, talvolta l'intera rete. Il protocollo proposto, chiamato Efficient Packet Converge Casting (EPC$^2$), mitiga la congestione al sink, ma coinvolgnedo solo un numero fissato di nodi, i vicini del sink. Un altro scenario che abbiamo analizzato in questa tesi, sono state le reti sottomarine di sensori che, come nel caso delle reti radio, possono essere utilizzato per molteplici applicazioni e quindi hanno ricevuto molta attenzione dal mondo della ricerca. Similmente alle reti radio, l'efficienza energetica e' un problema molto sentito. I nodi sono alimentati a batteria ed e' molto importante incrementare la vita della rete il piu' possibile. La profonda diversita' dell'ambiente in cui i nodi sono disposti crea nuove sfide per la ricerca che richiedono la progettazione di nuovi protocolli. Abbiamo affrontato il problema dell'efficienza energetica in reti sottomarine con due diversi approcci. Abbiamo studiato l'effetto del duty--cycle and della densita' dei nodi sul consumo energetico della rete, assumendo che i nodi potessero usare diversi livelli di potenza in trasmissione. Quindi abbiamo proposto uno schema di utilizzazione della banda disponibile per ottimizzare il consumo energetico, facendo leva sulla forte relazione tra distanza, frequenza e attenuazione del canale. Entrambe le soluzioni sono molto semplici e adatte ai dispositivi sottomarini che hanno forti limitazioni. Inoltre non richiedono una unita' centrale per essere coordinate, ma operano in modo asincrono e distribuito.

Thesis (M.S. in Information Systems and Operations)--Naval Postgraduate School, March 2007.
Thesis Advisor(s): Alex Bordetsky. "March 2007." Includes bibliographical references (p. 161-163). Also available in print.

Mobile data traffic is expected to increase substantially in the coming years, with data rates 1000 times higher by 2020, having media and content as the main drivers together with a plethora of new end-user services that will challenge existing networks. Concepts and visions associated with the ICT evolution like the network society, 50 billion connected devices, Industrial Internet, Tactile Internet, etc., exemplifies the range of new services that the networks will have to handle. These new services impose extreme requirement to the network like high capacity, low latency, reliability, security, seamless connectivity, etc. In order to face these challenges, the whole end-to-end network has to evolve and adapt, pushing for advances in different areas, such as transport, cloud, core, and radio access networks. This work investigates the impact of envisioned 2020 society scenarios on transport links for mobile backhaul, emphasizing the need for an integrated and flexible/adaptive network as the way to meet the 2020 networks demands. The evolution of heterogeneous networks and ultra-dense network deployments shall also comprise the introduction of adaptive network features, such as dynamic network resource allocation, automatic integration of access nodes, etc. In order to achieve such self-management features in mobile networks, new mechanisms have to be investigated for an integrated backhaul management. First, this thesis performs a feasibility study on the mobile backhaul dimensioning for 2020 5G wireless ultra-dense networks scenarios, aiming to analyze the gap in capacity demand between 4G and 5G networks. Secondly, the concept of an integrated backhaul management is analyzed as a combination of node attachment procedures, in the context of moving networks. In addition, the dynamic network resource allocation concept, based on DWDM-centric transport architecture, was explored for 5G scenarios assuming traffic variation both in time and between different geographical areas. Finally, a short view on techno-economics and network deployments in the 2020 time frame is provided.

