Research On Interference Management Schemes Based On Coordinated Resource Allocation For Indoor VLC Networks

Mobile communication traffic is increasing day by day,and people's requirement for network communication is more and more extensive and diverse.Visible light communication(VLC)can greatly alleviate the complex network pressure and provide the possibility to develop other new applicable network modes and communication services in the future.However,in the case of large number of users indoors,severe interference between users will affect network performance,so effective interference management mechanisms are necessary to ensure and improve the communication quality of VLC network.In this thesis,the issue of interference management applying coordinated transmission and resource allocation is discussed for multi-user VLC network environment indoors.The main work is as follows:1.In multi-user VLC networks indoors,a coordinated sub-carrier and power allocation algorithm is proposed,which takes both quality of service(Qo S)and fairness into account.First,in order to eliminate interference between users caused by the same frequency,there exists a regulation that visible light signal is transmitted by coordinated channels,that is multiple APs send the same information to users within the cross-coverage area with the same sub-carrier at the same time slot;Then,the relative ratio about the user rate exceeding the rate threshold that satisfies the basic communication is the Qo S,Qo S and rate fairness are as weighted factors for sub-carrier allocation;Furthermore,the transmitted power is divided equally according to the number of sub-carriers during the progress of sub-carrier allocation,in order to make full use of power,a three-step power allocation algorithm is implemented based on the principle of satisfying normal communication with the rate threshold,which includes superfluous power collection,defective power complement and residual power allocation.Finally,the experimental simulation verifies that the network spectrum efficiency,energy efficiency,average Qo S and fairness are effectively improved comparing with some representative algorithms.2.To enhance the efficiency and adaptability of interference management in multi-user VLC networks,an adaptive interference management mechanism with both power allocation and time slot allocation is proposed.First,a multi-user VLC network model is established,and the regulation is that location,number and channel state of user are not changed during a time slot.Then,to eliminate interference,based on coordinatedtransmission between multiple APs,a maximal independent set theory is applied,and users involved in each maximal independent set can not be interfered with each other,and the maximal independent set can be searched according to location of users at each time slot.Linear water filling power allocation algorithms are applied for each maximal independent set to optimize the network sum rate.Furthermore,to balance the communication experience between users better,when users scheduling is implemented at each time slot,the sum rate of users,rate fairness and delay fairness are as a comprehensive priority factor for each maximal independent set and the candidate maximal independent set with the largest comprehensive priority factor are selected at each time slot,in which users are scheduled at this time slot.Finally,through experimental simulation and comparison with other classical algorithms,the advantages of spectrum utilization,energy efficiency,rate fairness and delay fairness are verified in the proposed mechanism,and it can be adjusted adaptively to maintain network performance while the location,number of user or quality of channel is changed at different time slot.