Multichannel communication based on adaptive equalization in very shallow water acoustic channels

Abstract

Very shallow water acoustic communication channels are known to exhibit fading due to time-varying multipath arrivals. This is further complicated by impulsive snapping shrimp noise that is commonly present in warm shallow waters. Channel measurements and analyses were done to study the local shallow water characteristics. These measurements had helped verify and set the communication channel model and adaptive receivers presented in this thesis. This thesis also presents results from the use of single-carrier differential phase shift keying (DPSK) modulation. The receiver designs in the simulation and trial data analysis were based on combinations of least mean square (LMS) and recursive least square (RLS) algorithms with adaptive linear equalizer (LE) and decision feedback equalizer (DFE). In addition, multichannel combining (MC) and forward error correction (FEC) scheme such as turbo product codes (TPC) were employed to improve performance by removing correctable errors. Performance results based on simulated data as well as real data collected from the sea were also presented.