A major goal in distant-speech recognition is to transform speech signals of a target speaker into symbols in order to trigger a dialog manager. Spatio-temporal filters, so called beamformers, usually enhance the target speaker’s speech signals in a noisy and reverberant environment. However, a beamformer requires information on the target speaker’s position. A source localizer…
The central topic of this thesis is Reverberation. Reverberation is used as a global term to describe a series of physical and perceptual phenomena that occur in enclosed environments and relate to the acoustical interaction between a sound source and the enclosure. This work focuses on the effects of reverberation that are likely to occur…
This work is concerned with two image-processing problems, image deconvolution with incomplete observations and data fusion of spectral images, and with some of the algorithms that are used to solve these and related problems. In image-deconvolution problems, the diagonalization of the blurring operator by means of the discrete Fourier transform usually yields very large speedups….
This dissertation presents the outcome of investigations which envisaged to develop improved state and ?combined state and parameter? estimation algorithms for nonlinear signal models (during the contingent situations) where the complete knowledge of process and/or measurement noise covariance are not available. Variants of ?adaptive nonlinear estimators? capable of providing satisfactory estimation results in the face…
The use of low-cost CubeSats in the context of satellite formation flying appears favourable due to their small size, relatively low launch cost, short development cycle and utilisation of commercial off the shelf components. However, the task of managing complex formations using a large number of satellites in Earth orbit is not a trivial one,…
The fabrication of miniature electronics and sensors has encouraged the creation of a wide range of wireless enabled devices designed to be worn on the human body. This has led to the prominence of so-called wearable communications, which have emerged to satisfy the demand for wireless connectivity between these devices and with external networks. The…
Future wireless networks are envisioned to accommodate the heterogeneous needs of entirely different systems. New services obeying various constraints will coexist with legacy cellular users in the same frequency band. This coexistence is hardly achievable with OFDM, the physical layer used by current systems, because of its poor spectral containment. Thus, a myriad of multi-carrier…
When the noise affecting time series is colored with unknown statistics, a difficulty for periodic signal detection is to control the true significance level at which the detection tests are conducted. This thesis investigates the possibility of using training datasets of the noise to improve this control. Specifically, for the case of regularly sampled observations,…
Nowadays, energy efficiency (EE) for wireless communications is becoming a main economical and societal challenge. This thesis studies resource allocation (RA) in EE optimized wireless communication systems for various system models. The main body of this thesis consists of three parts. In the first part, EE optimization is studied in multiple input multiple output (MIMO)-orthogonal…
The provision of accurate positioning is becoming essential to our modern society. One of the main reasons is the great success and ease of use of Global Navigation Satellite Systems (GNSSs which has led to an unprecedented amount of GNSS-based applications. In particular, the current trend shows that a new era of GNSS-based applications and…
