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nÃo hà / One challenging task in multiple input multiple output (MIMO) systems design is to accommodate the multiple antennas in the mobile device without compromising the system capacity, due to spatial and electrical constraints. In this work, an experimental MIMO wireless channel characterization in an outdoor environment is performed in order to study the different factors that affect MIMO capacity. The data acquired during wideband channel measurement campaigns made in Stockholm, Sweden, were used in order to predict the impact of direction of arrival (DOA) distribution and polarization diversity on the channel capacity, choosing specific measurement routes and locations as well as different MIMO antenna array configurations. This thesis proposes a genetic algorithm (GA) to obtain the position and orientation of each MIMO array antenna that maximizes the ergodic capacity for a given propagation scenario. The simulations of the GA use the characterized experimental channel model, as a case of study, in order to evaluate the impact of different characteristics of the propagation environment in the capacity. Based on an interface between the antenna model and the propagation channel model, the ergodic capacity is considered as the objective function of the MIMO array optimization. Simulation results corroborate the importance of polarization and antenna pattern diversities for MIMO in small terminals. The results also show that the electromagnetic coupling effect can be exploited by the optimizer in order to decrease signal correlation and increase MIMO capacity. A comparison among uniform linear array (ULA), uniform circular array (UCA) and the GA-optimized array is also carried out, showing that the topology given by the optimizer is superior to that of the standard ULA and UCA arrays for the considered propagation channel. This work also presents a method for optimizing the capacity of MIMO antenna array systems with antenna selection, evolving the antenna array best suited for antenna selection in a given scenario. As a result of the proposed GA optimizer, different array configurations were obtained for cases with and without antenna selection, showing that true polarization diversity (TPD) schemes are particularly suited for antenna selection systems. / Uma questÃo bastante complicada no projeto de sistemas MIMO à acomodar as mÃltiplas antenas no dispositivo mÃvel sem comprometer a capacidade do sistema, devido a restriÃÃes elÃtricas e de espaÃo. Neste trabalho à desenvolvida a caracterizaÃÃo de um canal MIMO sem fio em ambiente externo para o estudo dos diferentes fatores que afetam a capacidade de comunicaÃÃo. Os dados adquiridos em campanhas de mediÃÃo feitas em Estocolmo foram utilizados para modelar o impacto da distribuiÃÃo de DOA e da diversidade de polarizaÃÃo na capacidade do canal, escolhendo rotas especÃficas de medida e diferentes configuraÃÃes de arranjos de antena. Essa tese propÃe um algoritmo genÃtico para obter a posiÃÃo e orientaÃÃo de cada antena do arranjo MIMO que maximizem a capacidade ergÃtica para um dado cenÃrio de propagaÃÃo. Baseando-se em uma interface entre o modelo de antena e o modelo de propagaÃÃo do canal, a capacidade ergÃdica à usada como funÃÃo objetivo da otimizaÃÃo do arranjo MIMO. Os resultados das simulaÃÃo indicam a importÃncia das diversidades de polarizaÃÃo e de padrÃo de antena para sistemas MIMO em terminais de pequeno porte. Os resultados tambÃm mostram que o efeito do acoplamento eletromagnÃtico pode ser explorado pelo otimizador para diminuir a correlaÃÃo do sinal aumentando assim a capacidade MIMO. TambÃm à feita uma comparaÃÃo entre arranjo linear uniforme(ULA), arranjo circular uniforme(UCA) e um arranjo otimizado pelo algoritmo genÃtico, mostrando que a topologia resultante do algoritmo genÃtico à superior tanto a ao arranjo ULA quanto ao arranjo UCA, para o canal de propagaÃÃo considerado. Este trabalho tambÃm apresenta um mÃtodo para otimizaÃÃo da capacidade de sistemas MIMO com seleÃÃo de antena, evoluindo um arranjo de antenas melhor adaptado para a seleÃÃo de antenas em um dado cenÃrio de propagaÃÃo. Como resultado do mÃtodo proposto, diferentes configuraÃÃes de arranjos foram obtidas para o caso com e sem seleÃÃo de antenas, mostrando que sistemas de diversidade de polarizaÃÃo(TPD) sÃo particularmente adequados para sistemas com seleÃÃo de antena.

This master’s thesis deals with optimizing the layout proposal of workplaces in a small engineering company. The work is to assess the current status, capacity calculation, design options to improve with subsequent selection of the optimal design and economic evaluation.

