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Access network reliability modelling using object orientation and fuzzy logicBirchenall, Colin Francis January 2000 (has links)
No description available.
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BROADBAND INVESTMENT AND REGULATIONJIANG, YANYAN 10 March 2010 (has links)
La tesi è strutturata in 3 capitoli e analizza gli investimenti e la regolamentazione nel broadband market".
Il primo capitolo analizza la letteratura teorica ed empirica sul rapporto tra gli investimenti e la regolamentazione nel settore delle telecomunicazioni. Il secondo capitolo fornisce un'analisi teorica sullo "stepping-stone theory". La terza parte fornisce un'analisi sull'impatto dei diversi regimi normativi per la costruzione della Next Generation Networks. / This dissertation is composed of three papers and discusses the issue of investment and regulation in broadband market.
The first paper reviews the specialized but growing branch of the literature. It surveys the relevant theoretical and empirical literature on the relationship between regulation, at both retail and wholesale level, and investment in telecoms infrastructures. Theoretical analyses state that with respect to retail (incentive) regulation, the firm‘s incentive to invest is related to the level of price cap. As for access regulation, mandatory unbundling can possibly discourage firms‘ incentive to invest, but this is not the case for all circumstances because some studies have displayed an opposite (positive) effect on investment. The influence of regulators‘ limited ability to make credible commitment ex ante is not negligible either. Evidence in empirical findings exhibits a certain disunity. The majority concludes that local loop unbundling based on forward-looking cost methodology discourages both ILECs and CLECs from investing in networks, so that the stepping-stone theory is possibly not supported by the data; other findings support the non-negative effect of access regulation on investment.
The second paper provides theoretical analysis on the stepping-stone theory. We dynamically model the competition between a vertically-integrated incumbent firm and a facilities-free new entrant in broadband market, where both firms are entitled with investment options: not only can the incumbent decide how much to spend in upgrading its existing network, but also the entrant can choose whether and when to invest on the construction of its own network. The analysis is conducted under three different kinds of competition: pure services-based, pure facilities-based and mixed competition. We find that the entrant's ability to provide value-added services affects the incumbent's investment choice. Our simulation results support the stepping-stone theory that access regulation provides an impetus for the entrant to invest in their own facilities after entering the market based on leased lines. It is also socially desirable because both the overall welfare and the consumer surplus are maximized in a regulated market under mixed competition.
The third paper studies impacts of different regulatory regimes on the construction of Next Generation Networks (NGNs). We model the competition between a vertically-integrated incumbent firm and a facilities-free entrant firm in broadband market, where the incumbent has an investment option to upgrade its current network to the NGN. In order to analyze how policy settings affect the incumbent firm‘s investment choice, three kinds of regulatory regimes are discussed: no regulation, partial regulation (only the traditional network is regulated and the NGN is unregulated) and full regulation (both the traditional network and the NGN are regulated). We find that not only the entrant‘s ability to provide value-added services, but also the substitution factor that indexes the decrease in consumers‘ willingness to pay for the traditional service once the investment occurs, affect the incumbent‘s investment choice. Moreover, the comparison of results under different regimes shows that the incumbent invests the most under partial regulation, which sheds some light on impelling the deployment of Next Generation Networks.
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Regulace přístupových sítí elektronických komunikací v ČR a její vliv na rozvoj odvětví / Regulation of access electronic communications networks in the Czech Republic and its impact on the industry developmentSekaninová, Renáta January 2008 (has links)
The thesis deals with the asymmetric ex-ante regulation applied in the electronic com-munications sector in order to strengthen the competitive ability of alternative operators at the expense of incumbent operators' competitiveness with the aim of reinforcing effective competition in the electronic communications markets. The author is concer-ned with the regulatory instrument entailing an obligation on the fixed incumbent opera-tors to open their access networks to other operators. This is called Local Loop Unbund-ling (LLU). The thesis assesses regulatory impacts on the Czech electronic communi-cations market. The market development in the Czech Republic certified the negative regulatory effect on the fixed alternative operators'motivation to build their own access infrastructure. The author tries to find the dismotivating elements of the present-day LLU regulatory form by means of the Czech LLU market analysis. The author adverts to the undesirable regulatory effect on both alternative operators'and incumbent opera-tors'investment motivation. The thesis offers reasoning why the pro-competitive regula-tory policy (inhibiting investments necessary for the sector development) is not appro-priate.
