Research On Downlink Scheduling Technology For Carrier Aggregation In LTE-Advanced System

The increasing demands of mobile users have accelerated the rapid development ofwireless communication technology. After LTE was introduced,3GPP (the3rd GenerationPartnership Project) proposed LTE-Advanced as a smooth evolution to4G, so as to achievehigher communication speed and greater system capacity. As one of the core technologiesfor LTE-Advanced, Carrier Aggregation is able to bring multiple continuous/discontinuous frequency bands together. In this way, system bandwidth can be extended,user demands for higher-data-rate services can be met, and user experiences can beenhanced. Carrier aggregation can achieve the aggregation of up to five carriers, whichmeans100M bandwidth. By the carrier aggregation technology, LTE-A can reach1Gbpsdownlink peak rate, and500Mbps of uplink peak rate.The introduction of carrier aggregation technology has brought a series of problems,such as load balancing among different component carriers, management of componentcarriers and so on. In addition, in a multi-carrier systems where LTE users and LTE-A userscoexist, the capability of connecting to carriers for the two types of users differs from eachother. Such differences often lead to the performance of LTE users not being guaranteed,and in that case the problem of poor user fairness will be very serious.This dissertation first describes the scenarios deployment and technology schemes ofcarrier aggregation, and then focuses on the scheduling algorithm of downlink carrieraggregation system. The dissertation then analyses the original algorithms, and proposes animproved scheduling algorithm accordingly. The improved algorithm, based on the jointscheduling, is designed to solve the problem of user unfairness and load balance amongdifferent carriers. Finally, the original algorithm and improved resource schedulingalgorithm are simulated based on the system simulation platform built. The simulationresults show that the improved algorithm can effectively ensure the performance of LTEusers, and improve user fairness. Additionally, the improved algorithm can achieve betterload balance, and resolutely the overall system throughput can be improved.