Research On Resource Allocation Algorithm In Heterogeneous VLC/RF Networks

With the rapid development of communication technology,traditional network technology is increasingly unable to meet the high communication rate required by users and accommodate more users at the same time,so heterogeneous networks have emerged.Considering that visible light communication(VLC)can achieve high communication rate while saving energy,and the radio frequency(RF)system can increase the communication coverage of the network,the concept of a heterogeneous VLC/RF hybrid network is proposed.However,how to build a heterogeneous VLC/RF network to meet the increasing demand for high-rate transmission is a problem that needs to be solved at present.This thesis first proposes a resource allocation algorithm model based on the maximum and minimum user data rates,to maximize the total throughput of the system.Then,the energy efficiency maximization problem of heterogeneous VLC/RF is considered.At the same time,in order to avoid channel estimation errors and the influence of this channel environment on the system,channel uncertainty state information is introducing,and a robust resource allocation algorithm problem model is proposed.The main work of this thesis is as follows:(1)In order to fully exploit the advantages of VLC and RF communication,this thesis proposes an indoor hybrid VLC/RF heterogeneous wireless network transmission model.Based on this model,the max-min transmit rate optimization problem is formulated to improve the user's fairness and network transmit rate under the consideration of the bandwidth constraint,the maximum transmit power constraint,and the minimum rate constraint of the user.The original non-convex optimization problem is transformed into a convex one by using the auxiliary variable method and the successive convex approximation method,where the analytical solutions are obtained by using the Lagrange dual method.The computational complexity is also analyzed.Simulation results verified the effectiveness of the proposed algorithm in terms of convergence and rate improvement.(2)In order to solve the problems of imperfect channel state information,low system energy efficiency,for a heterogeneous VLC/RF network with channel uncertainty,an energy efficiency maximization-based robust resource allocation algorithm is proposed.Considering the constraints of the maximum transmit power of VLC base station and RF base station,the transmit time of each user,the system band,and the quality of service requirement of VLC and RF users.Based on rate outage probability a robust efficiency maximization resource allocation problem is established under random channel uncertainties.By using Dinkelbach's method,the original optimization problem based on the outage probability is converted into an equivalent deterministic one which is transformed into two convex optimization subproblems by using the alternating optimization algorithm.An energy efficiency maximization algorithm based on alternate iteration is proposed.Simulation results show that the proposed algorithm has better robustness compared with the traditional algorithm.