适用于IEC 61850标准的以太网无源光网络DBA算法

在分析IEC 61850标准下网络报文传输特性的基础上,提出一种适用于IEC 61850标准网络报文传输的以太网无源光网络动态带宽分配算法。首先,该算法采用固定轮询周期,将带宽划分为采样值(SMV)、面向对象的变电站通用事件(GOOSE)、制造报文规范(MMS)这三类及三个优先级,优先保证SMV报文、GOOSE报文的实时传输,减少网络时延抖动。然后,采用改进的REPORT上传和GATE下发机制,提高了带宽利用率,并简要介绍了算法的典型应用系统及测试验证方案。最后,测试结果表明,该算法满足IEC 61850标准网络报文传输的实时性和快速性要求。     

一种基于时隙动态分配的FlexRay系统通信机制

汽车FlexRay总线系统中消息的调度方法直接关系到整车通信实时性。针对FlexRay系统静态段固定分配时隙机制的不足,提出一种静态时隙动态分配的消息调度机制(SDAS),给出该机制下调度器的状态转换模型和运行算法,并定量分析各静态消息最坏响应时间;在对FlexRay帧结构设计基础上,以静态段时间碎片最小为目标,以消息可调度和通信周期有界为约束条件,建立了SDAS机制下相关网络参数的配置方法。实验仿真结果表明,与固定分配时隙相比,SDAS机制能有效提高消息实时性和带宽利用率。     

基于海量存储云调度机制的云网络数据存储算法

针对当前云网络超宽带存储难以实现流量的分流,且存储过程中存在严重的存储效率低下及存储时延过高等问题,提出了一种基于海量存储云调度机制的云网络数据超带宽存储算法。采用周期调度及梯度优化方式,且综合考虑数据存储中使用强度,最小传输粒度等数字特征,对数据存储过程中的指纹梯度进行优化,且将该梯度引入到数据传输过程中,成功地实现了数据的流量分离,提高了数据存储效率。仿真实验表明,与当前广泛使用的超线性存储调度算法（super linear memory scheduling algorithm,SLMS）相比,本文算法的存储效率更高,能够在流量分离的前提下显著降低存储时延。     

Ethernet-PON上行带宽分配算法的研究

文章简要介绍了基于以太网的无源光网络(PON)这种新型接入网技术，简述了其优势，提出了业务分级的概念，并提出了基于OLT的上行带宽分配算法，通过动态请求分配机制，实现上行链路的高效利用。最后，通过建模仿真，分析该算法的延时特性。     

多跳中继宽带电力线通信网络中的OFDM跨层资源分配

为保障宽带电力线通信网络的有效性和可靠性,提出一种综合多跳中继宽带电力线通信网络的业务层、网络层、介质访问控制(Media Access Control,MAC)层和物理层信息的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)跨层资源分配方法。首先建立综合跨层信息的MAC层数据包调度效用值模型和基于公平性阈值控制的物理层子载波分配模型。提出为满足各用户服务质量需求的MAC层高效用值数据包优先调度准则。再将该模型和准则应用于宽带电力线通信网络各交叉节点的资源分配过程中。最后在典型电力线信道环境下对所提算法及对比算法进行仿真。仿真结果表明所提算法能够保证实时用户与非实时用户的通信速率和时延的服务质量需求,且具有较大的系统吞吐量和较好的时延特性,有效解决了多跳中继宽带电力线通信网络的OFDM资源分配问题。     

基于自适应编码和调制技术的802.16调度算法

IEEE 802.16标准具有面向连接的特性,能够为每个连接提供QoS保证.标准定义了QoS架构中BS与SS间交换信息的信令机制,但是并没有规定上行带宽分配的调度算法,而这正是目前802.16领域研究的热点.对于VoIP、流媒体等实时业务来说,其对延迟和延迟抖动非常敏感.针对这一情况,本文提出了一种调度算法,利用自适应编码和调制技术,通过动态变化调制和编码方式,以牺牲一定的传输速率为代价来保证链路的稳定工作.即使在无线网络状态不佳的情况下,连接的QoS需求也能得到保证,从而改善了实时业务的运行状况.     

