Le développement des modes alternatifs de règlement des différends dans les contrats administratifs est une nécessité. En effet, l’encombrement des juridictions administratives, conjugué au besoin d’un règlement des différends plus consensuel et apaisé, plaide en faveur de l’émergence d’une justice alternative. Néanmoins, l’ordre public encadrant l’activité des personnes publiques, et protégé par des normes impératives, impose que le développement des modes alternatifs soit régulé. À ce titre, l’étude du droit positif démontre que ce phénomène n’est pas inconnu dans le règlement des différends intéressant les contrats administratifs. Par exemple, les parties à un différend peuvent déjà librement recourir aux modes amiables (médiation, conciliation ou transaction), et quelques dérogations au principe d’interdiction faite aux personnes publiques de recourir à l’arbitrage sont prévues. Cela étant, les lacunes et les défaillances du régime actuel des modes alternatifs dans les contrats administratifs (absence de véritable statut du médiateur, défaut d’encadrement de la conciliation inter partes, complexité de la notion de concessions réciproques ou, encore, difficulté pour le juge administratif d’asseoir sa compétence en matière d’arbitrage international...) complexifient leur compréhension et leur mise en œuvre et risquent, par suite, d’accroître les violations de l’ordre public. Il est donc nécessaire de proposer un régime pérenne des modes alternatifs permettant d’assurer, d’une part, la protection des normes impératives du droit public et, d’autre part, la liberté des parties dans le choix et la conduite d’une justice alternative. Pour cela, leur futur régime devra autoriser l’arbitrage dans les contrats administratifs et le doter de garanties procédurales prenant en compte sa nature spécifique mais, aussi, certaines caractéristiques inhérentes aux personnes publiques et au droit administratif. De même, les procédures de médiation et de conciliation devront être améliorées afin d’assurer aux parties, un encadrement souple et favorable à la conclusion de transactions équilibrées et sécurisées. Enfin, ce régime devra définitivement consacrer le rôle du juge administratif. À cet effet, ce dernier pourra être amené à assister les parties dans la mise en œuvre des modes alternatifs (création d’un juge administratif d’appui dans l’arbitrage, combinaison des procédures de référé avec les modes amiables...). Le juge administratif devra être aussi chargé du contrôle de conformité de la solution alternative à l’ordre public. Cette attribution de compétence, qui résonne de plus fort en matière d’arbitrage international, est indispensable à la protection de l’intérêt public. Ce n’est qu’à ces conditions, que le développement des modes alternatifs de règlement des différends pourra prendre toute sa place dans les contrats administratifs. / The development of alternative dispute resolution in administrative contracts is a necessity. Indeed, the congestion of the administrative courts, combined with the need for a more consensual and calm settlement of disputes, pleads in favour of the emergence of an alternative justice. Nevertheless, the public order governing the activities of public bodies, and protected by imperative norms, requires that the development of alternative methods be regulated. As such, the study of positive law shows that this phenomenon is not unknown in the settlement of disputes concerning administrative contracts. For instance, the parties to a dispute can already freely resort to amicable methods (mediation, conciliation or settlement agreement), and some exceptions to the principle prohibiting public bodies from resorting to arbitration are provided for. However, the voids and shortcomings of the current system of alternative dispute resolution in administrative contracts (lack of proper status of the mediator, paucity of framework for inter partes conciliation, complexity of the concept of reciprocal concessions or, difficulty for the administrative judge to assert its competence in international arbitration...) make its understanding and implementation more complex and more prone to increasing public order violations. It is therefore necessary to propose a sustainable regime of alternative methods to ensure, on the one hand, the protection of peremptory norms of public law and, on the other hand, the freedom of the parties in the choice and conduct of an alternative justice. For that purpose, the future regime will have to authorize arbitration in administrative contracts and endow it with procedural guarantees taking into account its specific nature but also certain characteristics inherent in public entities and administrative law. Furthermore, the mediation and conciliation procedures will have to be improved in order to provide the parties with a flexible framework conducive to the conclusion of balanced and secure settlement agreements. Finally, this regime must definitively establish the role of the administrative judge. To this end, that judge may be called upon to assist the parties in the implementation of alternative methods (creation of an administrative support judge in arbitration, combination of interim reliefs with amicable procedures...). The administrative judge must also be responsible for checking the compliance of the alternative solution to the public order. This attribution of jurisdiction, which is resonates all the more in international arbitration, is fundamental for the protection of the public interest. It is only under these conditions that the development of alternative dispute resolution mechanisms can take its place in administrative contracts.

