Time-variant Adaptive Passive Time Reversal Equaliser and a Perspective for Environmental Focusing Method

Lussac P. Maia, António Silva, Sérgio M. Jesus

Abstract

High digital data throughput in Underwater Acoustic Communications (UAComm) is a challenging subject, specially in shallow water where the channel is a wave-guide causing multipath propagation and where Doppler effect usually occurs due to relative source-receiver motion jointly to ocean dynamics. The source and receiver sensors can be used for telemetry in point-to-point underwater communications or as nodes of an underwater acoustic network within the scope of oceanic research observatory or offshore activities. However, channel tracking is required for reliable digital underwater communications between the sensors, which is a hard task due to the complicated propagation of acoustic waves in the ocean. Equalisation is often required to perform a compensation method aiming to overcome the inter-symbol interference (ISI) caused by multipath propagation. The motivation of this work is to propose a compensation method deploying the adaptive passive time-reversal (ApTR) equaliser, aiming to perform ISI mitigation jointly to Doppler compensation in time-variant channels. The benefit given by ApTR processing would be the performance improvement in underwater communications between an active sensor and a vertical line array of receiver sensors, relying in well-succeed time-variant channel impulse response estimation. Furthermore, this position paper discusses the perspective of use an environmental focusing method for channel estimation within the ApTR equaliser, based on the idea that a set of oceanic acoustic physical parameters – which are generally estimated in low-frequency matched field processing problems like geoacoustic assessment, ocean tomography and source localization – could be conveniently used for channel compensation in high frequency underwater communications using a carefully chosen search space of replicas. The results are two fold: in one hand the equalisation shall improve the UAComm system, and in the other hand, the best match of channel parameters consequently yields a refined local environmental assessment.

References

  1. Baggeroer, A. B., Kuperman, W. A., and Mikhalevsky, P. N. (1993). An overview of matched field methods in ocean acoustics. IEEE Journal of Oceanic Engineering, 18(4):401-424.
  2. Bucker, H. P. (1976). Use of calculated sound fields and matched-detection to locate sound source in shallow water. Journal of Acoustical Society of America, 59:368-373.
  3. Collins, M. D. and Kuperman, W. A. (1991). Focalization: environmental focusing and source localization. Journal of Acoustical Society of America, 90(3):1410- 1422.
  4. Gomes, J., Silva, A., and Jesus, S. (2008). Adaptive spatial combining for passive time-reversed communications. Journal of Acoustical Society of America, (124):1038- 1053.
  5. Hinich, M. J. (1973). Maximum-likelihood signal processing for a vertical array. Journal of Acoustical Society of America, 54:499-503.
  6. Jesus, S. (1993). Broadband matched-field processing of transient signals in shallow water. Journal of Acoustical Society of America.
  7. Parvulescu, A. (1961). Signal detection in a multipath medium by m.e.s.s. processing. Journal of Acoustical Society of America, 33:1674.
  8. Porter, M. B. (2011). The BELLHOP Manual and User's Guide. Heat, Light, and Sound Research, Inc., La Jolla, CA, USA.
  9. Rodriguez, O. C. and Silva, A. J. (2012). The Time Variable Acoustic Propagation Model (TV-APM). Signal Processing Laboratory, FCT, Universidade do Algarve, http://www.siplab.fct.ualg.pt/tvapm.shtml.
  10. Tolstoy, A., Diachok, O., and Frazer, L. (1991). Acoustic tomography via matched-field processing. Journal of Acoustical Society of America, 89:1119-1127.
  11. Vilaipornsawai, U., Silva, A., and Jesus, S. M. (2014). Experimental testing of asymmetric underwater acoustic networks. In IEEE Fifth International Conference on Communications and Eletronics (ICEE), pages 118- 123, Danang, Vietnam. IEEE.
  12. Ziomek, L. J. (1995). Fundamentals of Acoustic Field Theory and Space-Time Signal Processing. CRC.
Download


Paper Citation


in Harvard Style

P. Maia L., Silva A. and M. Jesus S. (2015). Time-variant Adaptive Passive Time Reversal Equaliser and a Perspective for Environmental Focusing Method . In Proceedings of the 4th International Conference on Sensor Networks - Volume 1: SENSORNETS, ISBN 978-989-758-086-4, pages 103-108. DOI: 10.5220/0005330901030108


in Bibtex Style

@conference{sensornets15,
author={Lussac P. Maia and António Silva and Sérgio M. Jesus},
title={Time-variant Adaptive Passive Time Reversal Equaliser and a Perspective for Environmental Focusing Method},
booktitle={Proceedings of the 4th International Conference on Sensor Networks - Volume 1: SENSORNETS,},
year={2015},
pages={103-108},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0005330901030108},
isbn={978-989-758-086-4},
}


in EndNote Style

TY - CONF
JO - Proceedings of the 4th International Conference on Sensor Networks - Volume 1: SENSORNETS,
TI - Time-variant Adaptive Passive Time Reversal Equaliser and a Perspective for Environmental Focusing Method
SN - 978-989-758-086-4
AU - P. Maia L.
AU - Silva A.
AU - M. Jesus S.
PY - 2015
SP - 103
EP - 108
DO - 10.5220/0005330901030108