Long-Term Evolution (LTE) is the fourth generation (4G) wireless communications standard and its evolution is paving the path for the fifth generation (5G) technology. LTE is also considered for supporting public safety networks, Machine-to-Machine (M2M) communications, and many other applications. Hence, it is critical to ensure that the LTE system performs effectively even in harsh signaling environments. Unfortunately, LTE is vulnerable to intentional interference at the physical layer. We define the term LTE control channel spoofing, which refers to the case when an adversary sets a fake LTE-like base station (evolved NodeB or eNodeB) that transmits a partial or full LTE downlink frame to deceive LTE devices and hinder them from attaching to a real cell. Based on analyzing the initial cell selection process in the LTE specifications, we identify three different level of LTE control channel spoofing. We have built a testbed to demonstrate the feasibility of such an attack. The experimental results show that LTE control channel spoofing can cause permanent denial of service for LTE devices during the cell selection process. We propose effective mitigation techniques to enhance the immunity of LTE systems against all the three forms of LTE control channel spoofing, and ensure that it is secure and available when and where needed. Moreover, the commercial success of LTE and the resulting growth in mobile data demand have motivated cellular network operators to strive for new innovations. LTE-Unlicensed has been recently proposed to allow cellular network operators to offload some of their data traffic by accessing the unlicensed 5 GHz frequency band. There are three variants of LTE-Unlicensed that have been proposed in the industry. These variants differ in their operational features, but they enhance the capacity of LTE and represent a big milestone in its evolution toward 5G. However, LTE-Unlicensed faces several challenges when operating in the 5 GHz bands, as this spectrum is mainly occupied by Wi-Fi and by various radar systems. Therefore, we analyze the algorithms proposed in the industry for the LTE-Unlicensed and Wi-Fi coexistence, and we develop a new spectrum sharing technique for the coexistence between LTE-Unlicensed and radar systems. In order to analyze LTE-Unlicensed and Wi-Fi coexistence, we first explain the technical details of each of the three variants of LTE-Unlicensed, and we provide a comparative analysis of them in terms of their operational features. Then we develop an unbiased and objective evaluation of their proposed coexistence mechanisms with Wi-Fi systems, and numerically compare their performance. In order to emphasize the need for developing a new spectrum sharing technique for the coexistence between LTE-Unlicensed and radar systems, we first present the different regulatory requirements for the 5 GHz unlicensed bands in several world regions, and we perform a comprehensive survey on the different radar types within the 5 GHz sub-bands. Then we develop a novel spectrum sharing technique based on chance-constrained stochastic optimization to allow the LTE-Unlicensed eNodeB to share the spectrum efficiently with a radar system. The optimization problem is formulated to guarantee the minimum performance criteria for the radar operation, and at the same time allows the LTE-Unlicensed eNodeB to control its transmit power to maximize the performance for the serving LTE-Unlicensed device. A mathematical model is used to transform the stochastic optimization problem into a deterministic one, and an exhaustive search is used to solve the resulting optimization problem. Due to the power control mechanism resulting from the proposed algorithm, numerical results show a significant reduction in the protection distance required between the radar and the LTE-Unlicensed network for the two to coexist, as the proposed algorithm can allow the two systems to operate effectively with a protection distance of only 3.95% of the one imposed by the regulations.

Common control channels in cognitive radio (CR) ad hoc networks are spectrum resources temporarily allocated and commonly available to CR users for control message exchange. With no presumably available network infrastructure, CR users rely on cooperation to perform spectrum management functions. One the one hand, CR users need to cooperate to establish common control channels, but on the other hand, they need to have common control channels to facilitate such cooperation. This control channel problem is further complicated by primary user (PU) activities, channel impairments, and intelligent attackers. Therefore, how to reliably and securely establish control links in CR ad hoc networks is a challenging problem. In this work, a framework for control channel design and analysis is proposed to address control channel reliability and security challenges for seamless communication and spectral efficiency in CR ad hoc networks. The framework tackles the problem from three perspectives: (i) responsiveness to PU activities: an efficient recovery control channel method is devised to efficiently establish control links and extend control channel coverage upon PU's return while mitigating the interference with PUs, (ii) robustness to channel impairments: a reinforcement learning-based cooperative sensing method is introduced to improve cooperative gain and mitigate cooperation overhead, and (iii) resilience to jamming attacks: a jamming-resilient control channel method is developed to combat jamming under the impacts of PU activities and spectrum sensing errors by leveraging intrusion defense strategies. This research is particularly attractive to emergency relief, public safety, military, and commercial applications where CR users are highly likely to operate in spectrum-scarce or hostile environment.

