Measurements and accuracy evaluation in wireless space-time localization application under real-life conditions

Project Coordinator

M. Bertocco

Starting Date

January 2009

Ending Date

September 2012

Description

The main research topic of this project concerns the study of wireless systems for time-space localization, with a specific interest in measurement techniques for their characterization.In such context some relevant issues are not considered by the scientific community with adequate attention.

A first aspect concerns the definition of measurement techniques for the characterization of performaces of wireless sensor networks that are repeatable and traceable wit respect to international measurement unit samples. Moreover, the meaningful degree of test in a real context of the extracted measures is in many cases still an open question. In fact real-life is complicated by a number of aspects: the intrinsic nature of the radio-communication signal which in turn depends on many design and tuning parameters, radio communication impairments (including multipath effects), specific design or implementation choices at the hardware level, at the protocol layer, or at the processing (application) level. For these reasons the definitions of "meaningful sample", environment testing facility, or typical test are not trivial nor unique. The parameters that summarize system performances do not have a clear or unique definition. For instance, the concept of "immunity" in the international literature (e.g. from electromagnetic compatibility literature) is often defined in term of a subjective score in term of "immunity classes", while a quantitative metric should be more expressive. Again, the "degree of time synchronization" of the system (i.e. the whole network) is quantified with different parameters in the literature, with different practical implications. A first goal of the research project consists in discovering methods and metrics for an objective characterization of wireless sensor networks in applications of time-space localization. It is expected hence that definition will be provided with respect to the concepts of "measurement environment", "immunity", the various side conditions (such as interfering agents), and testing procedures in such a way to define a metrics that could in turn 1) make the tests repeatable,, 2) allow a clear comparison among the various design or implementation choices; 3) immunity (say affordability) of the whole system could be clearly understood.

A second relevant aspect consists in modeling and characterizing the actual behavior of clock circuits. Practical proposals make the  characterization a difficult task since clock circuits in a synchronized system may include many sub-systems reciprocally interacting, and may also include non linear feedback loops having an increasing abstraction complexity (from hardware to protocol or application layer). In this context an expected result is to obtain analytical models that could adequately describe the above issues having in mind two goals: to provide simulation method and models and the proposal of improved time synchronization techniques (e.g. clock correction procedure, servo clock algorithms, measurement procedures and timestamping procedures).

For each of the two above aspects, it is expected to support the results in two different ways. 1. By the design and implementation of a simulator that allow cross-layer experiments in such a way that both physical effects (interference, multipath, electromagnetic environment,...) and functional (protocol, application level algorithms) could be considered 2. By practical experiments with physical devices working in a real-life environment. such experiments will have the twofold goal of validating the definition of testing procedures and environment, as well as of providing performances to the synchronization techniques and models expected from the theoretical (or simulated) analysis.

Publications

  • GIORGI G., NARDUZZI C. Performance analysis of Kalman filter-based clock synchronization in IEEE 1588 networks. In: International IEEE Symposium on Precision Clock Synchronization for Measurement, Control and Communication, ISPCS 2009. Brescia, 12-16 Ottobre 2009.
  • DE DOMINICIS C.M., FERRARI P., FLAMMINI A., SISINNI E., BERTOCCO M., GIORGI G., NARDUZZI C., TRAMARIN F. Investigating WirelessHART coexistence issues through a specifically designed simulator. In: IEEE Instrumentation and Measurement Technology Conference I2MTC2009. Singapore, 5-7 May, 2009.
  • BERTOCCO M., SONA A., TRAMARIN F., Design of experiments for the assessment of coexistence between wireless networks. Proc. IEEE Instrumentation and Measurement Technology Conference I2MTC 2010.
  • GIORGI G., NARDUZZI C. Performance Analysis of Kalman Filter-based Clock Synchronization in IEEE 1588 Networks. Accepted for IEEE Transaction on Instrumentation and Measurement.
  • GIORGI G., NARDUZZI C. Robustness to SYNC packets loss in network synchronization. IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, Communication, ISPCS 2011, Monaco, Germany, September 2011.
  • GIORGI G., NARDUZZI C. Accurate Discrete-Time Clock Modelling for the Study of Network Synchronization. IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, Communication, ISPCS 2011, Monaco, Germany, September 2011. Poster format.
  • GIORGI G., NARDUZZI C. Confronto tra diversi metodi per la generazione di flicker noise. Atti del XXVIII Congresso Nazionale del Gruppo di Misure Elettriche ed Elettroniche. GMEE 2011.
  • TRAMARIN. F., GIORGI G., BERTOCCO M. Un simulatore per reti wireless di sensori. Atti del XXVIII Congresso Nazionale del Gruppo di Misure Elettriche ed Elettroniche. GMEE 2011.
  • SENO L., TRAMARIN F., VITTURI S., Influence of Real Components Behaviour on the Performance of Wireless Industrial Communication Systems. Proc. of the 20th IEEE ISIE. Poland, June 2011.

Tools