| Visible light communication VLC)is a wireless optical communication technology that has emerged with the development of light emitting diode(LED)lighting technology.Because white LED has the advantages of energy saving,long life and high reliability,and the response time is extremely short,it can form an indoor visible light wireless communication system while taking into consideration the illumination.Compared with other indoor communication systems,VLC-based indoor communication systems have the advantages of easy deployment,high positioning accuracy,low overhead,high security performance,large bandwidth,and fast communication speed.Due to the small coverage of a single LED light source,the LED array is often used to cover the entire indoor illumination coverage in practical applications.From the communication point of view,this forms a natural visible light cellular communication network.However,inter-cell interference,positioning and handover problems existing in conventional cellular communications still exist in visible-light cellular networks.Color-division multiplexing is a new technology in visible light communication.On the one hand by adopting three color channels of red,green and blue,it can increase the transmission capacity of the system,and on the other hand it provide new ideas for solving the problems in visible-light cellular communication networks.This thesis mainly studies how to solve the interference,localization and handover problems in visible light cellular communication by using the new color dimension of multi-color LED.The innovative work of this thesis mainly includes the following three aspects:·An indoor visible cellular network handover scheme based on non-uniform optical power allocation is proposed.This scheme combines the illumination and communication requirements of indoor visible light communication network,and obtains the arrangement of lamps in indoor visible light communication system through qualitative analysis and quantitative calculation.Based on this arrangement,the capacity of the system can be improved through the signal power inequality configuration of the RGB-LED three-way optical signal and the communication resources can be efficiently utilized.When the terminal performs the handover operation,this scheme can optimize the handover problem caused by different carrier attenuation of different frequency bands when using ordinary LED lights as access points.·An efficient access scheme for indoor visible-light cellular networks based on color-division multiplexing is proposed and tested for performance.Based on the RGB-LED as the access point,this scheme modulates the optical paths of three different colors in different ways according to the different requirements of the communication and positioning or handover.For the positioning and handover optical path,according to the small amount of data,and handover only needs to measure the characteristics of the received signal power,a simple on-off keying(OOK)modulation is performed;for the communication optical path,orthogonal frequency division multiplexing(OFDM)modulation is performed on the requirements of high rate and large bandwidth.At the receiving end,the data of different functional links can be separately demodulated by filters,and finally the feasibility of the scheme is verified by experiments and simullations.·An indoor visible-light cellular communication network demonstration platform was built and the corresponding software control module was developed.The demonstration platform can realize the positioning,handover and communicaiton of the terminal in the cell through the cooperation of the software and the hardware device.What's more it can also realize video surveillancethe.Through this system,the content of this thesis is improved and supplemented. |
PDF Full Text Request