Le spectre électromagnétique est une ressource naturelle dont l'usage doit être optimisé. Un grand nombre de travaux actuels visent à améliorer l'utilisation des fréquences radio en y introduisant un degré de flexibilité rendu possible par l'agilité en forme d'onde et en fréquence permise par la radio logicielle (SDR), ainsi que par les méthodes de traitement intelligent du signal (radio cognitive). Cette thèse se place dans ce contexte. Concrètement, nous considérons le problème de partage du spectre électromagnétique entre plusieurs utilisateurs sous contraintes d'interférence mutuelle. Notre objectif est de contribuer à l'évaluation du gain du partage de cette ressource rare qu'est le spectre électromagnétique. En étudiant le canal gaussien d'interférence avec l'interférence traitée comme du bruit additif gaussien aux différents récepteurs, nous avons trouvé une description géométrique et plusieurs caractérisations de la région des débits atteignables. Ensuite, considérant un cas plus réaliste où chaque utilisateur a une certaine qualité de service, nous avons trouvé une condition nécessaire et suffisante pour permettre la communication simultanée à travers le canal gaussien d'interférence pour deux utilisateurs. Dans un scénario de partage entre un utilisateur primaire ayant une plus grande priorité d'accès au spectre et un utilisateur secondaire, après avoir déterminé des bornes minimales pour le débit du primaire en fonction du schéma d'allocation de puissance de l'utilisateur secondaire, nous avons proposé une technique originale d'allocation de puissance pour l'utilisateur secondaire accédant de manière opportuniste au spectre sous contraintes de performance de coupure pour tous les utilisateurs. En particulier, cette technique d'allocation de puissance n'utilise que l'information sur l'état des canaux des liens directs allant de l'émetteur secondaire vers les autres points du réseau. Finalement, considérant des modèles de canaux plus réalistes; après avoir montré l'existence d'une zone d'exclusion autour du récepteur primaire (zone où il n'y a aucun transmetteur secondaire, dans le but de protéger l'utilisateur primaire contre les fortes interférences), nous avons caractérisé l'effet du shadowing et du path-loss sur cette zone d'exclusion du primaire. / In this thesis, we address the problem of spectrum-sharing for wireless communication where multiple users attempt to access a common spectrum resource under mutual interference constraints. Our objective is to evaluate the gains of sharing by investigating different scenarios of spectrum access. Studying the Gaussian Interference Channel with interferences considered as noise, we found a geometrical description and several characteristics of the achievable rate region. Considering a more realistic scenario, with each user having a certain QoS, we found necessary and sufficient condition to be fulfilled for simultaneous communication over the two-user Gaussian Interference Channel. Furthermore, we proposed two lower bounds for a single-primary-user mean rate, depending on the secondary user power control scheme. Specially, we investigated an original power control policy, for a secondary user, under outage performance requirement for both users and partial knowledge of the channel state information. Finally, considering a spectrums-haring with a licensee or primary user and several secondary or cognitive users, we showed the existence of an exclusive region around the primary receiver and we characterized the effects of shadowing and path-loss on this exclusive region (or no-talk zone).

