Research And Implementation Of Downlink Scheduling In The MAC Layer Of3GPP LTE System

Along with the rapid development and integration of the mobile communicationsand Internet technology, the mobile communication system must meet faster wirelessaccess、 full network seamless switch、lower transmission delay、a new multimediabusiness support、comprehensive data service bearer、 the higher QoS guarantee anda series of requirements, which bring difficulties and challenges to the design ofwireless communication systems.3GPP initiated the study of the long term evolution(Long Term Evolution, LTE) of the radio access network project in2004, includingEvolved access technology (E-UTRA), the evolution of the access network(E-UTRAN), and the core network evolution facing the the whole IP packet (such asthe System Architecture Evolution SAE). LTE project is the evolution of3Gtechnology, improved and enhanced3G radio access technology; LTE employsOFDM and MIMO as the only standard of wireless access network evolution;providing downlink326Mbit/s uplink86Mbit/s peak rate in the20MHz spectrumbandwidth; improving the performance of cell edge users, to improve the cell capacityand also reduce system latency. The3GPP hope to continue to maintain the advantageof the technology research and development in the field of mobile communications inthe continuing evolution of the wireless interface and the core network and to ensurethat in the next few years, or even longer, providing the growing demand forsatisfactory of the operators as well as users.This paper introduces three LTE classic algorithms: round-robin schedulingalgorithm, the largest carrier to interference algorithm, the proportional fairscheduling algorithm. It have complete description of the respective advantages anddisadvantages and PF algorithm DSP implementation which have the effectivecompromise among the two opposing aspects of maximize system throughput anduser fairness. Because the PF algorithm is a packet scheduling algorithm commonlyused in wireless communication, and has strong adaptability to different packetservice, we choose it simulation in the hardware. But because the PF algorithm cannot adapt to LTE packet services of high Qos requirements, we described schedulingalgorithm of packet services with high QoS requirements in LTE: APF algorithm andthe M-LWDF algorithm. We introduces a new algorithm named MFQ-M-LWDF algorithm associated priority of the different packet services in M-LWDF schedulingalgorithm on the basis of the user’s priority and the same user, and the performanceimproved, verified by simulation in two aspects of delay and throughput to prove thesuperiority of the MFQ-M-LWDF algorithm compared to the M-LWDF algorithm.