Wavelet multi-carrier spread spectrum communication system and method with frequency changing

Abstract

The invention discloses a wavelet multi-carrier spread spectrum communication system and method with frequency changing. The system comprises a signal transmission device and a signal receiving device. The signal transmission device comprises an encoder, a spread spectrum unit, a carrier modulation unit and a parallel-series conversion unit all of which are connected in sequence; the signal receiving unit comprises a series-parallel conversion unit, a wavelet carrier unit, a dispreading unit, a data demodulation unit and a decoder all of which are connected in sequence. The system carries out wavelet reverse transformation on multi-carrier spread spectrum signals according to channel frequency changing to finish the parallel-series conversion, the system can be answerable for a time-frequency selective channel, and the stability of the system is improved; meanwhile, the fast wavelet transformation is adopted, the system has high adaptation and low calculation complexity.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to a wavelet multi-carrier spread-spectrum communication system, in particular to wavelet multi-carrier spread-spectrum communication that can vary with channel time and frequency. Background technique [0002] The wireless channel has the characteristics of time-frequency selective attenuation and is affected by the multipath effect. In the existing wireless communication technology, in order to overcome the above problems, multi-carrier modulation technology is mainly used, that is, orthogonal frequency division multiplexing technology and spread spectrum The combination of technologies, that is, the use of multi-carrier spread spectrum communication systems to achieve data transmission. However, although the existing technical solutions of the multi-carrier spread spectrum communication system have high modulation efficiency and achieve a satisfactory transmission ...

AI Technical Summary

Problems solved by technology

However, although the existing technical solutions of the multi-carrier spread spectrum communication system have high modulation efficiency and achieve a satisfactory transmission rate, the receiving mechanism of OFDM is complicated, and the required protocol is also complicated. , the construction cost is high, and at the same time, because OFDM is implemented by fast Fourier transform, the frequency interval between subcarriers is fixed and minimum, so it is extremely sensitive to carrier frequency error

If there is any error in the carrier frequency caused by the Doppler effect and clock deviation caused by the relative motion between the transmitter and the receiver, the carrier frequency will lose its orthogonality and generate large inter-carrier interference, making the communication system reliable Unsatisfactory sex and adaptability

In addition, for frequency-selective channels, OFDM adopts a method of frequency dispersion, and its operation performance can achieve better results; for time-selective channels or time-frequency selective channels, Orthogonal frequency division multiplexing cannot cope with channel changes, and its operating performance often cannot achieve better results

In addition, OFDM is extremely sensitive to strong noise interference, and its reliability and adaptability are unsatisfactory in the case of large impulse noise interference

In order to overcome the problem of performance degradation caused by channel time-frequency variation in multi-carrier spread-spectrum communication systems, it is necessary to develop new multi-carrier spread-spectrum communication that can change with channel time-frequency variation and can simultaneously deal with strong noise interference However, the methods developed so far have high computational complexity and are difficult to implement in real-time communication systems.

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