应用于航空Ad Hoc网络的高负载优先级均衡MAC协议

针对航空Ad Hoc网络在高负载下的低时延信道接入问题,提出一种优先级与公平性协作的多信道MAC协议(PBLL/HL)。在多信道检测统计基础上加以改进,结合优先级机制,在高负载网络中适时截流低优先级业务,优化网络流量,保证高优先级业务低时延发送;设计公平性优先级阈值与冲突退避窗口算法(PCA),减小低优先级业务接入时延。仿真结果表明,PBLL/HL能够在高负载网络有效控制信道接入,维持良好的网络流量,降低网络平均接入时延(低优先级业务时延过载时降低10%以上),稳定高负载网络吞吐量(最大吞吐量88.1%,过载时吞吐量下滑平缓),解决了航空数据链高业务量带来的高时延和网络拥塞。     

TD-SCDMA中实现不同优先级用户接入控制方法研究

为了实现为不同接入等级用户提供不同紧急程度的接入服务，保证高优先级用户的优先接入。TD-SCDMA系统提供了接入等级控制机制。通过使用接入等级、接入服务等级、坚持度检查、UpPCH子信道分配等机制，TD-SCDMA系统实现了用户的接入优先级控制。本文从理论和实际的角度对此机制进行了分析，并进行了仿真验证，仿真结果表明该机制能有效实现不同优先级用户的接入优先级控制。     

一种面向实时业务的Ad Hoc网络MAC协议

为降低AdHoe网络中实时业务的端到端时延,提出了基于802．11DCF的改进协议。协议采用3种机制降低实时业务的时延：面向路径的连续转发机制将RTS中的转发信息携带在ACK中发送,给实时业务提供较高的接入优先级;标签交换机制使得中间节点可以在MAC层获取转发信息,加快了实时业务数据包的转发速度;重传控制机制减少了无效传输的超时数据包。仿真结果表明,在重负载条件下,改进协议中实时业务的时延比802．11DCF有大幅度的下降,网络吞吐量也有所提高。     

TWDM-PON中带有业务区分的混合资源调度算法

针对时分波分复用无源光网络长距离和广覆盖特性带来往返时延增大,造成高优先级业务时延性能严重恶化的问题,提出带有业务区分的混合资源调度算法.根据网络负载实时调整光网络单元组的波长数以实现资源共享,并动态划分子周期以对不同优先级业务进行区分服务;设计混合资源调度算法,以在线方式填充波长空隙,以离线方式保障资源高效调度.仿真结果表明,所提算法能够满足不同优先级业务的时延要求,保证服务质量,并提高信道利用率.     

基于创新扩散的多预约802.11e协议及性能分析

该文为Ad hoc网络媒质接入层提出了一种基于802.11e协议的支持区分服务支持的协议。该协议采取多预约机制提高高优先级数据业务在信道竞争中的优势,并且采用创新的扩散原理协调降低各个低优先级数据业务的接入概率,保护高优先级数据流,同时避免了这种协调信息在全网络范围内的洪泛。理论分析与仿真结果均表明,该扩展协议提高了高优先级数据流的接入概率和端到端吞吐量,显著的降低高等级业务的端到端时延及抖动。     

确保无线AdHoc网络服务质量的MAC协议研究

本文针对无线局域网中MAC层Qos支持技术进行了研究，在分析了现有的EDCF退避机制的静态参数设置方法的基础上，提出结合网络负载状况动态调节不同优先级业务的竞争窗口和退避时间，改变不同优先级业务的信道接入方式的方法。仿真结果表明，动态调节法相较于静态参数法在网络吞吐量、时延、碰撞率方面都有更好的表现。     

带有上行数据帧聚合的光无线融合接入网络节能机制

光无线融合接入网存在光网络单元利用率低,数据传输过程中控制开销较大的问题。该文提出一种带有上行数据帧聚合的节能机制,建立M/G/1模型分析数据帧在无线域节点及光域节点的队列时延,结合不同优先级业务的最大容忍时延,推导各优先级聚合帧在不同网络状态下的最佳长度,进而根据所得到的最佳帧长对光域节点进行休眠调度,在保障业务时延的前提下,尽可能地延长节点休眠时间长度,提高网络能量效率。仿真结果表明,所提方法在有效降低整个网络能耗的同时能够保证业务的时延性能。     

