Visible light communication light-dimming method based on special constellation point and inverse-return-to-zero coding

Abstract

The invention belongs to the technical field of the visible light communication, and discloses a visible light communication light-dimming method based on a special constellation point and inverse-return-to-zero coding. The light-dimming method is mainly composed of special constellation point modulation, inverse-return-to-zero coding and pulse forming; the special constellation point modulation format is circular (7,1) modulation; the inverse-return-to-zero coding adopts the high level to replace the low level of the traditional return-to-zero coding, thereby maintaining that the LED is in the lighting state even if the duty ratio is less; the flicker capable of being sensed by the human eye is avoided while the luminous efficiency is effectively improved; and meanwhile, the return-to-zero coding can cause the broadening of the spectrum and is bad for the realization of the visible light communication with limited bandwidth, so that the pulse forming is used for filtering to achieve an aim of compressing the spectrum. Compared with the traditional light-dimming scheme, the method disclosed by the invention has higher luminous effect and wider light-dimming range, and the relatively high transmission rate can be maintained at the same time.

Description

technical field [0001] The invention belongs to the technical field of visible light communication dimming, and in particular relates to a visible light communication dimming method based on special constellation point modulation and reverse return-to-zero coding. Background technique [0002] Smaller size, longer service life and lower power consumption make LED stand out in the field of lighting and are gradually replacing incandescent and fluorescent lamps. At the same time, the larger modulation bandwidth of LEDs has promoted the rise of a new type of wireless communication, visible light communication. Visible light communication, which has both lighting and communication functions, has become a strong competitor for future indoor wireless access networks. [0003] IEEE 802.15.7 is the first international standard for visible light communication, in which dimming control is highlighted for discussion. In this standard, the visible light dimming scheme is based on OOK ...

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Problems solved by technology

However, these codes have a common disadvantage. When the duty cycle is less than 50%, the signal is at zero level for a long time, and the LED can

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