Multi-dimensional mixed dimming method based on visible light communication MU-MIMO-OFDM system

Abstract

The invention discloses a multi-dimensional mixed dimming method based on visible light communication MU-MIMO-OFDM system, and belongs to the field of wireless communication. Firstly, a hybrid dimming module is constructed, a precoding matrix is designed, encoded signals are transmitted to a user of a receiving end through a visible light communication channel, and the direct current gain of a user channel matrix is calculated; the receiving vector of a single user is analyzed to obtain the signal-to-noise ratio of the user and the time domain signal after peak clipping is introduced, and a bit error rate expression of each user is established. Based on the equivalent channel matrix of the user, the maximum bit error rate of the system is taken as a constraint condition, a sending end antenna selection algorithm with the maximum singular value and the minimum singular value is designed, and an optimal working LED set is determined. The dimming precision is effectively improved, the correlation of user channels is reduced, the gain of user equivalent channels can be effectively improved, and the signal to interference plus noise ratio and the bit error rate performance of receiving end signals are effectively enhanced.

Description

technical field [0001] The invention belongs to the field of wireless communication, and in particular relates to a multi-dimensional hybrid dimming method based on a visible light communication MU-MIMO-OFDM system. Background technique [0002] As mobile data traffic has grown exponentially over the past two decades, the limitations of traditional RF mobile communications have become increasingly apparent. As one of the new communication technologies that has developed rapidly in recent years, visible light communication (Visible Light Communication, VLC) has hundreds of terahertz unlicensed visible light spectrum, and can be attached to the existing lighting infrastructure for communication. In addition, VLC will not cause interference to radio frequency communications in the same cell, and has no radiation to the human body and is highly safe. These advantages have promoted the rapid development of visible light communication, and at the same time put forward higher requ...

AI Technical Summary

Problems solved by technology

However, the existing dimming technology is mainly based on a single signal domain and space domain, which sacrifices the communication performance of the system respectively.

For example, analog dimming (Analogue Dimming, AD) technology is easy to cause peak clipping noise, especially for signal peak-to-average power ratio (Peak to Average Power Ratio, PAPR) [3] The higher visible light OFDM system has a greater impact; digital dimming technology (Digital Dimming, DD) usually needs to be combined with pulse width modulation (Pulse Width Modulation, PWM) to achieve different duty cycles, which is difficult to achieve synchronization and limits the system communication data rate [4] ; Although the spatial dimming technology can overcome the problems of peak clipping noise and rate limitation in the above-mentioned dimming technology, the dimming accuracy is still insufficient

In addition, the above-mentioned dimming technology has not considered the multi-user interference (Multi-User Interference, MUI) in the MU-MIMO system, so it is difficult to optimize the communication performance of the visible light MU-MIMO system at different brightness levels

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