LED visible light orthogonal multicarrier communication method with low peak average power ratio

Abstract

The invention discloses an LED visible light orthogonal multicarrier communication method with low peak average power ratio. The LED visible light orthogonal multicarrier communication method with low peak average power ratio comprises the steps of deducing and transforming a problem of optimizing a peak to average power ratio into a convex optimization problem based on a characteristic of OFDM subcarrier conjugate symmetry in visible light communication at a transmitting end; calculating a reserved subcarrier frequency threshold through a conventional convex optimization method; processing a signal in which the reserved subcarriers are inserted to obtain a time domain transmitting signal; and removing conjugate subcarriers from the signal at a receiving end, then filtering away the reserved subcarriers through a filtering module and finally demodulating to obtain a received signal. According to the LED visible light orthogonal multicarrier communication method with low peak average power ratio, a traditional subcarrier reservation method is applied to the visible light communication, the number and position of the reserved subcarriers are determined based on the channel characteristics in the visible light, deductive analysis is carried out based on the characteristic of the optical channel subcarrier conjugate symmetry, and the optimization problem of the peak average power ratio is accordingly solved. In addition, the LED visible light orthogonal multicarrier communication method with low peak average power ratio is applicable to a DCO-OFDM system and an ACO-OFDM system.

Description

technical field [0001] The invention relates to an LED visible light adaptive multi-carrier communication method with low peak-to-average power ratio, and belongs to the field of visible light communication system design. Background technique [0002] Visible light communication (VLC) has received extensive attention due to its unique advantages, such as high speed, high security, abundant unregulated bandwidth, and environmental protection. Visible light communication was initially implemented with on-off keying technology. In order to achieve higher spectral efficiency, multi-level quadrature amplitude modulation (M-QAM) and orthogonal frequency division multiplexing (OFDM) were used, and OFDM modulation was introduced. The symbols are sent in parallel on orthogonal sub-carriers, which can provide high-speed data transmission and combat multipath effects. [0003] Since the signal-emitting devices used in visible light communication (VLC) systems are LEDs, using intensity...

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Problems solved by technology

And it is necessary to add a DC bias to the real AC signal to make the signal a positive value. This method is simple to implement and has a high frequency utilization rate, which is twice that of ACO-OFDM, but increases the DC power consumption.

[0004] Although OFDM has many advantages, similar to the OFDM system in radio frequency communication, the OFDM system in visible light communication also has the problem that the signal peak-to-average power ratio PAPR is too high

A high PAPR will put forward high requirements on the linearity of the power amplifier at the transmitter. In an optical OFDM system, an excessively high PAPR will not only impose higher requirements on the linearity of the LED lamp but also the power amplifier. Because the power amplifier and the LED lamp Non-linear characteristics can cause nonlinear distortion, which can seriously degrade the overall performance of the system

At the same time, in the visible light communication DCO-OFDM system, high PAPR will also lead to an increase in the required DC bias, thereby increasing the system power consumption,

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