基于并行排队策略的天基光网络接入选择算法

针对卫星光网络接入选择算法不够灵活高效的问 题,研究了天基光网络中基于并行排队策略(PQS,parallel queuing strategy)的 动态在线式接入选择算法。分析接入选择问题的约束条件并建立数学模型,在 排队模型的基础上增加动 态优先级策略dps(dynamic priority strategy),实现不同优先级任务的区分服务;通过引 入时间敏感因子实现对不同优先级任务等待 时延区分度的调节,避免低优先级任务一直被高优先级任务抢占的问题;通过增加PQS使调 度 方案得到全局优化,缩短任务等待时延。仿真结果表明,本文算法将等待时延降低 30%左右,有效提升了接入调度的灵活和高效性。     

智能变电站通信业务优先级及其队列调度方法

电网的发展对智能变电站提出了全站一网的要求.为满足多种通信业务的不同服务质量(QoS)需求,并保证网络拥塞时关键业务的实时性与可靠性,提出了一种智能变电站业务优先级及其队列调度方法.综合考虑业务时延要求、业务对电网运行控制的重要度和业务流量大小3种因素,对站内通信业务进行了优先级划分;针对新的业务优先级,结合严格优先级...     

无线Ad hoc网络动态TDMA信道接入协议的研究

文章提出了一种新的基于动态时分多址接入(TDMA)方案适用于无线Ad hoc网络信道接入控制协议,分别为突发业务,实时业务和非实时业务提供相应顺序接入信道的优先级,并且在传输的过程中避免碰撞和保证突发业务有限的时延。最后通过仿真比较了动态TDMA、CSMA及MACA三种信道接入协议的性能。     

基于自相似流量水平分级预测的网络队列调度算法

网络流量的自相似特性会导致网络中数据的突发状态持续,为有效降低网络流量突发引起的队列排队时延和分组丢失率,提高不同优先级业务的传输能力,保障业务服务质量需求,提出了一种基于网络流量自相似特性的队列调度算法——P-DWRR。该算法设计了基于自相似流量水平分级预测结果的动态权值分配方法及服务量子更新方法,并根据业务优先级和队列等待时间确定队列的服务次序,以减小数据分组排队时延,降低分组丢失率。仿真结果表明,P-DWRR算法在满足网络不同业务优先级要求的基础上,降低了数据分组的排队时延、时延抖动和分组丢失率,性能优于DWRR和VDWRR。     

认知 mesh 网络服务区分的动态频谱接入策略

动态频谱接入策略是实现认知无线电网络高效利用频谱的关键。与传统认知无线电网络不同,认知mesh网络中不同QoS需求的多类型业务共同接入,为适应这一特点,提出服务区分的动态频谱接入策略。策略依据业务的QoS需求确立优先级,针对不同优先级业务采取不同的信道接入方案,实时业务依据最优传输延迟期望选择接入信道集合,在减小传输延迟的同时降低数据传输过程授权用户出现的概率,普通业务选择最优理想传输成功概率的信道,降低信道切换概率。理论与实验结果表明,与传统的认知网络频谱接入策略相比,提出的策略能提供不同业务的服务区分,满足实时业务的低延迟需求,降低数据传输的中断率,同时在授权信道空闲率与网络负载较大时吞吐量性能较优。     

An ATM queue manager handling multiple delay and loss priorities

The asynchronous transfer mode (ATM) technique has been widely accepted as a flexible and effective scheme to transport various traffic over the future broadband network. To fully utilize network resources while still providing satisfactory quality of service (QOS) to all network users, prioritizing the user's traffic according to their service requirements becomes necessary. During call setup or service provisioning, each service can be assigned a service class determined by a delay priority and a loss priority. A queue manager in ATM network nodes will schedule ATM cells departing and discarding sequence based on their delay and loss priorities. Most queue management schemes proposed so far only consider either one of these two priority types. The queue manager handles multiple delay and loss priorities simultaneously. Moreover, a cell discarding strategy, called push-out, that allows the buffer to be completely shared by all service classes, has been adopted in the queue manager. We propose a practical architecture to implement the queue manager by using available VLSI sequencer chips     

Performance evaluation of a priority‐based resource allocation scheme for multiclass services in IoT