A wireless mesh network is a mesh network implemented over a wireless network system such as wireless LANs. Wireless Mesh Networks(WMNs) are promising for numerous applications such as broadband home networking, enterprise networking, transportation systems, health and medical systems, security surveillance systems, etc. Therefore, it has received considerable attention from both industrial and academic researchers. This dissertation explores schemes for resource management and optimization in WMNs by means of network routing and network coding. In this dissertation, we propose three optimization schemes. (1) First, a triple-tier optimization scheme is proposed for load balancing objective. The first tier mechanism achieves long-term routing optimization, and the second tier mechanism, using the optimization results obtained from the first tier mechanism, performs the short-term adaptation to deal with the impact of dynamic channel conditions. A greedy sub-channel allocation algorithm is developed as the third tier optimization scheme to further reduce the congestion level in the network. We conduct thorough theoretical analysis to show the correctness of our design and give the properties of our scheme. (2) Then, a Relay-Aided Network Coding scheme called RANC is proposed to improve the performance gain of network coding by exploiting the physical layer multi-rate capability in WMNs. We conduct rigorous analysis to find the design principles and study the tradeoff in the performance gain of RANC. Based on the analytical results, we provide a practical solution by decomposing the original design problem into two sub-problems, flow partition problem and scheduling problem. (3) Lastly, a joint optimization scheme of the routing in the network layer and network coding-aware scheduling in the MAC layer is introduced. We formulate the network optimization problem and exploit the structure of the problem via dual decomposition. We find that the original problem is composed of two problems, routing problem in the network layer and scheduling problem in the MAC layer. These two sub-problems are coupled through the link capacities. We solve the routing problem by two different adaptive routing algorithms. We then provide a distributed coding-aware scheduling algorithm. According to corresponding experiment results, the proposed schemes can significantly improve network performance.

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada
The availability of GPS (Global Position Satellite) information in real-time via the RAJPO Datalink system will significantly increase the capacity of flight test and training ranges in terms of missions supported. This increase in mission activity will in turn impose more demands on mission planning in the range operations environment. In this context, network management tools which can improve the capability of range personnel to plan, monitor, and control network resources, are of significant interest. In this paper we describe the application of both simulation and artificial intelligence techniques to develop such network management tools.

Mobile Ad hoc Network of Networks (MANoN) are a group of large autonomous wireless nodes communicating on a peer-to-peer basis in a heterogeneous environment with no pre-defined infrastructure. In fact, each node by itself is an ad hoc network with its own management. MANoNs are evolvable systems, which mean each ad hoc network has the ability to perform separately under its own policies and management without affecting the main system; therefore, new ad hoc networks can emerge and disconnect from the MANoN without conflicting with the policies of other networks. The unique characteristics of MANoN makes such networks highly vulnerable to security attacks compared with wired networks or even normal mobile ad hoc networks. This thesis presents a novel security-management system based upon the Recommendation ITU-T M.3400, which is used to evaluate, report on the behaviour of our MANoN and then support complex services our system might need to accomplish. Our security management will concentrate on three essential components: Security Administration, Prevention and Detection and Containment and Recovery. In any system, providing one of those components is a problem; consequently, dealing with an infrastructure-less MANoN will be a dilemma, yet we approached each set group of these essentials independently, providing unusual solutions for each one of them but concentrating mainly on the prevention and detection category. The contributions of this research are threefold. First, we defined MANoN Security Architecture based upon the ITU-T Recommendations: X.800 and X.805. This security architecture provides a comprehensive, end-to-end security solution for MANoN that could be applied to every wireless network that satisfies a similar scenario, using such networks in order to predict, detect and correct security vulnerabilities. The security architecture identifies the security requirements needed, their objectives and the means by which they could be applied to every part of the MANoN, taking into consideration the different security attacks it could face. Second, realising the prevention component by implementing some of the security requirements identified in the Security Architecture, such as authentication, authorisation, availability, data confidentiality, data integrity and non-repudiation has been proposed by means of defining a novel Security Access Control Mechanism based on Threshold Cryptography Digital Certificates in MANoN. Network Simulator (NS-2) is a real network environment simulator, which is used to test the performance of the proposed security mechanism and demonstrate its effectiveness. Our ACM-MANoN results provide a fully distributed security protocol that provides a high level of secure, available, scalable, flexible and efficient management services for MANoN. The third contribution is realising the detection component, which is represented by providing a Behavioural Detection Mechanism based on nodes behavioural observation engaged with policies. This behaviour mechanism will be used to detect malicious nodes acting to bring the system down. This approach has been validated using an attacks case study in an unknown military environment to cope with misbehaving nodes.

