| The multi-layer visible light imaging communication system based on light-emitting diode(LED)and industrial camera,by the flexible configuration of diversity and multiple xi ng transmission mode,can effectively meet the demand of multi-attribute data transmitted in priorit ies,which is more suitable for some special scenarios.Recently,many scholars have carried on the positive exploration to the multi-layer visible light imaging communication system.However,the system is still in the development stage and many problems need to be further studied.This paper focused on the multi-attribute data transmission issues to make premilinary research,and we finished some works that included the coding modulation technologies,the detection and decoding algorithms and the signal constellation designs of the multi-layer visible light imaging communication systems,the main research works are summarized as follows:1.To solve the problem of two kinds of attribute data transmited in priorities,a double-layer visible light imaging system is studied,a novel layered trace-orthogonal code(LTOC)coding technology is proposed,and three kinds of signal constellation transmission schemes are designed.Due to the fact that the traditional coding technology is difficult to effectively realize the separation and detection of overlapped signals in the double-layer imaging system,a novel LTOC coding technology is proposed by combining the trace-orthogonal design(TOD)with the overlay coding technology.By employing the characteristics of signal trace-orthogonal,the minimum Euclidea n distance between signals is raised and the maximum likelihood(ML)detection of linear complexity is achieved on the condition of lossless coding complexity and code rates.Moreover,for a variety of application scenarios,we propose three kinds of signal constellation design with different power al ocation based on the closed-form solution of theoretical bit error rate(BER).Both theoretical analysis and simulation results show that the proposed coding technology can improve the performance of double-layer imnaging system effectively,and that three constellat io n designs can achieve different bit error rate performance2.To solve the problem of multi-attribute data transmited in priorities,the transmission model of multi-layer visible light imaging system is constructed,and the detection algorithms with low computational complexity is realized.By extending the existing model of double-layer imaging system,we develop a multi-layer imaging system model which can be used to transmit mult iattribute data in priorities.On the basis of the model,the coding technologies for multi-la yer imaging system are studied.Moreover,the ML detection algorithm of linear computatio na l complexity under traditional coding technology and the ML detection algorithm of low computational complexity under LTOC coding technology are realized.3.To improve the performance of multi-layer imaging system and meet the needs of various application scenarios,a multi-layer visible light imaging system based on space-time traceorthogonal code(STTOC)is proposed,and three kinds of signal constellation transmiss io n schemes are presented.By combining the advantages of the traditional coding technique and the LTOC coding technique,an STTOC coding technology is proposed.By the idea of "spatial domain orthogonal and temporal domain jointly" design,the proposed STTOC coding technology achieved some merits that the data rate is effectively increased,coding gain is obtained,and the maximum likelihood detection of linear complexity is realized.Moreover,to meet the needs of various application scenarios,three kinds of signal constellation transmission schemes are presented.Both theoretical analysis and simulation results show that the proposed STTOC coding technology can effectively improve the performance of multi-layer imaging system and three kinds of constellation design can meet the needs of various communications.4.To improve the performance of multi-layer imaging system under interference conditio n,a joint signal design and detection algorithm are proposed.First,the system model is presented based on the analysis of the causes and effects of the interpixel interference(ILI)at the receiver of the imaging system.Then,according to the characteristics of the multi-layer transmission system,a joint signal design and detection algorithm applied to multi-layer imaging system is proposed.Furthermore,with the help of the proposed signal design scheme,the optimal precoder is studied.Simulation results show the feasibility and effectiveness of the proposed joint detection algorithm and the proposed precoder design scheme. |
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