Retrofocusing techniques in a waveguide for acoustic communications

In the paper "Retrofocusing technique for high rate acoustic communications" [M. Stojanovic, J. Acoust. Soc. Am. 117, 1173-1185 (2005)], it is suggested that the time reversal approach requires a large number of array elements to compete with other approaches. Here the analysis of that paper is extended with a modified example to compare the performance of various approaches in three respects: (1) array element distribution across the water column, (2) channel normalization, and (3) phase delay across the array. In contrast, our results show that the time reversal approach combined with channel equalization can offer nearly optimal performance with a very small four element array.