MIMO (Multiple-Input Multiple-Output)-OFDM (Orthogonal Frequency Division Multiplexing)-CDMA (Code Division Multiple Access) spread spectrum method combined with selected mapping

Abstract

The invention belongs to the technical field of wireless communication, and discloses an MIMO (Multiple-Input Multiple-Output)-OFDM (Orthogonal Frequency Division Multiplexing)-CDMA (Code Division Multiple Access) spread spectrum method combined with selected mapping. The method comprises the steps of respectively performing constellation mapping, serial-parallel conversion and spread spectrum processing on information of each user, and then adding the information together to serve as an original frequency domain signal; selecting a variety of spread spectrum codes to serve as alternative sequences in a phase sequence generator, multiplying the alternative sequences with the original frequency domain signal to perform phase rotation on different subcarriers, respectively performing an IFFT(Inverse Fast Fourier Transform) operation after multi-channel transformation, and selecting the minimum PAPR (Peak to Average Power Ratio) to serve as a transmission time domain signal; performing FFT and signal combination on received signals to obtain a frequency domain signal after the phase rotation sequence; and restoring the user information according to sideband information, and de-spreading and restoring the signal through spread spectrum codes of different user information. The method disclosed by the invention improves the flexibility of the phase selection sequence, and is greatlyimproved on the aspects of peak-to-average ratio and bit error rate.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, in particular to a joint selective mapping MIMO-OFDM-CDMA spreading method. Background technique [0002] At present, the existing technologies commonly used in the industry are as follows: [0003] In the field of wireless communication, how to make the signal can be transmitted with high reliability in extremely low signal-to-noise ratio and high dynamic complex environment, and how to make the best use of limited frequency and power resources is a hot research topic in the field of wireless communication today. OFDM-CDMA (Multi Carrier-Code Division Multiple Access) is a new wireless transmission technology that combines OFDM (Orthogonal Frequency Division Multiplexing) and CDMA (Code Division Multiple Access). Because it combines the advantages of both CDMA and OFDM technologies, that is, it has the advantages of traditional CDMA anti-interference ability and large capacity, ...

AI Technical Summary

Problems solved by technology

[0007] (1) The selection of the phase rotation factor is single, which is not flexible enough, which leads to the limited gain of the SLM method for signal PAPR optimization and transmission bit error rate improvement;

[0008] (2) The influence of the correlation characteristics of the spreading code in the OFDM-CDMA system on the peak-to-average ratio of the system and the bit error rate of information transmission is not fully considered;

[0009] (3) It is necessary to transmit all the phase rotation factor information transmitted, and the transmission sideband information is large, resulting in low spectrum utilization

[0010] The difficulty and significance of solving the above technical problems: The current SLM method in the OFDM-CDMA system directly follows the SLM method in the OFDM system, and does not take into account the influence of the correlation characteristics of the spreading code itself on the system PAPR and transmission bit error rate in the OFDM-CDMA system

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