Study On QoS Packet Scheduling Algorithms In Downlink Of LTE System

With the rapid growth of wireless multimedia services, users need new network, which is equipped with faster transfer rate, wider bandwidth, less latency and lower operating cost, in order to solve the conflict between infinite demand and limited bandwidth of wireless resources. LTE is the most important part of packet scheduling, which can allocate wireless users a variety of wireless packet service and reasonable resource.The first two chapters of this thesis present the architecture and technical features of LTE, which also involve its performance characteristics and advantages. Then, this thesis focuses on the downlink. LTE is based on OFDM technology, while the downlink of OFDMA which makes it unique technical characteristics of the resource mapping. Then there is in-depth knowledge of MAC and with the study of it makes a solid foundation for the structure of the system.The next two chapters present the resource allocation of LTE and packet scheduling protection of QoS. They also analyze the results of packet scheduling and performance indicators of each factor, following is a detailed study of the current packet scheduling algorithm for a variety of classic, such as the RR algorithm, MAX C/I algorithm, PF algorithm, M-LWDF algorithm, and the performance of these algorithms. The comparison of these algorithms gives a theoretic reference of improvement and optimization.The last part of this thesis concludes the following aspects:first, the proposing of an improvement of the existing QoS; second, combining the classic PF algorithms and the limited problems, introducing a new PF-2 algorithm. In the simulation, in order to measure the performance of scheduling algorithm with high flow, based on MAX-MIN fairness index, this thesis proposes MIN-MAX-2 of the fairness of the comparison index. Finally, there are real-time service and non-real-time service in the simulation analysis. Then, this thesis compares PF-2 algorithm and the classical algorithm in fairness, packet loss rate, throughput, etc. Simulation results show that the PF-2 algorithm can ensure good latency, packet loss rate and throughput of cases. It is a good fair packet scheduling algorithm on the data with high flow.