Sparse Channel Estimation for OFDM-Based Underwater Acoustic Systems in Rician Fading With a New OMP-MAP Algorithm

• Published in: IEEE transactions on signal processing Vol. 67; no. 6; pp. 1550 - 1565
• Main Authors: Panayirci, Erdal, Altabbaa, Mhd Tahssin, Uysal, Murat, Poor, H. Vincent
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.03.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic mapping; Algorithms; Attenuation; Channel estimation; Communications systems; Computational efficiency; Computer simulation; Delays; Doppler effect; equalization; Fading; MAP estimation; Matching pursuit algorithms; Monte Carlo simulation; OFDM; Orthogonal Frequency Division Multiplexing; orthogonal matching pursuit; Rician channels; Signal processing algorithms; Underwater acoustic channel estimation; Underwater acoustics; Underwater communication
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2019.2893841

In this paper, a new channel estimation algorithm is proposed that exploits channel sparsity in the time domain for an orthogonal frequency division multiplexing (OFDM)-based underwater acoustical (UWA) communications systems in the presence of Rician fading. A path-based channel model is used, in which the channel is described by a limited number of paths, each characterized by a delay, Doppler scale, and attenuation factor. The resulting algorithm initially estimates the overall sparse channel tap delays and Doppler shifts using a compressed sensing approach, in the form of the orthogonal matching pursuit (OMP) algorithm. Then, a computationally efficient and novel channel estimation algorithm is developed by combining the OMP and maximum a posteriori probability (MAP) techniques for estimating the sparse complex channel path gains whose prior densities have complex Gaussian distributions with unknown mean and variance vectors, where a computationally efficient maximum likelihood algorithm is proposed for their estimation. Monte Carlo simulation results show that the mean square error and symbol error rate performances of the OMP-MAP algorithm uniformly outperforms the conventional OMP-based channel estimation algorithm, in case of uncoded OFDM-based UWA communications systems.