张刚 黄南飞 张天骐

摘 要：针对长期演进（LTE）移动通信系统下行链路传输中多用户的实时（RT）与非实时（NRT）业务传输性能需求问题，提出一种基于用户加权平均时延的改进型的最大加权延时优先（MLWDF）资源调度算法。该算法在考虑信道感知与用户服务质量（QoS）感知的基础上引入反映用户缓冲区状态的加权平均时延因子，该因子通过用户缓冲区中待传输数据与已发送数据的平均时延均衡得到，使具有较大时延和业务量的实时业务优先调度，提升了用户的性能体验。理论分析与链路仿真表明，提出算法在保证各业务时延及公平性的基础上，提升了实时业务的QoS性能，在用户数量达到50的条件下，对比MLWDF算法实时业务的丢包率降低了53.2%，其用户平均吞吐量提升了44.7%，虽牺牲了非实时业务的吞吐量，但仍优于VTMLWDF算法。实验结果表明，所提算法在多用户多业务传输条件下提升了实时业务的传输性能，并在QoS性能上明显优于对比算法。

关键词：长期演进系统;加权平均时延;服务质量;资源调度;实时业务;吞吐量

中图分类号：TP391.9

文献标志码：A

Abstract： Aiming at the transmission performance requirements of RealTime （RT） services and NonRealTime （NRT） services for multiuser in the downlink transmission of Long Term Evolution （LTE） mobile communication system， an improved Modified Largest Weighted Delay First （MLWDF） scheduling algorithm based on weighted average delay was proposed. On the basis of considering both channel perception and Quality of Service （QoS） perception， a weighted average dealy factor reflecting the state of the user buffer was utilized， which was obtained by the average delay balance of the data to be transmitted and the transmitted data in the user buffer. The RT service with large delay and traffic is prioritized， which improves the user performance experience.

Theoretical analysis and link simulation show that the proposed algorithm improves the QoS performance of RT services on the basis of ensuring the delay and fairness of each service. The packet loss rate of RT service of the proposed algorithm decreased by 53.2%， and the average throughput of RT traffic increased by 44.7% when the number of users achieved 50 compared with MLWDF algorithm. Although the throughput of NRT services are sacrificed， it is still better than VTMLWDF （Virtual Token MLWDF） algorithm. The theoretical analysis and simulation results show that transmission performances and QoS are superior to the comparison algorithm.

0 引言

隨着多媒体业务流、实时游戏和网络语音电话业务（Voice over Internet Phone， VoIP）等新兴业务的日益普及，通信技术需日益完善。改善不同业务的服务质量（Quality of Service， QoS）性能是长期演进（Long Term Evolution， LTE）[1]系统中基站（eNodeB）需要执行的一项重要任务。LTE下行资源调度算法[2]是通信系统中的研究热点，在调度算法中使用由信道质量指示（Channel Quality Indicator， CQI）反馈的信道感知和QoS感知实现了复杂度和传输性能之间的权衡。……