Publications (174) View all
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Article: Ultra-Wideband TOA Estimation in the Presence of Clock Frequency Offset
IEEE Transactions on Wireless Communications 04/2013; 12(4):1606-1616. · 2.59 Impact Factor -
Article: Range Estimation in Multicarrier Systems in the Presence of Interference: Performance Limits and Optimal Signal Design
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ABSTRACT: Theoretical limits on time-of-arrival (equivalently, range) estimation are derived for multicarrier systems in the presence of interference. Specifically, closed-form expressions are obtained for Cramer-Rao bounds (CRBs) in various scenarios. In addition, based on CRB expressions, an optimal power allocation (or, spectrum shaping) strategy is proposed. This strategy considers the constraints not only from the sensed interference level but also from the regulatory emission mask. Numerical results are presented to illustrate the improvements achievable with the optimal power allocation scheme, and a maximum likelihood time-of-arrival estimation algorithm is studied to assess the effects of the proposed approach in practical estimators.IEEE Transactions on Wireless Communications 11/2011; · 2.59 Impact Factor -
Article: Joint TOA and AOA Estimation for UWB Localization Applications
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ABSTRACT: A joint TOA/AOA estimator is proposed for UWB indoor ranging under LOS operating conditions. The estimator employs an array of antennas, each feeding a demodulator consisting in a squarer and a low-pass filter. Signal samples taken at Nyquist rate at the filter outputs are processed to produce TOA and AOA estimates. Performance is assessed with transmitted pulses with a bandwidth of either 1.5 GHz (type-1 pulses) or 0.5 GHz (type-2 pulses), which correspond to sampling rates of 3 GHz and 1 GHz, respectively. As expected, the estimation accuracy decreases with the pulse bandwidth. Ranging errors of about 10 cm and angular errors of about 1° are achieved at SNR of practical interest with type-1 pulses and two antennas at a distance of 50 cm. With type-2 pulses the errors increase to 35 cm and 3°. Comparisons are made with other schemes discussed in literature.IEEE Transactions on Wireless Communications 08/2011; · 2.59 Impact Factor -
Article: Code-multiplexed transmitted-reference UWB systems in a multi-user environment
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ABSTRACT: Recent studies have investigated alternative methods to the realization of transmitted-reference ultra-wideband communication systems. In addition to the conventional scheme, in which data and reference are separated in time, two other methods have been proposed in which the separation is achieved through a frequency shift or via code multiplexing. In a single-user scenario the alternative methods have advantages in terms of error rate and receiver implementation. In this paper the three schemes are compared in a multi-user environment. It is shown that even in the presence of multiple access interference the unconventional solutions are preferable and, in particular, the code multiplexing method has the best performance and is the simplest to implement.IEEE Transactions on Communications 04/2010; · 1.68 Impact Factor -
Conference Proceeding: Ranging algorithm for the IEEE 802.15.4a standard
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ABSTRACT: This paper proposes a ranging algorithm for impulse-radio ultra-wideband signals compliant with the IEEE 802.15.4a standard. The algorithm is suited for non-coherent receivers and is implemented in digital form. The achievable ranging accuracy depends on the sampling rate. Ranging errors on the order of 40 cm are obtained with a rate of 1 GHz at SNR=20 dB.Ultra-Wideband, 2009. ICUWB 2009. IEEE International Conference on; 10/2009
