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对宽带无线城域网(WMAN)而言,分组调度算法是保证用户服务质量(QoS)、平衡用户间公平性的关键。在研究比例公平调度算法(PF)算法与修正的最大加权时延优先算法(M-LWDF)的基础上,一种新的适用于宽带无线城域网实时业务的分组调度算法被提出,此算法引入了新的衡量服务队列负载的信息,能够实时地更新状态参数,提高了系统性能。仿真结果表明,此算法在保证系统吞吐量的同时,比M-LWDF算法具有更好的时延特性和公平性。 相似文献
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载波聚合是LTE-Advanced系统的关键技术之一。文章中重点介绍了载波聚合中的移动性无线资源管理(RRM:Radio Resource Manage-ment)机制。在引入该机制的基础上,传统的正比公平(PF:proportional fair)调度算法并不能够很好地保证用户之间在资源分配方面的公平性,因此提出了Balanced PF(BPF)算法。从系统级仿真结果可以看出,与传统的PF算法相比,BPF算法可以提升边缘用户的吞吐量性能,改善用户之间的公平性。 相似文献
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在非连续载波聚合(高频+低频)场景下,载波衰减特性不同,聚合的载波有不同的覆盖范围,使得不同用户可调度的载波数量不同,若使用传统比例公平( PF)算法会导致小区不同位置用户资源配置的不公平性。本文提出了一种分组权重PF调度算法( GWPF ),根据用户可调度的载波数量,将用户和载波分组,并引入加权因子对原比例公平算法进行加权处理,从而提高用户公平性。仿真结果表明GWPF较PF算法有着更好的用户公平性和边缘小区吞吐量。 相似文献
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准4G网络(LTE)即将商用会给人们带来更多的方便,以至于大量用户在日常生活中使用更多的QoS业务,这样系统会出现了拥塞和调度不够合理的情况,影响了高优先级业务的丢包率、时延和公平性。通过对LTE下行跨层分组调度各种算法的研究分析,从时延、丢包率、吞吐量和公平性等因素入手,在原有的比例公平性调度算法(PF)上进行改进,加入了补偿因子和付费权重值,使得改进型跨层调度算法,在吞吐量有一定提高的情况下,有效地降低了高优先级业务的丢包率和时延,并确保了高优先级业务的公平性。 相似文献
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针对目前PF改进型算法在LTE系统中保障增值业务GBR和区分增值业务速率的研究较少的问题。提出一种改进型PF算法,该算法通过引入信道控制因子、GBR保障因子和速率门限因子,从而实现增值业务的下行跨层调度。仿真结果表明该算法可以保障各增值业务的GBR以及实现不同付费等级的付费平均可达速率,同时保证增值业务用户间的公平性。 相似文献
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快速调度机制使系统可以根据所有用户的情况决定哪个用户可以使用信道,以何种速率使用信道,信道总是被与信道状况相匹配的用户所使用,这样在每个瞬间都可以达到最高的用户数据速率和最大的数据吞吐量,但同时兼顾每个用户的等级和公平性。文章首先对基于非实时业务无线分组调度算法进行分析,然后对各种算法在公平性方面进行了仿真。仿真分析表明:RR(轮询调度)、PF(正比公平)和APF(自适应正比公平)算法完全位于公平准则曲线的右侧,因此满足公平性准则的要求;RR算法具有最好的公平性。 相似文献
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针对HSDPA(高速下行分组接入)系统中几种支持非实时业务的经典分组调度算法Max C/I(最大载干比)和PF(正比公平)算法缺乏系统公平性的问题,提出一种基于HSDPA的快速公平分组调度算法。此算法在保证信道瞬时条件和系统吞吐量的前提下,旨在为那些平均吞吐量低于某一阈值的用户提供优先被服务的机会。仿真结果表明,此算法较之Max C/I和PF算法能够保证用户间的长期公平性。 相似文献
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云计算是完全基于互联网的新兴技术。云计算环境中的任务调度问题一直都是该领域的研究热点。合理高效的任务调度算法在云环境中能有效的缩短任务完成时间,提高系统负载均衡,更好的满足用户与云提供商的需求。本文研究了云平台的任务调度机制,探究了任务调度过程中的关键性指标。通过云仿真平台CloudSim实现并分析了顺序调度算法、Min-Min算法和Max-Min算法,对比其在随机生成用户任务负载与虚拟机计算资源的情况下的任务完成时间,实验证明Min-Min算法与Max-Min算法均优于顺序调度算法。以此为未来研究提供实验支撑和方向。 相似文献
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Cloud computing is an emerging domain that requires more algorithm and techniques for various process. The scheduling process in cloud computing platform needs a good algorithm to schedule the jobs of different users. The main objective of this approach is to develop a scheduling algorithm through iterative algorithm. Here, we use oppositional group search optimization algorithm for iterative process in cloud computing. Initially, we generate a population that contains a group of members and the members consist of the number of users and their respective jobs. The motto of our research is to schedule the user given jobs efficiently. We separate the members from the population based on the fitness function to perform different operations and to generate new members. We calculate the fitness for the new members and iterate the process until we get a stable best member for repeated iteration. Then, we schedule the jobs for the users based on the best member obtained. 相似文献
