Visible light multi-carrier transmission method using multiplicative clipping

Abstract

The invention discloses a visible light multi-carrier transmission method using multiplicative clipping. Positive value signals in each set of symmetrical time domain signals are reserved according to the characteristics of PAM-DMT modulation signals, and zero setting is conducted on negative value signals. The maximum optical signal threshold value is set as eta c, and when the data bit is larger than eta c, clipping is conducted after the data bit is multiplied with a given constant alpha. Then, the signal values at symmetrical positions are changed into preset fixed signal values from 0 so that the symmetrical position can serve as mark bits. A system receiving end determines signal clipping positions and the mark bits through an MAP detection method, signal recovery is conducted according to the multiplicative clipping principle used by a sending end, and therefore the sending signal detection is completed. By means of the method, the PAPR of emitted light signals is effectively reduced through multiplicative clipping, the method is easy to achieve, the system energy utilization rate is increased while the PAPR is restrained, the requirements a system for the linear ranges of power amplifiers and light-emitting diodes, the nonlinear distortion of signals in the electric domain and the light domain is reduced, and the overall performance of the system is improved.

Description

technical field [0001] The invention relates to a visible light multi-carrier transmission method using multiplicative clipping, which belongs to wireless optical communication technology. Background technique [0002] Due to the fact that it is not affected by the growing radio frequency coverage and enjoys a large amount of spectrum resources, visible light communication has attracted extensive attention in the field of next-generation wireless transmission. Since the current optical communication system generally adopts intensity modulation / direct detection (IM / DD), that is, the signal modulates the intensity of light, so it is necessary to ensure that the time domain signal is a positive real number. Binary on-off keying modulation (OOK) is simple to implement, but has poor energy efficiency. In order to improve the data transmission rate and spectrum utilization, and resist multipath fading at the same time, the discrete multi-tone modulation technique (DMT) derived fr...

AI Technical Summary

Problems solved by technology

Binary on-off keying modulation (OOK) is simple to implement but poor in energy efficiency

When the data at the input of the IFFT is in phase, its output will have a large peak value, thus causing an excessive peak-to-average ratio (PAPR)

[0006] Whether it is ACO-OFDM, DCO-OFDM, or PAM-DMT, there is a problem of too high PAPR

Excessive PAPR will not only increase the requirements for the linear range of analog-to-digital and digital-to-analog converters, but also make the signal easily enter the nonlinear region when passing through the circuit, resulting in signal distortion and a significant impact on the overall performance of the system

In the optical system, not only the power amplifier has nonlinearity, but also the light-emitting diode (LED) has nonlinearity, so the nonlinear effect caused by too high PAPR is more serious

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