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A hybrid frequency modulated CDMA communication systemLi, Tianshi 18 November 2008 (has links)
The wireless communications industry has experienced tremendous growth worldwide in the past decade. Numerous cellular communication systems have been developed to meet this need. In North America, AMPS, IS-54, 1S-95 and GSM are the most popular cellular systems ruling the market. In developing nations, Wireless Local Loop (WLL) services will be in great demand in the coming years. While some service providers may adapt existing cellular standards to this application, WLL does not require the support for mobility which is available in a full cellular system. As a result, substantial cost savings may be obtained through dedicated WLL implementations.
In this thesis, a new wireless communication system is investigated. The system combines the low cost and flexibility of analog frequency modulation with the capacity and multipath advantages of a Code Division Multiple Access (CDMA) system. This system aims to provide WLL telephone services at low cost, with wireline grade voice quality, fast infrastructure deployment and ease of planning.
In this thesis, a theory for FM/CDMA system performance is established. Closed form analytical expressions of signal to multiple. access interference ratio are obtained using both upper bounds and lower bounds. The hybrid system is also optimized for the optimum combination of modulation index and processing gain. In addition, a software test-bed is developed to model different FM demodulation schemes, evaluate the tradeoff of FM modulation index versus CDMA processing gain and the system robustness, compare the forward link and the reverse link system performance and investigate the effect of power control schemes. / Master of Science
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Sécurité des équipements grand public connectés à Internet : évaluation des liens de communication / Security of consumer devices connected to the Internet : communication channel evaluationBachy, Yann 09 July 2015 (has links)
Aujourd’hui, les équipements intégrant du logiciel et connectés à Internet sont de plus en plus nombreux et variés. Avec l’arrivée de l’“Internet des objets” et la tendance au “tout connecté”, de nombreux équipements de notre quotidien bénéficient maintenant d’une connexion à Internet : les Smart-TVs, les lecteurs DVD, les systèmes d’alarmes, les systèmes domotiques, jusqu’aux équipements facilitant l’hospitalisation à domicile de patients par exemple. Ces évolutions technologiques s’accompagnent malheureusement de problèmes de sécurité. L’utilisation massive du réseau Internet a facilité la propagation de logiciels malveillants, qui peuvent aujourd’hui cibler tout type d’équipement informatique et notamment les équipements connectés. Alors qu’il existe déjà des normes permettant d’évaluer la sécurité d’équipements informatiques industriels, leur application aux équipements grand public est encore limitée. La présence et la criticité des vulnérabilités qui peuvent affecter ces équipements sont encore mal connues car elles n’ont pas fait l’objet d’études approfondies. C’est précisément l’objectif de cette thèse, qui propose une méthode permettant de mener une analyse de vulnérabilités des équipements grand public connectés à Internet. Cette méthode est constituée de deux grandes phases : une phase d’analyse des risques suivie d’unephase d’expérimentations. L’analyse de sécurité d’un équipement, quelle qu’elle soit, nécessite une bonne connaissance de l’environnement de celui-ci. Afin de guider l’évaluateur dans cette tâche, nous proposons, dans une première phase, de nous fonder sur des méthodes d’analyse des risques existantes. Ces méthodes sont aujourd’hui bien éprouvées et permettent à l’évaluateur d’obtenir une vue globale des risques encourus par l’utilisation de l’équipement étudié. Ensuite, lors de la seconde phase de l’étude, l’évaluateur se concentre sur les risques les plus importants afin de montrer la faisabilité technique des scénarios menant aux risques considérés, à l’aide d’expérimentations. Étant donné le grand nombre et la diversité des connexions présentes sur les équipements connectés, il est important de mettre l’accent sur les scénarios d’attaque qui peuvent s’avérer riches, même si ces scénarios ont pour origine une vulnérabilité locale simple. Pour cette seconde phase, une méthode d’expérimentation est donc proposée pour étudier ces scénarios d’attaque, qui, de plus, ciblent des équipementsdont les spécifications ne sont pas forcément disponibles. Afin d’illustrer la méthode globale, cette thèse se fonde sur deux cas d’étude : les box ADSL et les téléviseurs connectés. Ces études