<p>Motivated by current applications in multihop transmission and ad hoc networks, the classical three-node relay channel consisting of a source-destination pair and a relay has received significant attention. One of the crucial aspects of the relay channel is the design of proper relaying protocols, i.e., how the relay should take part into transmission. The thesis addresses this problem and provides a partial answer to that.</p><p>In this thesis, we propose and study two novel relaying protocols. The first one is based on constellation rearrangement (CR) and is suitable for higher-order modulation schemes. With CR, the relay uses a bit-symbol mapping that is different from the one used by the source. We find the optimal bit-symbol mappings for both the source and the relay and the associated optimal detectors, and show that the improvement over conventional relaying with Gray mapping at the source and the relay can amount to a power gain of several dB. This performance improvement comes at no additional power or bandwidth expense, and at virtually no increase in complexity. The second one is a half-duplex decode-and-forward (DF) relaying scheme based on partial repetition (PR) coding at the relay. With PR, if the relay decodes the received message successfully, it re-encodes the message using the same channel code as the one used at the source, but retransmits only a fraction of the codeword. We analyze the proposed scheme and optimize the cooperation level (i.e., the fraction of the message that the relay should transmit). We compare our scheme with conventional repetition in which the relay retransmits the entire decoded message, and with parallel coding, and additionally with dynamic DF. The finite SNR analysis reveals that the proposed partial repetition can provide a gain of several dB over conventional repetition. Surprisingly, the proposed scheme is able to achieve the same performance as that of parallel coding for some relay network configurations, but at a much lower complexity.</p><p>Additionally, the thesis treats the problem of resource allocation for collaborative transmit diversity using DF protocols with different type of CSI feedback at the source. One interesting observation that emerges is that the joint powerbandwidth allocation only provides marginal gain over the relaying protocols with optimal bandwidth allocation. </p>

In wireless Communication, the need of radio spectrum increases nowadays. But in the system we are losing approximately 82-86% of spectrum most of the time due to the absence of Primary User (PU). To overcome this issue Cognitive Radio (CR) is an admirable approach. The concept of cooperative communication needs to be considering because high data rate is the demand for wireless services. Cooperative diversity in the network realized by 3-hop Decode, Amplify and Forward (DAF) and Decode and Forward (DF) and in 2-hop DF and Amplify and Forward (AF) Protocols implemented in cognitive radio communication network using Orthogonal Space Time Block Coding (OSTBC). The communication between end points is accomplished by using Multiple Input and Multiple Output (MIMO) antenna arrangement. During the Propagation, Alamouti Space Time Block Coding is used to accomplish spatial diversity and the encoded data is transmitted through Rayleigh fading channel. CR decodes the transmitted signal using Maximum Likelihood (ML) decoding method. Afterward signal broadcast toward the destination. To check the energy level of signal, energy detection technique applies at the Cognitive Controller (CC). Finally, CC will take ultimate decision for the presence of primary user if the energy level of signal is greater than predefined threshold level, it means PU is present otherwise it is absent. The main objective of this thesis is to analyze the performance of 3-hop and 2-hop communication network using relays. The performance is compared on the bases of two parameters i.e. Bit Error Rate (BER) and Probability of Detection (PD). The results are processed and validated by MATLAB simulation.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / A field programmable gate array (FPGA) is used to decode Inter-Range Instrumentation Group (IRIG) time code for a PC-based Time-Space-Position Information (TSPI) acquisition. The FPGA architecture can latch time via an external event trigger or a programmable periodic internal event. By syncing time with an external IRIG Group Type B (IRIG-B) signal and using an 8 megahertz (MHz) internal clock, captured time has 125 nanosecond (ns) precision. A Range Instrumentation Control System (RICS) application utilizing the FPGA design to capture IRIG time is presented and test results show matching time accuracy when compared to commercial IRIG time capture hardware components.