The quest for achieving an efficient, reliable and cost-effective network infrastructure in support of innovative and rich communication services has resulted in the advent and popularity of IP based converged Next Generation Networks (NGN). According to the ITU-T, the NGN has significant advantages such as support for end to end Quality of Service (QoS), generalised mobility, converged services between fixed & mobile networks and interworking with legacy networks. These networks require Network Management Systems (NMS), which play a key role in monitoring and administering them, to ensure smooth running of services and optimum utilisation of network resources. However, it has been observed that a disparity exists in the pace of development of the NGN and the existing NMSs. This thesis takes up the challenge of addressing this disparity by providing autonomic, intelligent and scalable NM solutions with focus on QoS Management, Distributed Monitoring & Control and Traffic Engineering. Traditional methods of network management do have shortcomings in providing the level of dependability and reliability which is required in the current NGN environment. Machine Learning (ML) approaches have gained popularity as the foundation of intelligent and automated systems, since they are capable of modelling the system behaviour through the process of learning, based on the observation of the system over a period of time. Once appropriately trained they can automatically estimate and predict future system behaviour with high accuracy and speed. Hence, the overall objective of this research is design, development and evaluation of ML based network management mechanisms for Admission Control , Distributed Monitoring & Control and Intelligent Traffic Engineering. In the pursuit of fulfilling the stated objective, the Bayesian Networks (BN) approach emerged as a viable and efficient solution to the identified specific problems.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada
Network-based instrumentation systems are rapidly replacing traditional fixed serial interconnected instrumentation in both commercial and military flight test environments. Modern network-based flight test systems are composed of large numbers of devices including high-speed network switches, data acquisition devices, recorders, telemetry interfaces, and wireless network transceivers, all of which must be managed in a coordinated fashion. Management of the network system includes configuring, controlling, and monitoring the health and status of the various devices. Configuration by hand is not a realistic option, so algorithms for automatic management must be implemented to make these systems economical and practical. This paper describes the issues that must be addressed for managing network-based flight test systems and describes a network management approach that was developed and employed to manage a large-scale network-based flight test system.

Background: The management accounting coordination in a horizontal network of small and medium sized companies entails numerous questions and potential complications that may vary according to the extent of cooperation chosen. Categorizing network co-operations along an imaginary market–hierarchy continuum might offer the theoretical foundation needed to further understand networks and as a consequence illuminate the link to the diverse management accounting issues.

Purpose: To analyze the management accounting systems in different forms of horizontal network co-operations.

Delimitations: It is not within the purpose of the thesis to discuss the various reasons why cooperative relationships are established in the first place, nor how they develop. Proceed of the study: A multiple case study of three Swedish networks composed of small/medium-sized firms was carried out with the help of thirteen interviews.

Conclusions: Empirical support is offered for both the business and functional network types. The model of Dahlgren et al. does not take into account that the degree of integration of the network supporting activities does not necessarily have to entail the equivalent degree of integration regarding the management accounting system. Hence, the typology of networks cannot be said to be conveniently applicable to study all horizontal networks, as the model may leave out certain significant dimensions that obstruct the understanding of a network.

The MultiProtocol Label Switching (MPLS) framework is used in many networks to provide efficient load balancing which distributes the traffic for efficient Quality of Service (QoS) provisioning in the network. If the MPLS framework is combined with Differentiated Services (DiffServ) architecture, together they can provide aggregate-based service differentiation and QoS. The combined use of DiffServ and MPLS in a network is called DiffServ-aware Traffic Engineering (DS-TE). Such DiffServ-based MPLS networks demand development of efficient methods for QoS provisioning. In this thesis, an automated manager for management of these DiffServ-based MPLS networks is proposed. This manager, called Traffic Engineering Automated Manager (TEAM), is a centralized authority for adaptively managing a DiffServ/MPLS domain and it is responsible for dynamic bandwidth and route management. TEAM is designed to provide a novel and unique architecture capable of managing large scale MPLS/DiffServ domains without any human interference. TEAM constantly monitors the network state and reconfigures the network for efficient handling of network events. Under the umbrella of TEAM, new schemes for Label Switched Path (LSP) setup/teardown, traffic routing, and network measurement are proposed and evaluated through simulations. Also, extensions to include Generalized MPLS (GMPLS) networks and inter-domain management are proposed.

