Method for improving underwater acoustic sparse orthogonal frequency division multiplexing multi-carrier modulation performance

Abstract

The invention discloses a method for improving underwater acoustic sparse orthogonal frequency division multiplexing multi-carrier modulation performance, and the method comprises the steps that a preamble employs an orthogonal frequency division multiplexing signal with a cyclic prefix as a template, and the preamble consists of two orthogonal frequency division multiplexing signal signals whichare close to each other, have the code element duration of T0 and are completely the same; performing correlation operation on the lead code of the signal at a receiving end to obtain a correlation function; timing and multiple Doppler estimation are carried out according to the frame header signal and the lead code, a Doppler spread factor estimated value is obtained step by step, and after Doppler compensation is carried out through resampling, a received signal with Doppler frequency shift eliminated is obtained; and performing orthogonal demapping on the demodulated receiving signal to obtain a bit stream signal, and decoding the bit stream signal through a dimensional bit channel to obtain original transmission data.

Description

technical field [0001] The invention relates to the technical field of digital multi-carrier transmission, in particular to a method for improving the performance of underwater acoustic sparse orthogonal frequency division multiplexing multi-carrier modulation. Background technique [0002] The relative movement of the transmitting and receiving ends of the wireless communication system will produce the Doppler effect, resulting in a difference between the signal frequency of the receiving end and the signal frequency of the transmitting end, causing the constellation diagram of the receiving end to rotate, and affecting QPSK (Quadrature Phase Shift Keying) demodulation Judgment, causing misjudgment and affecting the performance of the communication system. [0003] In the underwater acoustic system, due to the slow propagation speed of sound (only 1 / 200000 of the electromagnetic wave speed), according to the calculation formula of Doppler frequency shift, even the insignifi...

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Problems solved by technology

[0002] The relative movement of the transmitting and receiving ends of the wireless communication system will produce the Doppler effect, resulting in a difference between the signal frequency of the receiving end and the signal frequency of the transmitting end, causing the constellation diagram of the receiving end to rotate, and affecting QPSK (Quadrature Phase Shift Keying) demodulation Judgment, causing misjudgment and affecting communication system performance

[0003] In the underwater acoustic system, due to the slow propagation speed of sound (only 1 / 200000 of the electromagnetic wave speed), according to the calculation formula of Doppler frequency shift, even the insignificant transceiver end for land wireless communication moves relatively It will also lead to a large error between the two

In addition, the bandwidth of the underwater acoustic channel is limited, and the interval between adjacent subcarriers in the multi-carrier system is small, so the relatively small Doppler frequency shift will also cause the overlap between the subcarriers, which seriously affects the performance of the communication system.

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