Scheduling Algorithm with Quality of Service Support in IEEE 802.16 Networks

The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.

A New Fairness-Oriented Packet Scheduling Scheme with Reduced Channel Feedback for OFDMA Packet Radio Systems

In this paper, we propose a flexible and fairness-oriented packet scheduling approach for 3GPP UTRAN long term evolution (LTE) type packet radio systems, building on the ordinary proportional fair (PF) scheduling principle and channel quality indicator (CQI) feedback. Special emphasis is also put on practical feedback reporting mechanisms, including the effects of mobile measurement and estimation errors, reporting delays, and CQI quantization and compression. The performance of the overall scheduling and feedback re-porting process is investigated in details, in terms of cell throughput, coverage and resource allocation fairness, by using extensive quasistatic cellular system simulations in practical OFDMA system environment with frequency reuse of 1. The performance simulations show that by using the proposed modified PF ap-proach, significant coverage improvements in the order of 50% can be obtained at the expense of only 10-15% throughput loss, for all reduced feedback reporting schemes. This reflects highly improved fairness in the radio resource management (RRM) compared to other existing schedulers, without essentially com-promising the cell capacity. Furthermore, we demonstrate the improved functionality increase in radio re-source management for UE’s utilizing multi-antenna diversity receivers.

Packet Scheduling Algorithm for Real-Time Services in Broadband WMAN

Packet scheduling algorithm is the key technology to guarantee Quality of Service (QoS) and balance the fairness between users in broadband Wireless Metropolitan Area Network (WMAN). Based on the research of Proportional Fairness (PF) algorithm and Modified Largest Weighted Delay First (M-LWDF) algorithm, a new packet scheduling algorithm for real-time services in broadband WMAN, called Enhanced M-LWDF (EM-LWDF), was proposed. The algorithm phases in new information to measure the load of service queues and updates the state parameters in real-time way, which remarkably improves system performance.Simulation results show that comparing with M-LWDF algorithm, the proposed algorithm is advantageous in performances of queuing delay and fairness while guaranteeing system throughput.

Modeling and performance evaluation of QoS-aware job scheduling of computational grids

To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.

Improved Delay Priority Resource Scheduling with Low Packet Loss Rate for MBMS in LTE Systems

An improved delay priority resource scheduling algorithm with low packet loss rate for multimedia broadcast multicast service(MBMS)in long term evolution(LTE)systems is proposed in this paper.Real-time services in LTE systems require lower delay and packet loss rate.However,it is difficult to meet the QoS requirements of real-time services using the current MBMS resource scheduling algorithm.The proposed algorithm in this paper jointly considers user delay information and real-time channel conditions.By introducing the user delay information,the lower delay and fairness of users are guaranteed.Meanwhile,by considering the channel conditions of users,the packet loss rate can be effectively reduced,improving the system throughput.Simulation results show that under the premise of ensuring the delay requirements of real-time services,the proposed algorithm achieves a lower packet loss rate compared to other existing algorithms.Furthermore,it can achieve a good balance between system throughput and user fairness.

A QoS-Aware Packet Scheduling Mechanism in Cognitive Radio Networks for Smart Grid Applications

Cognitive radio sensor network is applied to facilitate network monitoring and management, and achieves high spectrum efficiencies in smart grid. However, the conventional traffic scheduling mechanisms are hard to provide guaranteed quality of service for the secondary users. It is because that they ignore the influence of diverse transition requirements in heterogeneous traffi c. Therefore, a novel Qo S-aware packet scheduling mechanism is proposed to improve transmission quality for secondary users. In this mechanism, a Qo S-based prioritization model is established to address data classification firstly. And then, channel quality and the effect of channel switch are integrated into priority-based packet scheduling mechanism. At last, the simulation is implemented with MATLAB and OPNET. The results show that the proposed scheduling mechanism improves the transmission quality of high-priority secondary users and increase the whole system utilization by 10%.