The connection of Distributed Generators (DGs) to a distribution network causes technical concerns for Distribution Network Operators (DNOs) which include power flow management, loss increase and voltage management problems. An Active Network Management System can provide monitoring and control of the distribution network as well as providing the infrastructure and technology for full integration of DGs into the distribution network. The Optimal Power Flow (OPF) method is a valuable tool in providing optimal control solutions for active network management system applications. The research presented here has concentrated on the development of a multi-objective OPF to provide power flow management, voltage control solutions and network optimisation strategies. The OPF has been shown to provide accurate solutions for variety of network topologies. It is possible to apply time-series of load and generation data to the OPF in a loop, generating optimal network solutions to maintain the network within thermal and voltage limits. The OPF incorporates not only the DG real power output maximisation, but also network loss minimisation as well as minimising the dispatch of DG reactive power. This investigation uses a direct Interior Point (IP) method as the solution methodology which is speed efficient and converges in polynomial time. Each objective function has been assigned a weighting factor, making it possible to favour one objective function and ignore the others. Contributions to enhance the performance of the IP OPF algorithm include a new generic barrier parameter formulation and a new swing bus formulation to model energy export/import in the main optimisation routine. A Terminal Voltage Regulator Mode (TVRM) and Power Factor Regulation Mode (PFRM) for DG were incorporated in the main optimisation routine. The main motivation is to compare these two decentralised DG control methods in terms of the achieving the maximum DG real power generation. The DG operation methods of TVRM and PFRM are compared with the optimisation results obtained from centralised dispatch in terms of the DG capacity achieved as it produces the optimum overall network solution. A suitable value of the droop and local voltage regulator dead-bands were determined for particular DGs. Furthermore, the effect of these decentralised DG control methods on distribution network losses are considered in a measure to assess the financial implications from a DNO's perspective.

This thesis considers the role of mathematical programming in asset management. Large, extensive distribution networks are the focus of the work. In particular, we look at how to determine the optimal policy for project release. Projects relating to the replacement of existing assets and network re-design may be prioritized, given capital rationing and/or performance improvement requirements in a regulated economic environment. We consider the role of two approaches to modelling under uncertainty in determining an optimal policy for project release in network asset management. These are Monte Carlo simulation and fuzzy linear programming. We focus on the maintenance and replacement issues of a large distribution network (network structured system) and consider the application of these modelling approaches to electricity distribution networks. The electricity companies who own the UK electricity distribution networks are under pressure to provide a high quality supply to customers at a minimum cost. For this particular replacement problem, a zero-one integer linear programming model is proposed for selecting an optimal project portfolio, based on the objectives and constraints of the network owner. The modelling approach described in this doctoral study would extend to the financial investment appraisal of capital projects to a broad range of manufacturing and energy-related industries such as power generation, refining in terms of environment issues and water supply. This thesis presents mathematical programming models, using case studies to illustrate some of the appropriate techniques for developing such models. These case study models consider uncertainty and use Monte Carlo simulation to generate more representative results. The models demonstrate the usefulness of Monte Carlo simulation from which we can make recommendations about this and alternative approaches.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 56).
This thesis analyzes scalable information-sharing network management. It looks into one of the large problems in network management today: finding information across different network domains. Information-sharing network management is a method to solving the problem, though it is important to make it scalable. The solution proposed uses the Publish-Subscribe Internet Routing Paradigm (PSIRP) inter-domain design as the base structure. The design borrows from Border Gateway Protocol ideas and uses the Chord protocol as one of the key methods of finding information. The conclusion after analyzing the scalability of PSIRP is that its use of Chord gives it an advantage that allows a tradeoff between performance and distribution.
by Nina X. Guo
M.Eng.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, December 2004.
Thesis advisor(s): Alex Bordetsky. Includes bibliographical references (p. 85-86). Also available online.

