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A visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation

A sub-carrier and self-adaptive technology, applied in the direction of multi-frequency code system, short-distance system, free space transmission, etc., can solve serious problems such as overall performance of VLC system, nonlinear distortion performance, increased system power consumption, etc., and achieve reduction System power consumption, reduce nonlinear distortion, achieve simple effects

Active Publication Date: 2019-05-21
SOUTHEAST UNIV
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Problems solved by technology

In radio frequency communication, too high PAPR will cause the signal envelope to exceed the linear region of the power amplifier, resulting in nonlinear distortion and performance degradation
Similarly, LED, as the main nonlinear source in visible light communication, is very sensitive to high PAPR signals. If this problem is not paid attention to, it will seriously affect the overall performance of the VLC system.
At the same time, in the DCO-OFDM system, high PAPR will also lead to an increase in DC bias, thereby increasing system power consumption

Method used

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  • A visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation
  • A visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation
  • A visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation

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Embodiment Construction

[0061] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution in the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0062] figure 1 It is a system block diagram of the low peak-to-average power ratio visible light orthogonal multi-carrier transmission method proposed by the present invention. like figure 1 , the visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation of the present invention is carried out according to the following steps:

[0063] 1. In the offline stage, according to the characteristics of the visible light communication channel, the reserved subcarriers are placed at the high frequency end, and the subcarriers in the high frequency band are continuously expanded to the low frequency bands according to the ratio of the reserved subcarriers;

[0064] 2. In the offline stage, the DNR-...

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Abstract

The invention discloses a visible light OFDM system self-adaptive low peak ratio method based on subcarrier reservation. The method comprises the following steps: (1) at a transmitting end, allowing binary bit information flow generated by an information source to be subjected to adaptive orthogonal amplitude modulation to form a frequency domain data signal of the transmitting end; (2) determining the number of reserved subcarriers and corresponding positions in the visible light communication system; (3) performing conjugate symmetry processing on the frequency domain data signal on the OFDMsubcarrier; (4) calculating a reserved subcarrier frequency domain value; (5) performing IFFT operation on the OFDM frequency domain signal, and adding a cyclic prefix to obtain a time domain electric signal for driving the LED; (6) carrying out direct current bias or clipping on the electric signal, and then an LED is driven to emit an optical signal; (7) at a receiving end, converting the optical signal into an electric signal through a photodiode; (8) converting the obtained electric signal into a frequency domain signal; And (9) demodulating to obtain binary information flow. According to the invention, the requirement of the system on the linearity of the power amplifier and the LED lamp is reduced, and the nonlinear distortion is reduced.

Description

Technical field: [0001] The invention relates to an adaptive low peak ratio method for a visible light OFDM system based on subcarrier reservation, and belongs to the field of visible light communication system design. Background technique: [0002] With the severe shortage of wireless spectrum resources, visible light communication technology (VLC) has emerged and is favored by researchers. Visible light communication technology is a technology that replaces radio frequency or microwave frequency band electromagnetic waves in traditional radio frequency communication with visible light as a wireless communication signal transmission carrier for information transmission. . Visible light communication uses light-emitting diodes (LEDs) and photodiodes (PDs) as transmitters and receivers, usually using intensity modulation (IM) and direct detection (DD), whose channel characteristics and positive real signal constraints make the total multi-technology in radio frequency commun...

Claims

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Application Information

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IPC IPC(8): H04B10/116H04L27/26
Inventor 张华郑坤
Owner SOUTHEAST UNIV
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