Decision Feedback Equalization for Underwater Acoustic Channels Deepthi Chander ( ) Pallavi Manohar ( )

Features of Underwater Acoustic (UWA) channels  Underwater acoustic channels - severely bandlimited High temporal and spatial variability of channel conditions and multipath propagation. Digital transmission-severe ISI caused. Non-Gaussian noise environments.

feedforward filter Input + Symbol decision feedback filter - Estimated symbol Adaptive Algorithm (RLS) Training symbol + - error Decision Feedback Equalizer

MSE convergence (AWGN)

MSE convergence (lognormal noise)

Error percent vs SNR (AWGN)

Error percent vs SNR (lognormal noise)

Simulation Set-up PROpogation channel SIMulator (PROSIM) - based channel model ( PROSIM used for simulations of broad-band (100Hz-10kHz) sound propagation Source depth=30 m Receiver depth = 40 m, Range=1 km Frequency = 500 Hz Channel constant for 0.2 minutes and multipath delay spread =0.685 seconds Data rate assumed = 1000 bps Noise: AWGN, coloured Adaptive algorithm: RLS

Channel response at 0.6 minutes

PROSIM channel model simulations AWGN Number of taps=32 Feedforward filter: 20 taps Feedback filter: 12 taps At 20 dB SNR : %of bits in error = 35.

Scatter plots

With Coloured noise (obtained using PROSIM)

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