Hybrid visible light communication method based on MPPM dimming control
A technology of visible light communication and dimming control, which is applied in the field of wireless optical communication, can solve the problem that the visible light modulation method cannot take into account the spectral efficiency and LED brightness adjustment effect at the same time, achieve high power efficiency, high power efficiency and spectral efficiency, and reduce complex degree of effect
Inactive Publication Date: 2020-05-19
JIANGNAN UNIV
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[0003] In order to solve the technical problem that the visible light modulation method in the prior art cannot simultaneously take into account spectral efficiency and LED brightness adjustment effect, the present invention provides a hybrid visible light communication method based on MPPM dimming control, which can simultaneously support visible light data communication and dimming control, At the same time, it has high spectral efficiency
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[0060] The present invention is based on a hybrid visible light communication method based on multiple pulse position modulation (MPPM for short) dimming control, which includes the following steps.
[0061] S1: Define the OFDM signal modulated by QAM as X, and the OFDM signal X satisfies Hermiral symmetry:
[0062] X=[0,X 1 ,0,X 3 ,...,X N-1 ];
[0063] S2: if figure 1 As shown, QAM modulation is performed on the OFDM signal data to make the OFDM signal into a frequency band signal, and the frequency band signal is constructed as a Hermitian symmetric matrix satisfying the symmetry characteristic, and then the IFFT transformation is performed to obtain the corresponding time domain signal, and the transformed matrix is added Cyclic prefix CP to obtain the final OFDM signal matrix;
[0064] Among them, the inverse fast Fourier transform operation is performed on the OFDM signal X, and the OFDM time domain signal is obtained as x n :
[0065]
[0066] and satisfy
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The invention provides a hybrid visible light communication method based on MPPM dimming control, and the method can support visible light data communication and dimming control at the same time and has high spectral efficiency. According to the technical scheme of the invention, the method comprises the steps: generating an OFDM signal with Hermitian symmetry, carrying out the reverse Fourier transform of the OFDM signal into a time domain signal with odd symmetry, and generating a brightness control sequence with even symmetry based on the basic principle of MPPM; preprocessing the OFDM signal matrix to ensure that the signal formed by superposing the OFDM signal matrix and the brightness control sequence is in the linear range; and finally, performing simple superposing of the OFDM signal matrix and the dimming sequence to obtain the driving signal of the light-emitting device, wherein the two signals at the receiving end can be correctly detected.
Description
technical field [0001] The invention relates to the technical field of wireless optical communication, in particular to a hybrid visible light communication method based on MPPM dimming control. Background technique [0002] Visible light communication combines LED technology with information transmission, does not occupy radio frequency spectrum resources, has broad application prospects, and has the advantages of low cost, high transmission rate, good confidentiality, and no electromagnetic radiation. OFDM is a multi-carrier modulation technology with high spectrum efficiency, which can effectively resist multipath fading and inter-symbol interference during wireless transmission, and is widely used in visible light communication technology; and visible light communication systems usually use low-cost , Low-complexity intensity modulation / direct detection (IM / DD) method, so visible light communication can only transmit positive real signals; in practical applications, whil...
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IPC IPC(8): H04B10/116
CPCH04B10/116
Inventor 薛晓妹李宝龙周颖洪焕东关少义
Owner JIANGNAN UNIV