To date the majority of research in the area of cooperative communications focuses on maximizing throughput and reliability while assuming perfect channel state information (CSI) and synchronization. This thesis, seeks to address performance enhancement and system parameter estimation in cooperative networks while relaxing these idealized assumptions. In Chapter 3 the thesis mainly focuses on training-based channel estimation in multi-relay cooperative networks. Channel estimators that are capable of determining the overall channel gains from source to destination antennas are derived. Next, a new low feedback and low complexity scheme is proposed that allows for the coherent combining of signals from multiple relays. Numerical and simulation results show that the combination of the proposed channel estimators and optimization algorithm result in significant performance gains. As communication systems are greatly affected by synchronization parameters, in Chapter 4 the thesis quantitatively analyzes the effects of timing and frequency offset on the performance of communications systems. The modified Cramer-Rao lower bound (MCRLB) undergoing functional transformation, is derived and applied to determine lower bounds on the estimation of signal pulse amplitude and signal-to-noise ratio (SNR) due to timing offset and frequency offset, respectively. In addition, it is shown that estimation of timing and frequency offset can be decoupled in most practical settings. The distributed nature of cooperative relay networks may result in multiple timing and frequency offsets. Chapters 5 and 6 address multiple timing and frequency offset estimation using periodically inserted training sequences in cooperative networks with maximum frequency reuse, i.e., space-division multiple access (SDMA) networks. New closed-form expressions for the Cramer-Rao lower bound (CRLB) for multiple timing and multiple frequency offset estimation for different cooperative protocols are derived. The CRLBs are then applied in a novel way to formulate training sequence design guidelines and determine the effect of network protocol and topology on synchronization parameter estimation. Next, computationally efficient estimators are proposed. Numerical results show that the proposed estimators outperform existing algorithms and reach or approach the CRLB at mid-to-high SNR. When applied to system compensation, simulation results show that application of the proposed estimators allow for synchronized cooperation amongst the nodes within the network. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2010-07-29 16:52:50.272

This diploma thesis deals with a design and optimization of mixer truck gearbox bearing arrangements. The gearbox is an important part of mixer truck. Major emphasis is put on design of main bearing which is a key component of the gearbox because of high load applied on it. Two basic criterions were considered in main bearing design – dynamic radial load capacity and contact stress in contact of roller and raceways. Developed two-stage optimizing algorithm is based on standard bearing and allows to design new bearing which is specialized for carrying output shaft of mixer truck gearbox.

Τα ασύρματα συστήματα τέταρτης γενιάς (4G) στοχεύουν σε πολύ υψηλές ταχύτητες μετάδοσης δεδομένων, 100 Mbps (Mega bits per second) για ταχέως κινούμενους πομποδέκτες και έως 1 Gbps για ακίνητους. Αυτός ο στόχος μπορεί να επιτευχθεί με τα συστήματα Πολλαπλής Εισόδου-Πολλαπλής Εξόδου (Multiple Input-Multiple Output, MIMO) τα οποία χρησιμοποιούν πολλές κεραίες στον πομπό και στο δέκτη. Ο στόχος της παρούσας διδακτορικής διατριβής (ΔΔ) εστιάζεται στην ανάλυση και βελτιστοποίηση αυτών των συστημάτων, υπό το πρίσμα των φαινομένων της σκέδασης και των διαλείψεων μικρής κλίμακας. Το αντικείμενο μελέτης συνοψίζεται στις ακόλουθες θεματικές ενότητες: α) μοντελοποίηση των ασυρμάτων καναλιών με διαλείψεις, β) απόδοση ακριβών και εύχρηστων μαθηματικών εκφράσεων της εργοδικής (μέσου όρου) χωρητικότητας των ασύρματων συστημάτων που χρησιμοποιούν πολλές κεραίες στο δέκτη, γ) αύξηση της εργοδικής χωρητικότητας του συστήματος ΜΙΜΟ χρησιμοποιώντας πληροφορία από το μέσο διάδοσης. Αρχικά περιγράφεται η γενική μοντελοποίηση του ασύρματου καναλιού που είναι αναγκαία για την κατανόηση βασικών εννοιών για την ανάλυση που θα ακολουθήσει. Αυτό έχει ως στόχο μία σύντομη περιγραφή των βασικών χαρακτηριστικών ενός οποιουδήποτε ασύρματου καναλιού και να γίνουν κατανοητές κάποιες σημαντικές έννοιες που προκύπτουν και χρησιμοποιούνται κατά κόρον στις ασύρματες επικοινωνίες. Πιο συγκεκριμένα, παρατίθενται βασικές θεωρητικές γνώσεις όπου περιγράφονται τα διάφορα προβλήματα διάδοσης, δίνοντας μια σύντομη περιγραφή των φυσικών φαινομένων που εμπλέκονται, χωρίς να εμβαθύνουμε σε πολύπλοκες μαθηματικές σχέσεις. Στη συνέχεια, γίνεται προσπάθεια ακριβέστερης μοντελοποίησης, με χρήση στοχαστικών διαδικασιών, των ασύρματων μη επιλεκτικών στη συχνότητα καναλιών με διαλείψεις (frequency non-selective fading channels) σε περιβάλλον τρισδιάστατης ανισοτροπικής σκέδασης καναλιού Rice. Με τον όρο ανισοτροπική εννοείται ότι η λήψη των διαφόρων συνιστωσών για το αζιμούθιο επίπεδο γίνεται από κάποιους τομείς γωνιών και όχι από όλες τις κατευθύνσεις, ενώ στο επίπεδο της ανύψωσης θεωρούμε την ύπαρξη ενός τομέα άφιξης των συνιστωσών στον οποίο η ισχύς δεν κατανέμεται ομοιόμορφα αλλά βάσει μιας κατανομής. Επιπλέον λόγω της θεώρησης καναλιού Rice, συμπεριλαμβάνεται η ύπαρξη μιας δεσπόζουσας συνιστώσας με σταθερό πλάτος η οποία συνήθως προέρχεται από