Data Processing Of Indoor MIMO&VLC System Based On DSP

The Visible Light Communication (VLC) technology has been more and more widely usedwith its electromagnetic spectrum without authentication, secure communication, confidentialityand other advantages. The Multiple-Input Multiple-Output (MIMO) technology increases the radiochannel capacity and spectrum utilization with the mode of spatial multiplexing but withoutincreasing the bandwidth of the antenna and the transmission power. This makes MIMO technologybecome an excellent choice for high-speed VLC system. VLC system based on MIMO technologyuses DSP chip to learn the channel correlation H-matrix, processing the received signal withH-matrix, then we can eventually recover the signal in real time. Thus, the use of DSP to processH-matrix is the key technology to recover the signal of transmitting end.Firstly, this paper describes the general theory of VLC and MIMO technology, and thenanalyses the principle of the indoor MIMO&VLC system, as well as the key technology of theMIMO system.Secondly, this paper describes the design and implementation of the indoorMIMO&VLC system based on DSP. The MSP430F149microcontroller is chosen as the controlchip of input end of signal in order to achieve effective control of those transmitted data. Theoptical imaging system is designed to ensure that the size of the spot to match the size of thereceiver array. This paper designs the scheme of data processing and implements the dataacquisition through the A/D module, the data transmission through the method of DMA and the datacommunication through the method of SCI. Then the system implement a test to discusse thefeasibility of the system in the cases of four spot strictly level the PIN array with or withoutoverlapping, under the condition of1Mb/s (transmission rate). The system recover the originalsignal entirely correct in both cases, so the result verifies the feasibility of the system.In the end, this paper analyses the necessity of improving sampling precision and rate ofsystem. Then it describes the interface design of Chip ADS8364and DSP, highlights the softwaredesign of A/D conversion and median filtering method. Then the system samples the internalvoltage(1.9V) of Chip TMS320F28335for10times, removes three values of the minimum andmaximum, and averages the four values of the middle. Through experimental tests, we could seethat the median filtering method can improve the sampled accuracy about7times.