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

Abstract With the current technological advancements, stage is being set for new ultra-responsive and robust 5G-enabled applications (e.g., virtual reality, Tactile Internet,…) to deliver critical real-time traffic. The emergence of such critical applications requires new networking models that can handle more connected devices with super high reliability and low latency communications. In the view of these research challenges, this thesis aims to propose new techno-economic models and networking paradigms needed in the redesign of wireless network architectures and protocols to support the connectivity requirements by which operators and users effectively benefit from new opportunities introduced by 5G-enabled applications. In this thesis, new paradigms in wireless network access are presented and analyzed. First, dynamic network architecture (DNA) is introduced, where certain classes of wireless terminals can be turned temporarily into an access point (AP) anytime while connected to the Internet. In this concept, a framework is proposed to optimize different aspects of this architecture. Furthermore, to dynamically reconfigure an optimum topology and adjust it to the traffic variations, a new specific encoding of genetic algorithm (GA) is presented. Then, a distributed user-centric spectrum sharing is developed based on DNA networks to enable user-provided access points pervasively share the unused resources. Next, a flexible cloud-based radio access network (FRAN) is proposed to offload traffic to DNA networks in order to provide low latency communications. In the sequel of the thesis, as a new paradigm, a context-aware resource allocation scheme based on adaptive spatial beamforming and reinforcement learning is proposed. In addition, semi-cognitive radio network (SCRN) as a new spectrum sharing model is developed to improve the utility of primary and secondary owners. / Tiivistelmä Nykyaikaisilla teknologisilla edistysaskeleilla mahdollistetaan uusien 5G-pohjaisien erittäin lyhyen vasteajan ja suuren luotettavuuden sovelluksien ilmestyminen kriittisen reaaliaikaisen informaation välittämiseen (esim. taktiiliset ja virtuaalitodellisuus-sovellukset). Näiden kaltaiset sovellukset vaativat uudenlaisia verkottumismalleja, jotka kykenevät käsittelemään enemmän laitteita suurella toimintavarmuudella ja matalalla latenssilla. Tämä väitöskirja ehdottaa näiden haasteiden valossa uusia teknis-taloudellisia malleja ja verkottumisparadigmoja, joita tarvitaan verkkoarkkitehtuurien ja -protokollien uudelleensuunnittelussa tulevaisuuden sovelluksien tarpeet huomioiden, joiden kautta operaattorit ja käyttäjät voivat hyödyntää tulevien 5G-sovelluksien tuomat mahdollisuudet. Tässä väitöskirjassa esitetään ja analysoidaan uusia paradigmoja langattomaan verkkoliityntään. Ensimmäisenä esitellään dynaaminen verkkoarkkitehtuuri (dynamic network architecture, DNA), missä tietyt langattomat terminaalit voidaan väliaikaisesti muuttaa liityntäpisteiksi milloin vain internetyhteyden ollessa käytettävissä. Tämän konseptin puitteissa ehdotetaan viitekehys sen eri osa-alueiden optimoimiseksi. Tämän lisäksi esitetään uusi spesifinen geneettisen algoritmin (GA) koodaus optimaalisen topologian dynaamiseen konfigurointiin ja sen säätämiseen tietoliikenteen määrän mukaan. Tämän jälkeen esitellään kehitetty hajautettu käyttäjäkeskeinen spektrinjako, joka perustuu DNA-verkkoihin ja joka mahdollistaa käyttämättömien resurssien kokonaisvaltaisen jakamisen käyttäjien kautta. Seuraavaksi työssä ehdotetaan joustavaa pilvipalvelu-pohjaista liityntäverkkoa (flexible cloud-based radio access network, FRAN) käyttäjädatan purkamiseksi DNA-verkoille matalalatenssisen tietoliikenteen tarjoamiseksi. Edellä mainittujen menetelmien seurauksena ehdotetaan uutta paradigmaa: Kontekstiriippuvaista resurssien allokointia perustuen adaptiiviseen spatiaaliseen keilanmuodostukseen ja vahvistusoppimiseen. Näiden lisäksi kehitetään uusi spektrinjakomalli puolikognitiivisille radioverkoille (semi-cognitive radio network, SCRN) ensisijaisien ja toissijaisien käyttäjien utiliteetin parantamiseksi.

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

There has been a steady growth in the traffic generated by Mobile Network Operators (MNOs), and by 2020 it is expected to overload the existing licensed spectrum capacity and lead to the problem of scarce resources. One method to deal with this traffic overload is to access unlicensed and shared spectrum bands using an opportunistic approach. The use of Licensed Shared Access (LSA) is a novel approach for spectrum sharing between the incumbent user (i.e., the current owner of the shared spectrum) and the LSA licensee (i.e., the temporary user of frequencies, such as an MNO). The LSA system allows the incumbent users to temporarily provide the LSA licensee with access to its spectrum resources. However, licensees must adopt vertical handover and traffic steering procedures to vacate their customers from the LSA band without causing interference, whenever this is required by the incumbent. These procedures should be carried out, de facto, before the base station is turned off as a part of a rapid release of unscheduled LSA band facing evacuation scenarios. Thus, in this dissertation, a cognitive mechanism is proposed to make decisions in advance to find the best target network(s) for evacuated customers in connected mode and with active traffic per class of service. On the basis of these decisions, the vertical handover and traffic steering procedures are carried out for the best target network(s), which are selected in advance and undertaken immediately to avoid interference between the licensee and incumbent services. Furthermore, this guarantees the seamless connectivity and QoS of evacuated customers and their traffic respectively, during and after the unscheduled evacuation scenarios. A performance evaluation conducted in a simulating scenario consisting of one LTE-LSA and three Wi-Fi networks, demonstrated that the proposed solution could be completed within the time required for the unscheduled evacuation, as well as, being able to ensure the QoS and seamless connectivity of the evacuees. The total execution time obtained during the performance evaluation of the proposed solution was around 46% faster than of two related works and could thus avoid interference between the licensee and incumbent services.

