基于Crossbar的可重构网络输入排队分域调度研究

为解决传统网络技术体系中交换结构无法满足大量差异化业务规模化应用的问题,本文基于可重构网络技术体系,采用选择关闭部分Crossbar交叉节点的分域模型,提出了分域调度的思想,分析并推导了承载组内的SDRR调度算法和域内最长队列优先调度算法。最后采用交换性能仿真平台对该调度算法进行了复杂度和时延的仿真比较,结果表明:分域调度的最长队列优先算法比一般最长队列优先算法相对复杂度低,且随着调度域个数增加,相对复杂度降低。在相同业务源输入条件下,Crossbar三分域调度算法的时延小于非分域调度算法的时延,接近公平输出排队调度算法的时延。     

基于REDP算法的动态QoS时延保障

针对无线多跳自组织网络中随机网络编码,之前提出了一种网络编码随机优先级检测调度算法(Random early detection with priority,REDP),对两条不同优先级的数据流建立Markov数学模型,推导出了引入REDP算法下数据流的单节点的时延数学表达式,该算法使得数据流能够根据自身优先级和拥塞程度调整丢包概率,从而主动丢弃数据包提前避免拥塞。文中将单节点时延问题拓展到多节点的网络拓扑结构中,提出了动态时延分配算法,该算法能够根据各个节点队列的缓存情况,动态调整各个节点的时延分配,仿真结果表明,动态时延分配算法能够实现实时数据流严格的Qo S时延保障,更利于视频、语音等实时业务流的传输。     

Ad hoc网络基于信息的调度算法

针对Ad hoc网络提出一种基于信息的调度策略。分组调度时,既考虑队列中剩余信息的多少又考虑原始的信息长度。仿真结果表明,算法改进了整个系统信息端到端的时延性能,并且不影响网络的吞吐量性能,不需要额外的通信开销。     

基于队列长度和时延约束的异步OPS权重调度

分组调度在异步光分组交换(OPS)节点中起着重要作用,一种智能的调度算法能减小分组的丢失率,增加节点的吞吐量,从而提高服务质量.文章提出了一种基于队列长度和时延约束的解决队列中分组"饿死"和时延问题的权重调度算法.算法通过计算队列长度和分组在队列中等待时间确定调度的权重值,以减小分组在核心节点处的资源竞争和等待时延,调度器计算每个输入端口的N×K个虚拟输出队列的权重值并调度最大权重值队列到可用的输出信道上.分析和仿真结果表明所提的权重调度算法具有高吞吐量和低分组丢失率特点.     

面向算力网络的多路径时敏优先调度机制

研究了一种面向算力网络的多路径低时延转发调度算法。该算法可以根据网络状态变化动态更新路径价值量生成路径转发决策，并在一定置信概率内以多路冗余发包的方式进行多路备份传输，降低路径传播时延。还提出了一种等级与队列映射算法，利用网络可编程技术改进设备转发逻辑，利用有限数量严格优先队列保障数据包近似按等级出队，降低数据排队时延。仿真实验结果表明，所提出方法可以降低数据传输时延及抖动，为算力网络业务提供稳定吞吐量。     

交换式工业以太网的队列调度算法分析

为了保证交换式工业以太网中实时数据端到端的传输时延和业务流传输的公平性,避免网络拥塞的出现,在对工业现场业务流类型分析的基础上,提出了一种基于SPQ_WRR队列调度的算法。为了验证该调度算法的有效性,采用了OPNET进行仿真,仿真结果表明,相比于传统的队列调度算法而言,该调度算法有效的保证了实时数据传输的实时性和业务流传输的公平性,同时起到了流量控制的作用,有效的避免了网络拥塞的出现。     

多模态网络中时间敏感网络模态的智能调度机制

针对多模态网络中时间敏感网络模态转发调度不确定、求解时间长等问题,提出了一种基于CSQF的时间敏感网络模态的联合路由与调度机制。综合考虑有界时延需求、网络状态和不同的路由机制,建立联合缓存队列和路由的混合资源调度模型,旨在优化整个网络的资源使用。基于深度强化学习方法,利用流量特征与缓存队列利用率来预测下一循环的缓存利用率。此外,基于多队列CSQF转发调度机制和基于缓存利用率的显式路由算法,提出了一种迭代调度算法,实现了确定性转发和资源分配。仿真结果表明,所提机制可以根据网络的资源使用情况有效地调整确定性应用的传输调度,与其他离线调度机制相比,具有更好的调度性能。     

FQLP:ATM网中一种新的实时业务调度算法

 本文提出了基于丢失优先权公平队列(FQLP)调度算法.理论分析和仿真实验表明FQLP调度算法能保证实时业务获得的网络资源不小于预约带宽,为实时业务提供确定的时延上界.FQLP调度算法利用ATM网络中的信元优先权机制,提高了网络资源的利用率.同时FQLP调度策略能保证信元的发送顺序.     

