Robust Underwater Telemetry With Adaptive Turbo Multiband Equalization
article
Abstract—In this paper, a multicarrier modulation scheme is
presented for acoustic communication at low signal-to-noise ratios
(SNRs). User bits are put through a rate 1/3 turbo encoder and
interleaved with periodic training bits. A maximal-length sequence
is prefixed for signal detection and equalizer convergence,
and the resulting bit stream is simultaneously modulated onto
multiple phase-shift keyed carriers. Since each subband carries
the same symbol sequence, the baseband ensemble is amenable
to multichannel equalization. An adaptive multiband equalizer
is thus constructed for joint equalization and despreading of the
frequency bands. Iterative equalization using soft information
from the turbo decoder further enhances the receiver performance.
A reduction in complexity is achieved by equipping the
subbands with separate recursive least squares tap updates, yet
guided by a common error signal. The proposed algorithms are
tested on acoustic data from the Baltic Sea, using eight subbands
of 460 Hz each, at an effective data rate of 75 b/s. Robust receiver
operation is demonstrated at overall receive SNRs down to -12 dB
in three different channels, which corresponds to an SNR per bit....
presented for acoustic communication at low signal-to-noise ratios
(SNRs). User bits are put through a rate 1/3 turbo encoder and
interleaved with periodic training bits. A maximal-length sequence
is prefixed for signal detection and equalizer convergence,
and the resulting bit stream is simultaneously modulated onto
multiple phase-shift keyed carriers. Since each subband carries
the same symbol sequence, the baseband ensemble is amenable
to multichannel equalization. An adaptive multiband equalizer
is thus constructed for joint equalization and despreading of the
frequency bands. Iterative equalization using soft information
from the turbo decoder further enhances the receiver performance.
A reduction in complexity is achieved by equipping the
subbands with separate recursive least squares tap updates, yet
guided by a common error signal. The proposed algorithms are
tested on acoustic data from the Baltic Sea, using eight subbands
of 460 Hz each, at an effective data rate of 75 b/s. Robust receiver
operation is demonstrated at overall receive SNRs down to -12 dB
in three different channels, which corresponds to an SNR per bit....
TNO Identifier
247961
Source
IEEE Journal of Oceanic Engineering, 34(October), pp. 645-655.
Pages
645-655
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