DCO-OFDM system direct current bias setting method applicable to visible light communication

Abstract

The invention relates to the field of visible light communication, and provides a DCO-OFDM system direct current bias setting method applicable to visible light communication. Channel coding is carried out information source information before the information source information is modulated; good error correction and detection performance of an error correction code is utilized, reliability and power utilization of a system are taken into account comprehensively, the clipping proportion of a time-domain signal is appropriately added at a sending end, direct current bias required by the system is reduced, and therefore the power utilization rate of the system and the illuminating brightness adjustable range are improved. A receiving end compensates for clipping distortion of the sending end through error correction capacity of a channel code. The DCO-OFDM system direct current bias setting method reduces the magnitude of the direct current bias which needs to be added when DCO-OFDM modulation is carried out by the sending end, the power utilization rate of the system is improved, the brightness adjusting range on the aspect of illumination of visible light communication is expanded to a certain extent, and reliability and applicability of the system are enhanced.

Description

technical field [0001] The present invention relates to the field of visible light communication, in particular to a DC bias setting method for a DCO-OFDM system suitable for visible light communication. Background technique [0002] Visible light communication (VLC) technology has attracted extensive attention in various fields in recent years. It has the application characteristics of lighting and communication in one, has relatively rich spectrum resources and good confidentiality, has relatively little impact on the human body, and is green and safe. Since visible light communication has the functions of lighting and communication at the same time, it is necessary to comprehensively consider the dual indicators of daily lighting requirements and communication reliability during design. [0003] Visible light communication systems usually adopt the transmission mode of intensity modulation / direct detection (IM / DD), which requires that the signal x(t) that modulates the l...

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Problems solved by technology

[0004] The DCO-OFDM system obtains the time-domain signal of modulated light intensity by adding a DC bias. The selection of the DC bias has always been a difficult problem in the design. Although a large DC bias reduces the clipping distortion of the signal, it leads to a decrease in the power utilization of the system. The rate is reduced, and the transmission power required to achieve the specified bit error rate performance is large. At this time, the brightness adjustment range of the system lighting is also very limited; the small DC bias will cause serious clipping distortion of the system and reduce reliability. The bit error rate is higher under the transmit power

At present, there are many methods for optimizing the DC bias in the traditional DCO-OFDM system and calculating the optimal DC bias in the DCO-OFDM system, but these methods do not consider the influence of the encoder on the DC bias in the actual system, resulting in the added DC Excessive bias reduces power utilization and reduces the brightness adjustment range of lighting

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