Research On Uplink Carrier Aggregation In LTE-Advanced System

At present, with the rapiddevelopment of mobile TV, mobile payment, mobilereal-time games, mobile Internet and other business, people have put forward higherrequirementsin respect of the rate of data transmission and the qualityof service. At thesame time, as to fulfill the users’ demand operators hope to reduce the cost of operation byincreasing the capacity of the system. At this point, ITU define the standard of4G systemand in order to achieve the requirements of IMT-A, LTE-Advanced system is determinedas the next version of LTE system by3GPP. In order to satisfy the LTE-Advanced systembandwidth of100M, LTE-Advanced system has introduced the technology of carrieraggregation, which can achieve the system bandwidth requirements of100M system by theaggregation of multiple discrete frequency resource.In the LTE-Advanced system, SC-FDMA in uplink is different from technology ofOFDM in downlink, so that the uplink scheduling scheme can only draw lessonsfrom thedesign of downlink system incarrier aggregation system. Thus it is also important to designuplink scheduling scheme for multi-carrier scheduling. Through analysis of the principle ofscheduling, after the LTE-Advanced system introduced into the carrier aggregationtechnology, the structure of uplink scheduling is no longer a simple RB levelscheduling,management for multi carriers makes the scheduling structure introduce anextra layer of CC level scheduling. Based on the analysis of the two existed basic CC levelscheduling plans: ICS/JCS, aiming at the shortcomings of the two algorithms, an improvedJCS scheme on the basis of the original JCS scheme is proposed in this paper.Through thedynamic management of carrier resources modified JCS scheme eliminates the defect ofthe ICS scheme without characteristic of carrier aggregation and gets rid of theshortcoming that UE always keeps connection with the component carrier in the JCSscheme. This modified scheme achieves the aims that the system throughput is littlechange in the case of the lower JCS system complexity. Because of the particularity ofuplink technology, when PUSCH resource is being allocated, LTE-Advanced system requires that uplink PUSCH resource allocated are continuous as far as possible in order toreduce uplink PAPR. The maximum envelope method which is put in this paper achievesthe objectives that the uplink PUSCH allocated resources are continuous, at the sametime,it can meet the requirement of user data. Finally combined with improved JCSscheme on the level of CC and uplink PUSCH allocation algorithm in the multi-carriersystem, the uplink resource allocation scheme is designed under multiple-carrier.Through the system simulation results, improved JCS program of CC level meets thedesign requirement,the maximum envelope method can meet the requirements ofcontinuous uplink resource allocation. By the simulation and analysis of uplink resourceallocation scheme in the multi-carrier system, the improved uplink resource allocationscheme gets the goal that resources of uplink multi-carrier is optimal used.