Waveform-independent frame-timing acquisition for UWB signals

In this paper, the problem of frame-level symbol timing acquisition for UWB signals is addressed. The main goal is the derivation of a frame-level timing estimator which does not require any prior knowledge of neither the transmitted symbols nor the received template waveform. The independence with respect to the received waveform is of special interest in UWB communication systems, where a fast and accurate estimation of the end-to-end channel response is a challenging and computationally demanding task. The proposed estimator is derived under the unconditional maximum likelihood criterion, and because of the low power of UWB signals, the low-SNR assumption is adopted. As a result, an optimal frame-level timing estimator is derived which outperforms existing acquisition methods in low-SNR scenarios.Peer Reviewe

Tècnica per millorar la tecnologia de banda ultra-ampla

En l'àmbit de la comunicació sense fils, la tecnologia de banda ultra-ampla permet d'obtenir comunicacions de molt elevada velocitat i té aplicacions molt diverses, entre elles els radars d'alta precisió o les transmissions multimèdia. D'altra banda, les peculiars característiques dels senyals de banda ultra-ampla fan que la seva recepció i sincronització presenti importants problemes. Investigadors de la UAB i de la UPC han dissenyat una tècnica per solventar-los.En el ámbito de la comunicación sin hilos, la tecnología de banda ultra- ancha permite obtener comunicaciones de muy elevada velocidad y tiene aplicaciones muy diversas, entre ellas los radares de alta precisión o las transmisiones multimedia. Por otra parte, las peculiares características de las señales de banda ultra-ancha hacen que su recepción y sincronización presente problemas importantes. Investigadores de la UAB y de la UPC han diseñado una técnica para solventarlos.In the field of wireless communication, ultra-wideband technology allows obtaining very high data-rates with diverse applications such as high accuracy radars and multimedia transmissions. However, the particular characteristics of ultra-wideband signals make their synchronization and reception very difficult. Researchers at UAB and UPC have designed a technique to solve this problem

Detection of PPM-UWB random signals

This paper focuses on the symbol detection problem of random pulse-position modulation (PPM) ultrawideband (UWB) signals in the absence of interframe interference. Particular attention is devoted to severely time-varying channels where optimal detectors are proposed for both uncorrelated and correlated scattering scenarios. This is done by assuming the received waveforms to be unknown parameters. In UWB communication systems, the assumption of unknown random waveforms is consistent with the fact that the received waveform has very little resemblance with the original transmitted pulse. In order to circumvent this limitation, a conditional approach is presented herein by compressing the likelihood ratio test with the information regarding the second-order moments of the end-to-end channel response. Both full-rank and rank-one detectors are derived. For the reduced complexity rank-one detector, an iterative procedure is presented that maximizes the J-divergence between the hypotheses to be tested. Finally, simulation results are provided to compare the performance of the proposed detectors in different propagation environments.Peer Reviewe

Waveform-independent frame-timing acquisition for UWB signals

In this paper, the problem of frame-level symbol timing acquisition for UWB signals is addressed. The main goal is the derivation of a frame-level timing estimator which does not require any prior knowledge of neither the transmitted symbols nor the received template waveform. The independence with respect to the received waveform is of special interest in UWB communication systems, where a fast and accurate estimation of the end-to-end channel response is a challenging and computationally demanding task. The proposed estimator is derived under the unconditional maximum likelihood criterion, and because of the low power of UWB signals, the low-SNR assumption is adopted. As a result, an optimal frame-level timing estimator is derived which outperforms existing acquisition methods in low-SNR scenarios.Peer Reviewe