ont été menées sur un panel d’équipements provenant des principaux fournisseurs d’accès à Internet et des principaux fabricants de téléviseurs, ce qui nous a permis de comparer les différents équipements présents sur le marché. Les vulnérabilités mises en évidence concernent en particulier les liens de communication (boucle locale pour les Box ADSL, interface DVB-T pour les Smarts TVs) reliant les équipements à leurs fournisseurs de service (FAI pour les Box ADSL, TV et VoD pour les Smart TVs). Ces liens de communication sont habituellement considérés de confiance et ne sont à notre connaissance pas ou peu étudiés jusqu’à présent. Cette thèse contribue ainsi à l’analyse de sécurité sur ces liens particuliers des équipements connectés et met en lumière des chemins d’attaque originaux.Enfin, cette thèse se termine par la présentation des différents mécanismes de protection existants afin d’empêcher l’introduction ou l’exploitation des failles de sécurité identifiées. / Today, equipment embedding software and an Internet connection are more and more numerous and various. With the emergence of “the internet of things” and the trend to interconnect everything, many equipment used in our every day life are now connected to the internet: Smart-Tvs, DVD players, alarm and home automation systems, and even health assistance home devices, for example. Unfortunately, these technological evolutions also introduce new security threats. The massive use of internet facilitates the propagation of malware, capable of targeting any computer device, and more specifically any internet connected device. Although several methods allowing security analysis of industrial systems exist, their application to home devices is still limited. The existence and the criticality of potential vulnerabilities in these devices are not well-known, because they have not been thoroughly studied. This is precisely the objective of this thesis, which presents a method allowing to carry out a vulnerability analysis of internet connected home devices. This method is composed of two main phases: a risk analysis phasefollowed by an experimental phase. The security analysis of any type of equipement, requires a good knowledge ofits environment. In order to guide the evaluator in this task, we propose, as a first step, to rely on existing risk analysis methods. These methods are now mature, and allow the evaluator to obtain a global view of the risks incurred by the usage of anequipment. Then, during the second step of our method, the evaluator concentrates on the most important risks in order to demonstrate the technical feasibility of the scenarios leading to the considered risks, by carrying out several experiments.Considering the large amount and the diversity of I/Os on connected devices, it is important to focus on specifically rich attack scenarios, possibly depending on a simple local vulnerability. For this second step, an experimental method is proposedin order to study these attack scenarios, which, moreover, target equipement whose specifications are not necessarily available.In order to illustrate the entire method, this thesis presents two case studies: Integrated Access Devices and Smart-Tvs. These studies are carried out on a panel of devices from major internet service providers and TV manufacturers, allowing us to compare several devices available on the market. The vulnerabilities pointed out, mainly concern the communication means (local loop for the IAD, DVB-T interface for the smart-TVs) connecting these devices to their service providers (ISP for the IAD, TV and VoD for the smart-TVs). These communication links are usually considered safe, and have been, to our knowledge, seldom explored. Thisthesis thereby contributes to the security analysis of these particular communication means for connected devices and points out some original attack paths. Finally, this thesis ends by presenting different existing security mechanisms that can be used to avoid exploitation of the identified weaknesses
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Determination of ADSL capacity in a generic exchange environmentVan Wyk, J.H. (Jacques Herman) 20 December 2006 (has links)
Please read the abstract in the front matter this document / Dissertation (M Eng (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted
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Local loop unbundling implementation model in South Africa's information communication and technology sector / T.J. ModiseModise, Tumelo Jacob January 2009 (has links)
The cellular operators (Vodacom, Cell C, MTN and now Virgin Mobile) market has over 39-million
mobile phone subscribers and the fixed operator (Telkom) has almost 5 million subscribers [13].