οπτική επαφή του πομπού με το δέκτη. Θεωρώντας συγκεκριμένες κατανομές για την άφιξη των συνιστωσών σε αυτούς τους τομείς από τη διεθνή βιβλιογραφία, εξάγεται αναλυτικά η συνάρτηση της αυτοσυσχέτισης και το φάσμα της ολίσθησης των συχνοτήτων σε αναλυτική μορφή και υπολογίζονται σημαντικά μεγέθη που εκφράζουν την ταχύτητα αυξομείωσης του σήματος και τη διάρκεια των διαλείψεων. Επιπλέον με αυτό τον τρόπο είναι δυνατόν να καθοριστεί η απόσταση μεταξύ των κεραιών που πρέπει να τηρείται ώστε να εξασφαλίζονται οι υψηλές επιδόσεις. Σε αστικό περιβάλλον, αποδεικνύεται ότι η ελάχιστη απόσταση μεταξύ των κεραιών ενός πομποδέκτη θα πρέπει να είναι μεγαλύτερη από ότι σε ένα υπαίθριο περιβάλλον. Στην επόμενη ενότητα επιτυγχάνεται η απόδοση ακριβών και εύχρηστων μαθηματικών εκφράσεων της εργοδικής (μέσου όρου) χωρητικότητας των ασύρματων συστημάτων που χρησιμοποιούν πολλές κεραίες στο δέκτη σε περιβάλλον Nakagami (που θεωρείται από τα πιο αντιπροσωπευτικά για την περιγραφή της ασύρματης διάδοσης σε κλειστούς χώρους) με όσο το δυνατό απλούστερες μαθηματικές συναρτήσεις. Με αυτό τον τρόπο, η ταχύτητα μετάδοσης δεδομένων εκφράζεται συναρτήσει των φυσικών παραμέτρων του συστήματος, δηλαδή το κανάλι, τον αριθμό των κεραιών κτλ. Ήδη έχουν γίνει πολλές δημοσιεύεις σε αυτό τον τομέα για διάφορες περιπτώσεις μοντελοποίησης των καναλιών (Rayleigh, Rice κτλ) και για διάφορες τεχνικές λήψης. Όμως υπάρχουν αρκετές περιπτώσεις όπου υπάρχουν κενά στη διεθνή βιβλιογραφία ή η έκφραση της χωρητικότητας δεν γίνεται με κλειστές μαθηματικές μορφές. Έτσι παρουσιάζονται αναλυτικές μαθηματικές εκφράσεις της εργοδικής χωρητικότητας των συστημάτων SIMO που δεν υπήρχαν έως τώρα στη διεθνή βιβλιογραφία, για διάφορες περιπτώσεις γνώσης του καναλιού. Αυτό γίνεται κάνοντας τον άμεσο παραλληλισμό των συστημάτων SIMO με τις διάφορες τεχνικές διαφορισμού. Εξετάζεται η εργοδική χωρητικότητα ενός συστήματος SIMO το οποίο λειτουργεί σε κανάλι διαλείψεων Nakagami-m στο οποίο όλες οι ζεύξεις είναι ανεξάρτητες αλλά δεν είναι κατά ανάγκη όμοιες. Συγκεκριμένα εξάγονται μαθηματικές εκφράσεις κλειστού τύπου για την εργοδική χωρητικότητα συστημάτων Equal Gain Combining και Selection Combining και Switch and Stay Combining δύο κλάδων. Επιπλέον, παρουσιάζεται για πρώτη φορά, η εργοδική χωρητικότητα ενός συστήματος SIMO στο οποίο δεν εφαρμόζεται καμία τεχνική διαφορικής λήψης και εξάγονται πολύ διδακτικά συμπεράσματα. Αυτό σημαίνει ότι ο δέκτης δεν έχει καμία πληροφορία για το κανάλι (no channel state information CSI) και απλά προσθέτει τα λαμβανόμενα σήματα από κάθε κλάδο-ζεύξη. Επιπλέον γίνεται προσπάθεια οι μαθηματικοί τύποι να είναι εύχρηστοι και υλοποιήσιμοι χωρίς την χρήση ιδιαίτερων μαθηματικών λογισμικών. Ουσιαστικά η μαθηματική έκφραση της χωρητικότητας των συστημάτων SIMO σε κανάλι διαλείψεων Nakagami-m, ανάγεται στην επίλυση ενός είδους ολοκληρώματος που περιέχει ταυτόχρονα τη λογαριθμική συνάρτηση, την εκθετική συνάρτηση και πολυώνυμα νιοστής δύναμης. Αυτός ο τύπος ολοκληρωμάτων είναι δυσεπίλυτος και προκύπτει συχνά στις ασύρματες επικοινωνίες. Στην τελευταία ενότητα, γίνεται προσπάθεια αύξησης του μέσου όρου της χωρητικότητας του συστήματος ΜΙΜΟ χρησιμοποιώντας πληροφορία από το μέσο διάδοσης. Πιο συγκεκριμένα μελετάται η πολιτική εκπομπής, αν ο πομπός γνωρίζει τις παραμέτρους του καναλιού οι οποίες είναι δυνατό να γνωστοποιηθούν στον πομπό σε ρεαλιστικό επίπεδο. Ως παράμετροι του καναλιού οι οποίες είναι απαραίτητο να είναι γνωστές, θεωρούνται ο μέσος όρος και η διασπορά του καναλιού που είναι δυνατό να μετρηθούν στην πράξη ιδιαίτερα για κανάλια που δε μεταβάλλονται πάρα πολύ γρήγορα στο χρόνο. Το πρόβλημα της μεγιστοποίησης της εργοδικής χωρητικότητας, στην γενική του μορφή έως τώρα αντιμετωπίζεται μόνο με χρονοβόρες υπολογιστικές μεθόδους που απαιτούν αρκετή υπολογιστική ισχύ, καθιστώντας τη λύση μη εφαρμόσιμη σε πραγματικό χρόνο και επομένως μη ρεαλιστική. Το πρόβλημα είναι δυσεπίλυτο και οι μόνες αναλυτικές λύσεις που υπάρχουν αναφέρονται σε ιδιαίτερες περιπτώσεις. Η παρούσα ΔΔ ασχολείται με τη μεγιστοποίηση της εργοδικής χωρητικότητας του συστήματος MISO (Multiple Input-Single Output) το οποίο χρησιμοποιεί την τεχνική beamforming στην εκπομπή. Το πρόβλημα επιλύεται και η λύση του ανάγεται στη λύση ενός συστήματος δύο εξισώσεων το οποίο λύνεται αριθμητικά. Έτσι είναι δυνατή η μεγιστοποίηση της χωρητικότητας σε πραγματικό χρόνο χωρίς ιδιαίτερη υπολογιστική ισχύ. Έως τώρα η προσέγγιση αυτού του προβλήματος γίνεται αποκλειστικά με αλγορίθμους μεγιστοποίησης μη γραμμικού προγραμματισμού. Επιπλέον εξετάζοντας τη λύση του απλού συστήματος , εξάγονται καθολικά συμπεράσματα που εκφράζουν το γενικό πρόβλημα. Για τη μεγιστοποίηση του συστήματος MISO beamforming, απαιτήθηκε η διανυσματική ανάλυση του μέσου όρου του καναλιού και του διανύσματος beamforming του πομπού σε μία κατάλληλη ορθοκανονική βάση. Έτσι το πρόβλημα ανάγεται στην εύρεση των γωνιών που σχηματίζει το διάνυσμα beamforming με την ορθοκανονική βάση ώστε να μεγιστοποιείται η χωρητικότητα για δεδομένες παραμέτρους του καναλιού. Με αυτή τη μέθοδο το πρόβλημα επιλύεται πολύ εύκολα με αριθμητικές μεθόδους. Αυτό δίνει, πέρα από την ίδια τη λύση, τη δυνατότητα να γίνει σύγκριση και με υπάρχουσες μεθόδους που προσέγγιζαν τη λύση, όπως η μεγιστοποίηση του σηματοθορυβικού λόγου (Signal to Noise Ratio, SNR). Επίσης αποδεικνύεται ότι το λαμβανόμενο SNR στο δέκτη επηρεάζει το διάνυσμα beamforming που μεγιστοποιεί την χωρητικότητα. Λαμβάνοντας υπόψη όλα αυτά, προτείνεται ένας κανόνας για την πολιτική εκπομπής του πομπού. Η μεθοδολογία που αναπτύχθηκε μπορεί να βοηθήσει