Research On Indoor Visible Light MIMO Technologies

Visible light communication(VLC)is a kind of newly emerging optical communication technology which is based on white LED as the light source,and takes into account both lighting and data transmission.White LED light source has the advantages of low power consumption,long service life,etc.,and it is developing into the next generation of green lighting source,and VLC has received extensive attention and research.Compared with the traditional wireless communication,visible light communication does not produce electromagnetic interference,does not need toapply for authorization,and it can be used as a supplement to wireless communication.Indoor lighting usually requires a large amount of LEDs,which provides a place for the application of visible light communication technology.But the distance of visible light propagating is short,easy to be interfered by natural light,and the technology of transmitting and receiving device is limited,which affects the capacity and spectrum efficiency of the system.In the large-scale application of visible light communication,there are still many technical difficulties to break through.Based on the research background and current research status of visible light communication technology,this research mainly focuses on the characteristics of indoor visible light communication channel,VLC MIMO preencoding scheme and the system design of VLC MIMO.The main work of this research can be summarized as follows.Firstly,the channel characteristics of the visible light communication system are studied,and typical visible light communication links are modeled,and the calculation formula of the channel DC gain is derived.The distribution of the light-intensity,optical power distribution(OPD)and channel impulse response are simulated.Secondly,the influence of two kinds of typical linear preencoding schemes is analyzed,and the effect of FOV on the performance of the receiver is analyzed.Different FOV is proposed to solve the problem of the channel rank deficiency in the multiuser preencoding scheme.With the mobility of the receiver,it is verified that the correlation of the channel matrix can be reduced effectively when the user's multiple receivers are distinguished by different FOV,and BER and SNR performance of the optical communication system are improved greatly.In the end,the design of VLC MIMO system is studied.From a practical perspective,the design types of three kinds of VLC MIMO system are compared,and the advantages and disadvantages of each system are summarized.The technology of VLC receiving and modulation and encoding are analyzed,and the improved scheme is put forward.The design of MAC frame format and PHY layer operating mode in IEEE 802.15.7 are studied.