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分组调度是HSDPA的核心技术之一,对网络性能有重要影响。在HSDPA分组调度功能和实现的基础上,重点分析对比3种典型分组调度算法原理及其对系统的影响,并通过实际测试验证,明确了不同调度算法对小区吞吐率的影响。结论:MAXCI算法下能够得到最大的系统吞吐量,公平性最差;RR算法公平性最好,系统资源利用率最低,吞吐率最小;EPF算法既考虑了用户的公平性,也能从一定程度上保证比较高的系统吞吐量,是一种实用的调度方法。 相似文献
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Ali Syed Hussain Krishnamurthy Vikram Leung Victor C.M. 《Mobile Computing, IEEE Transactions on》2007,6(6):633-648
This paper considers the problem of scheduling multiple users in the downlink of a time-slotted cellular data network. For such a network, opportunistic scheduling algorithms improve system performance by exploiting time variations of the radio channel. We present novel optimal and approximate opportunistic scheduling algorithms that combine channel fluctuation and user mobility information in their decision rules. The algorithms modify the opportunistic scheduling framework of Liu et al., (1993) with dynamic constraints for fairness. These fairness constraints adapt according to the user mobility. The adaptation of constraints in the proposed algorithms implicitly results in giving priority to the users that are in the most favorable locations. The optimal algorithm is an offline algorithm that precomputes constraint values according to a known mobility model. The approximate algorithm is an online algorithm that relies on the future prediction of the user mobility locations in time. We show that the use of mobility information in opportunistic scheduling increases channel capacity. We also provide analytical bounds on the performance of the approximate algorithm using the fundamental inequality of Dyer et al., (1986) for linear programs. Simulation results on high data rate (HDR) illustrate the usefulness of the proposed schemes for elastic traffic and macrocell structures 相似文献
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LIN Le-xiang LIU Yuan-an LIU Fang XIE Gang LIU Kai-ming GE Xin-yang 《中国邮电高校学报(英文版)》2012,19(1):44-49,123
In this paper,we focus on the resource scheduling in the downlink of long term evolution advanced (LTE-A) assuming equal power allocation among subcarriers.Considering the backward compatibility,the LT... 相似文献
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Abdallah K. Farraj 《Wireless Personal Communications》2014,74(2):933-952
This article investigates the scheduling of secondary users in a spectrum-sharing cognitive environment under the primary user’s outage probability constraint. A switched-diversity combining approach to schedule the secondary users is explored. Specifically, switch-and-examine, switch-and-stay, selection-combining, and post-selection scheduling algorithms are investigated. Secondary users’ average performance measures are derived for the scheduling algorithms and compared against those of a single-user cognitive system. Results of this work illustrate the trade-off between the complexity of a scheduling algorithm and its average performance. 相似文献