Some measured frequency domain characteristics of the underwater vector and scalar acoustic field components with applications to communication receivers

Abstract

Vector and scalar components of the underwater acoustic field can be used for multichannel signal demodulation [A. Abdi, et al., “A new vector sensor receiver for underwater acoustic communication,” in Proceedings of the Oceans (2007), pp. 1–10; A. Abdi and H. Guo, “A new compact multichannel receiver for underwater wireless communication networks,” IEEE Trans. Wireless Commun. 8, 3326–3329 (2009)]. In frequency domain-based communication methods such as orthogonal frequency division multiplexing (OFDM) using multiple collected signals, understanding the behavior of the channels in frequency domain is important for proper system design. In this paper, we examine the experimental data obtained by transmitting pilot tones for channel estimation, to estimate various channel frequency responses. More specifically, channel frequency responses of the X, Y and Z components of the underwater acoustic vector field are estimated, in addition to the scalar field component channel frequency response. Analysis of the measured frequency responses reveals differences in parameters such as condition numbers and eigenvalues of measured channel matrices. Knowledge of these parameters is needed for designing communication receivers that utilize the vector and scalar components of the acoustic field in frequency domain. [The work is supported in part by NSF, Grant IIP-1500123.]