σημαντικά στην επίλυση του γενικότερου προβλήματος της μεγιστοποίησης της χωρητικότητας σε συστήματα ΜΙΜΟ. / 4G Wireless Communication Systems aim at high data rates, 100 Mbps (Mega bits per second) for high speed transceivers and up to 1 Gbps for stationary transceivers. This target can be accomplished with Multiple Input Multiple Output (MIMO) Systems which use multiple antennas at both the transmitter and the receiver. The subject of this Philosophy Diploma (PhD) dissertation focuses on analysis and optimization of these systems, taking into account the effects of small scale fading and scattering which occur in a wireless channel. The subject of this study is summarized in the following thematic units: a) Fading channel modelling b) Closed-form mathematical expressions for the ergodic capacity of wireless systems which use multiple antennas at the receiver c) increase MISO ergodic capacity through channel state information. Initially, the general wireless fading channel model is described which is necessary for the better understanding of the analysis used in this dissertation. This aims at a brief description of the basic characteristics of the wireless channel. Specifically, general theoretical knowledge of propagation channel is presented, giving a description of the phenomena occurring in the channel without presenting complex mathematical expressions. Next, using stochastic procedures, an accurate model of frequency non-selective Rician fading channel with 3 dimensional anisotropic scattering is presented. The term anisotropic means that the arrival of the multipath components comes from some specific sectors and not from any direction. In the elevation plane, we assume a sector for the arrival of the multipath components in which power does not arrive uniformly but follows a specific distribution. In addition, assuming a communication system operating in a Rice fading channel, a dominant component is included which usually represents the Line of Sight (LOS) component between the transmitter and the receiver. Taking into account international literature and assuming specific probability density functions for the angle of arrivals in these sectors, analytical mathematical expressions of the auto-correlation function and the power spectral density of the received signal are derived. Moreover important measures of the level crossing rate and the average duration of fades are calculated. By this analysis, the system designer is able to estimate the optimal distance between antennas in order to assure high performance of the communication system. It is proved that the distance between antennas should be greater in rural than in urban environments. In the next section, accurate closed-form mathematical expressions for the ergodic capacity of SIMO (Single Input Multiple Output) systems in Nakagami fading channel are derived with the help of known and easy to use mathematical functions (Nakagami fading is appropriate for indoor channel modelling). Thus channel capacity is expressed with respect to the physical system parameters such as: amount of fading, number of antennas etc. Many studies have been published for different cases of fading channel models (Rayleigh, Rice, etc) and diversity techniques. But for some cases there are no mathematical expressions for the ergodic capacity or it is expressed in a no closed form way. Thus in this study, new analytical mathematical expressions for the ergodic capacity of SIMO systems with different channel knowledge cases are derived. Also the relation between diversity techniques and SIMO systems is taken into account. We assume that the SIMO system operates in a Nakagami fading channel where each branch is statistically independent but not identically distributed. More precisely, new ergodic capacity formulas for dual Equal Gain Combining, Selection Combining and Switch and Stay Combining techniques are presented. In addition, a new mathematical formula for the ergodic capacity of a SIMO system with no channel knowledge is presented, resulting in useful conclusions. All these mathematical expressions are calculated with mathematical functions that are included in any mathematical software. Essentially, the calculation of the ergodic capacity of SIMO systems in Nakagami fading channels entails the calculation of an integral which contains the logarithmic function, the exponential function and n power polynomials. This type of integral is intractable and arises frequently in wireless communications. In the last section, the ergodic capacity of a MIMO channel using channel state information is studied. In particular, this dissertation studies the transmit strategy if the transmitter knows the statistical parameters of the channel which is feasible in a realistic scenario. The statistical parameters of the channel that have to be transferred to the transmitter are channel mean and covariance. These parameters can be measured in practice especially for low time variant channels. Transmitter optimization problem, in its general form, is tackled only with hard optimization methods which are not feasible for real time applications due to large processing time. The problem is intractable and the only analytical solutions in literature are referred to special cases. The current dissertation studies the ergodic capacity optimization problem of a MISO (Multiple Input-Single Output) system which uses beamforming as its transmit strategy. The problem is solved through a system of two equations which is solved numerically. Thus