Generalized mixed visible light modulation method and device

Abstract

The invention discloses a generalized mixed visible light modulation method and device. The method comprises the following steps: transmitting a generalized ACO-OFDM signal on partial odd sub-carrier,and multiplying with a signal amplification factor; transmitting a DCO-OFDM signal on even sub-carrier and residual odd sub-carrier, and multiplying with the signal amplification factor; respectivelyperforming discrete Fourier transform on the generalized ACO-OFDM signal and the DCO-OFDM signal, and performing single-polarity processing on the converted ACO-OFDM signal, and adding DC bias on theconverted DCO-OFDM signal so as to acquire a to-be-sent signal frame; and controlling the visible light driving current after performing amplitude limiting, digital-to-analog conversion and filtering, thereby acquiring and sending the visible light communication signal. Through the modulation method disclosed by the invention, the system resource can be flexibly distributed, the signal amplitudedistribution can be optimized, the signal truncated noise is suppressed, the communication performance under light-dimming constraint is improved, the spectrum efficiency and the optical power efficiency are balanced, and the whole system performance is improved.

Description

technical field [0001] The invention relates to the technical field of digital signal transmission, in particular to a generalized mixed visible light modulation method and device. Background technique [0002] VLC (Visible Light Communication, Visible Light Communication) is a technical means to realize wireless communication on the basis of LED lighting, which uses a light source to send out high-frequency signals that cannot be detected by the naked eye to transmit information. With its wide spectrum, green energy saving, deep coverage, and the characteristics of organic combination with lighting, it has a good development prospect. [0003] Compared with traditional modulation schemes, such as OOK (On-Off Keying, binary on-off keying) modulation and PPM (Pulse Position Modulation, pulse position modulation) modulation, OFDM (Orthogonal Frequency Division Multiplex, orthogonal frequency division multiplexing) modulation It has the advantages of high spectral efficiency, ...

AI Technical Summary

Problems solved by technology

Among them, DCO-OFDM modulation makes its time-domain signal non-negative by adding DC offset, which is inefficient in terms of optical power; ACO-OFDM modulation only transmits data symbols on odd subcarriers, which is inefficient in terms of bandwidth. High; ADO-OFDM modulates positive polarity ACO-OFDM signals on odd subcarriers, and modulates DCO-OFDM signals on even subcarriers, its bandwidth efficiency is better than ACO-OFDM, and its optical power efficiency is better than DCO-OFDM, but due to ACO -OFDM and DCO-OFDM time-domain signals are both positive numbers, which can easily cause the signal amplitude to be too large and enter the nonlinear region of the system, resulting in truncation and deteriorating system performance

In addition, the number of subcarriers occupied by the above three modulation methods is fixed and cannot be changed according to system requirements.

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