Research Of Adaptive Channel Equalization And Dimmable Encoding Technology For Visible Light Communication

Visible light communication (VLC) has attracted much attention and inspired significant research activities as the rapid development of green source light emitting diode (LED) and conventional wireless communication not satisfying the increasing demand of indoor access. LED is viewed as one of the most promising technology area in21th century. Compared with traditional luminance sources, LED has many charming advantages, such as small size, less weight, long life, high brightness, high power efficiency. With the reducing cost in manufacture, LED is expected to be the most important luminance device. As the increasing need of real-time wideband application, traditional radiofrequency (RF) systems can not satisfy the constantly increasing demand for wireless data transmission, such as mobile TV and CMMB. Utilizing higher frequency source has become a common idea in the area of academy and industry. Due to above reasons, indoor visible light communication (VLC) is proposed to provide indoor wireless coverage. This technique is viewed as the hybrid achievement which can link the conventional optical communication and radio frequency (RF) wireless communication. More and more researchers regard it as a forward technique.Due to the existing LED lights modulation bandwidth is relatively low, it cannot meet the current real-time transmission of big data source. So the most important thing is how to improve the LED light modulation bandwidth with the existing hardware condition. However, the communication quality will be worse when LED lights is getting dimmer, so the LED dimming technology is becoming a good method to proper it. But many dimming schemes will reduce the system transmission capacity, thereby coding dimming of LED lights is becoming a good method to solve the communication problems in dark environment.The main innovation of this paper includes the following two points:· This paper proposes an adaptive channel equalization system to solve the problem of low modulation bandwidth, proposes the using of decision feedback equalizer to overcome the problem of indoor LED array channel equalization, utilize minimum mean square error algorithm to optimize the feedback equalizer coefficients of each part, and find the moving speed for different positions and set the training sequence when to send and how to send.· The paper proposes a packet-based statistical channel coding scheme to solve the problem of the worse communication in darker environment, changing the ratio of the original input data stream of the low and high technical level. Probabilistic thinking is utilized to achieve LED dimming. The results of the BER show that the packet-based statistical dimming coding allows LED lights in different light conditions can maintain good communication performance.