Topology Driven Cooperative Self Scheduling for Improved Lifetime Maximization in WSN

In Wireless Sensor Network(WSN),scheduling is one of the important issues that impacts the lifetime of entire WSN.Various scheduling schemes have been proposed earlier to increase the lifetime of the network.Still,the results from such methods are compromised in terms of achieving high lifetime.With this objective to increase the lifetime of network,an Efficient Topology driven Cooperative Self-Scheduling(TDCSS)model is recommended in this study.Instead of scheduling the network nodes in a centralized manner,a combined approach is proposed.Based on the situation,the proposed TDCSS approach performs scheduling in both the ways.By sharing the node statistics in a periodic manner,the overhead during the transmission of control packets gets reduced.This in turn impacts the lifetime of all the nodes.Further,this also reduces the number of idle conditions of each sensor node which is required for every cycle.The proposed method enables every sensor to schedule its own conditions according to duty cycle and topology constraints.Central scheduler monitors the network conditions whereas total transmissions occurs at every cycle.According to this,the source can infer the possible routes in a cycle and approximate the available routes.Further,based on the statistics of previous transmissions,the routes towards the sink are identified.Among the routes found,a single optimal route with energy efficiency is selected to perform data transmission.This cooperative approach improves the lifetime of entire network with high throughput performance.

Particle Swarm Optimization Based Approach for Resource Allocation and Scheduling in OFDMA Systems

Orthogonal Frequency-Division Multiple Access (OFDMA) systems have attracted considerable attention through technologies such as 3GPP Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). OFDMA is a flexible multiple-access technique that can accommodate many users with widely varying applications, data rates, and Quality of Service (QoS) requirements. OFDMA has the advantages of handling lower data rates and bursty traffic at a reduced power compared to single-user OFDM or its Time Division Multiple Access (TDMA) or Carrier Sense Multiple Access (CSMA) counterparts. In our work, we propose a Particle Swarm Optimization based resource allocation and scheduling scheme (PSORAS) with improved quality of service for OFDMA Systems. Simulation results indicate a clear reduction in delay compared to the Frequency Division Multiple Access (FDMA) scheme for resource allocation, at almost the same throughput and fairness. This makes our scheme absolutely suitable for handling real time traffic such real time video-on demand.

Class of Service Support Layer for Wireless Mesh Networks

This paper presents an add-on Class of Service (CoS) layer for wireless mesh networks. The proposed protocol is applicable for contention-based MACs and is therefore compatible with most of the Wireless Local Area Network (WLAN) and Wireless Sensor Network (WSN) protocols. The protocol has a locally centralized control for managing data flows, which either reserve a fixed bandwidth or are weighted by fair scheduling. The protocol reduces transmission collisions, thus improving the overall throughput. IEEE 802.11 adhoc WLAN has been taken as a platform for simulations and prototyping for evaluating the protocol performance. Network Simulator Version 2 (NS2) simulations show that the CoS protocol efficiently differentiates bandwidth, supports bandwidth reservations, and reaches less than 10 ms transfer delay on IEEE 802.11b WLAN. Testing with a full prototype implementation verified the performance of the protocol.

A Service Ratio-Based Dynamic Fair Queueing Algorithm for Packet-Switching Networks

A new weighted fair queueing algorithm is proposed, which uses the novel flow-based service ratio parameters to schedule flows. This solves the main drawback of traditional weighted fair queneing algorithms- the packet-based calculation of the weight parameters. In addition, this paper proposes a novel service ratio calculation method and a queue mangement technology. The former adjusts the service ratio parameters adaptively based on the dynamics of the packet lengths and thee solves the unfairness problem induced by the variable packet length. The latter improves the utilization of the server＇s queue buffer and reduces the delay jitter through restricting the buffer length for each flow.

