Nicolo Decarli

Network Experimentation for Cooperative Localization

This paper introduces the notion of network experimentation and proposes an experimentation methodology particularly suited for cooperative wireless networks. Based on this methodology we performed extensive measurement campaigns and compare various cooperative localization techniques under a common setting. Network experiments enable (i) the quantification of cooperation benefits, (ii) the development of techniques for harnessing environmental information, and (iii) the characterization of network localization algorithms. As a case study, we consider ultrawide bandwidth cooperative location-aware networks in cluttered indoor environments and evaluate their performance based on measurements collected from network experiments.

LOS/NLOS detection for UWB signals: A comparative study using experimental data

In this paper the problem of detecting the channel state between LOS and NLOS conditions is addressed using UWB signals. A new distribution-based identification approach is proposed and its performance is compared with that of other classic schemes. To this purpose experimental data collected in realistic environments have been used.

An UWB-UHF semi-passive RFID System for localization and tracking applications

We present a novel radio-frequency identification (RFID) system with capability of localization and tracking of passive or semi-passive tags. Localization and tracking features are enabled by backscatter modulation on ultra-wide bandwidth tags antenna. A ultra-high frequency signal allows the wake-up of the tags enabling the reduction of energy consumption and ensuring compatibility with existing RFID systems. The overall system as well as the reader and tag architectures are introduced. The localization and tracking performance evaluation is presented in some reference scenarios.

Detection of Multiple Tags Based on Impulsive Backscattered Signals

Passive and semipassive ultrawideband (UWB) radio-frequency identification (RFID) technology has been recently proposed to offer high-accuracy localization capabilities in next-generation RFID systems. This technology relies on the modulation of backscattered signals, i.e., backscatter modulation, from multiple tags present in the environment. The detection of multiple tags based on backscattered signals is challenging in harsh environments with nonideal conditions such as clutter, near-far interference effects, and clock drift. This paper analyzes the detection of multiple tags employing UWB backscatter modulation and proposes practical signaling, spreading codes, and detection schemes that are robust to nonideal conditions. A case study is presented to evaluate the performance of the proposed technique for the detection of multiple tags based on impulsive backscattered signals.

Passive UWB RFID for Tag Localization: Architectures and Design

In the new scenarios foreseen by the Internet of Things, industrial and commercial systems will be required to detect and localize tagged items with high accuracy, as well as to monitor the level of certain parameters of interest through the deployment of wireless sensors. To meet these challenging requirements, the adoption of passive and semi-passive ultra-wideband (UWB) radio-frequency identification (RFID) appears a promising solution, which overcomes the limitations of standard Gen.2 ultra-high frequency (UHF) RFID. The design and implementation of such systems pose several practical constraints, impacting the overall network architecture. In this paper, the main issues and challenging aspects for the design of a UWB-RFID network considering architectural and protocol choices are discussed in a unitary framework, and practical solutions, accounting for the presented issues, are proposed. Moreover, the possible integration of UWB-RFID with standard Gen.2 UHF-RFID is proposed as an interesting option, discussing architectural solutions, their advantages, and drawbacks.

Semi-passive UHF-UWB RFID: Architecture and localization performance

In this paper we present an innovative UHF-UWB Radio-Frequency IDentification (RFID) system adopting semi-passive tags, which is capable of overcoming several limitations of available systems while avoiding the use of active devices, ensuring both identification and real-time item localization. Implementation challenges are described, preliminary measurement results are shown and an example of the localization performance is presented.

The GRETA architecture for energy efficient radio identification and localization

This paper presents an overview of the innovative solutions developed within the Italian project GRETA (GREen TAgs and sensors with ultra-wide-band identification and localization capabilities), whose aim is the development of a distributed and comprehensive system for identification, localization, tracking and monitoring in indoor scenarios. The system is based on hybrid UWB-UHF RFID tags, and the realization and experimental validation of novel tag prototypes based on environmentally friendly materials is a major achievement of the project.

Ziv-Zakai bound for time delay estimation of unknown deterministic signals

This paper investigates theoretical limits on time delay estimation performance when the received waveform is unknown. Considering that the Cramér-Rao bound for the time delay estimation error cannot be derived in this case, the analytical expression of the Ziv-Zakai bound is provided and discussed.

Stop-and-Go Receivers for Non-Coherent Impulse Communications

Novel non-coherent impulse communications receivers are proposed to alleviate excessive noise collection in clustered multipath channels. To this aim, a stop-and-go strategy based on energy detection in the autocorrelation receiver or in the energy detection receiver is employed. This strategy enables the selective collection of useful signal portions only, allowing the integration interval to be kept large without noise penalty. To implement this strategy, a blind method is employed, using model order selection based on information theoretic criteria, which optimizes the performance of the proposed receiver and does not require the estimation of channel parameters. The bit error probability of the proposed stop-and-go receivers is evaluated, and our results highlight the considerable performance gain at the expense of a small increase in complexity.

Performance of UWB backscatter modulation in multi-tag RFID scenario using experimental data

Future advanced radio-frequency identification (RFID) systems are expected to provide both identification and high-definition localization of objects with improved reliability and security while maintaining low power consumption and cost. Ultrawide bandwidth (UWB) technology is a promising solution for next generation RFID systems to overcome most of the limitations of current narrow bandwidth RFID technology such as: reduced area coverage, insufficient ranging resolution for accurate localization, sensitivity to interference and scarce multiple access capability. In this paper, the UWB technology is applied to semi-passive RFID relying on backscatter modulation. The potential performance of backscatter RFID communication using UWB signals is investigated in terms of clutter suppression and multiple access capability using both simulated and experimental data.