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In this dissertation we consider cooperative communication systems with relay conferencing, where the relays own the capabilities to talk to their counterparts via either wired or wireless out-of-band links. In particular, we focus on the design of conferencing protocols incorporating the half-duplex relaying operations, and study the corresponding capacity upper and lower bounds for some typical channels and networks models, including the diamond relay channels (one source-destination pairs and two relays), large relay networks (one source-destination pairs and N relays), and interference relay channels (two source-destination pairs and two relays). First, for the diamond relay channels, we consider two different relaying schemes, i.e., simultaneous relaying (for which the two relays transmit and receive in the same time slot) and alternative relaying (for which the two relays exchange their transmit and receive modes alternatively over time), for which we obtain the respective achievable rates by using the decode-and-forward (DF), compress-and-forward (CF), and amplify-and-forward (AF) relaying schemes with DF and AF adopted the conferencing schemes. Moreover, we prove some capacity results under some special conditions. Second, we consider the large relay networks, and propose a "p-portion" conferencing scheme, where each relay can talk to the other "p-portion" of the relays. We obtain the DF and AF achievable rates by using the AF conferencing scheme. It is proved that relay conferencing increases the throughput scaling order of the DF relaying scheme from O(log(log(N ))) for the case without conferencing to O(log(N )); for the AF relaying scheme, it achieves the capacity upper bound under some conditions. Finally, we consider the two-hop interference relay channels, and obtain the AF achievable rates by adopting the AF conferencing scheme and two different decoding schemes at the destination, i.e., single-user decoding and joint decoding. For the derived joint source power allocation and relay combining problem, we develop some efficient iterative algorithms to compute the AF achievable rate regions. Moreover, we compare the achievable degree-of-freedom (DoF) performance of these two decoding schemes, and show that single-user decoding with interference cancellation at the relays is optimal.

God läsförmåga är en förutsättning för att kunna ta till sig information i vårt samhälle. För att uppnå läsförmåga krävs att kunna avkoda. När avkodningen blir svår behöver eleverna hjälp för att ta sig vidare.  Syftet med denna litteraturstudie är att belysa vad aktuell forskning säger om läsinlärningen hos elever i avkodningssvårigheter samt lärares betydelse för dessa elever, för att få kunskap inom området. För att uppfylla studiens syfte har följande frågeställningar formulerats:   Vilka orsaker kan ligga bakom avkodningssvårigheter hos elever? <ul type="disc">Hur kan lärare stötta elever som är i avkodningssvårigheter?   Studien som gjorts är en litteraturstudie. Olika vetenskapliga publikationer har använts, såsom vetenskapliga artiklar och avhandlingar bestående av både nationell och internationell forskning. Stegvis gjordes en noggrann analys av materialet. Dessutom har en bilaga varit underlag för studien.   Resultatet på första frågan visar att de elever som inte har den fonologiska medvetenheten är mest utsatta i sin läsutveckling. Vidare framkommer i resultatet hur elevers syn på sig själva är en bidragande faktor för läsutvecklingen. Även lärares brist på kunskaper om elevers läsinlärning framkommer som ett viktigt bidrag i studien. Resultatet på studiens andra fråga visar vikten av att agera skyndsamt. Eleverna behöver träna på den fonologiska medvetenheten för att befästa den alfabetiska koden. Vidare framkommer motivation, självförtroende samt vikten av att få beröm och uppmuntran som faktorer där elevers läsutveckling gynnas. Likaså har lärare en betydande roll vad gäller den egna kompetensen om läsinlärningen samt att ha ett variationsrikt arbetssätt i undervisningen. Slutsatsen som dras utifrån resultatet är att den fonologiska medvetenheten är viktig då den utgör grunden till avkodning. Den fonologiska medvetenheten uppnås genom variationsrik undervisning. Att återkommande uppmuntra och berömma eleverna bör vara lärares förhållningssätt. Lärares kompetens inom läsinlärningen utgör en viktig roll för att skapa en god undervisning.

