Integrated sensing and communication signal design for under-ice current field distributed estimation

Aimed at the under-ice distributed current field estimation, this paper investigates the integrated sensing and communication signal design and its signal processing methods considering the acoustic channel characteristics. Firstly, the preamble of integrated sensing and communication signal is specially designed. To meet the requirement for high-precision time of arrival estimation, Zadoff-Chu (ZC) sequence is combined with linear frequency modulation (LFM) signal or hyperbolic frequency modulation (HFM) signal to construct a preamble signal, denoted as the LFM-ZC signal and HFM-ZC signal. Owing to the smaller autocorrelation mainlobe possessed by the designed preamble signals, the multipath interference resistance and delay resolution capability are improved. Moreover, a channel-estimation-aided accurate measurement method is presented to estimate the time of arrival in the paper. Using the designed preamble signal, a bidirectional least square is first employed to roughly estimate the channel and obtain the position difference between the time corresponding to the maximum correlation peak and the signal arrival time. Next, the orthogonal matching pursuit algorithm is used to estimate the channel impulse response, enabling accurate detection of the first arrival acoustic ray to determine the time of arrival. Simulation results show that the designed preamble signals can accurately estimate time of arrival in the under-ice channel with small multipath delay difference. In addition, a better Doppler and channel estimation performance of LFM-ZC and HFM-ZC signals is obtained.