Consumers of digital contents are empowered with numerous technologies allowing them to produce perfect copies of these contents and distribute them around the world with little or no cost. To prevent illegal copying and distribution, a technology called Digital Rights Management (DRM) is developed. With this technology, consumers are allowed to access digital contents only if they have purchased the corresponding licenses from license issuers. The problem, however, is that those consumers are not allowed to resell their own licenses- a restriction that goes against the first-sale doctrine. Enabling a consumer to buy a digital license directly from another consumer and allowing the two consumers to fairly exchange the license for a payment are still an open issue in DRM research area. This thesis investigates existing security solutions for achieving digital license reselling and analyses their strengths and weaknesses. The thesis then proposes a novel Reselling Deal Signing (RDS) protocol to achieve fairness in a license reselling. The idea of the protocol is to integrate the features of the concurrent signature scheme with functionalities of a License Issuer (LI). The security properties of this protocol is informally analysed and then formally verified using ATL logic and the model checker MOCHA. To assess its performance, a prototype of the RDS protocol has been developed and a comparison with related protocols has been conducted. The thesis also introduces two novel digital tokens a Reselling Permission (RP) token and a Multiple Reselling Permission (MRP) token. The RP and MRP tokens are used to show whether a given license is single and multiple resalable, respectively. Moreover, the thesis proposes two novel methods supporting fair and secure digital license reselling. The first method is the Reselling Deal (RD) method which allows a license to be resold once. This method makes use of the existing distribution infrastructure, RP, License Revocation List (LRL), and three protocols: RDS protocol RD Activation (RDA) protocol, and RD Completion (RDC) protocol. The second method is a Multiple License Reselling (MLR) method enabling one license to be resold N times by N consumers. The thesis presents two variants of the MLR method: RRP-MR (Repeated RP-based Multi-Reselling) and HC-MR (Hash Chain-based Multi-Reselling). The RRP-MR method is designed such that a buyer can choose to either continue or stop a multi-reselling of a license. Like the RD method, the RRP-MR method makes use of RP, LI, LRL, and the RDS, RDA, and RDC protocols to achieve fair and secure reselling. The HC-MR method allows multiple resellings while keeping the overhead on LI at a minimum level and enable a buyer to check how many times a license can be further resold. To do so, the HC-MR utilises MRP and the hash chain cryptographic primitive along with LRL, LI and the RDS, RDA and RDC protocols. The analysis and the evaluation of these three methods have been conducted. While supporting the license reselling, the two methods are designed to prevent a reseller from (1) continuing using a resold license, (2) reselling a non-resalable license, and (3) reselling one license a unauthorised number of times. In addition, they enable content owners of resold contents to trace a buyer who has violated any of the usage rights of a license bought from a reseller. Moreover, the methods enable a buyer to verify whether a license he is about to buy is legitimate for re-sale. Furthermore, the two methods support market power where a reseller can maximise his profit and a buyer can minimise his cost in a reselling process. In comparison with related works, our solution does not make use of any trusted hardware device, thus it is more cost-effective, while satisfying the interests of both resellers and buyers, and protecting the content owner's rights.