Comparisons of link-adaptation-based scheduling algorithms for the WCDMA system with high-speed downlink packet access

The wideband code division multiple access (WCDMA) system with high-speed downlink packet access (HSDPA) is an important next-generation wireless system. By adopting adaptive modulation, efficient scheduling, and hybrid automatic repeat request technologies, it can support data rates of up to 10 Mb/s in the mobile cellular environment. Among these techniques, the scheduling algorithm plays a key role in realizing the HSDPA concept. A good scheduling algorithm should consider all the important factors, including channel impact, delay issues, and fairness. In this paper, a fairness index is adopted to examine the fairness performance of current link-adaptation-based scheduling algorithms, including the maximum carrier-to-interference (C/I), round-robin, proportional fair, and exponential rule schedulers. It is found that when multi-type services are supported, the fairness performance of current scheduling algorithms, including the round-robin scheduler, can be further improved even though the round-robin scheduler is viewed as the scheduler of the greatest fairness. Thus, a new scheduling algorithm, namely the queue-based exponential rule scheduler, is developed. Through simulations, it is shown that in the context of multi-type services the fairness performance of the queue-based exponential rule scheduler can surpass that of all the other schedulers in the time-multiplexing fashion, while maintaining good throughput and delay performance.     

Optimal Network Rate Allocation under End-to-End Quality-of-Service Requirements

We address the problem of allocating transmission rates to a set of network sessions with end-to-end bandwidth and delay requirements. We give a unified convex programming formulation that captures both average and probabilistic delay requirements. Moreover, we present a distributed algorithm and establish its convergence to the global optimum of the overall rate allocation problem. In our algorithm, session sources selfishly update their rates as to maximize their individual benefit (utility minus bandwidth cost), the network partitions end-to-end delay requirements into local per-link delays, and the links adjust their prices to coordinate the sources' and network's decisions, respectively. This algorithm relies on a network utility maximization (NUM) approach, and can be viewed as a generalization of TCP and active queue management (AQM) algorithms to handle end-to-end QoS. We extend our results to deterministic delay requirements when nodes employ Packet-level Generalized Processor Sharing (PGPS) schedulers.     

用于电力系统信息综合传输的改进加权公平队列调度算法

为保证电力系统信息综合传输中各种信息业务的服务质量,提出一种改进的最坏情况下公平的加权公平队列(improved worst-case fair weighted fair queueing plus,IWF2Q)调度算法。该算法通过在WF2Q算法的虚拟开始时间和虚拟完成时间计算公式中引入"虚拟延迟时间",解决了电力系统信息综合传输中由WF2Q算法导致的推迟传输高优先级信息业务分组的问题。以NS2为工具,建立了基于区分服务体系结构模型的IEEE 14母线系统信息综合传输网络仿真模型,运用网络仿真方法定量评估了以IWF2Q算法实现基于区分服务体系结构模型的电力系统信息综合传输时各类信息业务的实时性和公平性。仿真结果表明,IWF2Q算法降低了高优先级信息业务分组延时,同时兼顾综合传输的各类信息业务间的公平性,证明了IWF2Q算法的有效性和可行性。     

宽带电力线载波通信物理层资源分配新算法

宽带电力线载波基于正交频分复用技术可实现电力串行通信数据的并行传输,增强了电力通信系统的实时性与高效性.针对宽带电力线载波通信资源分配问题,文中提出了一种低复杂度的物理层资源分配算法,首先基于等功率分配方式确定各用户为满足其最低速率需求所需的子载波集合,将多用户资源分配问题降维成单用户资源分配问题,之后对各用户所分配的子载波集进行功率优化,实现系统吞吐量的进一步提升.实验表明所提算法在满足更多用户并发业务的最低传输速率需求的同时,有效提升了网络吞吐量.     