Although the telecommunication sector has been experiencing this significant growth (in terms of
numbers), monopolisation of the local loop by Telkom has also resulted in communication prices that
are not affordable to the majority of South Africans. The government of South Africa has identified
cost of telecommunication services as one of the key initiatives that must be addressed to improve
equal levels of access to ICT services in general.
Local Loop Unbundling (or LLU for short) has been identified by the South African government as a
tool that will minimise control that Telkom has over the copper cable connecting exchanges to
customers whilst at the same time driving down the costs of Telecommunication in the country.
Although some countries have successfully implemented local loop unbundling, some have not been
so successful [3]. This dissertation proposes ICT Systems and processes South Africa needs to have
in place to become one of the few success stories. The proposed model was validated against the
different models adopted in countries like France, Portugal, United Kingdom and Austria.
This dissertation develops a model for implementing local loop unbundling in the South African ICT
sector. Local loop unbundling (in short LLU) has been successfully (and unsuccessfully) implemented
in a number of countries around the world [3]. The model being proposed recommends best practices
to be followed by all stakeholders to ensure successful deployment of local loop unbundling. The
research takes a closer look at the South African ICT sector and makes recommendations on
processes and systems that are necessary to ensure successful deployment of local loop unbundling
in South Africa. The dissertation is written from the view of Telkom (The incumbent Operator),
competitors (existing ones and new entrants) and the Regulator (ICASA) and focuses mainly on:
Technical Processes and Challenges that must be addressed
Regulatory Process and Challenges that must be addressed
Economic Challenges that must be addressed
Comparison to international ICT Markets and
Recommendations and Conclusions.
The dissertation also covers the development of the Local loop unbundling model charter, Local Loop
Management website and processes (Annexure A and B) developed (using HTML) used for the
management of the unbundling process.
Keywords:
o Local loop o Caged Co-location / Thesis (M.Ing. (Development and Management Engineering)--North-West University, Potchefstroom Campus, 2009.
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Local loop unbundling implementation model in South Africa's information communication and technology sector / T.J. ModiseModise, Tumelo Jacob January 2009 (has links)
The cellular operators (Vodacom, Cell C, MTN and now Virgin Mobile) market has over 39-million
mobile phone subscribers and the fixed operator (Telkom) has almost 5 million subscribers [13].
Although the telecommunication sector has been experiencing this significant growth (in terms of
numbers), monopolisation of the local loop by Telkom has also resulted in communication prices that
are not affordable to the majority of South Africans. The government of South Africa has identified
cost of telecommunication services as one of the key initiatives that must be addressed to improve
equal levels of access to ICT services in general.
Local Loop Unbundling (or LLU for short) has been identified by the South African government as a
tool that will minimise control that Telkom has over the copper cable connecting exchanges to
customers whilst at the same time driving down the costs of Telecommunication in the country.
Although some countries have successfully implemented local loop unbundling, some have not been
so successful [3]. This dissertation proposes ICT Systems and processes South Africa needs to have
in place to become one of the few success stories. The proposed model was validated against the
different models adopted in countries like France, Portugal, United Kingdom and Austria.
This dissertation develops a model for implementing local loop unbundling in the South African ICT
sector. Local loop unbundling (in short LLU) has been successfully (and unsuccessfully) implemented
in a number of countries around the world [3]. The model being proposed recommends best practices
to be followed by all stakeholders to ensure successful deployment of local loop unbundling. The
research takes a closer look at the South African ICT sector and makes recommendations on
processes and systems that are necessary to ensure successful deployment of local loop unbundling
in South Africa. The dissertation is written from the view of Telkom (The incumbent Operator),
competitors (existing ones and new entrants) and the Regulator (ICASA) and focuses mainly on:
Technical Processes and Challenges that must be addressed
Regulatory Process and Challenges that must be addressed
Economic Challenges that must be addressed
Comparison to international ICT Markets and
Recommendations and Conclusions.
The dissertation also covers the development of the Local loop unbundling model charter, Local Loop
Management website and processes (Annexure A and B) developed (using HTML) used for the
management of the unbundling process.
Keywords:
o Local loop o Caged Co-location / Thesis (M.Ing. (Development and Management Engineering)--North-West University, Potchefstroom Campus, 2009.
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