the problem is extremely simplified and beamforming capacity optimization is feasible even for real time applications. So far this problem was tackled with non linear programming optimization methods. Also examining the solution for the MISO system, it is provided intuition into the problem. Also general results are presented which express the general problem. Beamforming capacity optimization solution was achieved by following an analytical approach that projects the beamforming vector on an appropriate orthonormal basis defined by the eigenvectors of the channel covariance matrix. Thus the problem reduces to calculation of the angles between the beamforming vector and the orthonormal basis which maximize capacity for given channel parameters. Following this method, the problem is solved very easily through numerical root finding algorithms. Besides the solution itself, a comparison against existing approximate solutions is possible, e.g. SNR (Signal to Noise Ratio) maximization solution. It is proved that the optimal beamforming vector is dependent on the received SNR. Taking into account all the arising results, a rule of thumb for the transmit policy is proposed. In addition, the used method can help significantly towards the solution of the MIMO transmitter optimization problem.

The integration of distributed energy sources and systems is of high relevance for the transition towards a more sustainable energy system. Taking into consideration the  amount of emissions produced by the heating sector, which account for at least half of the energy demand in buildings, district heating systems have the potential to play a key role in the transition, by enabling the integration of various energy sources and provide flexible energy services to the grid. The objective of this research is to evaluate the potential for flexible sector coupling between the electrical and heating sectors, utilizing thermal energy storage alongside various heat generation units, including heat pumps and a combined heat and power (CHP) unit. To examine this concept, we used a district heating facility located in Oskarshamn, Sweden, as our case study. At present, the production mix at this facility comprises various production units- that utilize mainly biomass as their fuel source, including wood pellets, wood chips, and occasionally, bio-oil. Extensive research was conducted to review the existing literature and gain a comprehensive understanding of the technologies and concepts associated with FSC. This thorough examination allowed for a comprehensive overview of the current state-of-the-art in FSC. As the main contributions of this work, two numerical models respectively for production and dispatch optimization were developed and simulated complementary, concerning the thermal and electrical system of the studied plant. A dispatch model was developed with the aim of analyzing the operating behaviour of the system, identifying the available energy sources and optimizing their hourly dispatch. Subsequently, utilizing the open-access tool for capacity and investment optimization (OSeMOSYS), various scenarios were examined to evaluate the potential of thermal energy storage (TES), where a water tank was found to be the most cost-effective solution, and heat pump integration in enhancing the plant performance and providing flexibility. The study was divided into two distinct time periods. The first period focused solely on hourly dispatch optimization until 2035. In the second period, the analysis extended to include investment optimization, followed by the subsequent dispatch optimization until 2050, hence, using both tools. To effectively compare and assess the different scenarios, several key performance indicators (KPIs) were chosen, including the levelized cost of energy (LCOE), capital expenditure (CAPEX), generation costs, and emissions. These scenarios were designed to account for variations in crucial variables such as electricity prices, the plant’s self-consumption potential, and the capital cost of storage. By considering the aforementioned factors, a comprehensive analysis was conducted to determine the optimal approach for maximizing performance and cost-effectiveness. It is important to mention that the electrical self-consumption within the plant was considered as one of the potential improvements. While the potential for electrical self-consumption was mainly studied on a shorter-term, the variability in the capital cost of the TES system was better considered on the long-term investment analysis. From the different simulations, the cases where self-consumption is included result in smaller operating costs, as producing electricity via the CHP unit of the plant is cheaper on average than the prices offered by the local distribution company. The obtained capacities for TES and the heat pump vary among the studied scenarios. Higher electricity prices favor investments in alternative fuel boilers like wood chips or wood pellets, while lower electricity prices result in increased TES capacities and higher heat pump production. The capital cost of storage also determines the capacity chosen for the storage water tank, sometimes investing a bit more to gain efficiency and reduce operational costs. Throughout the project, various sustainability aspects have been addressed. These encompass environmental responsibilities, with a focus on reducing CO2 emissions, enhancing social equity by implementing a more efficient heating system within the municipality, and assessing the economic