Research On Transmission Mechanism Of Aggregated Visible Light And Radio Frequency Communication System

Due to the exponential increase of wireless devices and the Internet of things(Io T)applications,an explosive growing number of wireless devices and the increasing demand for high-speed data services give rise to great pressure on conventional wireless communication networks,including but not limited to radio frequency(RF)spectrum crisis.Visible light communication(VLC),which with huge license-free-spectrum is a promising for B5 G /6G with huge licensefreespectrum.At the same time,VLC still creates many challenges for various indoor applications due to the following problems: 1.It is easily blocked by obstacles and has a limited coverage area;2.The crisis of rapid battery depletion.In order to solve the above problems,this thesis studies simultaneous lightwave information and power transfer(SLIPT)in VLC systems that takes into account both communication and energy harvest,and establishes transmission mechanism of the VLC-RF aggregated system which transmits information at the same time by VLC and RF.The contents and innovations are as follows:Firstly,to realize the passive power supply,this thesis investigates a novel SLIPT in VLC systems,where a photo diode and a solar panel are utilized as the information receiver and the energy harvester,respectively.By systematically analyzing signal processing,this thesis obtains the explicit expressions to characterize the illumination-rate-energy region.Based on the derived expressions,this thesis investigates the downlink unicast transmission of MISO SLIPT VLC networks,and propose the total transmit power minimization problem under the rate requirements,the minimum energy harvesting requirements,and dimming control constraints.Moreover,for the sake of users' fairness,this thesis further investigates the beamformer design to maximize the minimal rate under both minimum energy harvesting and dimming control constraints.Finally,the numerical results feasibility of the proposed SLIPT system,and eveals that the energy harvesting threshold will reduce the transmission rate.Then,to make up for the defect that VLC is easily blocked by obstacles,this thesis investigates the VLC-RF aggregated system based on the continuous input.First,this thesis derives the expression of the transmission rate of the VLC-RF aggregated system,and develops optimal power allocation schemes for the aggregated VLC-RF systems for the single and the multilight-emitting diode scenarios.Moreover,this thesis studies the energy efficiency maximization problem of the considered system with the minimum rate requirement,transmitted power constraint,and the dimming control consideration which is non-convex.By using the Dinkelbach-type algorithm,we tackle this problem by solving a sequence of convex problems which converges to the global solution.Finally,numerical results show that the aggregated VLC-RF systems can increase the transmission rate compared with RF system,and eveals that the rate threshold will reduce the energy efficiency.Finally,since the actual communication input is mostly distributed by discrete constellation points,this thesisv investigates the VLC-RF aggregated system based on the discrete constellation inputs,and establish optimization mechanism of probability distribution of discrete constellation points and transmission rate.This thesis first derives the transmission rate expressions in the aggregated VLC-RF system,and propose transmission rate optimization mechanism with respect to the constellation distribution and power allocation jointly.Since the transmission rate expression is not a closed-form expression,the algorithm complexity is high and can only reach sub-optimal.This thesis further derives the upper and lower bounds of the transmission rate,and studies the lower bound of transmission rate maximization problem with respect to the constellation distributions and power jointly.Multiple numerical results show that the proposed optimization scheme can increase the transmission rate compared with the equal probability input,and depicts the optimal probability distribution of the discrete constellation points under different signal-to-noise ratios.This thesis contains 40 figures,13 tables and 98 references in total.