Abstract During the last couple of decades a lot of research efforts have been spent on developing different spectrum sharing concepts. As the traditional regulatory methods for spectrum allocation are proving inadequate in responding to a growing need for mobile spectrum in a timely manner and finding spectrum for exclusive use is getting increasingly difficult, the political atmosphere is also becoming more and more receptive to new innovative spectrum sharing concepts that increase the efficiency of spectrum use. These concepts also provide regulatory authorities an opportunity to fundamentally change the current major operator driven mobile market and thereby to allow new players and innovative services to surface. However, there is still a gap between the work done by the research community and the work of the regulatory authorities. In this thesis, the aim is to clarify the reasons behind this gap by analysing three prevailing regulatory spectrum sharing concepts: Licensed Shared Access, the three-tier model and TV white space concept. As different stakeholders involved in spectrum sharing – the incumbent user, the entrant user and the regulatory authority – have very diverse roles in spectrum sharing, their incentives and key criteria may vary significantly. In order for a spectrum sharing concept to have a chance in a real life deployment, all these perspectives need to be carefully considered. In fact, a feasible spectrum sharing concept is a delicate balance between the viewpoints of different stakeholders, not necessarily the one offering the most efficient spectrum utilization. This thesis analyses spectrum sharing concepts from all these perspectives and as a consequence unveils the common process model for implementing a spectrum sharing concept in real life, highlighting the distinct roles of different stakeholders in its phases. / Tiivistelmä Parin viimeisen vuosikymmenen aikana tutkimusyhteisö on kehittänyt valtavasti eri käsitteitä ja tuloksia taajuuksien yhteiskäyttöön. Matkapuhelinoperaattoreiden nopeasti kasvavan tiedonsiirto- ja taajuustarpeen myötä myös poliittinen ilmapiiri on muuttunut vastaanottavaisemmiksi uusille jaetuille taajuuksienkäyttömalleille, joilla voidaan sekä lisätä taajuuksien käytön tehokkuutta että mahdollistaa uusien toimijoiden ja innovatiivisten palvelujen kehitys. Taajuuksien yhteiskäyttömalleihin liittyvä tutkimustyö ei kuitenkaan usein palvele suoraan taajuusviranomaisten tarpeita. Tämän työn tavoitteena on selvittää syitä tähän kolmen vallitsevan joustavan taajuuksienkäyttökonseptin avulla: lisensoidun taajuuksien yhteiskäyttömallin, kolmitasoisen taajuuksien yhteiskäyttömallin ja TV kaistojen yhteiskäyttömallin. Eri toimijoilla on hyvin erilaiset roolit taajuuksien yhteiskäytössä ja siksi sekä heidän kannustimensa että keskeiset kriteerit voivat olla hyvin erilaiset. Käytäntöön sopiva jaetun taajuudenkäytön malli onkin usein kompromissi eri näkemysten omaavien toimijoiden kesken, ei välttämättä taajuuksien käytöltään tehokkain vaihtoehto. Tässä työssä analysoidaan eri taajuuksien yhteiskäyttömalleja sekä eri toimijoiden näkökulmia. Analyysin tuloksena luodaan yleinen prosessimalli taajuuksien yhteiskäyttömallien toteutukselle sekä identifioidaan eri toimijoiden roolit sen eri vaiheissa.

