Design And Implementation Of Spatial Modulation In VLC

With the advent of the 5G,wireless communication has become an indispensable part in our daily life.Compared to the microwave communication,visible light communication(VLC)has the advantages of limitless bandwidth,large capacity,high transmission rate,good secrecy and flexible deployment,which is gradually become the focus of extensive attention among researchers.Except traditional signal domain information to convey information,optical spatial modulation(OSM)also carry additional information by the LED index.Sicne only one LED carrying information in time interval,OSM can avoid the inter-channel interference(ICI)and synchronization problems in optical multi-input multi-output(OMIMO)system.OSM can reach a compromise between transmission rate,energy efficiency,and computational complexity.At present,the researches on the transmission rate,antenna selection,signal detection and power allocation have been done by various research institutions.However,there are few studies in the Hardware circuit design and system implementation.Therefore,according to the OSM principle and the characteristics of the VLC channel,the hardware circuit of the SM-VLC system is designed in this thesis.Meanwhile,the modulation and demodulation program designs are accomplished on the basis of FPGA.Finally,this dissertation implements a entire visible light spatial modulation communication system.The specific research contents are as follows:(1)A 4×4 SM-VLC system hardware circuit is implemented.A method of using channel estimation results to implement LED serial number recognition is proposed,and the schematic diagram and PCB design are completed.The transmiter of the system is composed of a power supply circuit and an LED drive circuit;the receiver is mainly composed of a preamplifier circuit,a filter circuit,a main amplifier circuit,an LED serial number identification circuit,a channel estimation circuit,and an FPGA minimum system.(2)Using Altera's Cylone IV series EP4CE6E22C8 as FPGA chip,OSM modulation and demodulation module program are designed based on Verilog HDL in this thesis.According to the characteristics of spatial modulation,a clock synchronization method is designed.Subsequently,the Model Sim simulation software is used to verify the logic function.Finally,the designed SM-VLC system is tested and analyzed is this thesis.The test results indicate that the maximum bandwidth of a single channel is 1 MHz,and the maximum bandwidth of the SM-VLC system is 4 MHz under the condition of a transmission distance is 20 cm.At the same time,the SM-VLC system is tested.The results show that the designed program can implement signal modulation,transmission and demodulation.Compared with OMIMO,OSM can effectively reduce ICI.