A. Silva, asilva@ualg.pt
J. Huillery, jhuillery@ualg.pt
S.M. Jesus, sjesus@ualg.pt
Institute for Systems and Robotics, University of Algarve
Campus de Gambelas, PT-8005-139 Faro, Portugal
Ref.: 23rd International Conf. on Advanced
Information Networking and Applications, Bradford, May 2009
Abstract:
Underwater acoustic communication networks have attracted attention for its
applications in many areas such as mine warfare, rapid environmental assessment
or search and rescue, where there is the need for conserted action of a group
of observers/actuators. A common requirement in most of these applications is
the need to make accessible to the global (terrestrial/aerial) user network
large amounts of critical underwater collected data. This paper addresses this
requirement by using multichannel nodes providing an asymmetrical
point-to-point (P2P) connection where the upload link has a much higher data
rate than the download link. The emphasis of this work is not so much on the
final channel throughput but on establishing the optimal processing of
spatially distributed multichannel nodes that serve as interface between the
underwater nodes and the global/user network. The adopted strategy relies on
passive time-reversal which can be viewed as a spatial pre-equalizer for each multichannel
node. Then an intersymbol interference optimal combination of various nodes is divised
for balancing poor communications of one or more nodes in the network. The
method and techniques are theoretically derived and applied to real data
acquired with a network of 2 surface buoys over an environmentally challenging
area off the coast of Portugal in July 2007.
Keywords:
Underwater networks, underwater communications, spatially distributed multichannel,
multi-node optimal combination, time-reversal.