Research On Delay-Aware Scheduling Algorithm Based On OPNET

LTE(Long Term Evolution)downlink resource scheduling is the key technology to ensure the quality of LTE mobile communication system.With the development of mobile Internet,users require higher QoS(Quality of service)of real-time services.It is important to study how to ensure real-time services QoS,to improve the quality of the user experience with limited spectrum resources,while ensuring the throughput of non-real time traffic and the fairness between the two.The MAC scheduler is an important and crucial entity of the LTE and is responsible for efficiently allocating the radio resources among mobile users who have different Qo S.Based on this background,this thesis carries out the following research work.First,the scheduling technology in LTE system is summarized.Specifically,the scheduling process,scheduling indicators,MAC scheduling entity,dynamic and semi-persistent scheduling,and link adaptation technology are introduced in detail.Secondly,the impact of multi-QoS-aware MAC scheduling on end-user application performance is studied for different types of services and their characteristics.The performance of the downlink MAC scheduling algorithm considering GBR(guaranteed bit rate)and Non-GBR(non-guaranteed bit rate)bearers is verified and analyzed.It shows how the MAC scheduler can serve users of different services while satisfying the different QoS requirements of each bearer.Finally,under the condition of network congestion,the QoS of the mobile terminal is greatly reduced,and a delay-aware scheduling scheme is proposed for this purpose.The proposed scheme is implemented realistically and uses QCI-DSCP(QoS Class Identifier-Differentiated Services Code Point)mapping in the transport layers in the LTE backhaul network,taking into account the user's QoS and QoE(Quality of Experience).The queuing scheduling algorithm is applied in a flexible way to consider the priorities of different service types.The proposed algorithm is verified and analyzed by using OPNET 18.0 which is a system-level simulation platform.The simulation results show that this scheme can significantly improve LTE QoS and QoE performance.