一种CSMA与动态预约TDMA相结合的混合多址接入策略

针对移动自组织网络要承载实时和非实时业务的要求,提出一种的CSMA与动态预约TDMA相结合的混合多址接入策略,详细介绍了该策略的时隙分配算法。CSMA机制保证网络中每个节点公平高效的接入信道,动态预约TDMA机制确保有实时业务的节点能够准时无碰撞的接入信道,两种机制的结合使用,满足了实时和非实时业务同时传输的要求,充分的利用了带宽资源。     

面向边缘计算的人工鱼群搜索任务调度

如何将计算任务分配到合适的边缘计算资源上进行计算,以满足边缘计算环境下用户的计算需求、提高用户任务请求 的服务质量,是边缘计算中面临的关键问题。 本文提出一种基于人工鱼群搜索的边缘计算任务调度方法(AFETSA)。 将人工 鱼群搜索算法和边缘计算任务调度模型相结合,采用非线性递减函数动态地调整人工鱼的视野范围和步长,以提高启发式任务 调度算法的全局搜索能力,降低任务的计算时延;同时与禁忌搜索算法进行融合,通过引入忌禁表,在每一次迭代中防止算法陷 入局部最优,提高算法的寻优能力。 CloudSim3. 0 仿真平台实验评测结表明,本文所提 AFETSA 方法和已有的 AFSA、ACO 和 PSO 这 3 种调度算法相比,在任务执行时间、算法稳定性、负载均衡方面都有明显的提升,可充分利用边缘服务器计算资源,提 升计算任务的计算性能,有效解决边缘计算中任务调度不均导致的时延过高和负载不均衡问题。     

QoS-aware dynamic bandwidth allocation algorithm for Gigabit-capable PONS

The Gigabit-capable passive optical network (GPON) technology is being considered as a promising solution for the next-generation broadband access network. Since the network topology of the GPON is point-tomultipoint, a media access control called dynamic bandwidth allocation (DBA) algorithm is an important factor for determining the performance of the GPON. In this paper, we propose a new DBA algorithm to effectively and fairly allocate bandwidths among end users. This DBA algorithm supports differentiated services—a crucial requirement for a converged broadband access network with heterogeneous traffic. In this article we first reviewed the signaling and configuration of the DBA, and then proposed a new DBA scheme that implemented QoS-based priority for this need to maximally satisfy the requirements of all optical network units (ONUs) and provide differentiated services. Analyses and simulation results show that the new algorithm can improve the bandwidth utilization and realize the fairness for both different ONUs and services.     

基于贪心流量调度的智能变电站过程层网络拓扑高可用无缝冗余配置方法

泛在电力物联网背景下,智能变电站中负责运行状态上传与控制命令下达的过程层网络负载将急剧升高。传统IEC61850标准协议中的高可用性无缝冗余(High-Availability Seamless Redundancy,HSR)通信链路配置方法由于数据副本在存在环路的网络内循环产生额外流量与额外传输延时,存在信息传输实时性差的缺点。因此,提出基于贪心流量优化算法的过程层网络拓扑高冗余无缝配置方法。首先,在分析采用HSR技术的智能变电站过程层网络工作原理的技术上,提出两种高可用性无缝冗余配置方案:交叉(Cross-Links,CLs)方案与四连通环(Four-Connected Rings,FCRs)方案。其次,为避免过程层网络在流量汇聚时易产生拥塞导致传输时效性变差,提出基于贪心算法的流量调度策略。最后,基于Opnet的变电站仿真算例表明,与传统网络拓扑配置方案相比,所提方案的数据平均传输跳数与传统拓扑方案比下降50%,而采用贪心算法的过程层网络流量调度策略在数据拥塞时的传输延时、丢包率和吞吐量衰退服务分别降低32.7%,63.5%和33.3%。因此,所提方案能够显著提升智能变电站过程层网络性能。     

Predictive call admission control for multimedia streaming in CDMA cellular environments

Third-generation (3G) wireless networks based on code-division multiple access (CDMA) have been engineered to provide mobile users with voice as well as advanced packet data services. Support of Internet-based multimedia streaming services is considered a critical factor for future deployment of such networks. Provisioning streaming services in a dependable way, however, requires supporting data transmission at relatively high data rates while maintaining session quality during both intracell and intercell user movements. In this paper, an adaptive bandwidth allocation and admission control scheme is proposed for managing network resources for a streaming service. Streaming requests are assumed to be served by an adaptive server capable of choosing suitable video streaming parameters (e.g., video resolution, frame rate, and encoding parameters) in response to possible requests from the wireless network to vary the currently allocated bandwidth. The devised admission control scheme exploits a priori knowledge of user mobility patterns to minimize the risk of running into an overload condition after acceptance of a new multimedia streaming connection. The obtained simulation results show that, compared to a nonpredictive admission control scheme, the proposed scheme achieves a lower forced-termination probability and higher throughput, while consuming less base-station transmission energy.     