Modern information networks are so integral to everyday business and society that even short period of downtime can adversely affect many thousands of users. Because of the inherently heterogeneous nature of network devices and protocols, these networks are typically administered using a range of command-line interface (CLI) tools and graphical user interface (GUI) tools from many different vendors. Mastering all these different tools takes time and experience and it is often hard to get an integrated, high-level view of the network. This means network administrators may inadve1iently misconfigure their systems or overlook a potential threat. To explore some of these issues, this project evaluated State Model Diagrams (SMDs) as both a network administration tool and as a way of teaching administrators about fundamental networking concepts. SMDs are an abstract modelling tool that allows experienced practitioners and novices to grasp the complexities of network administration by identifying essential networking objects, processes, and concepts without getting bogged down in too many distracting details. In 2007 and 2008, ECU post-graduate students doing networking courses were given a comprehensive demonstration of SMDs. The students then completed a questionnaire on how they thought SMDs compared to other network tools and how they thought SMDs could be practically applied. A result of twenty (48.8%) of positive responses from among 41 participating students have clearly demonstrated that SMDs were potentially useful as a NM tool for managing network systems and provided a richer conceptual understanding aligned with that of an expert. In this research study, the results showed that SMDs would help most of the participants understand and administer their networks, and a majority believed that SMDs would help reduce the fundamental complexity of their multi-tool work environment. Lastly, fu1iher research is required with a larger and more varied population but the results so far indicate that SMDs are a valuable tool for network administrators.

