S. Menci

University of Florence, Florens, Tuscany, Italy

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Publications (6)

  • Source
    G. Binazzi · L. Chisci · F. Chiti · [...] · S. Menci
    [Show abstract] [Hide abstract] ABSTRACT: This paper deals with the application of Kalman filtering (KF) techniques to the localization of a swarm of mobile agents in a wireless sensor network (WSN). In particular, both extended (EKF) and unscented (UKF) Kalman filters have been investigated referring to a typical urban scenario with energetic and resource constraints. A cooperation strategy among sensor nodes, based on a virtual diversity scheme, has been introduced allowing the swarm tracking under severe propagation conditions. The effectiveness of the proposed solution has been assessed by means of simulations concerning a squad of robots moving in realistic scenarios. It has been shown that UKF achieves a higher accuracy and reliability than EKF in localizing the barycenter of the robot squad. Further, the proposed solution provides advantages in terms of measurement update frequency and, hence, of energy saving.
    Full-text Conference Paper · Jul 2009
  • [Show abstract] [Hide abstract] ABSTRACT: This paper deals with an efficient secure communication system based on a speech watermarking approach. The main goal of the system is to efficiently support air traffic control (ATC) communications by improving safety and security of the existing ATC equipment embedding digital side information into speech signals in order to allow an automatic identification of the talker. An implementation based on the use of the well known LPC (linear predictive coding) principle is discussed. The LPC residual is split up into voiced and unvoiced segments; while the voiced segments cross the system unmodified, the watermarking data are embedded into the unvoiced segments, spectrally similar to a white noise. The watermark signal is decoded by a very similar scheme. We provide also a statistical analysis on the unvoiced parts of the ATC communications that demonstrates the system feasibility. In addition to this, an optimization of the entire system has been also performed to increase performance. The obtained results highlight that the watermark data are nearly imperceptible and provide a data channel with rate from 2000 to 5000 kbits/s, with high robustness to channel noise; the system requires only modular, low-cost and easy-to-install encoders and decoders, maintaining compatibility with legacy RF DSB-AM transceivers. Moreover, it is well suited both for the actual 25 kHz RF channels and for the new 8.33 kHz European RF channels. Copyright © 2008 John Wiley & Sons, Ltd.
    Article · Jul 2009 · Security and Communication Networks
  • [Show abstract] [Hide abstract] ABSTRACT: This paper deals with the study of low-cost efficient techniques of GNSSINS integration for the realization of a surveillance system for the terrestrial vehicular traffic in an airport. This system will have to enable accurate, continuous and reliable tracking of each ground vehicle operating in airport area in support of maintenance and management of aircrafts. High accuracies are required to give the ground control a precise and dynamic view of the airport situation, in order to optimize the ATM (Air Traffic Management) activity; this is particularly important in large hubs. In order to integrate satellites and sensors measurements we relied on Kalman filtering, a powerful signal processing tool for optimal blending of heterogeneous data sources. Specifically, we used an integration architecture named tightly coupled, where only one Kalman filter is used to integrate pseudorange, Doppler and sensor measurements. We will show that our hybrid receiver is a rather simple but extremely efficient solution to this problem.
    Chapter · Jan 2008
  • [Show abstract] [Hide abstract] ABSTRACT: This paper deals with a class of localization protocols conceived for applications to wireless sensor networks (WSN), in the presence of typical energetic and resource constraints. It has been supposed that only one mobile anchor node is always localized by resorting to global navigation satellite system (GNSS) support system. The first scheme proposed (GNSS Alone, GA) assumes that sensor nodes may interact only with this anchor node to evaluate their own positions. In addition to this, a smart cooperation strategy among sensor nodes, i.e., GNSS in ranging (GIR) scheme, has been introduced to face possible anchor node outage, due to hostile operation scenario. The proposed solutions have been in-depth characterized and evaluated within a practical scenario. The obtained results point out the protocol localization accuracy, latency and overhead, with respect to the nodes density. According to this, the most suited applications for both GA and GIR approaches are indicated.
    Conference Paper · Dec 2007
  • Source
    F. Chiti · R. Fantacci · S. Menci
    [Show abstract] [Hide abstract] ABSTRACT: This paper presents the design, the analysis and the optimization of some efficient channel coding schemes for the enhanced data services provisioning within next generation wireless systems, specifically the TETRA Release 2 system. Three different turbo codes schemes are compared: the parallel and serial concatenation of convolutional codes, respectively, PCCC and SCCC, and block turbo coding (BTC). Basing on the specific-services, some practical rules are drawn to lead to an efficient codes design, while respecting the physical and MAC layers features. By means of numerical simulations, SCCC are proved to outperform not only BTC but also PCCC, though the latter is the scheme widely accepted within the majority of communications standards. Besides, the advantages obtained both in terms of performance and complexity, afford the high-speed, interactive and QoS-oriented multimedia services supply.
    Full-text Conference Paper · Jun 2005
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: A GNSS receiver (GPS, Galileo) operating in a civil aircraft is exposed to the signals transmitted from ATC (air traffic control) surveillance sensors, aeronautical navigation systems and other non-aeronautical systems. The present study aims to investigate Galileo E5/L5 in-band and out-of-band interference due to some ATC systems (primary and secondary radars, and VOR, DME, ILS, and TACAN Navaids), in terms of SNR and accuracy degradation. We performed the analysis through both a theoretical approach and a simulations activity. Through the theoretical approach, we analyzed the interference effects expressing the results in terms of SNR degradation as a function of the aircraft-ATC systems distance. We discovered that if the GNSS receiver is covered within 3 dB beam width by the ATC system antenna, the interference in not negligible. For this reason, we analyzed the pulse blanking mitigation technique that is able to blank the interference with a negligible GNSS SNR degradation. In addition, exploiting the CNIT (National Interuniversity Telecommunication Consortium) Galileo simulator, opportunely modified, we analyzed the effects of the radar/Navaids interferences in terms of degradation of Galileo positioning accuracy, either with and without the mitigation process. The simulation activity has been performed considering a scenario closer to a real one, of an aircraft approaching Roma-Fiumicino airport. Both the theoretical analysis and the simulation activity is highlighted and the DME system effects on Galileo receivers could be disruptive without the application of the mitigation technique. The latter technique blanks all the interference effects with a simple algorithm and a limited increase in receiver complexity.
    Full-text Conference Paper · Jun 2005