Abstract This thesis examines radio resource management techniques for multicell multi-input single-output (MISO) downlink networks. Specifically, the thesis focuses on developing linear transmit beamforming techniques by optimizing certain quality-of-service (QoS) features, including, spectral efficiency, fairness, and throughput. The problem of weighted sum-rate-maximization (WSRMax) has been identified as a central problem to many network optimization methods, and it is known to be NP-hard. An algorithm based on a branch and bound (BB) technique which globally solves the WSRMax problem with an optimality certificate is proposed. Novel bounding techniques via conic optimization are introduced and their efficiency is illustrated by numerical simulations. The proposed BB based algorithm is not limited to WSRMax only; it can be easily extended to maximize any system performance metric that can be expressed as a Lipschitz continuous and increasing function of the signal-to-interference-plus-noise (SINR) ratio. Beamforming techniques can provide higher spectral efficiency, only when the channel state information (CSI) of users is accurately known. However, in practice the CSI is not perfect. By using an ellipsoidal uncertainty model for CSI errors, both optimal and suboptimal robust beamforming techniques for the worst-case WSRMax problem are proposed. The optimal method is based on a BB technique. The suboptimal algorithm is derived using alternating optimization and sequential convex programming. Through a numerical example it is also shown how the proposed algorithms can be applied to a scenario with statistical channel errors. Next two decentralized algorithms for multicell MISO networks are proposed. The optimization problems considered are: P1) minimization of the total transmission power subject to minimum SINR constraints of each user, and P2) SINR balancing subject to the total transmit power constraint of the base stations. Problem P1 is of great interest for obtaining a transmission strategy with minimal transmission power that can guarantee QoS for users. In a system where the power constraint is a strict system restriction, problem P2 is useful in providing fairness among the users. Decentralized algorithms for both problems are derived by using a consensus based alternating direction method of multipliers. Finally, the problem of spectrum sharing between two wireless operators in a dynamic MISO network environment is investigated. The notion of a two-person bargaining problem is used to model the spectrum sharing problem, and it is cast as a stochastic optimization. For this problem, both centralized and distributed dynamic resource allocation algorithms are proposed. The proposed distributed algorithm is more suitable for sharing the spectrum between the operators, as it requires a lower signaling overhead, compared with centralized one. Numerical results show that the proposed distributed algorithm achieves almost the same performance as the centralized one. / Tiivistelmä Tässä väitöskirjassa tarkastellaan monisoluisten laskevan siirtotien moniantennilähetystä käyttävien verkkojen radioresurssien hallintatekniikoita. Väitöskirjassa keskitytään erityisesti kehittämään lineaarisia siirron keilanmuodostustekniikoita optimoimalla tiettyjä palvelun laadun ominaisuuksia, kuten spektritehokkuutta, tasapuolisuutta ja välityskykyä. Painotetun summadatanopeuden maksimoinnin (WSRMax) ongelma on tunnistettu keskeiseksi monissa verkon optimointitavoissa ja sen tiedetään olevan NP-kova. Tässä työssä esitetään yleinen branch and bound (BB) -tekniikkaan perustuva algoritmi, joka ratkaisee WSRMax-ongelman globaalisti ja tuottaa todistuksen ratkaisun optimaalisuudesta. Samalla esitellään uusia conic-optimointia hyödyntäviä suorituskykyrajojen laskentatekniikoita, joiden tehokkuutta havainnollistetaan numeerisilla simuloinneilla. Ehdotettu BB-perusteinen algoritmi ei rajoitu pelkästään WSRMax-ongelmaan, vaan se voidaan helposti laajentaa maksimoimaan mikä tahansa järjestelmän suorituskykyarvo, joka voidaan ilmaista Lipschitz-jatkuvana ja signaali-(häiriö+kohina) -suhteen (SINR) kasvavana funktiona. Keilanmuodostustekniikat voivat tuottaa suuremman spektritehokkuuden vain, jos käyttäjien kanavien tilatiedot tiedetään tarkasti. Käytännössä kanavan tilatieto ei kuitenkaan ole täydellinen. Tässä väitöskirjassa ehdotetaan WSRMax-ongelman ääritapauksiin sekä optimaalinen että alioptimaalinen keilanmuodostustekniikka soveltaen tilatietovirheisiin ellipsoidista epävarmuusmallia. Optimaalinen tapa perustuu BB-tekniikkaan. Alioptimaalinen algoritmi johdetaan peräkkäistä konveksiohjelmointia käyttäen. Numeerisen esimerkin avulla näytetään, miten ehdotettuja algoritmeja voidaan soveltaa skenaarioon, jossa on tilastollisia kanavavirheitä. Seuraavaksi ehdotetaan kahta hajautettua algoritmia monisoluisiin moniantennilähetyksellä