In the last decade, cellular networks have been characterized by an ever-growing user data demand. This caused increasing capacity shortfall and coverage issues, aggravated by inefficient fixed spectrum management policies and obsolete network structures. From a practical point of view, novel technical and architectural solutions have been proposed to frame next generation cellular networks, capable of meeting the identified target performance to satisfy the user data demands. Specifically, new spectrum management policies based on the so-called dynamic spectrum access (DSA), together with hierarchical approaches to network planning, where a tier of macro base stations is underlaid with a tier of massively deployed low-power small base stations, are seen as promising candidates to achieve this scope. The resulting two-tiered network layout may improve the capacity of current networks in several ways, thanks to a better average link quality between the devices, a more efficient usage of spectrum resources and a potentially higher spatial reuse. In this thesis, we focus on the challenging problem arising when the two tiers share the transmit band, to capitalize on the available spectrum and avoid possible inefficiencies. In this case, the coexistence of the two tiers is not feasible, if suitable interference management techniques are not designed to mitigate/cancel the mutual interference generated by the active transmitters in the network. This thesis is divided in three main parts, and proposes a rather exhaustive approach to the development of new DSA and interference management techniques, to go from the theoretical basis up to a proof-of-concept development.

<p>A cognitive radio network is a multi-user system, in which different radio units compete for limited resources in an opportunistic manner, interacting with each other for access to the available resources. The fact that both users and spectrum holes (i.e., under-utilized spectrum sub-bands) can come and go in a stochastic manner, makes a cognitive radio network a highly non- stationary, dynamic and challenging wireless environment. Finding robust decentralized resource-allocation algorithms, which are capable of achieving reasonably good solutions fast enough in order to guarantee an acceptable level of performance, is crucial in such an environment. In this thesis, a novel dynamic spectrum management (DSM) scheme for cognitive radio networks, termed the self-organizing dynamic spectrum management (SO-DSM), is described and its practical validity is demonstrated using computer simulations. In this scheme, CRs try to exploit the primary networks’ unused bands and establish link with neighbouring CRs using those bands. Inspired by human brain, the CRs extract and memorize primary network’s and other CRs’ activity patterns and create temporal channel assignments on sub-bands with no recent primary user activities using self-organizing maps (SOM) technique. The proposed scheme is decentralized and employs a simple learning rule with low complexity and minimal memory requirements. A software testbed was developed to simulate and study the proposed scheme. This testbed is capable of simulating CR network alongside of a cellular legacy network. In addition to SO-DSM, two other DSM schemes, namely centralized DSM and no-learning decentralized DSM, can be used for CR networks in this software testbed. The software testbed was deployed on parallel high capacity computing clusters from Sharcnet to perform large scale simulations of CR network. The simulation results show, comparing to centralized DSM and minority game DSM (MG-DSM), the SO-DSM decreases the probability of collision with primary users and also probability of CR link interruption significantly with a moderate decrease in CR network spectrum utilization.</p> / Doctor of Philosophy (PhD)