TRS Scheduling for Improved QoS Performance in Cloud System

Numerous methods are analysed in detail to improve task schedulingand data security performance in the cloud environment. The methodsinvolve scheduling according to the factors like makespan, waiting time,cost, deadline, and popularity. However, the methods are inappropriate forachieving higher scheduling performance. Regarding data security, existingmethods use various encryption schemes but introduce significant serviceinterruption. This article sketches a practical Real-time Application CentricTRS (Throughput-Resource utilization–Success) Scheduling with Data Security(RATRSDS) model by considering all these issues in task scheduling anddata security. The method identifies the required resource and their claim timeby receiving the service requests. Further, for the list of resources as services,the method computes throughput support (Thrs) according to the number ofstatements executed and the complete statements of the service. Similarly, themethod computes Resource utilization support (Ruts) according to the idletime on any duty cycle and total servicing time. Also, the method computesthe value of Success support (Sus) according to the number of completions forthe number of allocations. The method estimates the TRS score (ThroughputResource utilization Success) for different resources using all these supportmeasures. According to the value of the TRS score, the services are rankedand scheduled. On the other side, based on the requirement of service requests,the method computes Requirement Support (RS). The selection of service isperformed and allocated. Similarly, choosing the route according to the RouteSupport Measure (RSM) enforced route security. Finally, data security hasgets implemented with a service-based encryption technique. The RATRSDSscheme has claimed higher performance in data security and scheduling.

一种改进近端优化的多目标流QoS调度策略

软件定义网络可以搭载灵活的流调度策略来提升网络服务系统的服务质量,但随着业务流量复杂度的提升,现有的流调度算法会因场景匹配度的下降而导致性能受到影响。为此提出一种基于深度强化学习的智能路由策略。该策略通过软件定义网络收集各链路信息,基于长短期记忆网络与近端策略优化算法实现特征提取与状态感知,最终决策生成符合业务场景下服务质量(quality of service,QoS)目标的动态流量调度策略,并实现QoS最大化。实验结果表明,所提的方案与现有的路由策略相比可以使整套系统QoS指标提升7.06%,有效地提升了业务系统的吞吐率。

低复杂度的OFDMA系统调度与资源分配算法

针对多用户多业务OFDMA系统存在的缺陷与不足,提出了一种低复杂度的分组调度与资源分配算法.该算法考虑队列状态、QoS要求、信道情况和业务优先级等信息,分别定义了实时轮询服务、非实时轮询服务和尽力而为服务的效用函数,算法在满足各种业务延时、传输速率和丢包率约束条件下,通过最大化非实时业务总吞吐量实现调度和资源分配.仿真结果表明,与已有算法相比,该算法在非实时业务总吞吐量下降不大的情况下,在性能和复杂度之间取得了较好的折中.

一种多用户MIMO/OFDMA系统的资源分配和调度方案

针对下行多用户多入多出/正交频分复用系统,提出了一种适合多业务类型的资源分配和调度算法.综合考虑了不同业务类型的服务质量需求,根据用户的信道条件、吞吐量和队列状态确定调度优先级;结合用户信道的空间相关性进行用户选择、功率分配和比特加载.通过充分利用空、时、频多用户分集增益。在保证实时业务最小时延要求和非实时业务最小速率要求的同时,最大化系统的吞吐量.仿真结果说明,所提算法在系统吞吐量、丢包率及最小速率满足率方面得到了改善.

宽带OFDMA系统有效支持QoS的分组调度算法

提出了2种适用于多用户正交频分复用多址接入(OFDMA)系统的分组数据调度算法,分别是多载波正比公平(MPF)算法和增强容量的MPF算法.理论分析和数值结果表明,2种算法都能保证用户的不同业务质量(QoS)要求,并且实现用户数据的公平发送,但是与MPF相比,增强容量的MPF算法具有更大的灵活性和更高的系统吞吐量.

OFDM下行链路的跨层自适应传输算法

提出了一种适用于正交频分复用(OFDM)下行(前向)链路的跨层自适应传输算法.算法考虑了物理层的信道状态信息、功率约束以及数据链路层(DLL)的业务和用户的调度公平.基于比例公平原则和注水原理,给出了算法的6个具体步骤.仿真结果表明该跨层传输方案优于单纯在物理层采用子载波和功率分配自适应算法的方案,相对于后者能够提高用户数据包的传输成功率和降低包的传输时延,并能支持更多的用户.