Network slicing has recently been proposed as one of the main enablers for 5G networks; it is bound to cope with the increasing and heterogeneous performance requirements of these systems. To "slice'' a network is to partition a shared physical network into several self-contained logical pieces (slices) that can be tailored to offer different functional or performance requirements. Moreover, a key characteristic of the slicing paradigm is to provide resource isolation as well as an efficient use of resources. In this context, a slice is envisioned as an end-to-end virtual network which permits that the infrastructure operators lease their resources to service providers (tenants) through the dynamic, and on-demand, deployment of slices. Tenants may have complete control over the slice functions and resources, and employ them to satisfy their client’s demands. Recent works on slicing for Radio Access Networks (RANs) just focus on general architectures and frameworks for the management and instantiation of network slices avoiding details on how the slices are implemented and enforced in the wireless devices. Even more, while some techniques for slice enforcement already exist, most of them concentrate on cellular technologies, ignoring WiFi networks. Despite of their growing relevance and ubiquity, there are not many works addressing the challenges that appear when trying to apply slicing techniques over WiFi networks. In this scenario, this thesis contributes to the problem of slicing WiFi networks by proposing a solution to enforce and control slices in WiFi Access Points. The focus of this work is on a particular and complex variant of network slicing called QoS Slicing, in which slices have specific performance requirements. The main thesis contributions are divided in three: (1) a detailed analysis of the network slicing problem in RANs in general and in WiFi in particular, as well as a study and definition of the QoS Slicing problem, (2) a resource allocation model and mechanism for Wifi devices, and (3) a QoS Slicing solution to enforce and control slices with performance requirements in WiFi Access Points. Given the novelty of the slicing concept and the complexity of the problem, a detailed study of the slicing problem was performed providing a comprehensive definition of the slicing concept, as well as a classification of the slicing variants. It is also introduced the two main problems of slicing wireless resources: resource allocation and isolation. In the scope of those problems, this thesis contributes with a novel approach where the resource allocation problem is divided on two sub-tasks: Dynamic Resource Allocation, and Enforcement and Control. As a previous step to the construction of a QoS Slicing solution, it is proposed a novel method of proportionally distributing resources in WiFi networks, by means of the airtime. The proposed mechanism (called ATERR) is based on considering the airtime as the wireless resource to be shared and allocated. An analytical model of the ATERR algorithm is also developed, which shed light on how such resources could be split and on the capacities and limitations of the proposal. The validity of the proposed model is assessed by means of a simulation-based evaluation on the NS-3 framework. Finally, regarding the QoS Slicing problem, it is considered two different performance requirements: a guaranteed minimum bit rate and a maximum allowable delay. The resource allocation problem to the different slices is formulated as a stochastic optimization problem, where each slice's requirement of bit rate and delay is modeled as a constraint. A solution to the aforementioned problem is devised using the Lyapunov drift optimization theory to obtain an approximate deterministic problem. With this solution, it is developed a novel queuing and scheduling algorithm which allows implementing the obtained solution in WiFi devices.
Network slicing ha estat recentment proposat com un dels aspectes claus de les xarxes 5G i s'espera que permeti afrontar les creixents demandes de rendiment que tindran aquests sistemes. Fer slicing consisteix en fer particions d'una xarxa física compartida en diverses parts (slices) lògiques autocontenidas que poden ser adaptades per oferir diferents requeriments funcionals o de rendiment. Més encara, una característica clau del paradigma de slicing és el de proveir aïllament dels recursos així com permetre un ús eficient dels mateixos. En aquest context, una slice es pot considerar com una xarxa virtual d'extrem a extrem que permet als operadors d'infraestructura arrendar els seus recursos a proveïdors de servei (arrendatari) mitjançant el desplegament dinàmic i sota demanda de slices. Els arrendataris poden tenir control complet sobre els recursos i funcions de la slice i utilitzar-los per satisfer les demandes dels seus clients. Treballs recents sobre slicing en xarxes d'accés sense fil s'han enfocat en arquitectures generals i esquemes de gestió per al desplegament de slicing. En aquest sentit, no s'ha aprofundit en detalls de com s'implementen i controlen les slices en els dispositius sense fils. A més, encara hi ha algunes tècniques per al control de slices, la majoria es concentren en tecnologies per a xarxes mòbils i no tenen en compte les xarxes WiFi malgrat la seva creixent rellevància i omnipresència. En aquest escenari, aquesta tesi contribueix al problema de slicing en xarxes WiFi proposant una solució per implementar i controlar slices en punts d'accés WiFi. El treball es concentra en slicing amb qualitat de servei (QoS Slicing), una variant complexa del problema on les slices tenen requeriments de rendiment específics. Les principals contribucions de la tesi es divideixen en tres: (1) una detallada anàlisi del problema de network slicing en xarxes d'accés sense fil i en particular en WiFi, així com un estudi i definició dels problemes de QoS Slicing, (2) un model i mecanisme per a l'assignació de recursos en dispositius WiFi, i (3) una solució per QoS Slicing que implementa i controla slices amb requeriments de rendiment en punts d'accés WiFi. Donada la novetat del concepte de slicing i la complexitat del problema, es va realitzar un estudi detallat del problema de slicing on es proveeix una definició completa del concepte de slicing. A més, s'introdueixen els dos principals problemes del slicing: l'assignació de recursos i l'aïllament. En aquest sentit, aquesta tesi contribueix amb una estratègia original on el problema d'assignació de recursos es divideix en dues tasques: l'assignació dinàmica de recursos i el control de l'assignació. Com un pas previ a la construcció d'una solució per QoS Slicing, es proposa un mètode original per a la distribució proporcional de recursos en xarxes WiFi mitjançant el control del temps de transmissió. El mecanisme proposat (anomenat ATERR) es basa en considerar el temps de transmissió com el recurs a ser compartit i assignat. També es va desenvolupar un model analític de l'algoritme ATERR del qual es poden obtenir les capacitats i limitacions del mecanisme. La validesa del model proposat és estudiada mitjançant una avaluació basada en simulacions sobre l'entorn NS-3. Finalment, pel que fa al problema de QoS Slicing, es van considerar dos requeriments diferents: una garantia de taxa de transmissió mínima i un màxim de latència permès. El problema d'assignació de recursos per a les diferents slices es va formular com un problema d'optimització estocàstica on els requeriments de cada slice es modelen com una restricció. Es va elaborar una solució al problema anterior utilitzant la teoria d'optimització de Lyapunov per obtenir un problema determinista aproximat. Amb aquesta solució, es va desenvolupar un algoritme d'assignació del temps de transmissió per a dispositius WiFi.

