A time-reverse underwater acoustic communication method based on filtered multi-tone modulation

Abstract

The invention discloses a time reversal acoustic communication method based on filtered multitone modulation. The method comprises the following steps of: at a transmitting terminal, dividing a communication band into a plurality of subcarriers, and then, performing serial / parallel conversion on an information sequence and modulating the information sequence to the plurality of subcarriers for parallel transmission, wherein the subcarriers have the same bandwidth, pass bands of the subcarriers are non-overlapped, stop bands of the subcarriers have a strong suppression property, and a guard band is not arranged between the subcarriers; at a receiving terminal, demodulating the received signals to a base band, suppressing inter-symbol interference and noise jamming for the base band signals through a time reversal and adaptive equalization technology, and obtaining an estimation value of the information sequence after performing parallel / serial conversion on a decision value output from adaptive equalization. According to the invention, by a filtered multitone modulation technology, the width of code element symbols is spread, the scope of the code elements affected by multipath spreading is reduced, and consequently, the aim of reducing residual inter-symbol interference remaining after time reversal processing and improving performance of time reversal acoustic communication is realized.

Description

technical field [0001] The invention belongs to the field of underwater acoustic communication, in particular to a time-reversal underwater acoustic communication method based on filter multi-tone modulation with high reliability. Background technique [0002] High-speed time-counterback acoustic communication is a research hotspot in the field of time-counterback acoustic communication in recent years. The improvement of the communication rate reduces the width of the symbol and increases the range of the symbol affected by the uncompressed multipath in the anti-water acoustic communication at the time of single carrier, thereby reducing the communication performance and increasing the computational complexity of adaptive equalization. In order to reduce the impact of multi-path extension, multi-carrier technology can be combined with time-reversal technology. Chinese patent CN201210008467.1 proposes an underwater acoustic communication method based on joint processing of ...

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Problems solved by technology

Chinese patent CN201210008467.1 proposes an underwater acoustic communication method based on joint processing of time inversion and OFDM. However, due to the serious multipath effect of the underwater acoustic channel, in order to ensure the orthogonality between subcarriers within a symbol, OFDM The bandwidth of subcarriers must be very narrow, and too narrow subcarriers will cause the communication system based on OFDM technology to be more sensitive to frequency offset. In order to ensure communication performance, this method must use more complex frequency offset compensation technology

In order to overcome the problem that the underwater acoustic communication method is sensitive to frequency offset during OFDM, Song A. et al. EL288) proposed a new multi-carrier TR underwater acoustic communication method, the sub-carrier bandwidth of this method is wide, the pass-bands do not overlap each other, the stop-band has high suppression, and the adjacent sub-carriers are inserted Therefore, this method has a strong ability to resist frequency offset, and the received sub-signal can also use the second-order phase-locked loop technology commonly used in single-carrier underwater acoustic communication for frequency offset compensation. However, due to the use of guard bandwidth in this method, Therefore, compared with the single-carrier anti-underwater acoustic communication method, the frequency band utilization of this method will be reduced

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