Adaptive low peak ratio method for visible light ofdm system based on subcarrier reservation
A sub-carrier, adaptive technology, applied in multi-frequency code systems, short-range systems, free space transmission and other directions, can solve the problems of serious VLC system overall performance, nonlinear distortion performance, increase system power consumption, etc., to reduce System Power Consumption, Reduced Nonlinear Distortion, Simple Effects
Active Publication Date: 2022-02-15
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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[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. Such as 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 D...
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The invention discloses an adaptive low peak ratio method for a visible light OFDM system based on subcarrier reservation. The method of the present invention includes: (1) at the transmitting end, the binary bit information flow generated by the information source undergoes adaptive quadrature amplitude modulation to form a frequency domain data signal at the transmitting end; (2) determining the number of reserved subcarriers in the visible light communication system and the corresponding position; (3) perform conjugate symmetry processing on the frequency domain data signal on the OFDM subcarrier; (4) calculate the frequency domain value of the reserved subcarrier; (5) perform the IFFT operation on the OFDM frequency domain signal, and add The cyclic prefix is used to obtain the time-domain electrical signal for driving the LED; (6) DC bias or clipping is performed on the electrical signal, and then the LED is driven to emit an optical signal; (7) At the receiving end, the optical signal is converted into an electrical signal through a photodiode; ( 8) Transform the obtained electrical signal into a frequency domain signal; (9) Demodulate to obtain a binary information stream. The invention reduces the system's requirement on the linearity of the power amplifier and the LED lamp, and reduces nonlinear distortion.
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...
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IPC IPC(8): H04B10/116H04L27/26
Inventor 张华郑坤
Owner SOUTHEAST UNIV