Network management is fundamental for assuring high quality services required by each user for the effective utilization of network resources. In this research, we propose the use of a decentralized, flexible and scalable Multi-Agent based system to monitor and manage rural broadband networks adaptively and efficiently. This mechanism is not novel as it has been used for high-speed, large-scale and distributed networks. This research investigates how software agents could collaborate in the process of managing rural broadband networks and developing an autonomous decentralized network management mechanism. In rural networks, network management is a challenging task because of lack of a reliable power supply, greater geographical distances, topographical barriers, and lack of technical support as well as computer repair facilities. This renders the network monitoring function complex and difficult. Since software agents are goal-driven, this research aims at developing a distributed management system that efficiently diagnoses errors on a given network and autonomously invokes effective changes to the network based on the goals defined on system agents. To make this possible, the Siyakhula Living Lab network was used as the research case study and existing network management system was reviewed and used as the basis for the proposed network management system. The proposed network management system uses JADE framework, Hyperic-Sigar API, Java networking programming and JESS scripting language to implement reasoning software agents. JADE and Java were used to develop the system agents with FIPA specifications. Hyperic-Sigar was used to collect the device information, Jpcap was used for collecting device network information and JESS for developing a rule engine for agents to reason about the device and network state. Even though the system is developed with Siyakhula Living Lab considerations, technically it can be used in any small-medium network because it is adaptable and scalable to various network infrastructure requirements. The proposed system consists of two types of agents, the MasterAgent and the NodeAgent. The MasterAgent resides on the device that has the agent platform and NodeAgent resides on devices connected to the network. The MasterAgent provides the network administrator with graphical and web user interfaces so that they can view network analysis and statistics. The agent platform provides agents with the executing environment and every agent, when started, is added to this platform. This system is platform independent as it has been tested on Linux, Mac and Windows platforms. The implemented system has been found to provide a suitable network management function to rural broadband networks that is: scalable in that more node agents can be added to the system to accommodate more devices in the network; autonomous in the ability to reason and execute actions based on the defined rules; fault-tolerant through being designed as a decentralized platform thereby reducing the Single Point of Failure (SPOF) in the system.

Includes bibliographical references.
The author proposes a hybrid network/host interworking scheme to allow the MN to transition smoothly between different access networks supporting two distinct mobility approaches.

Thesis (M.S. in Computer Science and M.S. in Information Technology Management)--Naval Postgraduate School, September 2002.
Thesis advisor(s): Cynthia E. Irvine, Timothy E. Levin. Includes bibliographical references (p. 71-72). Also available online.

The explosive growth in worldwide communication via the Internet has increased the reliance oforganizations and individuals on the electronically transmitted information, which consequentlycreated rising demands to protect data from information leakage, corruption or alteration duringtransmission. Various security service requirements are demanded among different applications andcustomers with consideration of respective data sensitivity level, performance requirement andmonetary investment. It becomes important to provide end-to-end security service commitment tosatisfy the diverse customers needs. We expect the Quality of Protection (QoP) to fulfill end-to-endsecurity service commitment to be integrated within the emerging QoS networks to support secure QoSInternet service. For clarity, we call both of QoP and QoS ?Quality of Network Services? (QoNS).The security issues surrounding the QoNS (QoP and QoS) provisioning have been studied in my PhDresearch. The thesis is composed of two main parts, i.e. QoP security and QoS security. First, thepolicy issues of QoP security service are analyzed and automatic policy generation algorithms arepresented. Furthermore, a signaling protocol is designed to provide end-to-end security service forQoP. The protocol is designed to be secure to protect messages against possible forgery andmodification attacks. Second, the threats to the QoS signaling protocol RSVP are analyzed andcountermeasures are proposed. In addition, the intrusion detection methods for QoS attacks directly ondata flow are investigated and experimented.

Approved for public release; distribution is unlimited.
Mobile Ad Hoc Networking (MANET) technologies are highly desirable in tactical environments because they are able to communicate with neighboring devices over one or more hops in order to extend connectivity to areas where a fixed infrastructure is not available or is not possible. There are many factors which can influence the performance and reliability of a MANET. Communications links within the MANET are continuously fluctuating due to device location, power, or environmental factors. Devices within the MANET can enter the network and then disappear due to the devices losing connectivity because of their physical location relative to other nodes within the network. A network management system (NMS) that can provide for MANET administration in both simulation-based and real-time operational environments provides additional value for this network. The objectives for this network management system is to allow users to predict, monitor, and control network behavior, this specifically includes viewing and remotely managing variables such as node status, node location, attached equipment, channel selection, frequencies, error rates, and network utilization.

