The Decision Feedback Equalizer (DFE) is a known method of channel equalization which has performance superiority over linear equalizer. The best performance of DFE is obtained, commonly, with training period which is used for initial acquisiton of channel or recovering changes in the channel. The training period requires a training sequence which reduces the bit transmission rate or is not possible to send in most of the situations. So, it is desirable to skip the training period. The Unsupervised (Blind) DFE (UDFE) is such a DFE scheme which has no training period. The UDFE has two modes of operation. In one mode, the UDFE uses Constant Modulus Algorithm (CMA) to perform channel acquisition, blindly. The other mode is the same as classical decision-directed DFE. This thesis compares the performances of the classical trained DFE method and the UDFE. The performance comparison is done in some channel environments with the problem of timing error present in the received data bearing signal. The computer aided simulations are done for two stationary channels, a time-varying channel and a frequency selective Rayleigh fading channel to test the performance of the relevant equalizers. The test results are evaluted according to mean square error (MSE), bit-error rate (BER), residual intersymbol interference (RISI) performances and equalizer output diagrams. The test results show that the UDFE has an equal or, sometimes, better performance compared to the trained DFE methods. The two modes of UDFE enable it to solve the absence of training sequence.

This thesis presents various studies on energy efficient design of wireless networks. It starts with a survey on recent shortest path based energy efficient routing algorithms developed for ad hoc and sensor networks, making a comprehensive classification for these algorithms. In addition to energy efficient design, sustainable and environmentally friendly deployment of wireless networks demands increased use of renewable energy. However, this calls for novel design principles to efficiently utilize the variation in the availability of the energy. The thesis continues with an investigation of state-of-the-art resource management and scheduling algorithms developed for energy harvesting wireless sensor networks. Building on the stateof- the-art, the main contribution of this thesis is to formulate and solve a utility maximizing scheduling problem in a multiuser broadcast channel with an energy harvesting transmitter. The goal is to determine the optimal power and time allocations to users between energy arrivals. The structural properties of the problem are analyzed, and its biconvexity is proved. A Block Coordinate Descent (BCD) based algorithm is developed to obtain the optimal solution. Two simple and computationally scalable heuristics, PTF and ProNTO, which mimic the characteristics of the optimal policy, are proposed. Finally, an online algorithm, PTF-On,that will bypass the need for offline knowledge about the energy harvesting statistics, is developed. PTF-On uses a Kalman filter based energy harvesting prediction algorithm, developed in this thesis, to predict the energy that will arrive in the future.

Staggering the pulse repetititon intervals is a widely used solution to alleviate the blind speed problem in Moving Target Indication (MTI) radar systems. It is possible to increase the first blind speed on the order of ten folds with the use of non-uniform sampling. Improvement in blind speed results in passband fluctuations that may degregade the detection performance for particular Doppler frequencies. Therefore, it is important to design MTI filters with non-uniform interpulse periods that have minimum passband ripples with sufficient clutter attenuation along with good range and blind velocity performance. In this thesis work, the design of MTI filters with non-uniform interpulse periods is studied through the least square, convex and min-max filter design methodologies. A trade-off between the contradictory objectives of maximum clutter suppression and minimum desired signal attenuation is established by the introduction of a weight factor into the designs. The weight factor enables the adaptation of MTI filter to different operational scenarios such as the operation under low, medium or high clutter power. The performances of the studied designs are investigated by comparing the frequency response characteristics and the average signal-to-clutter suppression capabilities of the filters with respect to a number of defined performance measures.Two further approaches are considered to increase the signal-to-clutter suppression performance. First approach is based on a modified min-max filter design whereas the second one focuses on the multiple filter implementations. In addition, a detailed review and performance comparison with the non-uniform MTI filter designs from the literature are also given.

Sjukvårdsrådgivning via telefon har blivit allt vanligare i västvärlden. Tekniska lösningar har utarbetas som underlättar för de döva att själva kontakta sjukvården via telefon. Sjuksköterskor inom primärvården kommunicerar då med de döva via text- eller bildtelefoni. Studiens syfte var att beskriva döva och sjuksköterskors erfarenheter och upplevelser av sjukvårdsrådgivning via telefon. Sex sjuksköterskor och fem döva intervjuades med öppna frågor. Resultatet analyserades med konventionell innehållsanalys. Resultatet visar att för sjuksköterskorna är det mest framträdande upplevelsen av svårigheter att förstå och bli förstådd. För de dövas är det viktigaste att de, trots olika tekniska lösningar, har svårigheter att få kontakt med vårdcentralerna. Båda grupperna är eniga om att språket, den skrivna svenskan, kan vara en svårighet, särskilt för de äldre döva. För att komma förbi hindren och nå målen har båda grupperna utvecklat olika strategier. En gemensam strategi är att då kommunikationen via telefon upplevs som otillräcklig, planeras för ett personligt möte tillsammans med tolk. Svårigheterna att få kontakt gjorde att de döva ibland dröjde med att söka vård. Sjuksköterskorna upplevde att de döva som grupp, ibland var sjukare då de tog kontakt, än patientgruppen i stort. Båda grupperna framförde en oro för vad som kan hända vid allvarliga tillstånd om kontakt och förståelse inte fungerar tillfredställande. Konklusionen indikerar att kontaktvägarna till primärvården måste förbättras för de döva. Möjligheten förden döve och sjuksköterskan att kommunicera på sitt förstaspråk underlättar förståelsen och den möjligheten behöver utvecklas. Vårt resultat bör kunna utgöra ett underlag för förbättringsarbete och fortsatt forskning inom området.