光突发交换网络中Jitter-EDF调度算法的研究

提出了一种应用于OBS网络中的Jitter-EDF调度算法来减小时延抖动对实时性突发QoS的影响,设计了基于该算法的OBS网络中核心路由器的主要结构,讨论了此算法实现的可能性,并推导出端到端时延的上下限和时延抖动的上限,最后结合具体网络拓扑进行了仿真和分析。结果表明,Jitter-EDF调度算法能够将时延抖动的幅度平均降低到30%～40％,有效保证了实时性应用对时延抖动的要求。     

基于多业务的队列调度算法研究

讨论了几种典型的调度算法,并在WRR基础上提出一种针对多业务的调度算法(MWRR),同时描述了算法的实现过程。该算法根据各队列的延迟时间比来动态调整队列的调度次序。MWRR算法能够降低多业务的端对端时延,为多业务提供更好的QoS保证。最后通过仿真,证明了该算法的优越性。     

Network queue scheduling algorithm based on self-similar traffic level grading prediction

Self-similarity characteristic of network traffic will lead to the continuous burstness of data in the network.In order to effectively reduce the queue delay and packet loss rate caused by network traffic burst,improve the transmission capacity of different priority services,and guarantee the service quality requirements,a queue scheduling algorithm P-DWRR based on the self-similarity of network traffic was proposed.A dynamic weight allocation method and a service quantum update method based on the self-similar traffic level grading prediction results were designed,and the service order of the queue according was determined to the service priority and queue waiting time,so as to reduce the queuing delay and packet loss rate.The simulation results show that the P-DWRR algorithm can reduce the queueing delay,delay jitter and packet loss rate on the basis of satisfying the different service priority requirements of the network,and its performance is better than that of DWRR and VDWRR.     

Media Synchronization and QoS Packet Scheduling Algorithms for Wireless Systems

Wireless multimedia synchronization is concerned with distributed multimedia packets such as video, audio, text and graphics being played-out onto the mobile clients via a base station (BS) that services the mobile client with the multimedia packets. Our focus is on improving the Quality of Service (QoS) of the mobile client's on-time-arrival of distributed multimedia packets through network multimedia synchronization. We describe a media synchronization scheme for wireless networks, and we investigate the multimedia packet scheduling algorithms at the base station to accomplish our goal. In this paper, we extend the media synchronization algorithm by investigating four packet scheduling algorithms: First-In-First-Out (FIFO), Highest-Priority-First (PQ), Weighted Fair-Queuing (WFQ) and Round-Robin (RR). We analyze the effect of the four packet scheduling algorithms in terms of multimedia packet delivery time and the delay between concurrent multimedia data streams. We show that the play-out of multimedia units on the mobile clients by the base station plays an important role in enhancing the mobile client's quality of service in terms of intra-stream synchronization and inter-stream synchronization. Our results show that the Round-Robin (RR) packet scheduling algorithm is, by far, the best of the four packet scheduling algorithms in terms of mobile client buffer usage. We analyze the four packet scheduling algorithms and make a correlation between play-out of multimedia packets, by the base station, onto the mobile clients and wireless network multimedia synchronization. We clarify the meaning of buffer usage, buffer overflow, buffer underflow, message complexity and multimedia packet delay in terms of synchronization between distributed multimedia servers, base stations and mobile clients.     

A Modified Dynamic Weighted Round Robin Cell Scheduling Algorithm

In this paper, we propose the modified dynamic weighted round robin (MDWRR) cell scheduling algorithm, which guarantees the delay property of real‐time traffic and also efficiently transmits non‐real‐time traffic. The proposed scheduling algorithm is a variation of the dynamic weighted round robin (DWRR) algorithm and guarantees the delay property of real‐time traffic by adding a cell transmission procedure based on delay priority. It also uses a threshold to prevent the cell loss of non‐real‐time traffic that is due to the cell transmission procedure based on delay priority. Though the MDWRR scheduling algorithm may be more complex than the conventional DWRR scheme, considering delay priority minimizes cell delay and decreases the required size of the temporary buffer. The results of our performance study show that the proposed scheduling algorithm has better performance than the conventional DWRR scheme because of the delay guarantee of real‐time traffic.     

