Research On User-centric Multi-user Scheduling In Indoor Visible Light Communication

Owing to the advantages of abundant frequency spectrum resource,high data transmission rate,low energy consumption,and none of electromagnetic radiation,Visible Light Communication(VLC)is getting more and more attention in recent years.VLC uses the Light Emitting Diode(LED)as the light source,and the information can be transmitted by the high speed light and dark flashing signal carried by the LED.The huge potential of VLC has aroused widespread concerns and researches of domestic and foreign scholars,and how to allocate the system resources is the focus of the researches.At present,most of the researches are for point-to-point VLC and it is difficult to improve the system capacity,so in this paper the multi-user scheduling problem is studied in indoor VLC at the scenario of multiple Access Points(APs)and multiple users.There are multiple APs and users at indoor VLC scenario.Due to the existence of interference between users,the system capacity is low at the traditional AP-centric point-to-point cell construction method.In addition,unlike the radio frequency communication,the accumulation of first reflection of beam could also affect multi-user scheduling problem.The existing scheduling mechanism of VLC could not guarantee the user's QoS(Quality of Service,QoS)requirements,so in this paper we consider the effect of heterogeneous QoS in scheduling mechanism and explore to establish a more practical multi-user scheduling mechanism.To solve the interference problem at the indoor VLC scenario of multiple APs and multi-users,this paper researches the user-centric multi-user scheduling algorithm,and explores the priority computing mechanism that is suitable for multi-user scheduling algorithm.At the same time,the influence of the Aggregate Interference(AI)on the user-centric multi-user scheduling algorithm is analyzed,and the multi-user scheduling mechanism with heterogeneous QoS provisioning is proposed.The main work of this paper is as follows:On the basis of graph theory,the user-centric multi-user scheduling algorithm is studied in indoor VLC.The interference between users reduces the system capacity at the traditional indoor VLC cell construction method.So this paper researches theuser-centric multi-user scheduling algorithm on the basis of graph theory.And the weighted interference graph is established to present the relationship among users,while reducing the complexity of searching the maximum weighed independent set in the weighted interference graph based on the greedy algorithm.The user-centric multi-user scheduling algorithm overcomes the interference between users and improves the system capacity while guaranteeing the fairness of the users.By simulation,the Proportional Fair(PF)scheduling mechanism is studied,which is more suitable for the our user-centric multi-user scheduling algorithm.And this paper also analyzes the influence of indoor VLC receiver's field of view on the user-centric multi-user scheduling algorithm.In addition,this paper studies the aggregate interference problem in indoor VLC,and proposes a multi-user scheduling mechanism which could guarantee the user's heterogeneous QoS requirements.Considering the reflection particularity of the beam and the condition that there exists multiple communication cells in the room,in this paper the aggregate interference concept is put forward in indoor VLC multi-user scheduling problem,and the influence of AI on the user-centric multi-user scheduling algorithm is given by simulation.On the basis of effective capacity and effective bandwidth theory,the effective bandwidth factor is introduced into the PF scheduling mechanism.So at each time slot,the scheduling system could schedule users and form multiple communication cells according to the channel state,average data rate and QoS requirement of the user.Under the premise of ensuring the system capacity,each user's statistical QoS requirement are satisfied,and the communication system is more close to the actual indoor VLC communication scenario.This paper studies multi-user scheduling problem from new perspective and method at the indoor VLC multiple APs and multi-user scenario.The research results could provide certain theoretical basis and reference value for the research and future application of VLC network.