In this work, a novel method is proposed to optimize the array geometry for DOA estimation. The method is based on minimization of fine error variances with the constraint that the gross error probability is below a certain threshold. For this purpose, a metric function that reflects the gross and fine error characteristics of the array is offered. Theoretical analyses show that the minimization of this metric function leads to small DOA estimation error variance and small gross error probability. Analyses have been carried out under the assumptions of planar array geometry, isotropic array elements and AWGN. Genetic algorithm is used as an optimization tool and performance simulation is performed by comparing the DOA estimation errors of optimized array to a uniform circular array (UCA). Computer simulations support the theoretical analyses and show that the method proposed leads to significant improvement in array geometry in terms of DOA estimation performance.

In coherent receivers, the effect of the multipath fading channel on the transmitted signal must be estimated to recover the transmitted data. In this thesis, the channel phase and data estimation problems are investigated in a transmitted data sequence when the channel is modeled as slowly fading, frequency non-selective channel. Channel phase estimation in a transmitted data sequence is investigated and data estimation is obtained in a symbol-by-symbol MAP receiver that is designed for minimum symbol error probability criterion. The channel phase is quantized in an interval of interest, the trellis diagram is constructed and Viterbi decoding algorithm is applied that uses the phase transition and observation models for channel phase estimation. The optimum coherent and noncoherent detectors for binary orthogonal and PSK signals are derived and the modulated signals in a sequence are detected in symbol-by-symbol MAP receivers.Simulation results have shown that the performance of the receiver with phase estimation is between the performance of the optimum coherent and noncoherent receiver.

The demand for faster data transmission has been increasing since the wide acceptance of the Internet. To meet this ever increasing demand, optical communication systems use Wavelength Division Multiplexing (WDM) to transport more information per fiber by utilizing multiple wavelength channels. Multi-wavelength laser sources are one of the most important components of such WDM systems. In this thesis a multi-wavelength laser source is proposed. A fiber Sagnac loop filter is used to produce a grid pattern with peaks at a certain set of wavelengths. Then any desired channel is chosen from the grid by using an adjustable Fiber Bragg Grating.

In this study, emitter identification techniques have been investigated and a schema has been proposed to solve the emitter identification problem in Electronic Warfare systems. Clustering technique, histogram based deinterleaving techniques and a continuous wavelet transform based deinterleaving technique have been reviewed. A receiver simulator software has been developed to test the performance of these techniques and to compare them against each other. To compensate the disadvantages of these techniques, a schema utilizing the beneficial points of them has been developed. With the modifications proposed a resultant schema has been obtained. Proposed schema uses clustering and deinterleaving together with other proposed modifications. Tests made through out this study have shown that this usage improves performance of emitter identification system. Hence, proposed schema can be used to identify the emitters in real EW systems.

In this thesis work, the implementations of the monopulse amplitude comparison and phase comparison DF algorithms are performed on an FPGA platform. After the mathematical formulation of the algorithms using maximum-likelihood approach is done, software simulations are carried out to validate and find the DF accuracies of the algorithms under various conditions. Then the algorithms are implemented on an FPGA platform by utilizing platform specific software tools. Block diagrams of the hardware implementations are given and explained in detail. Then simulations of hardware implementation of both algorithms are performed. Using the results of the simulations, DF accuracies under certain conditions are evaluated and compared to software simulations results.

The characteristics of slotted circular waveguides with different dimensions, including cutoff frequencies of TE and TM modes, impedance and modal field distributions will be analyzed using the generalized spectral domain approach. The Method of Moment will be applied, basis functions that include the edge conditions will be used and a computer program will be developed. Obtained results will be presented for different number, depth and thickness of coupling slots, and compared with available data to demonstrate the accuracy and the efficiency of the approach. Plots of the electric and magnetic field lines corresponding to the dominant as well as a number of higher order modes will be presented for quadruple ridge case.