Thesis (MTech(Electrical Engineering)--Cape Peninsula University of Technology, 2012
Wireless sensor networks (WSNs) have long been separate networks using non-standard, custom and application speci c protocols. The arrival of IPv6 over Low power Wireless Personal Area Network (6LoWPAN) changes this, with the Internet Protocol (IP) being the common protocol between conventional IP networks and Wireless Sensor Networks. Through the use of 6LoWPAN implementations like blip, developed for the WSN operating system TinyOS, it is possible to make use of the advantages that the common IP layer brings. This includes the reuse of techniques, protocols and software that are already developed for, and in use on, conventional IP networks.One such protocol is the Simple Network Management Protocol (SNMP), which is a User Datagram Protocol (UDP) based protocol used for monitoring and management in conventional IP networks. This work describes an implementation of the rst version of the SNMP in nesC for TinyOS using the blip 6LoWPAN implementation. The SNMPv1 software agent imple- mentation requires no modi cation to the 6LoWPAN stack and responds to standard SNMP get and set requests. This means that standard SNMP software can be used to communicate with the implemented SNMP software agent. Therefore network monitoring packages like Nagios and Cacti can be used to monitor wireless sensor networks.Relevant background information is discussed, ranging from the division of commu- nication between network nodes into logical layers, to similar work done and the Simple Network Management Protocol. The implementation of the SNMP software agent is ex- amined, along with the anatomy of an SNMP GetRequest message in aid of understanding the structure of SNMP messages.The SNMP agent implementation is then tested against network monitoring tools like Cacti, Nagios and applications from the Net-SNMP package. The results verify the correct operation of the SNMP software agent and demonstrate the added functionality that the software agent provides.

NFV is an emerging network architecture to increase flexibility and agility within operator's networks by placing virtualized services on demand in Cloud data centers (CDCs). One of the main challenges for the NFV environment is how to efficiently allocate Virtual Network Functions (VNFs) to Virtual Machines (VMs) and how to minimize network latency in the rapidly changing network environments. Although a significant amount of work/research has been already conducted for the generic VNF placement problem and VM migration for efficient resource management in CDCs, network latency among various network components and VNF migration problem have not been comprehensively considered yet to the best of our knowledge. Firstly, to address VNF placement problem, we design a more comprehensive model based on real measurements to capture network latency among VNFs with more granularity to optimize placement of VNFs in CDCs. We consider resource demand of VNFs, resource capacity of VMs and network latency among various network components. Our objectives are to minimize both network latency and lead time (the time to find a VM to host a VNF). Experimental results are promising and indicate that our approach, namely VNF Low-Latency Placement (VNF-LLP), can reduce network latency by up to 64.24% compared with two generic algorithms. Furthermore, it has a lower lead time as compared with the VNF Best-Fit Placement algorithm. Secondly, to address VNF migration problem, we i) formulate the VNF migration problem and ii) develop a novel VNF migration algorithm called VNF Real-time Migration (VNF-RM) for lower network latency in dynamically changing resource availability. As a result of experiments, the effectiveness of our algorithm is demonstrated by reducing network latency by up to 59.45% after latency-aware VNF migrations.

The description of a Network Management Package (NMP) for Packet Communications Units (PCUs) in a Local Area Network (LAN) is presented. The LAN consists of a Sytek LocalNet 20, a Sytek System 2000, a Sytek System 6000, and a Concord Data Systems Token/Net. The NMP accesses and controls the local and remote PCUs on the networks. The communication interface software module is responsible for opening and closing the session between the PC and PCU ports. The NMP supports a set of operations used by a network manager to control and manage the network PCUs. The user uses the NMP to integrate each PCU and check and set its attributes. The NMP was developed to run in the Computer Engineering Research Laboratory and in the University of Arizona broadband cable plant. The NMP allows different PCUs (local or remote) to check and modify PCU's attributes while users work on their own PCUs. (Abstract shortened with permission of author.)