1. Decision Feedback Equalization for Underwater Acoustic Channels Deepthi Chander (05407003) Pallavi Manohar (05407002)

2. 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.

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

4. MSE convergence (AWGN)

5. MSE convergence (lognormal noise)

6. Error percent vs SNR (AWGN)

7. Error percent vs SNR (lognormal noise)

8. 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

9. Channel response at 0.6 minutes

10. 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.

11. Scatter plots

13. With Coloured noise (obtained using PROSIM)

15. THANK YOU