Abstract:

In order to improve the data rate and reliability of underwater communication systems, a soft channel estimation based joint iterative equalization and decoding scheme is proposed for underwater communications. The receiver updates the coefficients of the sparse soft channel estimator by using the soft information calculated from the extrinsic log likelihood ratio fed by the softinsoftout (SISO) decoder. Channel estimation and equalization performance can be greatly improved by iteratively exchanging soft information between SISO equalizer and SISO decoder. Experimental results show that after the second iteration, the proposed scheme can achieve errorfree data transmission of 2 kb/s in a range of 1.8 km, and bandwidth of 2 kHz.