Flexible OFDM Transceiver for Underwater Acoustic Channel: Modeling, Implementation and Parameter Tuning

Abstract

Acoustic signals are a first choice in underwater communication since sound waves face very low attenuation in water compared to radio frequency (RF). However, the tendency of receiver to detect multipath signals (due to signals bouncing off surface or the bottom) induces large delay spreads and thus strong channel frequency selectivity. Additionally, rapid spatial and temporal variations in underwater acoustic (UWA) channel makes it hostile for communication systems based on single carrier modulation. Multicarrier modulation techniques, on the other hand, can greatly improve bandwidth utilization and help deal with time dispersal effects. Orthogonal frequency division multiplexing (OFDM) is a proven multicarrier communication system having capabilities to cope with frequency selectivity and delay spreads effectively. OFDM has started to get attention for being a simpler alternative to high complexity and high maintenance single carrier systems in UWA communication systems. This work proposes a Matlab model of an OFDM transceiver along with UWA channel characterization based on Rician shadowed fading model as it perfectly characterizes the way in which a shallow UWA channel behaves. Eventually, the proposed design allows implementation of various OFDM modulation methods and to perform Monte Carlo simulations for bit error rate comparisons together with the ability to tune multiple UWA channel parameters.