Sammanfattning Syftet i studien är att belysa musiklärarens dilemma i valet mellan musik som uttryck och musik som skolämne. I detta arbete presenteras hur den personliga utvecklingen över tid påverkar prioriteringar och didaktiska val i musiklärares identitetsskapande. Studien bygger på musiklärares livserfarenheter. Empirin omfattar djupintervjuer med tre musiklärare vilka har många års erfarenhet av undervisning i musik. Deras berättelser tolkades och bearbetades utifrån ett sociokulturellt perspektiv för att skapa förståelse för hur de i sin yrkesroll identifierar sig själva som musiker och/eller musiklärare. Vidare hur detta identitetsskapande fått betydelse för musikundervisningen. Resultatet beskriver det frirum och handlingsutrymme lärarna upplever finns i deras praktikmiljö och skapas för musikundervisning. I resultatet framkommer att lärarna pendlar mellan musikerrollen och lärarrollen. Vidare att de utifrån styrdokumenten och sin sociala hemvist ofta uttrycker sin upplevelse av musikens och musicerandets djupare dimension och effekterna därav i deras undervisning. Detta visar hur dilemmat i valet mellan musik som uttryck och musik som skolämne ständigt är närvarande i musikläraryrket. / Abstract The purpose of the study is to shed light on the music teacher's dilemma in the choice between music as expression and music as school subject. This work presents how personal development over time affects priorities and didactic choices for music teachers' identity creation. The study describes three music teachers' life experiences. The method conducted was as in-depth interviews with three music teachers, who have many years of experience in teaching music. Their life stories were interpreted and processed from a socio-cultural perspective with the aim to understand how they in their professional role identify themselves as musicians and/or music teachers. The result shows that a teacher´s identity creation is important for music education. The teacher´s in this study describes how the free space and space of action effect their internship environment and subject for music teaching. The result shows that the teachers commute between the role of musician and the role of teacher. Furthermore, based on the governing documents and their social domicile, they often express their experience of the deeper dimension of music and making music and the effects thereof in their teaching. This shows how the dilemma in the choice between music as expression and music as school subject is constantly present in the music teaching profession.

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The goal of this work is to investigate and advance a research on various topics, vital for the development of the future generations of optical communication technology. In the first part of the work, we present a fast and efficient simulation method of structured light free space optics (FSO) channel effects from propagation through the turbulent atmosphere. Information content encoded on the information-bearing beams relevant to the propagation in the context of the direct detection can be expressed in the form of the decomposition matrix at the receiver. To construct these matrices outside of the experiment, a complete physical simulation of some sort needs to occur. Due to the model assumptions, current beam generation techniques based on the phase-screen approximation method can be very slow and are fundamentally limited in their predictive power. We propose to circumvent that with a data-driven approach for decomposition matrix simulation with a Conditional Generative Adversarial Network (CGAN) synthetic simulator. In the second part, we focus on predicting the beam wander of the beam subject to turbulence at the receiver. We present an Recurrent Neural Network - based simulator, designed to predict the future beam wander position based on the previous measurements. The Recurrent Neural Network (RNN) architecture and training method are described. The proposed approach is demonstrated using under-sampled Gaussian beam experimental data as the worst case and over-sampled simulated data for both Gaussian beams and structured light beams as the best case. In the final part of this work, we discuss the Kramers - Kronig receiver, recently proposed promising pseudo-coherent communication scheme. We detail the operating procedure and developed simulation of this scheme, and provide both experimental and simulation results. In experiment, we present a case of proof-of-concept joint sensing and communication over an optical fiber. In simulation, we present a BER analysis of a KK NN decoder in presence of log-normal turbulence and AWGN.

