Joint Interference Mitigation with Channel Estimated in Underwater Acoustic System

Orthogonal frequency-division-multiplexing (OFDM) has been actively pursued in underwater acoustic communications. However, OFDM is extremely sensitive to carrier frequency offset (CFO) which cause significant problems. The utilization and performance of traditional channel estimation are poor. Although underwater acoustic communication was recently the focus of research, literatures on joint interference mitigation with channel estimation using compressed sensing (CS) in underwater acoustic OFDM has been very limited. In the Cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) system, a novel method was proposed which combined interference mitigation with channel estimation based on compressed sensing (CS). We propose a two-step approach which contains resampling and high-resolution uniform residual Doppler compensation by null subcarriers. After Doppler compensation, exploiting sparsity in the delay-Doppler domain, CS-based channel estimation is adopted for an increase in spectral efficiency though a reduction of the number of pilot symbols. Simulations and tank experiments have verified the better performance of the receiver based on the joint interference and CS channel estimation. The proposed CFO compensation method can reduce the BER. The Joint interference estimation with CS-based channel estimation has better performance than that with LS channel estimation.