Boucle gravité quantique (LQG) est une tentative pour résoudre le problème de la gravité quantique. Boucle cosmologie quantique (LQC) est une tentative d'appliquer LQG à la cosmologie précoce. Le but de LQC est de se connecter LQG avec des observations. Il est très difficile d'observer les effets de la gravité quantique parce que la densité d'énergie énorme est très probablement nécessaire. Ceci est exactement pourquoi l'Univers est choisi comme une étape pour rechercher des phénomènes de gravité quantique.Le résultat central de LQC est que la grande singularité bang est remplacé par un gros rebond. Toutefois, ce ne sont pas quelque chose qui est possible d'observer aujourd'hui. Pour cette raison, nous avons étudié la façon dont les perturbations cosmiques sont affectées par LQC. Nous avons utilisé l'approche dite d'algèbre déformée, et nous avons calculé les spectres obtenus pour les deux perturbations scalaires et tenseurs. Les spectres que nous avons trouvé ne sont pas compatibles avec l'observation. Cependant cela ne peut abeille considérée comme très forte preuve contre LQG car il y a trop d'hypothèses sur le chemin. Plutôt cela est le résultat de cette interprétation spécifique de LQC.Nous avons également étudié la dynamique de fond (la partie homogène des équations) de LQC. Depuis lent-roll inflation est essentielle pour expliquer de nombreuses caractéristiques de l'univers, y compris le CMB, nous voulons savoir si lent-roll inflation est compatible avec LQC. Nous avons constaté que, en effet, il est. Si un champ d'inflation potentiel carré est ajouté à la théorie, le rebond va lever l'énergie potentielle suffisante pour fournir environ 145 e-plis de lent-roll inflation. Toutefois, lorsque anisotropies sont pris en compte, le montant de l'inflation diminue, et peut même disparaître complètement s'il y a trop de cisaillement au moment du rebond.Nous avons dérivé l'équation Friedman modifié pour anisotrope LQC. Cela nous a permis d'étudier anisotrope LQC pas seulement numériquement, mais aussi analytiquement, qui nous a donné une compréhension beaucoup plus complète de la situation que ce qui était connu auparavant.Enfin, nous avons étudié certains aspects géométriques de l'espace de Sitter, qui a donné lieu à deux considérations très différentes. Tout d'abord nous avons constaté que nous pouvons, pour une théorie générale de la cosmologie modifiée et sous certaines hypothèses assez conservatrices, tirer la dynamique d'un univers spatialement incurvée, étant donné la dynamique d'un un espace plat. Cela est pertinent dans les théories telles que LQC, où il est plus facile de trouver la solution plate que celle incurvée. Deuxièmement, nous proposons un mécanisme possible pour l'origine et la renaissance de l'Univers. / Loop quantum gravity (LQG) is an attempt to solve the problem of quantum gravity. Loop quantum cosmology (LQC) is an attempt to apply LQG to early cosmology. The purpose of LQC is to connect LQG with observations. It is very hard to observe any quantum gravity effects because enormous energy density is most likely required. This is exactly why the early Universe is chosen as a stage to search for quantum gravity phenomena.The central result of LQC is that the big bang singularity is replaced by a big bounce. However this is not something that is possible to observe today. For this reason, we have investigated how cosmic perturbations are affected by LQC. We have used the so called deformed algebra approach, and have calculated the resulting spectrums for both scalar and tensor perturbations.The spectrums that we have found are not compatible with observation. However this can not bee taken as very strong evidence against LQG since there are too many assumptions on the way. Rather this is a result for this specific interpretation of LQC.We have also studied the background dynamics (the homogenous part of the equations) of LQC. Since slow-roll inflation is essential in explaining many features of the universe, including the CMB, we want to know if slow-roll inflation is compatible with LQC. We have found that, indeed, it is. If a square potential inflation field is added to the theory, the bounce will lift the potential energy enough to provide around 145 e-folds of slow-roll inflation. However, when anisotropies are taken into account, the amount of inflation decreases, and can even disappear completely if there is too much shear at the time of the bounce.We have derived the modified Friedman equation for anisotropic LQC. This has allowed us to study anisotropic LQC not just numerically, but also analytically, which has given us a much more comprehensive understanding of the situation than what was known before.Finally, we have studied some geometric aspects of de Sitter space, which has resulted in two very different considerations. Firstly we found that we can, for a general theory of modified cosmology and under some quite conservative assumptions, derive the dynamics for a spatially curved universe, given the dynamics of a spatially flat one. This is relevant in theories such as LQC, where it is easier to find the flat solution than the curved one. Secondly, we propose a possible mechanism for the origin and rebirth of the Universe.