toimiviin verkkoihin. Tarkastelun kohteena olevat optimointiongelmat ovat: P1) lähetyksen kokonaistehon minimointi käyttäjäkohtaisten minimi-SINR-rajoitteiden mukaan ja P2) SINR:n tasapainottaminen tukiasemien kokonaislähetystehorajoitusten mukaisesti. Ongelma P1 on erittäin kiinnostava, kun pyritään kehittämään mahdollisimman pienen lähetystehon vaativa lähetysstrategia, joka pystyy takaamaan käyttäjien palvelun laadun. Ongelma P2 on hyödyllinen tiukasti tehorajoitetussa järjestelmässä, koska se tarjoaa tasapuolisuutta käyttäjien välillä. Molempien ongelmien hajautetut algoritmit johdetaan konsensusperusteisen vuorottelevan kertoimien suuntaustavan avulla. Lopuksi tarkastellaan kahden langattoman operaattorin välisen spektrinjaon ongelmaa dynaamisessa moniantennilähetystä käyttävässä verkkoympäristössä. Spektrinjako-ongelmaa mallinnetaan käyttämällä kahden osapuolen välistä neuvottelua stokastisen optimoinnin näkökulmasta. Tähän ongelmaan ehdotetaan ratkaisuksi sekä keskitettyä että hajautettua resurssien allokoinnin algoritmia. Hajautettu algoritmi sopii paremmin spektrin jakamiseen operaattorien välillä, koska se vaatii vähemmän kontrollisignalointia. Numeeriset tulokset osoittavat, että ehdotetulla hajautetulla algoritmilla saavutetaan lähes sama suorituskyky kuin keskitetyllä algoritmillakin.

Les bandes des fréquences, telles qu'elles sont aménagées aujourd'hui, sont statiquement allouées. Afin d'améliorer la productivité et l'efficacité de l'utilisation du spectre, une nouvelle approche a été proposée : le "partage dynamique du spectre". Les régulateurs, les industriels et les scientifiques ont examiné le partage des bandes fédérales entre les détenteurs de licences (utilisateurs primaires) et les nouveaux entrants (utilisateurs secondaires). La nature d'un tel partage peut faciliter les attaques d'inférence et mettre en péril les paramètres opérationnels des utilisateurs primaires. Par conséquent, le but de cette thèse est d'améliorer la confidentialité des utilisateurs primaires tout en permettant un accès secondaire au spectre. Premièrement, nous présentons une brève description des règles de partage et des exigences en termes de confidentialité dans les bandes fédérales. Nous étudions également les techniques de conservation de confidentialité (obscurcissement) proposées dans les domaines d'exploration et d'édition de données pour contrecarrer les attaques d'inférence. Ensuite, nous proposons et mettons en œuvre notre approche pour protéger la fréquence et la localisation opérationnelles contre les attaques d'inférence. La première partie étudie la protection de la fréquence opérationnelle en utilisant un obscurcissement inhérent et explicite pour préserver la confidentialité. La deuxième partie traite la protection de la localisation opérationnelle en utilisant la confiance comme principale contre-mesure pour identifier et atténuer un risque d'inférence. Enfin, nous présentons un cadre axé sur les risques qui résume notre travail et s'adapte à d'autres approches de protection de la confidentialité. Ce travail est soutenu par des modèles, des simulations et des résultats qui focalisent sur l'importance de quantifier les techniques de préservation de la confidentialité et d'analyser le compromis entre la protection de la confidentialité et l'efficacité du partage du spectre / Radio frequencies, as currently allocated, are statically managed. Spectrum sharing between commercial users and incumbent users in the Federal bands has been considered by regulators, industry, and academia as a great way to enhance productivity and effectiveness in spectrum use. However, allowing secondary users to share frequency bands with sensitive government incumbent users creates new privacy threats in the form of inference attacks. Therefore, the aim of this thesis is to enhance the privacy of the incumbent while allowing secondary access to the spectrum. First, we present a brief description of different sharing regulations and privacy requirements in Federal bands. We also survey the privacy-preserving techniques (i.e., obfuscation) proposed in data mining and publishing to thwart inference attacks. Next, we propose and implement our approach to protect the operational frequency and location of the incumbent operations from inferences. We follow with research on frequency protection using inherent and explicit obfuscation to preserve the incumbent's privacy. Then, we address location protection using trust as the main countermeasure to identify and mitigate an inference risk. Finally, we present a risk-based framework that integrates our work and accommodates other privacy-preserving approaches. This work is supported with models, simulations and results that showcase our work and quantify the importance of evaluating privacy-preserving techniques and analyzing the trade-off between privacy protection and spectrum efficiency