Research On Multi-layer Optical Camera Communication

Optical camera communication systems often use a light emitting diode(LED)array or liquid crystal display(LCD)as the transmitter.Charge coupled device(CCD)or complementary metal oxide semiconductor(CMOS)imaging devices such as the high speed cameras are utilized to capture the image of transmitter.Then the transmitted information can be extract through image processing.After the message is split into different priorities,it is loaded on each layer transmitting units with diverse degrees of diversity according to different priorities.The higher-priority data is transmitted in higher diversity mode with higher robustness but lower data rate,whereas the lower-priority data is sent using higher multiplexing scheme with higher data rate but lower robustness.The multi-layer OCC system in both validity and reliability of communication can make the information classification criteria more accurate,so as to meet the needs of complex and diverse application scenarios.Based on the analysis of the OCC system basic principle and the concept of layered transmission combined with the M-ary double-layer OCC system,this dissertation mainly researches on the OCC system basic model,coding and detection technology,the main works are as follows:1.After the research of the basic principle and the model of the OCC system,the design scheme of double-layer OCC signal is optimized by the introduction of M-ary modulation.And the information extraction is realized by using the maximum likelihood(ML)detection algorithm.By presenting the basic principle and the model,combining diversity and multiplexing mode selection,the system's channel characteristic is analyzed.In order to fully utilize the resources of the lower layer which usually occupies more power in existing double-layer system,the M-ary modulation is introduced into the lower layer signal.The message can be detected by using a low-complexity ML detection algorithm.Finally,computer simulations verified the system feasibility.2.By analyzing the basic realization principle of multi-layer OCC,under the simple system model,according to the signal model,an M-ary detection algorithm based on maximum likelihood is proposed.For the purpose of improving the applicability of OCC to diversified application scenarios,this paper gives the transceiver signal model of the simple multi-layer OCC system,after analyzing the basic realization principle.Combined with the signal model,the M-ary detection algorithm for multi-layer system is put forward.The M-ary detection algorithm has perfect performance through the simulation analysis.In a simple multi-layer OCC system,the algorithm has a relatively low computational complexity.Then the performance of system using M-ary detection algorithm is analyzed from two aspects of the overall and stratification.3.In view of the problem that the high complexity of the M-ary detection algorithm is relatively high in the complex multi-layer OCC system,a new encoding and detection algorithm based on the additively uniquely decomposable code(AUDC)is proposed.Then the complexity and detection performance of the algorithm are optimized.By introducing the basic concepts and coding criterion of AUDC,the complex multi-layer OCC system transceiver signal model is built.According to the signal model,a kind of detection algorithm based on AUDC is proposed and optimized with complexity and detection performance.The algorithm can simultaneously achieve low complexity and relatively good detection performance.It is more suitable for the information transmission in the complex multi-layer OCC system.The detection performance of the algorithm is analyzed in the multi-layer OCC system,and the complex system is designed to prove the adaptive advantage of the algorithm.