Multi-source ofdm transmission method and transmitter for visible light communication

Abstract

Disclosed is a multi-light-source OFDM emitting method used for visible light communications. The multi-light-source OFDM emitting method comprises the steps that modulating symbols are divided into N routes through serial-parallel conversion and are modulated onto N routes of sub carrier waves from f<0> to f<N-1> to obtain N routes of subcarrier wave signals, the N routes of subcarrier wave signals are loaded to N LED light sources to respectively generate a light signal, and the LED light sources are separated from one another so that the light signals can be overlapped in space. The invention further provides a multi-light-source OFDM emitter used for visible light communications. The invention further provides a multi-light-source emitter used for visible light communications. The multi-light-source OFDM emitter comprises a serial / parallel conversion module used for converting the modulating symbols into the N routes, a modulating module used for modulating the N routes of signals onto the N routes of subcarrier waves from f<0> to f <N-1> respectively, and the N LED light sources which are used for loading the N routes of subcarrier waves so as to generate the light signals. The multi-light-source OFDM emitter can obviously reduce the requirements for the linear region range of devices, and meanwhile, improve the power efficiency to a certain degree.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a multi-light source OFDM transmitting method and a transmitter for visible light communication. Background technique [0002] LED lighting technology has been rapidly popularized due to its advantages of energy saving, long life, and reliability, and the visible light communication technology based on white LEDs has also emerged. Visible light communication technology utilizes the fast switching response characteristics of LEDs to send loading information in the form of illumination light through free space, and at the same time uses photoelectric conversion devices such as PDs (photodiodes) to receive optical signals and convert them into electrical signals to obtain information. However, the limited physical bandwidth of LEDs is a bottleneck restricting the promotion of this technology. [0003] OFDM is a special multi-carrier transmission technology, which ...

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Problems solved by technology

In addition, the maturity of the FFT / IFFT algorithm is very high, which also reduces the calculation amount of the structure

[0005] Using the typical structure of the OFDM system for visible light communication, the transmission and reception of signals are implemented as figure 2 As shown, however, the OFDM signal has extremely high peak power, and its peak-to-average power ratio (PAPR) is very large, which not only greatly reduces the power efficiency (because the LED cannot modulate negative signals, it is necessary to increase the DC bias, or reduce small signal amplitude), and put forward strict requirements on the range of the linear region of the device (to ensure that the signal does not suffer from serious nonlinear distortion such as amplitude cut-off)

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