Free-space optical communication (FSO) has been proposed as an attractive alternative to radio frequency communication in the sense that it provides wide bandwidth and high capacity without requirement of license. However, the scalability of FSO link is limited by pointing error, atmospheric turbulence, and loss. Especially, when it comes to the FSO link between moving platforms, it is imperative works to analyze the statistical channel model considering accurate pointing errors and atmospheric turbulence at the same time. In this paper, we analyze performance of FSO links over various atmospheric situations with pointing errors. First, we assume strong turbulence and obtain a unified approximation of the composite probability density function (PDF) of channel gain, which embraces generalized pointing error models. This approximation leads to new unified formulas for the bit error rate (BER) and outage capacity of a FSO link, which account for the two possible detection mechanisms of intensity modulation/direct detection (IM/DD) and heterodyne detection. Secondly, we statistically derive the unified composite PDF containing all possible pointing error models based on weak turbulence model. In addition, we analyze BER performance in FSO communication with IM/DD and heterodyne detection technology based on the derived unified composite PDF results. Finally, we investigate the ergodic capacity of unmanned aerial vehicle (UAV)-based FSO links over random foggy channel. More specifically, we derive composite PDF and close approximation for the moments of the composite PDF using the statistical model of a UAV-based 3D pointing error and a random foggy channel. With it, we obtain upper bound and asymptotic approximation of the ergodic capacity for the two possible detection techniques of IM/DD and heterodyne detection at high and low signal-to-noise ratio (SNR) regimes.

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<p>Free-space optical (FSO) communication has witnessed rapid development recently in response to ever-increasing demands for greater bandwidth. FSO links provide fiberspeed with the flexibility of wireless. Commercially available systems offer transmission speeds up to 2.5 Gbps, 5 Gbps and 10 Gbps, and demonstration systems report data rates as high as 160 Gbps. Its advantages also include license free operation, high immunity to interference, and ease of deployment. However, FSO systems are sensitive to adverse weather conditions such as fog, rain and snow.</p> <p>In order to improve the availability of FSO channels degraded by atmospheric turbulence and varying weather conditions, the effects of channel gain variations must be compensated. In this thesis, two rate-adaptive techniques, punctured low-density parity-check (LDPC) codes and Raptor codes, are studied using experimental data measured over a1.87 km terrestrial FSO link.</p> <p>Rate-adaptive performances with punctured LDPC codes and Raptor codes are evaluated in terms of outage probability and throughput. In comparison to uncoded system, rate-adaptive systems with both techniques demonstrate significant improvement of throughput and mitigation of outage probability especially in rainy weather. Due to its flexible rate-adaptation and simple hardware implementation, Raptor coded systems are judged more applicable to be implemented in field-programmable gate array (FPGA) based hardware. A dedicated decoding structure is proposed and tested, showing remarkable improvement in resource efficiency as compared to traditional Gauss-Jordan (GJ) decoding structures.</p> / Master of Applied Science (MASc)

<p> Wireless LAN mesh networks (WMNs) are a cost effective way of deploying wireless LAN (WLAN) coverage over extended areas. As WMNs become more populated, scalability issues may arise due to the co-channel interference which is inherent in publicly available RF (radio frequency) channels. This co-channel interference can severely degrade network capacity and link reliability and may eventually make it impossible to operate with the frequency channels for which the network was originally designed. In this thesis, this problem is addressed by selectively installing supplementary free-space optical (FSO) links when RF link performance has deteriorated. The frequency assignment problem is solved using a heuristic technique based on a genetic algorithm. In order to determine the quality of the results, the proposed algorithm is compared with a lower bound solution obtained using an Integer Linear Programming (ILP) formulation.</p> <p> Another advantage of FSO links is that they may reduce node power consumption compared with conventional RF links. This may be an important consideration in cases where power consumption at the nodes is important, such as in solar powered mesh networks. Power consumption estimates of RF and FSO links are obtained and compared for different data rates. This data is then used along with historical solar insolation data to estimate the solar panel and battery sizes required to guarantee a given node outage probability. The results show that no extra provisioning is required for replacing the deployed wireless nodes with new FSO links.</p> / Thesis / Master of Applied Science (MASc)