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Exploiting additional radio spectrum is key to respond to the unprecedented capacity demands of mobile broadband communication systems in recent years. In fact, most of the frequency bands suitable for mobile communications are already in use by other radio services, and spectrum refarming is usually not possible or constitutes a highly time-consuming procedure. At the same time, several field measurement...
Blind audio source separation (BASS) arises in a number of applications in speech and music processing such as speech enhancement, speaker diarization, automated music transcription etc. Generally, BASS methods consider multichannel signal capture. The single microphone case is the most difficult underdetermined case, but it often arises in practice. In the approach considered here, the main source...
We investigate in this paper the performance achieved by some SDMA (Space Division Multiple Access) access techniques in a Broadcast channel configuration. The study includes the two basic linear precoding schemes present in the literature namely the CF (Closed Form) and the Iterative precoding techniques. These techniques have already been widely studied for the i.i.d Rayleigh channel. In fact, these...
This paper proposes a new double iterative procedure for sum-rate maximization in a Multiuser MIMO system (MU-MIMO). The proposed algorithm is based on joint precoder and decoder optimization involving two different decoding schemes. For that we considered a precoding algorithm namely the iterative SJNR (Signal to Jamming and Noise Ratio) precoder combined with two iterative receivers. The first receiver...
Performance bounds provide a solid theoretical ground for comparing different localization methods. Similarly to the actual performance, they depend on two factors, namely the accuracy of the available data that are used for localization and the geometry of the network. While the impact of the accuracy of the available data has been studied extensively, the literature on the impact of network geometry...
For existing localization algorithms, Non-Line-of-Sight (NLOS) propagation introduces some problems for the determination of the mobile position. This is because most of these algorithms depend on the information extracted from the Line-of-Sight (LOS) path such as Time-of-Arrival (ToA) or Time-Difference-of-Arrival (TDoA) received by either one or more Base Stations. On the contrary, algorithms based...
In this paper we compare general unitary beamforming to constant modulus unitary beamforming in terms of achievable sum-rate for MIMO broadcast channels. We give a complete analysis of both schemes in the 2 × 2 multi-user MISO configuration. Furthermore, we study the regime of asymptotically high signal-to-noise ratio. For growing number of transmit antennas the sum-rate gap between both schemes is...
The communication between a multiple-antenna transmitter and multiple receivers (users) with either a single or multiple-antenna each can be significantly enhanced by providing the channel state information at the transmitter (CSIT) of the users, as this allows for scheduling, beamforming and multiuser multiplexing gains. The traditional view on how to enable CSIT has been as follows so far: In time-division...
In a system comprising of a multiple antenna enabled base station (BS) and multiple single antenna users, very high data rates can be obtained if BS transmits to multiple users simultaneously. This simultaneous transmission to multiple users over the same bandwidth is realizable only if BS knows the forward channels linking its transmit antennas to these users. We study a time-division duplexed (TDD)...
Simultaneous transmission of multiple data streams from a multiple antenna base station (BS) to multiple single antenna users gives significant gain in spectral efficiency as compared to when a single such user is being served. This simultaneous transmission to multiple users is realizable only if BS knows the forward channels linking its transmitting antennas to these users which requires channel...
Precise automatic music transcription requires accurate modeling and identification of the spectral content of the audio signal. Whereas a deterministic model in terms of modulated periodic signals allows to distinguish different notes, the presence of multiple notes separated by octaves poses a big problem since they share the same periodicity, and hence completely overlapping spectral content. In...
Precise automatic music transcription requires accurate modeling and identification of the spectral content of the audio signal. But music can not be reduced to a succession of notes, and an accurate transcriptor should be able to detect other performance characteristics, such as slow tempo variations or, depending on the instrument detecting some interpretation effects. In a pedagogic way a student...
This paper examines a beamforming approach towards reducing the power consumption in oversampling sigma delta (SigmaDelta) analog to digital converters (ADC's) for multiuser antenna array communication systems. We propose a setup where the output of the ADC's are fed-back to the input of a SigmaDelta modulator through a beamformer to cancel the contributions of interfering signals. We examine the...
The absolute gain of multi-user diversity in the context of a downlink channel is the focus of this contribution. Enjoying multi-user diversity gain first requires the channel information availability at the transmitter (CSIT) in a normal downlink (DL) system. Although multi-user diversity gains have been specified well, but the burden of exchange of information required is not rigorously accounted...
Since the introduction of the diversity-multiplexing tradeoff (DMT) by Zheng and Tse for ML reception in frequency-flat MIMO channels, some results have been obtained also for the DMT of frequency-selective MIMO channels and for the DMT of suboptimal receivers such as linear (LEs) and decision-feedback equalizers (DFEs) for frequency-selective SIMO channels or frequency-flat MIMO channels. We have...
The ESPRIT algorithm is an attractive solution to many parameter estimation problems due to its low computational cost. In this paper we apply ESPRIT to the estimation of the angle of arrivals (AoA), the angle of departures (AoD), the delays and the Doppler shifts of different components of the received signal. Due to the structure of the channel impulse response matrix of a MIMO-OFDM system, these...
Common localization approaches require a large amount of information to be available in order to achieve identifiability, when the signal propagates in a strictly Non-Line-of-Sight (NLOS) environment. Furthermore, even if they achieve identifiability, they usually perform poorly. In this contribution we investigate the conditions that must be met for identifiability to be feasible and for performance...
Concerning the uncertainty of channels and peak power constraint, we give a new practical layering scheme to do reliable transmission. In our scheme, Walsh matrix is employed to do layer-time coding. Regarding columns of a layer-time coding matrix as layers and rows as time, after Walsh layer-time coding, interference among layers can be removed or diminished by adding rows up. When there are layers...
We address the issue of low complexity linear equalization for cyclic-prefix (CP) and zero-padded (ZP) block transmissions (OFDM). While cyclic-prefix (CP) OFDM does not exploit frequency diversity offered by multipath fading, use of appropriate redundant linear preceding permits a linear equalizer (LE) to benefit from full diversity in the frequency selective channel. We exploit excess time of block...
Location estimation in multipath environments (ME) can lead to significantly higher accuracy if the information contained in the Non-Line-of-Sight (NLOS) signal components is exploited thoroughly with the use of multiple antennas at both sides of a communication system and with the aid of appropriate channel modeling. In this contribution, this information is exploited and a Maximum-Likelihood (ML)...
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