The solid-body reverberating ultrasound communications channel and its OFDM interference

In this paper we present an analytical approach to the solid-state ultrasound communications channel. Channel reverberations and the long associated channel delay spreads pose the possibility that the channel length exceeds that of the moderate cyclic prefix in an orthogonal frequency division multiplexing (OFDM) system, resulting in intersymbol and intercarrier interference. We present a channel model based on the propagation material characteristics and evaluate the extent and impact of the intrinsic OFDM interferences. We derive an analytical expression and show with simulations that the intersymbol and intercarrier interference (ISI and ICI) are spectrally concentrated to the lower frequencies of the OFDM multiplex.