Research On Multi-led Cooperative Visible Light Communication Systems

Visible light communication technology,a new generation of wireless communication technology with dual functions of lighting and communication,with the advantages of security,high confidentiality,no electromagnetic interference,low cost and so on,has been widely concerned by all circles.Multi-LED cooperative visible light communication system can provide ubiquitous coverage for communication and lighting,provide higher transmission rate,better communication quality,greater flexibility for lighting intensity control required by eye safety criteria.In this paper,the performance such as mean square error,energy efficiency and achievable rate are taken into account.The optimization design of the cooperative visible light communication system with multiple light sources is carried out and the different scenes of multiple receivers and multiple users are taken into account.Firstly,this paper introduces the basic knowledge of VLC system,including transmitter model,receiver model,channel model and noise model.Furthermore,the basic capacity model of visible light communication system and the typical MIMO visible light communication system are introduced.Then,this paper studies the precoding and dc bias optimization design of MIMO visible light communication system.The design considers the non-negative constraint of signal and two different optical power constraints: per-LED optical power constraint and total optical power constraint respectively and then optimizes to minimize the mean square error of received signal.In this paper,the non-negative objective function and constraints of the optimization problem are safely converted into convex form,and then the optimization problem under the per-LED optical power constraint can be converted into a convex problem.Then,an iterative algorithm is designed to solve the optimization problem under the total optical power constraint according to the optimization design under the per-LED optical power constraint.Finally,the performance of the proposed optimization design is verified by simulation.Afterwards,this paper studies the energy efficiency optimization design of MIMO visible light communication system,taking into account the non-negative constraint of signal,optical power constraint,electrical power constraint,rate constraint and bit error rate constraint,to jointly optimize the power,dc bias and rate in order to maximize the energy efficiency of the system.In this paper,the original multi-variable optimization problem is converted into a single-variable optimization problem.Then,an iterative algorithm is designed to address the problem.Finally,the performance of the proposed algorithm is verified by simulation.Finally,this paper studies the optimization design of multi-user multi-LED visible light communication system.In this paper,we derive the lower limit of the system's achieveable rate.Then,we consider the nonnegative constraint and per-LED optical power constraint respectively and optimize the precoding design with the goal of maximizing this lower limit.Then,an iterative algorithm is designed to solve the complex non-convex problem.Finally,the performance of the proposed algorithm is verified by simulation.