Recently, the deployment of novel smart network concepts, such as the Internet of things (IoT) or machine‐to‐machine communication, has gained more attention owing to its role in providing communication among various smart devices. The IoT involves a set of IoT devices (IoTDs) such as actuators and sensors that communicate with IoT applications via IoT gateways without human intervention. The IoTDs have different traffic types with various delay requirements, and we can classify them into two main groups: critical and massive IoTDs. The fundamental promising technology in the IoT is the advanced long‐term evolution (LTE‐A). In the future, the number of IoTDs attempting to access an LTE‐A network in a short period will increase rapidly and, thus, significantly reduce the performance of the LTE‐A network and affect the QoS required by variant IoT traffic. Therefore, efficient resource allocation is required. In this paper, we propose a priority‐based allocation scheme for multiclass service in IoT to efficiently share resources between critical and massive IoTD traffic based on their specific characteristics while protecting the critical IoTDs, which have a higher priority over the massive IoTDs. The performance of the proposed scheme is analyzed using the Geo/G/1 queuing system focusing on QoS guarantees and resource utilization of both critical and massive IoTDs. The distribution of service time of the proposed system is determined and, thus, the average waiting and service times are derived. The results indicate that the performance of the massive IoTDs depends on the data traffic characteristics of the critical IoTDs. Furthermore, the results emphasize the importance of the system delay analysis and demonstrate its effects on IoT configurations.     

优先级网络性能的网络演算分析

基于网络演算理论,对考虑信道差错过程影响的优先级网络系统性能进行了综合分析;基于网络演算推导出信道差错过程的随机到达曲线,在此基础上,获得不同优先级用户的随机服务曲线,进而分析相应的网络服务保证,即时延边界和存储空间边界。基于不同的业务到达模型,研究了不同系统配置下的时延边界,并对相应数值结果加以深入分析。     

系统服务等级约束下提高认知无线网络可达业务负荷的研究

针对现有方案在系统服务等级约束下可能会降低认知无线网络可达业务负荷的问题,提出了一种新的频谱共享机制以提高系统服务等级约束下具有异构业务的认知无线网络可达业务负荷.该机制的主要思想是根据实时业务和非实时业务的不同延时特性,分别引入剥夺优先权和缓冲队列,进而同时减小异构次用户呼叫的强制中断概率和阻塞概率.仿真结果表明,所提机制能有效提高系统服务等级约束下认知无线网络的可达业务负荷.     

QoS-oriented packet scheduling scheme for opportunistic networks

The unique characteristics of opportunistic networks (ONs), such as intermittent connectivity and limited network resources, makes it difficult to support quality of service (QoS) provisioning, particularly to guarantee delivery ratio and delivery delay. In this paper, we propose a QoS-oriented packet scheduling scheme (QPSS) to make decisions for bundle transmissions to satisfy the needs for the delivery ratio and delivery delay constraints of bundles. Different from prior works, a novel bundle classification method based on the reliability and latency requirements is utilized to decide the traffic class of bundles. A scheduling algorithm of traffic class and bundle redundancy is used to maintain a forwarding and dropping priority queue and allocate network resources in QPSS. Simulation results indicate that our scheme not only achieves a higher overall delivery ratio but also obtains an approximate 14% increase in terms of the amount of eligible bundles.     

Cross-Layer Enhancement to Support TCP-Based Traffics in WLANs

Widespread deployment of wireless local area networks and a gradual increase in streaming applications have brought about a demand for improved quality of service (QoS) in wireless networks. However, increasing user datagram protocol based high priority multimedia traffic and the class differentiation introduced in QoS protocols, has resulted into transmission control protocol (TCP) starvation and increased spurious timeouts. While today’s Internet traffic is still dominated by TCP based applications, the negative effects of IEEE 802.11e enhanced distributed coordination function (EDCF) scheme on TCP performance in the presence of high priority traffic have not been extensively explored. In this paper, the performance of TCP in 802.11e WLAN competing with high priority traffic is examined. The prioritised adaptive enhanced scheme (PAD_EDCF) is proposed. The proposed scheme gives priority to TCP control packets in order to improve the low traffic transmission flow and acquires additional capability of adjusting the MAC parameters based on the traffic load condition. Simulation results demonstrate that the proposed scheme significantly improves TCP performances in terms of traffic efficiency, throughput and reduces delay.