viability of these initiatives. In conclusion, the study provides evidence and showcases the viability of implementing FSC in Oskarshamn’s power plant, as results from the different scenarios commonly show that FSC could bring down the total costs, as well as the amount of CO2 emissions on a long-term basis. Based on the findings, additional recommendations are proposed to optimize the plant’s performance and leverage the potential of this innovative approach. The proposed recommendations include increasing the time resolution in the model simulations to improve result accuracy and exploring different scenarios, which may involve considering various electricity or fuel price predictions, among other factors. / Integreringen av distribuerade energikällor och energisystem är av stor betydelse för övergången till ett mer hållbart energisystem. Med hänsyn till det utsläpp från värmesektorn, som står för minst hälften av energibehovet i byggnader, har fjärrvärmesystem potential att spela en nyckelroll i omställningen genom att möjliggöra integrering av olika energikällor och tillhandahålla flexibla energitjänster till nätet. Syftet med denna forskning är att utvärdera Potentialen för flexibel sektorkoppling (FSC) mellan el- och värmesektorerna, med hjälp av termisk energilagring tillsammans med olika värmeproduktionsenheter, inklusive värmepumpar och en kombinerad kraftvärmeproduktion (CHP). För att undersöka detta koncept, använde vi en fjärrvärmeanläggning i Oskarshamn, Sverige, som vår fallstudie. För tillfället består produktionsmixen vid denna anläggning av olika produktionsenheter som huvudsakligen använder biomassa som bränslekälla, inklusive träpellets, träflis och ibland bioolja. Omfattande forskning genomfördes för att granska den befintliga litteratur och få en heltäckande förståelse för de tekniker och koncept som är förknippade med FSC. Denna grundliga undersökning möjliggjorde en omfattande översikt av det aktuella kunskapsläget inom FSC. Som de viktigaste bidragen i detta arbete utvecklades och simulerades två numeriska modeller för produktions- respektive leveransoptimering, som berör det termiska och elektriska systemet i den studerade anläggningen. En fördelningsmodell utvecklades i syfte att analysera systemets driftsbeteende, identifiera tillgängliga energikällor och optimera deras fördelning per timme. Med hjälp av det verktyget med öppna tillgång (open-aceess) för kapacitets- och investeringsoptimering (OSeMOSYS) undersöktes därefter olika scenarier för att utvärdera potentialen för termisk energilagring (TES), där en vattentank visade sig vara den mest kostnadseffektiva lösningen, och integration av värmepumpar för att förbättra anläggningens prestanda och ge flexibilitet. Studien var uppdelad i två olika tidsperioder. Den första perioden fokuserade enbart på optimering av timfördelning fram till 2035. Under den andra perioden utvidgades analysen till att omfatta investeringsoptimering, följt av efterföljande optimering av driften fram till 2050, vilket innebär att båda verktygen användes. För att effektivt kunna jämföra och bedöma de olika scenarierna valdes flera viktiga nyckelprestandaindikatorer (KPI:er), inklusive den nivellerade energikostnaden (LCOE), kapitalinvesteringar (CAPEX), produktionskostnader och CO2 utsläpp. Dessa scenarier utformades för att ta hänsyn till variationer i viktiga variabler som elpriser, anläggningens självkonsumtionspotential och kapitalkostnaden för lagring. Med hänsyn till de ovan nämnda faktorerna genomfördes en omfattande analys för att fastställa den optimala metoden för att maximera prestanda och kostnadseffektivitet. Det är viktigt att nämna att den elektriska självförbrukningen inom anläggningen betraktades som en av de potentiella förbättringarna. Medan potentialen för elektrisk självförbrukning främst studerades på kortare sikt, beaktades variationen i kapitalkostnaden för TES-systemet bättre i den långsiktiga investeringsanalysen. De olika simuleringarna visar att de fall där självförbrukning ingår resulterar i lägre driftskostnader, eftersom elproduktionen via kraftvärmeverket i genomsnitt är billigare än de priser som erbjuds av det lokala distributionsbolaget. De erhållna kapaciteterna för TES och värmepumpen varierar mellan de studerade scenarierna. Högre elpriser gynnar investeringar i alternativa bränslepannor som flis eller träpellets, medan lägre elpriser resulterar i ökad TES-kapacitet och högre värmepumpsproduktion. Kapitalkostnaden för lagring avgör också vilken kapacitet som väljs för vattentanken (some en TES), ibland investerar man lite mer för att öka effektiviteten och minska driftskostnaderna. Under hela projektet har olika hållbarhetsaspekter beaktats. Dessa omfattar miljöansvar, med fokus på att minska CO2-utsläppen, öka den sociala rättvisan genom att införa ett mer effektivt värmesystem inom kommunen, och bedöma den ekonomiska bärkraften i dessa initiativ. Sammanfattningsvis visar studien att det är möjligt att implementera FSC i Oskarshamns kraftverk, eftersom resultaten från de olika scenarierna visar att FSC kan sänka de totala kostnaderna samt mängden CO2-utsläpp på lång sikt. Baserat på resultaten föreslås ytterligare rekommendationer för att optimera anläggningens prestanda och utnyttja potentialen i denna innovativa metod. De föreslagna rekommendationerna inkluderar att öka tidsupplösningen i modellsimuleringarna för att förbättra resultatens noggrannhet och utforska olika scenarier, vilket bland annat kan innebära att man överväger olika el- eller bränsleprisprognoser.

