Abstract
This work considers the problem of segmenting heart sounds into their fundamental components. We unify statistical and data-driven solutions by introducing Markov-based Neural Networks (MNNs), a hybrid end-toend framework that exploits Markov models as statistical inductive biases for an Artificial Neural Network (ANN) discriminator. We show that an MNN leveraging a simple onedimensional Convolutional ANN significantly outperforms two recent purely data-driven solutions for this task in two publicly available datasets: PhysioNet 2016 (Sensitivity: 0.947 +/- 0.02; Positive Predictive Value : 0.937 +/- 0.025) and the CirCor DigiScope 2022 (Sensitivity: 0.950 +/- 0.008; Positive Predictive Value: 0.943 +/- 0.012). We also propose a novel gradient-based unsupervised learning algorithm that effectively makes the MNN adaptive to unseen datum sampled from unknown distributions. We perform a cross dataset analysis and show that an MNN pre-trained in the CirCor DigiScope 2022 can benefit from an average improvement of 3.90% Positive Predictive Value on unseen observations from the PhysioNet 2016 dataset using this method.

Abstract
This paper presents a frequency offset estimation approach to ultra wide band Impulse Radio (UWB-IR) systems based upon the classical idea by Schmidl and Cox. The approach secures low complexity by exploiting the low duty cycle of the time hopping access, assures estimation robustness for all UWB-IR bands by working in the frequency domain, attains quasi optimal performances (at 0.5 dB from the Cramer Rao lower bound) by a careful settings choice, and accomplishes robustness at low signal to noise ratio by a suitable combining algorithm. Performance in a realistic IEEE 802.15.4a scenario are also provided. © 2009 IEEE.

Abstract
Ultra Wide Band (UWB) systems based on Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) modulation, similarly to traditional OFDM systems, are particularly sensitive to oscillators instability, as carrier and sampling frequency offsets between the transmitter and the receiver destroy the subchannel orthogonality. Precise carrier and sampling frequency offsets estimation and compensation at the receiver side are therefore necessary, and should use methods with moderate complexity due to the high system transmission rates that require fast acquisition times. We formulate algorithms that are based upon the received frequency domain symbols, where the effect of both offsets can be observed, and jointly estimate them with either a linear least squares or maximum likelihood approach. The performance of the algorithms is assessed through simulation in a realistic UWB channel scenario and compared with previous literature results.

Abstract
A novel analytical Gaussian approximation is developed for the evaluation of the distortion spectrum introduced by a nonlinear amplifier. This method allows to consider high-order distortion contributions when the device is driven by a broadband signal with Gaussian amplitude distribution. The results are applied to a ninth-order power series model based on well known single-tone and two-tone analysis parameters. The cascade of two or more amplifiers is investigated as well providing a complete set of tools for the early system specification of broadband transceivers. Simulations shows excellent agreement even for high input power levels, when former third-order and fifth-order approximations fail to yield accurate predictions. © 2008 IEEE.

Abstract
A Simulink blockset for the fast evaluation of the non linear distortion caused by RF amplifiers, mixers and BaseBand amplifiers in broadband transmission systems such as the orthogonal frequency division multiplexing (OFDM) adopted in the WLAN or more recently in the UWB standard is presented. Each amplifier block within the tool is described by a ninth-order power series extracted from classical one-tone and two-tones parameters. The distortion description is directly deduced from the spectral analysis of the system, thus avoiding the need for time consuming, time domain simulations and providing a powerful tool for the fast evaluation of the design requirements. A Gaussian approximation is adopted to simplify calculations for high order distortion terms spectra. The blocks within the tool can be cascaded providing analytical predictions for the chain of two or more amplifiers as well. A simulation comparison to a time domain simulator proves that the model keeps reliable up to very high input power levels, outperforming former third-order and fifth-order power series approximations in the literature. ©2008 IEEE.

Abstract
Orthogonal Frequency Division Multiplexing (OFDM) systems guarantee transmissions free from intersymbol interference (ISI) and interchannel interference (ICI) over frequency selective channels, provided that the channel delay spread is less than the duration of the cyclic-prefix (or the zero-padding guard interval). However, it is realistic to consider practical implementation scenarios in which the channel delay spread exceeds this limit so that both ISI and ICI do arise. We show that in such cases, the objective of symbol synchronization should be to maximize the ratio of the total useful received power over all subcarriers to the total power of ISI and ICI for the given channel realization, and that this aim can be achieved through a proper choice of the symbol timing. We also present a practical low-complexity synchronization scheme for this case and show that its performance tops the results obtained by the best existing correlation-based timing estimators. Furthermore, we determine upper bounds on the achievable signal-to-interference ratio based on the ideal assumptions of either perfect channel state information or at least knowledge of the channel statistical description, and show that they are very closely approached by the proposed method. © 2009 IEEE.