La thèse se propose d’abord de redéfinir la notion de conversion. L’analyse du droit positif montre que la définition classique de la conversion, comme l’opération qui consiste à tirer d’un acte nul un acte nouveau valable, peut s’élargir à un double point de vue. On ne s’était occupé que de la conversion des actes juridiques ; on a découvert qu’elle peut être étendue aux actes instrumentaires. Dans le même sens, on n’avait envisagé qu’une cause de la conversion, la nullité d’un acte ; on admet aujourd’hui qu’elle pouvait opérer à la suite d’une cause survenant a posteriori, à l’instar de la caducité, la prescription, la forclusion et la résolution. La conversion peut, dès lors, être définie comme la technique qui donne effet, par la volonté de la loi ou du juge, à un acte juridique, qui n’a pu se former, à cause d’un vice originaire, ou qui n’a pu survivre, en raison d’une cause survenant a posteriori, lorsque les éléments qui demeurent correspondent à la définition d’une figure juridique nouvelle, satisfaisant l’objectif économique poursuivi par les parties.La thèse se propose également de moderniser ou de rénover le régime de la conversion. La conversion modernisée exige l’intervention active du juge pour vérifier que les conditions de la conversion sont réunies, mais aussi et surtout pour se prononcer sur son opportunité. La conversion place de la sorte le juge au rang de véritable formateur ou de « faiseur» du contrat. Les analyses doctrinales qui présentent la conversion comme reposant sur une prétendue volonté virtuelle des parties sont artificielles. Il n’y a pas cependant lieu de diaboliser l’office du juge en prétendant que la conversion est un procédé exorbitant et autoritaire. Les inquiétudes que peut faire naître l’accroissement du rôle du juge dans la conversion s’apaisent dès lors que le juge est tenu de puiser les éléments de l’acte nouveau dans l’acte initial. Elles doivent encore être tempérées par la recherche constante d’un acte nouveau qui répond au but initialement voulu par les parties.L’ambition de cette thèse était donc double : la redéfinition de la notion de conversion, d’une part et la rénovation de son régime, d’autre part. Au regard de cette analyse renouvelée, la conversion est vouée à un avenir prospère en tant que technique tendant au sauvetage des actes juridiques. / The thesis proposes to redefine the notion of conversion. The analysis of positive law shows that the classical definition of conversion, such as (like) the operation which consists in drawing from a null act a valid new act, may be extended from a double point of view. All that had been done was the conversion of legal acts; it has been discovered that it can be extended to instrumental acts. In the same sense, there had been contemplated only one cause of conversion, the nullity of an act; it is now accepted that it could operate as a result of a case arising a posteriori, like the lapse, the prescription, the foreclosure and the resolution. Conversion may, therefore, be defined as the technique which gives effect, by the will of the law or the judge, to a legal act which has not been formed because of an original defect or which Was able to survive because of a posteriori cause when the elements which remain correspond to the definition of a new legal figure satisfying the economic objective pursued by the parties.The thesis also proposes to modernize or renovate the regime of conversion. The modernized conversion requires the active intervention of the judge to verify that the conditions of the conversion are met, but also and especially to decide on its expediency. Conversion thus places the judge at the rank of true trainer or "maker" of the contract. The doctrinal analyzes which present conversion as based on an alleged virtual will of the parts are artificial. There is, however, no need to demonize the office of the judge by claiming that conversion is an exorbitant and authoritarian process. The anxiety which may arise from the increase of the role of the judge in conversion is appeased as soon as the judge is obliged to draw the elements of the new act into the original act. They have yet to be tempered by the constant search for a new act which responds to the original purpose of the parties.The ambition of this thesis was therefore twofold: the redefinition of the notion of conversion on the one hand and the regeneration of its regime on the other. In view of this renewed analysis, conversion is destined for a prosperous future as a technique for the rescue of legal acts.

The importance of cooperative relaying communication in substituting for, or complementing, multiantenna systems is described, and a brief literature review is presented. Amplify-and-forward (AF) and decode-and-forward (DF) relaying are investigated and compared for a dual-hop relay channel. The optimal strategy, source and relay optimal power allocation, and maximum cooperative gain are determined for the relay channel. It is shown that while DF relaying is preferable to AF relaying for strong source-relay links, AF relaying leads to more gain for strong source-destination or relay-destination links. Superimposed and selection AF relaying are investigated for multirelay, dual-hop relaying. Selection AF relaying is shown to be globally strictly outage suboptimal. A necessary condition for the selection AF outage optimality, and an upper bound on the probability of this optimality are obtained. A near-optimal power allocation scheme is derived for superimposed AF relaying. The maximum instantaneous rates, outage probabilities, and average capacities of multirelay, dual-hop relaying schemes are obtained for superimposed, selection, and orthogonal DF relaying, each with parallel channel cooperation (PCC) or repetition-based cooperation (RC). It is observed that the PCC over RC gain can be as much as 4 dB for the outage probabilities and 8.5 dB for the average capacities. Increasing the number of relays deteriorates the capacity performance of orthogonal relaying, but improves the performances of the other schemes. The application of rateless codes to DF relaying networks is studied by investigating three single-relay protocols, one of which is new, and three novel, low complexity multirelay protocols for dual-hop networks. The maximum rate and minimum energy per bit and per symbol are derived for the single-relay protocols under a peak power and an average power constraint. The long-term average rate and energy per bit, and relay-to-source usage ratio (RSUR), a new performance measure, are evaluated for the single-relay and multirelay protocols. The new single-relay protocol is the most energy efficient single-relay scheme in most cases. All the multirelay protocols exhibit near-optimal rate performances, but are vastly different in the RSUR. Several future research directions for fixed-rate and rateless coded cooperative systems, and frameworks for comparing these systems, are suggested. / Communications

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