Choosing the correct angle of electrical tilt in a radio base station is essential when optimizing for coverage and capacity. A reinforcement learning agent can be trained to make this choice. If the training of the agent in the real world is restricted or even impossible, alternative methods can be used. Training in simulation combined with an approximation of the real world is one option that comes with a set of challenges associated with the reality gap. In this thesis, a method based on Bayesian optimization is implemented to tune the environment in which domain randomization is performed to improve the quality of the simulation training. The results show that using Bayesian optimization to find a good subset of parameters works even when access to the real world is constrained. Two off- policy estimators based on inverse propensity scoring and direct method evaluation in combination with an offline dataset of previously collected cell traces were tested. The method manages to find an isolated subspace of the whole domain that optimizes the randomization while still giving good performance in the target domain. / Rätt val av elektrisk antennvinkel för en radiobasstation är avgörande när täckning och kapacitetsoptimering (eng. coverage and capacity optimization) görs för en förstärkningsinlärningsagent. Om träning av agenten i verkligheten är besvärlig eller till och med omöjlig att genomföra kan olika alternativa metoder användas. Simuleringsträning kombinerad med en skattningsmodell av verkligheten är ett alternativ som har olika utmaningar kopplade till klyftan mellan simulering och verkligheten (eng. reality gap). I denna avhandling implementeras en lösning baserad på Bayesiansk Optimering med syftet att anpassa miljön som domänrandomisering sker i för att förbättra kvaliteten på simuleringsträningen. Resultatet visar att Bayesiansk Optimering kan användas för att hitta ett urval av fungerande parametrar även när tillgången till den faktiska verkligheten är begränsad. Två skattningsmodeller baserade på invers propensitetsviktning och direktmetodutvärdering i kombination med ett tidigare insamlat dataset av nätverksdata testades. Den tillämpade metoden lyckas hitta ett isolerat delrum av parameterrymden som optimerar randomiseringen samtidigt som prestationen i verkligheten hålls på en god nivå.

El mundo de las telecomunicaciones está cambiando de un escenario donde únicamente las personas estaban conectadas a un modelo donde prácticamente todos los dispositivos y sensores se encuentran conectados, también conocido como Internet de las cosas (IoT), donde miles de millones de dispositivos se conectarán a Internet a través de conexiones móviles y redes fijas. En este contexto, hay muchos retos que superar, desde el desarrollo de nuevos estándares de comunicación al estudio de la viabilidad económica de los posibles escenarios futuros. En esta tesis nos hemos centrado en el estudio de la viabilidad económica de diferentes escenarios mediante el uso de conceptos de microeconomía, teoría de juegos, optimización no lineal, economía de redes y redes inalámbricas. La tesis analiza la transición desde redes centradas en el servicio de tráfico HTC a redes centradas en tráfico MTC desde un punto de vista económico. El primer escenario ha sido diseñado para centrarse en las primeras etapas de la transición, en la que ambos tipos de tráfico son servidos bajo la misma infraestructura de red. En el segundo escenario analizamos la siguiente etapa, en la que el servicio a los usuarios MTC se realiza mediante una infraestructura dedicada. Finalmente, el tercer escenario analiza la provisión de servicios basados en MTC a usuarios finales, mediante la infraestructura analizada en el escenario anterior. Gracias al análisis de todos los escenarios, hemos observado que la transición de redes centradas en usuarios HTC a redes MTC es posible y que la provisión de servicios en tales escenarios es viable. Además, hemos observado que el comportamiento de los usuarios es esencial para determinar la viabilidad de los diferentes modelos de negocio, y por tanto, es necesario estudiar el comportamiento y las preferencias de los usuarios en profundidad en estudios futuros. Específicamente, los factores más relevantes son la sensibilidad de los usuarios al retardo en los datos recopilados por los sensores y la cantidad de los mismos. También hemos observado que la diferenciación del tráfico en categorías mejora el uso de las redes y permite crear nuevos servicios empleando datos que, de otro modo, no se aprovecharían, lo cual nos permite mejorar la monetización de la infraestructura. También hemos demostrado que la provisión de capacidad es un mecanismo válido, alternativo a la fijación de precios, para la optimización de los beneficios de los proveedores de servicio. Finalmente, se ha demostrado que es posible crear roles específicos para ofrecer servicios IoT en el mercado de las telecomunicaciones, específicamente, los IoT-SPs, que proporcionan servicios basados en sensores inalámbricos utilizando infraestructuras de acceso de terceros y sus propias redes de sensores. En resumen, en esta tesis hemos intentado demostrar la viabilidad económica de modelos de negocio basados en redes futuras IoT, así como la aparición de nuevas oportunidades y roles de negocio, lo cual nos permite justificar económicamente el desarrollo y la implementación de las tecnologías necesarias para ofrecer servicios de acceso inalámbrico masivo a dispositivos MTC. / The communications world is moving from a standalone devices scenario to a all-connected scenario known as Internet of Things (IoT), where billions of devices will be connected to the Internet through mobile and fixed networks. In this context, there are several challenges to face, from the development of new