Multi-system clear optical pulse amplitude modulation and demodulation methods used in visible light communication system
A technology of visible light communication and amplitude modulation, which is applied in the direction of AM carrier system, short-distance system, free space transmission, etc. It can solve the problem that traditional PAM technology cannot be directly applied to visible light communication system, PAM technology does not have the function of light and dark control, light source flicker, etc. question
Inactive Publication Date: 2014-12-03
HARBIN INST OF TECH
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Problems solved by technology
PAM realizes the transmission of information by using different amplitudes to represent the original data. The traditional multi-ary PAM technology includes M=2 b different amplitudes, each amplitude has an equal interval d, if the traditional PAM technology is directly applied to the visible light communication system, the problem of limited bandwidth can be solved, but, as mentioned above, there will be some problems : First, because the amplitude change is determined by the original data, it is easy to cause light source flickering. Second, PAM technology does not have the function of light and dark control
However, under the premise of meeting the threshold, the traditional PAM will have a large amplitude change, so the safe and reliable use of LEDs also limits the use of PAM in visible light communication systems.
Based on the above considerations, traditional PAM technology cannot be directly applied to visible light communication systems
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specific Embodiment approach 1
[0033] Specific implementation mode 1. Combination figure 1 Describe this specific implementation mode, which is used in the multi-ary return-to-zero optical pulse amplitude modulation and demodulation method in the visible light communication system. The modulation method: first convert the M-ary system data of the visible light communication system into Gray code, and then use MRZOPAM method to modulate the system data into amplitude pulses;
[0034] The specific process of modulating system data into amplitude pulses in the method of MRZOPAM is as follows:
[0035] Amplitude pulse modulation is by changing the amplitude A of the return-to-zero optical pulse corresponding to each symbol of the Gray code corresponding to the M-ary system data i achieved;
[0036] The amplitude A i is according to the formula:
[0037] A i =a BS +[G i +1]×a slot
[0038] Obtained; where: G i is the Gray code corresponding to the system data, a BS is the fundamental amplitude in the ...
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The invention discloses multi-system clear optical pulse amplitude modulation and demodulation methods used in a visible light communication system, relating to multi-system clear optical pulse amplitude modulation and demodulation methods. A modulation method for increasing data transmission rate of the visible light communication system is designed by aiming at the indoor illumination requirement, ensuring that a light source does not flicker in a data transmission process and giving consideration to a light and shade control function of the light source. The modulation method comprises the step of modulating system data of M system of the visible light communication system into clear amplitude type pulses by adopting an MRZOPAM method. The modulation method is realized by changing the amplitude of a clear pulse corresponding to a Gray code of system data of the M system; and the demodulation method comprises the step of obtaining demodulated data from the modulated clear amplitude pulse according to a demodulation formula. The invention is suitable for the visible light communication system.
Description
technical field [0001] The invention relates to a method for modulating and demodulating the amplitude of a multi-ary return-to-zero amplitude optical pulse. Background technique [0002] In recent years, due to the widespread use of LEDs, LED-based visible light communication technology has attracted extensive research attention. The characteristic of visible light communication is that it is harmless to the human body, provides a safe communication environment, does not require frequency band application, and will not affect aviation equipment or medical equipment. [0003] At present, one of the research hotspots of visible light communication is how to improve the communication rate of visible light communication system, and the solution is mainly to study and improve the modulation method. Considering the special transmission medium of visible light and the characteristics of the system that needs to take into account the lighting, the following points need to be consi...
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IPC IPC(8): H04L27/04H04L27/06H04B10/116
Inventor 任广辉何胜阳阳云龙凌龙王刚毅任路铭
Owner HARBIN INST OF TECH