iRGRR/PM：一种新的高速crossbar分组调度策略

iRGRR(iterative Request-Grant-based Round-Robin)算法是一种输入排队crossbar调度算法,具有硬件易实现、可扩展性强、性能优良等优点.在此基础上,该文提出一种新的高速crossbar分组调度策略iRGRR/PM(iRGRR with Packet Mode),可以更好地支持IP分组的调度,能够被应用于高速、大容量的路由器中.与iRGRR算法相比,iRGRR/PM简化了分组输出重组模块的设计,并且提高了crossbar的带宽资源利用率.文中简单分析了两种算法间的分组时延关系,并进行了详尽的仿真研究.结果表明:在相同条件下,iRGRR/PM算法具有更高的吞吐量,尤其在非均匀业务流下能获得接近100%的吞吐量;调度长分组时,iRGRR/PM算法具有更好的时延性能.     

Logarithmic Delay for N ×N Packet Switches Under the Crossbar Constraint

We consider the fundamental delay bounds for scheduling packets In an N times N packet switch operating under the crossbar constraint. Algorithms that make scheduling decisions without considering queue backlog are shown to incur an average delay of at least O(N). We then prove that O(log(N)) delay is achievable with a simple frame based algorithm that uses queue backlog information. This is the best known delay bound for packet switches, and is the first analytical proof that sublinear delay is achievable in a packet switch with random inputs.     

Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks简

In order to establish a route supporting multi-constrained quality of service（QoS）, increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm（IAMQER） is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.     

基于无线传感器网络的业务流调度算法

实时性要求是无线传感器网络调度算法性能评价的重要内容。对于实时性要求很高的应用场合,调度算法的首要标准是降低数据包的传输时延。针对无线传感器网络的业务流调度问题,结合传统的加权循环调度算法WRR,着眼于解决无线传感器网络中业务流突发引起的时延性能下降问题,提出了新的调度算法-WSWRR。新算法合理分配传感器节点的数据感知和传输时间,使节点在不需要工作时转入低功耗的休眠模式,且能在满足应用要求服务质量的前提下,高效利用节点能量,延长整个传感器网络的生命周期。通过仿真实验,验证了新算法在调度突发数据包时性能得到了很好的改善,且没有增加网络的整体能耗,证明了WSWRR算法的有效性。     

基于QoS付费业务的LTE下行跨层分组调度算法

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。     

Active intra-ONU scheduling with proportional guaranteed bandwidth in long-reach EPONs

The unused slot remainder (USR) problem in Ethernet Passive Optical Networks and long-reach Passive Optical Networks (LR-PONs) results in both a lower bandwidth utilization and a greater packet delay. In a previous study by the current group, an Active intra-ONU Scheduling with predictive queue report scheme was proposed for resolving the USR problem by predicting the granted bandwidth in advance based on the arrival traffic estimates of the optical network units (ONUs). However, it was found that the higher bandwidth prediction error in the proposed scheme prevents the network performance from being improved. Accordingly, the present study proposes a non-predictive-based ONU scheduling method designated as Active intra-ONU Scheduling with proportional guaranteed bandwidth (ASPGB) to improve the performance of LR-PONs. In the proposed method, the maximum guaranteed bandwidth of each ONU is adapted dynamically in accordance with the ratio of the ONU traffic load to the overall system load. Importantly, the proposed dynamic bandwidth allocation approach reduces the dependence of the network performance on the granted bandwidth prediction since the maximum guaranteed bandwidth determined by the Optical Line Terminal more closely approaches the actual bandwidth demand of each ONU. To solve the idle time problem arising in the event of an excess bandwidth reallocation, ASPGB is integrated with an improved early allocation (IEA) algorithm (a kind of Just-In-Time scheduling). The simulation results show that the IEA-ASPGB scheme outperforms previously published methods in terms of bandwidth utilization and average packet delay under both balanced and unbalanced traffic load conditions.     

Load balancing routing with queue overflow prediction for WSNs

The ease of deployment of Wireless Sensor Networks (WSNs) makes them very popular and useful for data collection applications. Nodes often use multihop communication to transmit data to a collector node. The next hop selection in order to reach the final destination is done following a routing policy based on a routing metric. The routing metric value is exchanged via control messages. Control messages transmission frequency can reduce the network bandwidth and affect data transmission. Some approaches like trickle algorithm have been proposed to optimize the network control messages transmission. In this paper, we propose a collaborative load balancing algorithm (CoLBA) with a prediction approach to reduce network overhead. CoLBA is a queuing delay based routing protocol that avoids packet queue overflow and uses a prediction approach to optimize control messages transmission. Simulation results on Cooja simulator show that CoLBA outperforms other existing protocols in terms of delivery ratio and queue overflow while maintaining a similar end-to-end delay.