Ethernet-oriented rate-adaptive variable-frame-length OFDM visible light communication system

Abstract

The invention discloses a Ethernet-oriented rate-adaptive variable-frame-length OFDM visible light communication system. The system comprises a transmitting end and a receiving end, wherein the transmitting end comprises an Ethernet interface, a PHY chip, an OFDM modem, a DAC, an electric amplifier, a Bias-Tee and a light emitting diode; the Ethernet interface is electrically connected with the PHY chip; the OFDM modem is electrically connected with the DAC; the DAC is electrically connected with the electric amplifier; the electric amplifier is electrically connected with the Bias-Tee; and the receiving end comprises a photodiode, a trans-impedance amplifier and an ADC. According to the invention, when the FIFO at the transmitting end has a space larger than 64 bytes, buffered Ethernet data can be read for modulation and transmission, then through channel estimation and compensation, the time domain or frequency domain response of a channel is estimated, the received data is corrected and recovered, and after demapping and FIFO module delay are utilized, a frame of complete Ethernet data is obtained, so that the time delay can be obviously reduced while the adaptive variable frame length is realized.

Description

technical field [0001] The invention relates to the field of visible light communication systems, in particular to an Ethernet-oriented rate adaptive variable frame length OFDM visible light communication system. Background technique [0002] Visible light communication system refers to a wireless communication method that uses electromagnetic waves in the visible light band as information carriers and uses light-emitting diodes to send out high-speed bright and dark flashing signals to directly transmit information. Visible light communication has the characteristics of green environmental protection, low power consumption, and high confidentiality. It has been widely used in fields such as underground and underground operations. [0003] Ethernet (Ethernet) is a computer local area network networking technology. In order to transmit data with specific meaning to the receiver through the physical medium, the visible light communication system needs to use the Ethernet pro...

AI Technical Summary

Problems solved by technology

However, when the Ethernet data splicing that needs to be sent is not a multiple of the data source required for OFDM modulation in one frame, and there is a large subcarrier spacing, it is necessary to fill in a lot of useless data to modulate a frame of OFDM signal

For example, when Mod (the amount of Ethernet data currently required to be transmitted, the amount of data required for one frame of OFDM modulation) is greater than one-tenth of the amount of data required for one frame of OFDM modulation, it will cause almost a waste of OFDM frame

This will cause the entire system to have a large enough rate margin for the rate of OFDM modulation and demodulation on the one hand, and on the other hand, it will cause a large delay in data buffering and frame cutting, resulting in waste of resources and overall system failure. performance degradation

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