Au cours de la dernière décennie, les réseaux cellulaires ont connu une augmentation exponentielle de la demande de données. En conséquence, nous constatons des chutes de capacités occasionnelles et des problèmes de couverture, aggravés par des politiques de gestion du spectre inefficaces et des structures réseaux obsolètes. Le développement de nouvelles politiques pour le management du spectre, telles que les schémas de dynamic spectrum access (DSA), permettra, avec le déploiement de réseaux multi-niveaux, de traiter les problèmes précédemment évoqués et encadrer les réseaux mobiles de prochaine génération. Un réseau ainsi conçu pourra augmenter la capacité offerte par les réseaux actuels et atteindre les niveaux de performance requis par les demandes de data des utilisateurs, via une utilisation plus efficace du spectre disponible et une meilleure réutilisation spatiale. Dans cette thèse, nous nous concentrons principalement sur le problème inhérent au fait de posséder deux niveaux de transmission au sein de notre réseau (mini et macro stations de base) qui doivent dès lors se partager une bande commune, capitaliser sur le spectre disponible et éviter les situations d’interférences où elles s’annihilent mutuellement. Dans ce cas, la question de la coexistence se pose et elle ne peut être atteinte que si des techniques de management d’interférence sont développées pour mitiger/annuler l’interférence générée par ces deux transmetteurs. Le travail se décompose en trois parties et propose une approche plutôt exhaustive pour le développement de nouvelles techniques de DSA et gestion de l'interférence, d’un niveau purement théoriques aux premières trames de preuve de concept. / In the last decade, cellular networks have been characterized by an ever-growing user data demand. This caused increasing capacity shortfall and coverage issues, aggravated by inefficient fixed spectrum management policies and obsolete network structures. From a practical point of view, novel technical and architectural solutions have been proposed to frame next generation cellular networks, capable of meeting the identified target performance to satisfy the user data demands. Specifically, new spectrum management policies based on the so-called dynamic spectrum access (DSA), together with hierarchical approaches to network planning, where a tier of macro base stations is underlaid with a tier of massively deployed low-power small base stations, are seen as promising candidates to achieve this scope. The resulting two-tiered network layout may improve the capacity of current networks in several ways, thanks to a better average link quality between the devices, a more efficient usage of spectrum resources and a potentially higher spatial reuse. In this thesis, we focus on the challenging problem arising when the two tiers share the transmit band, to capitalize on the available spectrum and avoid possible inefficiencies. In this case, the coexistence of the two tiers is not feasible, if suitable interference management techniques are not designed to mitigate/cancel the mutual interference generated by the active transmitters in the network. This thesis is divided in three main parts, and proposes a rather exhaustive approach to the development of new DSA and interference management techniques, to go from the theoretical basis up to a proof-of-concept development.

One of the enabling technologies for Long Term Evolution (LTE) deployments is the femtocell technology. By having femtocells deployed indoors and closer to the user, high data rate services can be provided efficiently. These femtocells are expected to be depolyed in large numbers which raises many technical challenges including the handover management. In fact, managing handovers in femtocell environments, with the conventional manual adjustment techniques, is almost impossible to keep pace with in such a rapidly growing femtocell environment. Therefore, doing this automatically by implementing Self Organizing Network (SON) use cases becomes a necessity rather than an option. However, having multiple SON use cases operating simultaneously with a shared objective could cause them to interact either negatively or positively. In both cases, designing a suitable coordination policy is critical in solving negative conflicts and building upon positive benefits. In this work, we focus on studying the interactions between three self optimization use cases aiming at improving the overall handover procedure in LTE femtocell networks. These self optimization use cases are handover, Call Admission Control (CAC) and load balancing. We develop a comprehensive, unified LTE compliant evaluation environment. This environment is extendable to other radio access technologies including LTE-Advanced (LTE-A), and can also be used to study other SON use cases. Various recommendations made by main bodies in the area of femtocells are considered including the Small Cell Forum, the Next Generation Mobile Networks (NGMN) alliance and the 3rd Generation Partnership Project (3GPP). Additionally, traffic sources are simulated in compliance with these recommendations and evaluation methodologies. We study the interaction between three representative handover related self optimization schemes. We start by testing these schemes separately, in order to make sure that they meet their individual goals, and then their mutual interactions when operating simultaneously. Based on these experiments, we recommend several guidelines that can help mobile network operators and researchers in designing better coordination policies. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-12-05 22:35:27.538

The diploma thesis focuses on classification of emotions. Thesis deals about parameterization of sounds files by suprasegment and segment methods with regard for next used of these methods. Berlin database is used. This database includes many of sounds records with emotions. Parameterization creates files, which are divided to two parts. First part is used for training and second part is used for testing. Point of interest is self-organization network. Thesis includes Matlab´s program which can be used for parameterization of any database. Data are classified by self-organization network after parameterization. Results of hits rates are presented at the end of this diploma thesis.