基于TRDP的网络优先级调度优化方法研究

将实时以太网应用于列车是未来列车通信网络发展的必然趋势。基于应用列车实时数据协议(train real-time data pro-tocol, TRDP)的车载设备搭建列车网络系统模拟试验平台,研究列车通信过程中各子控制系统的时延特性。通过测试多种发送周期下过程数据和消息数据的网络诱导时延来分析网络性能表现,为改善对实时性要求较高的消息数据传输时延,提出一种优化的优先级调度方法。使用网络演算方法对TRDP协议默认优先级调度方法和优化方法分别进行时延上界推导,最后在试验平台上应用该优化方法的同时测得多组时延数据。两种调度方法下的测试数据对比结果表明,该优化方法可在满足其它优先级数据传输时延要求的前提下,将较高优先级消息数据的时延在本地和跨编组网络下有效减少8.621 ms和13.545 ms,以此验证了该研究对提升列车实时以太网络性能的可行性。     

以太无源光网络中的媒质访问控制研究

以太无源光网络(EPON)借助以太网的简单、易升级等特性,成为一种非常有前途的宽带接入网。EPON是一个点对多点的拓扑结构网络,下行方向利用广播方式传输,而上行方向采用多个ONU共享传输媒质的多址接入方式。为了既能提高传输效率,又避免ONU间的发送冲突,选取一种适当的媒质访问控制机制仲裁各个接入,对维护QoS十分必要。文章重点探讨了动态时隙分配(DBA)机制及其不可或缺的轮询协议设计,使OLT通过轮询动态合理地为每个ONU分配所需的带宽。     

Scheduling algorithms for high-throughput packet data service in cellular radio systems

This paper examines the performance of a number of scheduling algorithms for the wireless packet data access evolution of third-generation cellular systems. The algorithms are analyzed using three different wireless channel models (two pedestrian, one vehicular). For each channel model, a comparison of the performance of the algorithms using outdated channel state information plus margins tuned to provide an average 1% packet error rate, as well as using perfect channel prediction in order to determine the supportable bit rate and transmission format for each user, has been carried out. The performance of the algorithms is evaluated in terms of the average throughput per sector as a function of the number of users. The average delay per packet and per user versus the number of users per sector and the distributions of allocated slots per user are also determined as a measure of the fairness of each algorithm. It is also shown that the use of outdated information and margins can be an effective substitute for prediction, provided that the outdated measurements are reasonably accurate.     

基于负载再分配的边缘计算任务均衡调度策略

目前5G异构网络的计算卸载机制在边缘节点资源方面和电力业务调度算法时延与负载均衡方面存在问题。综合考虑边缘服务器负载均衡和业务计算时延,针对min-min算法与max-min算法的不足,文中提出了基于电力业务优先级二次再分配的均衡调度算法。该算法根据业务的最大容忍时延划分业务的优先级,并且根据最小完成时间标准差确定长短业务比例,实现业务的预分配。基于各个边缘服务器的负载情况,该算法再将高负载边缘服务器上的业务分配给负载低的服务器,实现二次再分配。仿真结果表明,与典型的算法相比较,所提算法缓解了现有技术中存在的以上问题,降低了计算时延,实现负载均衡,提高了系统资源利用率。     

电力系统监控视频传输速率自适应控制设计

为解决电力系统视频监控工程领域的实际技术问题,提出一种电力系统监控实时视频传输速率的自适应控制方案。系统可以根据网络传输时间、传输延迟和数据包丢失率等参数对网络拥塞状况进行监测,并按照传输速率自适应控制的一定算法动态地调整视频发送端的输出速率,具有一定的鲁棒性,从而改善视频输出质量。经实验测试,该系统在减小视频数据包丢失率、提高网络带宽利用率和避免网络拥塞等方面,具有良好的对比效果。