standards to the study of the economical viability of the different future scenarios. In this dissertation we have focused on the study of the economic viability of different scenarios using concepts of microeconomics, game theory, non-linear optimization, network economics and wireless networks. The dissertation analyzes the transition from a Human Type Communications (HTC) to a Machine Type Communications (MTC) centered network from an economic point of view. The first scenario is designed to focus on the first stages of the transition, where HTC and MTC traffic are served on a common network infrastructure. The second scenario analyzes the provision of connectivity service to MTC users using a dedicated network infrastructure, while the third stage is centered in the analysis of the provision of services based on the MTC data over the infrastructure studied in the previous scenario. Thanks to the analysis of all the scenarios we have observed that the transition from HTC users-centered networks to MTC networks is possible and that the provision of services in such scenarios is viable. In addition, we have observed that the behavior of the users is essential in order to determine the viability of a business model, and therefore, it is needed to study their behavior and preferences in depth in future studios. Specifically, the most relevant factors are the sensitivity of the users to the delay and to the amount of data gathered by the sensors. We also have observed that the differentiation of the traffic in categories improves the usage of the networks and allows to create new services thanks to the data that otherwise would not be used, improving the monetization of the infrastructure and the data. In addition, we have shown that the capacity provision is a valid mechanism for providers' profit optimization, as an alternative to the pricing mechanisms. Finally, it has been demonstrated that it is possible to create dedicated roles to offer IoT services in the telecommunications market, specifically, the IoT-SPs, which provide wireless-sensor-based services to the final users using a third party infrastructure. Summarizing, this dissertation tries to demonstrate the economic viability of the future IoT networks business models as well as the emergence of new business opportunities and roles in order to justify economically the development and implementation of the new technologies required to offer massive wireless access to machine devices. / El món de les telecomunicacions està canviant d'un escenari on únicament les persones estaven connectades a un model on pràcticament tots els dispositius i sensors es troben connectats, també conegut com a Internet de les Coses (IoT) , on milers de milions de dispositius es connectaran a Internet a través de connexions mòbils i xarxes fixes. En aquest context, hi ha molts reptes que superar, des del desenrotllament de nous estàndards de comunicació a l'estudi de la viabilitat econòmica dels possibles escenaris futurs. En aquesta tesi ens hem centrat en l'estudi de la viabilitat econòmica de diferents escenaris per mitjà de l'ús de conceptes de microeconomia, teoria de jocs, optimització no lineal, economia de xarxes i xarxes inalàmbriques. La tesi analitza la transició des de xarxes centrades en el servici de tràfic HTC a xarxes centrades en tràfic MTC des d'un punt de vista econòmic. El primer escenari ha sigut dissenyat per a centrar-se en les primeres etapes de la transició, en la que ambdós tipus de tràfic són servits davall la mateixa infraestructura de xarxa. En el segon escenari analitzem la següent etapa, en la que el servici als usuaris MTC es realitza per mitjà d'una infraestructura dedicada. Finalment, el tercer escenari analitza la provisió de servicis basats en MTC a usuaris finals, per mitjà de la infraestructura analitzada en l'escenari anterior. Als paràgrafs següents es descriu amb més detall cada escenari. Gràcies a l'anàlisi de tots els escenaris, hem observat que la transició de xarxes centrades en usuaris HTC a xarxes MTC és possible i que la provisió de servicis en tals escenaris és viable. A més a més, hem observat que el comportament dels usuaris és essencial per a determinar la viabilitat dels diferents models de negoci, i per tant, és necessari estudiar el comportament i les preferències dels usuaris en profunditat en estudis futurs. Específicament, els factors més rellevants són la sensibilitat dels usuaris al retard en les dades recopilats pels sensors i la quantitat dels mateixos. També hem observat que la diferenciació del tràfic en categories millora l'ús de les xarxes i permet crear nous servicis emprant dades que, d'una altra manera, no s'aprofitarien, la qual cosa ens permet millorar la monetització de la infraestructura. També hem demostrat que la provisió de capacitat és un mecanisme vàlid, alternatiu a la fixació de preus, per a l'optimització dels beneficis dels proveïdors de servici. Finalment, s'ha demostrat que és possible crear rols específics per a oferir servicis IoT en el mercat de les telecomunicacions, específicament, els IoT-SPs, que proporcionen servicis basats en sensors inalàmbrics utilitzant infraestructures d'accés de tercers i les seues pròpies xarxes de sensors. En resum, en aquesta tesi hem intentat demostrar la viabilitat econòmica de models de negoci basats en xarxes futures IoT, així com l'aparició de noves oportunitats i rols de negoci, la qual cosa ens permet justificar econòmicament el desenrotllament i la implementació de les tecnologies necessàries per a oferir servicis d'accés inalàmbric massiu a dispositius MTC. / Sanchis Cano, Á. (2018). Economic analysis of wireless sensor-based services in the framework of the Internet of Things. A game-theoretical approach [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/102642