Decision Feedback Equalization for Underwater Acoustic Channels
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Transcript of Decision Feedback Equalization for Underwater Acoustic Channels
Decision Feedback Equalization for Underwater Acoustic Channels
Deepthi Chander (05407003)
Pallavi Manohar (05407002)
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.
feedforwardfilter
Input
+ Symboldecision
feedbackfilter
-
Estimated symbol
AdaptiveAlgorithm (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
(www.saclantc.nato.int/mast/prosim/mainpg/main.html)• 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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