Wide-band ambiguity functions and affine Wigner distributions
Signal Processing
Wireless Communications
Motion effect modeling in multipath configuration using warping based lag-Doppler filtering
ICASSP '09 Proceedings of the 2009 IEEE International Conference on Acoustics, Speech and Signal Processing
Time-frequency characterization and receiver waveform design for shallow water environments
IEEE Transactions on Signal Processing
Underwater acoustic communication channels: propagation models and statistical characterization
IEEE Communications Magazine
IEEE Transactions on Signal Processing
Wideband discrete transformation of acoustic signals in underwater environments
Asilomar'09 Proceedings of the 43rd Asilomar conference on Signals, systems and computers
Wideband Weyl symbols for dispersive time-varying processing ofsystems and random signals
IEEE Transactions on Signal Processing
Unitary equivalence: a new twist on signal processing
IEEE Transactions on Signal Processing
Group delay shift covariant quadratic time-frequencyrepresentations
IEEE Transactions on Signal Processing
Discrete time-scale characterization of wideband time-varying systems
IEEE Transactions on Signal Processing
Discrete Time-Frequency Characterizations of Dispersive Linear Time-Varying Systems
IEEE Transactions on Signal Processing
Joint scale-lag diversity in wideband mobile direct sequence spread spectrum systems
IEEE Transactions on Wireless Communications
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The underwater environment can be considered a system with time-varying impulse response, causing time-dependent spectral changes to a transmitted acoustic signal. This is the result of the interaction of the signal with the water column and ocean boundaries or the presence of fast moving object scatterers in the ocean. In underwater acoustic communications using mediumto-high frequencies (0.3-20 kHz), the nonstationary transformation on the transmitted signals can be modeled as multiple timedelay and Doppler-scaling paths. When estimating the channel, a higher processing performance is thus expected if the techniques used employ a matched channel model compared to those that only compensate for wideband effects. Following a matched linear time-varying wideband system representation, we propose two different methods for estimating the underwater acoustic communication environment. The first method follows a canonical time-scale channel model and is based on estimating the coefficients of the discrete wideband spreading function. The second method follows a ray systemmodel and is based on extracting time-scale features for different ray paths using the matching pursuit decomposition algorithm. Both methods are validated and compared using communication data from actual underwater acoustic communication experiments.