面向多应用混部的性能保障方法综述

数据中心的高投入和低资源利用率一直是云服务提供商关注的问题.面对这个难题,直接的解决方案是在同等资源上混合部署更多的应用以提高资源使用效率.然而,由于混部应用对共享资源的竞争导致了应用间的性能干扰,从而影响了应用的性能、服务质量(quality of service,QoS)和用户满意度,因此如何保障应用的性能已成为混部场景下的关键问题.着重从应用和集群特征分析(基础)、干扰检测(前提)、单节点资源分配(微观层面策略)和集群作业调度(宏观层面策略)4个方面阐述多应用混部性能保障的相关背景、挑战和关键技术.在不同的混部场景下,由于应用和集群特征等不同,性能保障工作所面临的挑战和问题复杂度也各异,例如单位资源上混合部署的应用数量会直接影响到搜索资源空间的时间开销,应用的运行方式会影响到共享资源的竞争强度.因此,从问题复杂度角度出发,从应用和集群特征、资源干扰维度和混部应用个数3个维度对相关研究工作面临的挑战进行讨论和分析.探讨了面向高密度混部场景应用性能保障方法的发展方向和挑战,认为全栈式的软硬件协同方法是保障高密度混部下应用性能的趋势,该方法有助于全面地提升应用性能的可靠性和数据中心的资源利用率.

一种基于OFDM的具有QoS保证的无线IP分组调度算法

根据无线正交频分复用(OFDM)系统的多载波并行传输特性及多用户无线通信系统的特点,利用跨层交互算法,提出了1种适用于IP分组业务的无线多业务分组调度算法(AS-OFDM).该算法通过在系统的网络层、链路层及物理层之间传递系统信息,实现了无线资源的自适应分配和IP分组的自适应调度.仿真试验表明,同传统的IP调度算法相比,该调度算法在保证不同业务的服务质量(QoS)的条件下,能够实现对无线资源更为有效的利用和保证并具有相同业务需求的不同用户之间的公平性.

4D-MAP:Multipath Adaptive Packet Scheduling for Live Streaming over QUIC

In recent years,live streaming has become a popular application,which uses TCP as its primary transport protocol.Quick UDP Internet Connections(QUIC)protocol opens up new opportunities for live streaming.However,how to leverage QUIC to transmit live videos has not been studied yet.This paper first investigates the achievable quality of experience(QoE)of streaming live videos over TCP,QUIC,and their multipath extensions Multipath TCP(MPTCP)and Multipath QUIC(MPQUIC).We observe that MPQUIC achieves the best performance with bandwidth aggregation and transmission reliability.However,network fluctuations may cause heterogeneous paths,high path loss,and band-width degradation,resulting in significant QoE deterioration.Motivated by the above observations,we investigate the multipath packet scheduling problem in live streaming and design 4D-MAP,a multipath adaptive packet scheduling scheme over QUIC.Specifically,a linear upper confidence bound(LinUCB)-based online learning algorithm,along with four novel scheduling mechanisms,i.e.,Dispatch,Duplicate,Discard,and Decompensate,is proposed to conquer the above problems.4D-MAP has been evaluated in both controlled emulation and real-world networks to make comparison with the state-of-the-art multipath transmission schemes.Experimental results reveal that 4D-MAP outperforms others in terms of improving the QoE of live streaming.

OFDMA系统实时业务分组调度算法

在移动通信系统中,常见的调度算法在处理实时业务时一般为信道状况好的用户分配过多的资源,而信道状况差的用户获得的调度机会相对较少。为保证实时业务的延迟要求,并兼顾不同用户间的公平性,基于正交频分多址接入系统,提出一种实时业务分组调度算法。在调度过程中,采用丢弃过期数据包的策略节省了系统资源。对信道状况好的用户采用较大的调度间隔,并采用高阶的调制编码方案将累积的数据包在一个调度间隔内发送,从而给予信道状况差的用户更多的调度机会。仿真结果证明,提出的算法能较好的满足实时业务的延迟要求,相对于改进的最大权重延迟优先算法和正比公平算法提高了用户间的公平性。