<p>This master thesis has been done at Enea Epact AB. The purpose of this thesis is to develop and implement a Link Quality Control algorithm for GPRS/EPGRS in the current testing tool. A Link Quality Control (LQC) shall take quality values from mobile stations and base stations and decide a codingsscheme that opimizes the throughput of data. </p><p>The Advantage with LQC is that it adapts the used coding scheme to the channel quality. If the channel quality is too bad for the used coding scheme, a slower coding scheme with more redundancy should be selected. On the other hand, if the channel quality is too good for the used coding scheme, LQC should recommend a faster coding scheme with less redundancy. </p><p>The testing tool is now using a static coding schme that doesn’t change during a data session. An LQC is therefore necessary for better simulation of the traffic and to make the tests more real.</p>

<p>The GSM network technology has been developed and improved during several years which have led to an increased complexity. The complexity results in more network parameters and together with different scenarios and situations they form a complex set of configurations. The definition of the network parameters is generally a manual process using static values during test execution. This practice can be costly, difficult and laborious and as the network complexity continues to increase, this problem will continue to grow.This thesis presents an implementation of an automated performance optimization algorithm that utilizes genetic algorithms for optimizing the network parameters. The implementation has been used for proving that the concept of automated optimization is working and most of the work has been carried out in order to use it in practice. The implementation has been applied to the Link Quality Control algorithm and the Improved ACK/NACK feature, which is an apart of GSM EDGE Evolution.</p> / <p>GSM-nätsteknologin har utvecklats och förbättrats under lång tid, vilket har lett till en ökad komplexitet. Denna ökade komplexitet har resulterat i fler nätverksparameterar, tillstånd och standarder. Tillsammans utgör de en komplex uppsättning av olika konfigurationer. Dessa nätverksparameterar har hittills huvudsakligen bestämts med hjälp av en manuell optimeringsprocess. Detta tillvägagångssätt är både dyrt, svårt och tidskrävande och allt eftersom komplexiteten av GSM-näten ökar kommer problemet att bli större.Detta examensarbete presenterar en implementering av en algoritm för automatiserad optimering av prestanda som huvudsakligen använder sig av genetiska algoritmer för att optimera värdet av nätverksparametrarna. Implementeringen har använts för att påvisa att konceptet med en automatiserad optimering fungerar och det mesta av arbetet har utförts för att kunna använda detta i praktiken. Implementeringen har tillämpats på Link Quality Control-algoritmen och Improved ACK/NACK-funktionaliteten, vilket är en del av GSM EDGE Evolution.</p>

The GSM network technology has been developed and improved during several years which have led to an increased complexity. The complexity results in more network parameters and together with different scenarios and situations they form a complex set of configurations. The definition of the network parameters is generally a manual process using static values during test execution. This practice can be costly, difficult and laborious and as the network complexity continues to increase, this problem will continue to grow.This thesis presents an implementation of an automated performance optimization algorithm that utilizes genetic algorithms for optimizing the network parameters. The implementation has been used for proving that the concept of automated optimization is working and most of the work has been carried out in order to use it in practice. The implementation has been applied to the Link Quality Control algorithm and the Improved ACK/NACK feature, which is an apart of GSM EDGE Evolution. / GSM-nätsteknologin har utvecklats och förbättrats under lång tid, vilket har lett till en ökad komplexitet. Denna ökade komplexitet har resulterat i fler nätverksparameterar, tillstånd och standarder. Tillsammans utgör de en komplex uppsättning av olika konfigurationer. Dessa nätverksparameterar har hittills huvudsakligen bestämts med hjälp av en manuell optimeringsprocess. Detta tillvägagångssätt är både dyrt, svårt och tidskrävande och allt eftersom komplexiteten av GSM-näten ökar kommer problemet att bli större.Detta examensarbete presenterar en implementering av en algoritm för automatiserad optimering av prestanda som huvudsakligen använder sig av genetiska algoritmer för att optimera värdet av nätverksparametrarna. Implementeringen har använts för att påvisa att konceptet med en automatiserad optimering fungerar och det mesta av arbetet har utförts för att kunna använda detta i praktiken. Implementeringen har tillämpats på Link Quality Control-algoritmen och Improved ACK/NACK-funktionaliteten, vilket är en del av GSM EDGE Evolution.

This master thesis has been done at Enea Epact AB. The purpose of this thesis is to develop and implement a Link Quality Control algorithm for GPRS/EPGRS in the current testing tool. A Link Quality Control (LQC) shall take quality values from mobile stations and base stations and decide a codingsscheme that opimizes the throughput of data. The Advantage with LQC is that it adapts the used coding scheme to the channel quality. If the channel quality is too bad for the used coding scheme, a slower coding scheme with more redundancy should be selected. On the other hand, if the channel quality is too good for the used coding scheme, LQC should recommend a faster coding scheme with less redundancy. The testing tool is now using a static coding schme that doesn’t change during a data session. An LQC is therefore necessary for better simulation of the traffic and to make the tests more real.