Spreadspectrum orthogonal frequency-division multiplexing (SS-OFDM), which appliesspread spectrum technique into OFDM, performs robustly in severely multipathfading underwater channels. However, this technology is sensitive to thefrequency shift. Furthermore, communication in underwater acoustic (UWA)channels is more vulnerable to Doppler effect than other wireless channels dueto the low speed of acoustic signal propagation. It presents challenges forcommunication between underwater mobile nodes. Therefore, accurate Dopplerfrequency shift estimation and compensation is important. Aself-designed receiver structure for SS-OFDM system including a novel Dopplerscale estimation method and channel estimation via compressed sensing method isproposed. The simulation and experimental results offer strong proofs for ourscheme to be a viable option for acoustic communication between underwatermobile nodes and compressed sensing method outperforms the conventionalleast-squares (LS) method in channel estimation.
Sparse Channel Estimation for Multicarrier Underwater Acoustic Communication: From Subspace Methods to Compressed Sensing
