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The radio access technology for railway communications is expected to migrate from GSM for Railways (GSM-R) to a more suitable generation of communication systems for the services offered nowadays, like the fourth generation (4G) or the fifth generation (5G). Recently, considerable attention has been devoted to high-speed trains since this particular environment poses challenging problems in terms...
Time-Modulated Arrays (TMAs) perform angular diversity through the adaptive beamforming of their harmonic patterns with the advantage of employing a single Radio Frequency (RF) front-end. Rectangular pulses typically used in TMAs are not the best ones to efficiently distribute the spectral energy among the harmonics exploited. We propose a family of pulses, the so-called Sum of Weighted Cosines (SWC),...
LTE is designed to support user velocities of up to 500 km/h where experiments are expensive, time-consuming and dangerous. Fortunately, such experiments can be emulated at lower velocities by time-stretching the transmit signals. This method preserves the spatial properties of the mobile radio channel but performs a spectral compression. In this paper, we propose a new set of methods that preserve...
In this work, an evaluation of the fourth generation (4G) waveform performance in underground tunnel scenarios has been carried out with the help of hardware testbeds. The equipment for the measurements has been deployed inside the carriage of an underground train, and the antenna elements were located both outside and inside the carriage. The experiments consisted of narrowband and wideband propagation...
Railway and telecommunication companies have showed a great interest in deploying broadband mobile wireless networks in high-speed trains with the aim of supporting both provisioning of passenger services and automatic train control and signaling. This motivates the study of broadband wireless communications between a base-station transmitter and a mobile receiver whose antennas are placed on the...
We study the performance of a Digital Communication System (DCS) when transmitting over a multipath wireless channel and using a Time-Modulated Array (TMA) at the receiver. We show that the TMA Sideband Radiation can be usefully exploited to extract the angle diversity from the wireless channel. Such angle diversity is used to combine the signals at the TMA output to improve the performance of the...
Modern wireless communication systems, such as WiMAX, rely on Orthogonal Frequency Division Multiplexing, a very robust modulation against frequency-selectivity, but very sensitive to time-selectivity, which is a typical feature in mobility scenarios. In this work, experimental measurements in real scenarios are carried out by employing WiMAX signals including the standard-compliant pilot signals...
In this work we consider the optimization of the power assigned to the user streams in a coordinated base station downlink environment with Orthogonal Frequency Division Modulation (OFDM). In this scenario the base stations perform distributed cooperative processing with a block diagonalization scheme to remove interference among users. Two schemes based on the waterfilling technique are proposed...
Recently, analog joint source-channel coding has been proposed as a means of achieving near-optimum performance for high data rates with a very low complexity. However, no experimental evaluation showing the practical feasibility of this scheme has been performed to date. In this paper, we describe a software-defined radio implementation of an analog joint source-channel coded wireless transmission...
In this work, we present physical layer throughput measurement results of a WiMAX link implemented according to IEEE 802.16-2004. The measurements were carried out in an alpine and an urban scenario using the Vienna MIMO Testbed. We compare the measured throughput to three different theoretical bounds: 1) the channel capacity, 2) the mutual information, and 3) a so-called ??achievable throughput??...
Recent endocardial mapping systems reconstruct an instantaneous image of the endocardial electrical activity performing the inverse problem of electrocardiography (IPE), which consists of estimating the endocardial surface potentials from intracavitary probe potentials. Even though the IPE has been long studied, it still being paid attention due to its ill-posed nature, and many different regularization...
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