Research On The Key Technologies Of Massive Multi-Color MIMO Visible Light Communications

With the advent of a new era of connectivity,many new wireless applications have emerged,whose implementation depends on the ultra-high-speed transmission method of high-bandwidth spectrum.Meanwhile,high-speed communication network need to be instlled in various public areas with different size.Besides,"Industry 4.0" dominated by intelligent manufacturing puts forward higher requirements for the internet of things communication.Massive multi-color visible light communications(mMC-VLC)makes full use of spatial and color domain resources to achieve dual multiplexing of multi-path and multi-color interference,and has great advantages to meet the requirements.Aiming at the problems of large gaps in the number of units of transmitter and receiver,high correlation,and mobility of the receiver for the mMC-VLC considering multipath and multi-color interference,several key technologies are proposed.The main contents and innovation points are as follows:1.Aiming at the problem that the pathological characteristics of the system are sensitive to large-scale multicolor detectors to signal disturbances,and the large-scale transmitting end provides conditions for data transmission using different LED layouts,an activation system with a low pathological layout is studied.The basic unit of mMC-VLC is multi-color LED,which isregarded as the merger of multiple sets of multi-color visible light communication.The huge size of the system's transmitter provides conditions for data transmission utilizing different LED layouts,so low ill-condition layouts are researched.The theories of LED colorimetry are introduced.Then,when considering the lighting and communication requirements of a single group of multi-color LED,the power ratio of each color satisfing the colorimetric constraint,the total optical power constraints,and the signal amplitude constraints is studied.Besides,the causes of homochromatic multi-path interference and heterochromatic multi-color interference are analyzed,and the model of mMC-VLC system considering both interferences is established.In order to maximize the multi-path and multi-color multiplexing gain of the system,the channel gain matrix of the system under the constraint of low ill-condition layout should reach the full rank.The ill-conditioned characteristic of different channel gain matrices affect the performance of the system detection algorithm.The low ill-condition layout is determined under this power ratio,and the fitting curve of the optimal layout parameters and the vertical distance between the transmitter and receiver is simulated.2.For the large number of basic units at the transceiver end of the large-scale multicolor visible light system and the large inter-channel correlation,an adaptive spatial layout selection technique is proposed.The optimal layout parameters suitable for the vertical distance of different transceivers are obtained..High channel interference and the gap between the number of transmitter and receiver units are the main factors limiting the performance of mMCVLC.Based on the model of mMC-VLC,adaptive satial-layout selection(ASLS)techniques are proposed.The optimal layout parameter problems under layout constraints of the circle closed and linear are formulated for a fixed receiver position.To be adaptive to the receiver position,the fitting curves of the optimal layout parameter and Dv under both layout constraints are obtained,Dv is vertical distance between the transmitter and receiver plane.The closest layout-selected principle is proposed to solve the problem that LEDs may not perfectly form optimal parameter layout due to the indeterminate LEDs interval of mMC-VLC.The maximal available N corresponding to every receiver position is obtained for ASLS.The extension of OMS-SM technology for mMCVLC is proposed as a comparison of ASLS.3.In order to realize the wide spectrum interference and the compromise transmission of the target signal existing in the large-scale multi-color system using the actual optical filter,the real-time optimal tracking angle technology is proposed.The optimal alignment method of each PD adapted to the relative offset angle of the transceiver is designed.Wide-spectrum interference(WSI)caused by overlap among the spectra of different color LEDs when considering the realistic filters decreases the reliability of the MC-VLC systems.The wide-FOV PDs are employed to reduce the interruption probability and improve the receiver mobility,whose availability and alignment style greatly influence the WSI and target signal(TS)of MC-VLC system.Real-time optimal tracking angles(ROTAs)is proposed to quickly ascertain the optimal tracking angles to minimize the total WSI of MC-VLC and ensure the reliable transmission of TS,achieving the trade-off alignment style of PDs.The optimization problem is formulated,and the ROTAs and ES algorithm are proposed.The analytical solution of ROTAs converges on the numerical solution of ES,which have ultra low complexity.The optimal tracking angles adapts to the relative offset angle between the transmitter and the receiver denoted by ?.The better BER performance is achieved by the system with ROTAs at different ?.