Autorizado por el autor, pero con restricción para ser publicada a texto completo hasta el año 2011 / La presente memoria se realiza con el objetivo de diseñar y construir un prototipo para la interfaz de un Sistema Detector de Plagio en Documentos Digitales, con criterios de usabilidad, de modo que sea aceptado por los diferentes usuarios del sistema. En diversos estudios hechos alrededor del mundo, se muestra que entre un 40% y un 60% declara haber usado textos de internet sin indicar su procedencia, lo que es definido como plagio. Esto se condice con la tendencia mundial enunciada en los mismos estudios, que indica que el uso de internet para los informes escolares y universitarios ha facilitado que suceda plagio, especialmente en informes digitales. Las causas de este fenómeno son diversas, destacando el fácil acceso a la información y la ignorancia respecto de buenas prácticas para el desarrollo de informes escritos. Considerando el problema expuesto, se plantea que el desarrollo de un Sistema Detector de Plagio en Documentos Digitales para el idioma español, que tenga criterios de usabilidad y que sea insertado de manera adecuada en el proceso de asignación y entrega de informes escritos, será usado por los diferentes actores del proceso de modo de disminuir la ocurrencia del plagio, facilitando a los profesores la detección de éste y desincentivando la copia en los estudiantes. En la actualidad existen sistemas detectores de plagio, la mayoría de ellos diseñados para el idioma inglés, y enfocados en la detección de la copia textual. Lo anterior provoca que estos sistemas ignoren las complejidades del idioma español y no consideren otros tipos de plagio, como el que sucede al usar sinónimos o al cambiar el orden de las palabras. Basándose en la observación de los sistemas actuales y del proceso a intervenir, se diseña un sistema donde diferentes usuarios pueden acceder a informes de copia predeterminados. Se construye un prototipo de las interfaces que utilizarán los profesores y se aplica un Test de Usabilidad para evaluar la herramienta. En el test de usabilidad se encuentra que el 100% de los participantes se declara satisfecho con la herramienta, y se concluye que, si bien el prototipo es altamente usable, en especial por su facilidad de aprendizaje, existen espacios para mejorarlo. Para esto, se proponen cambios en la usabilidad y en el proceso del sistema, orientados a la simplificación de la herramienta. Se concluye que es mejor un sistema que sea independiente de cada establecimiento y enfocado principalmente en los Profesores, no siendo necesario levantar toda la información de cada colegio, centrándose en quiénes serán los usuarios del sistema y, al mismo tiempo, potenciales clientes. Así, se facilita que el sistema cumpla su principal objetivo: la detección de plagio.

The usage of wireless communication has increased over the past few years. Most wired communications are replaced by wireless communication for ease of use. Wireless communication transfers confidential information like personal information and credentials between two entities. We can't probably say that it is safe to send this information via wireless communication. As more data is sent, more attacks happen to steal the data. Hence, it is necessary to implement secure methods to transfer the data between source and receiver. In this communication channel, we use secrecy capacity as a parameter to measure how data is sent securely between source and destination. Generally, to achieve high system performance, the information is sent with low power, but this reduces the signal efficiency at the receiver. So, in this thesis, we have implemented cooperative transmission to increase the efficiency of low power signals by adding the relays between source and destination. This thesis consists of two relays. The relay that obtains the maximum signal-to-noise ratio is selected for the primary communication link. The other relay sends the signal to the eavesdropper to confuse the eavesdropper. In this thesis, we have derived the mathematical expression for SNR at receiver eavesdropper, and also we have derived a word for outage probability and secrecy capacity. Then, we simulated the Matlab code to obtain results on how the secrecy capacity affects by changing the various parameters like path loss exponent and fading severity parameter and suggests which environment is better to maintain high secrecy capacity. We also analysed the system performance and secrecy capacity in the presence of eavesdropper as well.

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