The Study Of Channel Characteristics In MIMO-VLC System

Because white LED has the feature of high brightness, low power consumption, high reliability and long life, it applies in business more and more widely. In 21st century, the concept of "Green lighting" and "Green communication" is more and more popular, because of its double function of lighting and communication; indoor visible light communication technology gets more and more attention. The low modulation bandwidth characteristic of white LED limits the data transfer rate of visible light communication system. In order to obtain gigabytes of data transfer rate, researchers have proposed indoor visible light multiple input multiple output system.First, this thesis introduces the research background and meaning of indoor VLC technology, summarizes the basic principle of indoor visible light communication. In order to improve data transmission rate, we bring MIMO technology into VLC system that constitutes MIMO-VLC system. Then, this thesis introduces the basic principles of imaging MIMO-VLC system and non-imaging MIMO-VLC system. Second, we study the luminance distribution and light power distribution in whole room based on MIMO-VLC system. Third, we study channel characteristics of MIMO-VLC system, mainly including the following respects:1. Analysis and simulation of impulse response in MIMO-VLC system. On the basis of studying many VLC impulse response algorithms, considering the complexity and accuracy of algorithm, we choose the iteration impulse response algorithm based on fixed point to study impulse response characteristics in MIMO-VLC system. Then, we analyze multipath interference of MIMO-VLC system when LED array and detector array lay on different relative position based on impulse response.2. The study of LED array layout optimization in MIMO-VLC system. We study the mean and variance of multipath interference under different LED array configuration at 100 Mbps data transmission rate based on impulse response algorithm, then we consider the double function of communication and lighting, study optical power and the luminance distribution under different LED array configuration, get an optimized layout.3. We study the features of channel matrix rank when LED array and detector array is under a symmetrical position. Analysis shows that the channel matrix is full rank when LED array and detector array lay on a symmetrical position.4. We study the relationship between channel matrix rank with the receiver’s field of view (FOV). Finally, we summarize the whole work, and look forward to the next phase of work.This thesis focuses on the channel characteristics of MIMO-VLC system, then studies LED layout optimization problems based on the channel characteristics. Our studies have a significant guiding meaning for designing MIMO-VLC system. The conclusion can provide technical support for implementing MIMO-VLC system.