A visible light ofdm communication device with infrared compensation and full-range dimming

Abstract

The invention discloses a visible light OFDM communication device with infrared compensation and full-range dimming, comprising: a dimming pulse generator, a signal source, an OFDM modulator, a visible light LED driver, an infrared LED driver, a commercial visible light LED lighting source, a low-power infrared LED compensation light source, photoelectric detector, dimming pulse discriminator, normalization processor, OFDM demodulator and sink. Through the above method, the infrared compensation full-range dimming visible light OFDM communication device of the present invention can not only adjust the light in a full range but also transmit OFDM signals, and the transmission rate and transmission quality of OFDM signals are hardly affected during dimming. It greatly reduces the dependence of signal transmission performance on the dimming duty cycle in traditional solutions, and effectively reduces system complexity.

Description

Technical field [0001] The present invention relates to the field of indoor visible light communication devices, in particular to a visible light OFDM communication device with infrared compensation and full-range dimming. Background technique [0002] Energy-saving LED technology has become the first choice for indoor lighting facilities. LED-based visible light communication is an additional function of indoor lighting facilities because of its advantages such as energy saving and environmental protection, not occupying scarce wireless spectrum resources, and good information confidentiality. In recent years, it has become a research hotspot in the field of communications. Orthogonal frequency division multiplexing (OFDM) transmission technology has been widely used in indoor visible light communication systems because of its advantages such as high channel utilization, strong resistance to multipath fading and low implementation complexity. [0003] As the most basic function o...

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Problems solved by technology

Therefore, in order to ensure the normal transmission of OFDM signals, the dimming range will be limited and cannot reach the full range;

[0006] (2). Since no signal is transmitted during the "off" dimming time slot, when there is no lighting in the room, that is, when the duty cycle D=0%, there is no basic communication link;

[0007] (3). Since no signal is transmitted in the "off" dimming time slot, the OFDM signal transmitted in the current "on" dimming time slot needs to wait for the OFDM signal in the subsequent "on" dimming time slot until the receiving end receives the OFDM demodulation can only be performed when the signals of the "on" dimming time slot are spliced ​​into a whole OFDM frame, so there is a problem of signal transmission delay;

[0008] (4). Since the OFDM subcarrier symbol modulation order is not considered, if the duty cycle is changed while changing the subcarrier symbol modulation order in order to keep the transmission rate constant, the circuit design will be complicated

[0010] (1). Since the infrared light link is used as the main high-speed communication link, and the visible light link is used as the low-speed auxiliary communication link, in order to achieve a certain quality of high-speed communication, the power of the infrared light source must be higher. Thus affecting human health, at the same time, the potential of high-speed communication of visible light sources has not been effectively developed;

[0011] (2). Because it does not have the dimming function of the LED light source, it does not conform to the design concept of the modern indoor lighting system;

[0012] (3). Since the signal waveforms emitted by the visible light source and the infrared light source are completely different, the two signals will interfere with each other when receiving. The receiving mechanism is not perfect, which can easily cause misjudgment and affect the quality of communication;

[0013] (4). Since the high-speed infrared symbols cannot cross the edge position of the "on" and "off" dimming time slots of visible light, the infrared signal and the visible light pulse signal must be completely synchronized (that is, the edges of the two symbols need to be aligned), which Greatly increased system complexity;

[0014] (5). Due to the lack of OFDM modulation, the communication system has poor anti-multipath fading ability;

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