| Visible light communication(VLC)has been considered as an important supplementary technology of broadband access and short-distance communication in the future,which can provide lots of potential bandwidth,free-license and has no electromagnetic interference.In recent years,with the development of high-speed communication,WDM Technology(WDM)has been widely applied in VLC system,and the color of light source has also evolved from white fluorescent LED to multicolor LED.However,with the increase of the color of the light source,the white light LED at the transmitter side becomes more difficult.The difficulty of the receiver to separate the channel is also increasing.Although there are some uses of optical antennas for transmitting and receiving terminals currently,it also has some deficiencies.To solve the problem above,first of all,this paper studied a white light transmitting antenna for multi-color VLC system,and focus on four-color VLC system.The system includes integrating rod model and Fresnel lens model.Based on the theoretical analysis and simulations of the two models,two white transmitting antenna systems are designed: the square rod system and the hexagon rod system.Through comparison and analysis,it is found that the performance of the square rod system is better than the hexagon's when the light source is four-color LEDs.This antenna can illuminate 750mm×750mm area evenly at the 1.77 m communication distance.In the whole illumination area,the uniformity reaches as high as 73.37%,no color difference,and the total illumination value of 224.15 lx.Besides the square rod system can achieve340 Mbps transmission rate and the SNR is stable in mobile communication.At the end of the chapter,this paper proposed a design scheme of white light transmitting antenna with small divergence angle,whose efficiency is 84.53% higher than the above antenna's,and it is suitable for visible light communication system with little illumination area.Second,this paper studied two kinds of sub-channel receiving antenna in multicolor VLC system.One is two-channel directional receiving antenna with 81.2% optical efficiency,high optical gain and 3° field angle.This paper verified the feasibility and correctness of this antenna to achieve sub-channel data transmission by experiments.Another is four-channel receiving antenna with a large field of view(100°),through 3optical prism realizing four channel transmission.The efficiency of this antenna is higher than 72.79% in all field of view and all channels,and its optical gain is about 10.This antenna provides a more suitable receiving antenna design scheme for multichannel VLC system. |
PDF Full Text Request