Research On Scheduling Algorithm In LTE-A System With Carrier Aggregation

With the discussion of LTE-Advanced in3GPP meeting，the options of therequirement and technology evolution become more and more mature. In the process ofthe evolution from LTE to LTE-Advanced, the requirement of wider bandwidth is one ofthe most important factors that affect the evolution. So3GPP proposed carrieraggregation technology. At present, scheduling algorithm in LTE-A system with carrieraggregation is the research focus.This paper mainly researches the scheduling algorithms in LTE-A system withcarrier aggregation. At first, this paper detailedly introduces the scheduling theory inLTE system, discusses the signalings related with scheduling and expounds the classicalscheduling algorithms in LTE system. And then in allusion to the resource schedulingwith carrier aggregation, this paper proposes a scheduling algorithm to improve the celledge users throughput and fairness between all users, a dynamic adjustment schedulingalgorithm based on cell edge users traffic and a modified PF algorithm with both LTE-Auser and LTE Rel-8user in cell system.For the non-contiguous carrier aggregation scene, in allusion to the disadvantage ofpoor experience of the cell edge users with existing algorithm and in order to improvethe cell edge users throughput and fairness between all users, this paper proposes a celledge user prior proportional fair algorithm. Simulation results indicate that thisalgorithm can fairly improve the cell edge users throughput and fairness between allusers. In addition, it can adjust the cell edge users throughput and fairness between allusers through controlling the size of a. Based on the research of the cell edge user priorproportional fair algorithm, in allusion to the situation of user traffic non-uniformdistribution, it dynamically adjusts CEPPF/PF algorithm and PF-A algorithm accordingto the cell edge user traffic proportion b. Through the simulation we can see that when bis small, that using CEPPF/PF algorithm sacrifices the system throughput but improvesthe cell edge users throughput and fairness between all users; when b is large, theperformance of the cell edge users throughput and fairness between all users when usingPF-A algorithm is better than when using the CEPPF/PF algorithm and PF algorithm.For the contiguous carrier aggregation scene, combined with the case of resourcesscheduling under carrier aggregation with both LTE-A user and LTE Rel-8user in cellsystem and in allusion to the defect of PF scheduling algorithm—when a user channel quality suddenly becomes poor and stays in the condition long time, using the PFalgorithm may lead to the user can’t get service in a relatively long period of time, thispaper proposes the MPF algorithm. Simulation shows that the MPF algorithm doesgood compromising between system throughput and fairness between users. Thescheduling gain of MPF scheduling algorithm relative to PF scheduling algorithm islarger than1, so MPF scheduling algorithm is better than PF scheduling algorithm.