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1.
无线介质计算机通信网络中周期优先轮询服务策略的研究   总被引:1,自引:0,他引:1  
本文讨论无线介质计算机通信网络中周期优先轮询服务策略,传输的排队延时分析是在中心控制器和若干外围控制器所构成的轮询模型上进行的。文中分析了引起出界和入界延时的原因、对其性能进行了计算机模拟、讨论了该方法在无线计算机网络中的应用。  相似文献   

2.
有限的资源和随机的需求是排队论存在的基础,而在如今的社会,这种现象越发广泛和复杂。我们将要求服务的顾客和提供服务的机构组合成一个系统,称之为排队系统。这种系统存在于各个方面,本文研究的是排队论运用在通信网络中的各端业务问题。排队论系统分为优先制排队系统和非优先制排队系统,本文描述了带有非强占权优先制的排队系统,其模型为两队中其中一对带有优先制度的M/M/1的模型。根据此模型可以定义变量,画出状态转移图并列出状态方程,最后求出稳态解。通过性能分析发现,带有优先权的M/M/1模型系统与一般模型相比性能将会有所提高,这也是优先制度的体现。  相似文献   

3.
数据通信网络中的分组和交换节点可以用排队论的模型模拟分析。文章针对分组集散量和服务时间的最优解问题,对数据通信网络建立一个基于M/G/C/C状态独立排队网络模型,并运用RSM算法确定输入变量与因变量之间的关系,通过对响应的优先次序和期望值进行优化运算得到最大分组集散量和最短服务时间。  相似文献   

4.
陈勇  吕恩建  陈泉 《半导体光电》2008,29(1):105-109
光分组交换的输出队头阻塞引起分组的平均排队时延增加.分析了可变长分组的特点,提出了基于抢先方式的短包抢先调度(PSPP)算法,以减少分组在输入排队中的平均等待时间.在PSPP算法中,短包可以抢占长包的传输时间,获得优先的服务.分析和仿真结果表明,当到达业务负载为中或较低时,短包优先调度算法使短包的平均排队时延接近零,所有分组的平均等待时延减小,该算法还保证具有实时特性的TCP业务获得较低的平均等待时延.  相似文献   

5.
针对目前以面向对象的方法描述的网络管理机制仅仅关注管理操作细节的局限性,该文提出以服务的概念建模网络管理机制,扩展了对操作机制的商务过程特性、流程和策略等方面内容的描述能力.首先,通过建立网络管理功能、商务过程元素以及网络管理服务三者间的对应关系,使网络管理服务兼具操作细节和商务过程两方面的内容.然后,提出了包括服务接口、信息、语义、流程和策略的网络管理服务描述内容以及一种自顶向下和自底向上相结合的网络管理服务分析过程,并进行了举例说明.以面向服务的方法描述网络管理操作机制,符合面向客户和商务过程的电信运营策略,支持自动和灵活的运营过程,并可以有效指导网络管理及运营支撑系统的分析、设计、实施和集成.  相似文献   

6.
该文提出了一种在CDMA网络中基于网络优化的动态信道分配策略,它针对恒定比特率(CBR)业务建立了一种整数规划的数学模型,它不是每个时隙进行一次信道分配而是若干个时隙根据当前所有用户的状态统筹做一次调度,目的是使得用户QoS和系统性能得到折中考虑.通过仿真,相对于传统话音优先和按照优先级排队的分配算法,这种优化算法在保证业务的QoS的同时使得信道利用率得到提高。  相似文献   

7.
吴国福  韩岗  窦文华 《通信学报》2010,31(10):170-179
提出了短路径优先策略构造拓扑匹配的覆盖网络.为了快速获取短距离节点信息,引入网络距离预测技术和空间填充曲线技术.基于被动路标的网络距离预测方法,以较小的网络开销和部署成本准确估计网络距离,基于查表的对角线空间填充曲线映射算法,提高筛选临近节点的速度.最后给出短路径优先的覆盖网络构造详细过程.实验结果表明所提方法可有效提高覆盖网络与物理网络的拓扑匹配程度.  相似文献   

8.
该文针对无线传感器网络中能量有限问题,提出了一种基于有限反馈的协同MIMO策略.该策略基于梯度算法,用1bit反馈来自动地调整簇头节点和协同簇头节点的发射功率.对无线传感器网络中基于有限反馈的Alamouti码的协同MISO系统的误码率进行了理论分析,推导了基于有限反馈Alamouti码的协同MISO策略能耗的契尔诺夫上限表达式.理论分析和仿真结果都表明,该文提出的协同MISO策略与基于标准Alamouti码的协同策略相比,无线传感器网络的总能耗更低,能效更高,且当簇头节点和协同簇头节点一直选择较好信道对应的节点来发送信息时,即最优策略,无线传感器网络的总能耗更低.  相似文献   

9.
分析了ATM网络中公平排队算法的原理和要求,在此基础上提出了基于帧的公平排队服务算法.通过分析计算表明它具有低时延,有限的不公平性和易于实现等特点.  相似文献   

10.
考虑一个有两类顾客到达的单服务台的排队系统。两类顾客的到达过程均为泊松过程,第一类顾客较第二类顾客具有强占优先权,且第二类顾客由于第一类顾客的到达而变得不耐烦,其"耐性时间"服从负指数分布。两类顾客的服务时间服从相同参数的负指数分布,服务规则是强占优先服务,在高负荷条件下用Matlab编程对此排队系统进行模拟仿真,为处理此类排队问题提供了一个新方法。  相似文献   

11.
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  相似文献   

12.
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.  相似文献   

13.
This paper presents an approximate analysis of delay performance in the timer-controlled priority scheme of single-service token passing systems, where each priority queue is allowed to transmit one message at a time. This is the practical case of real-time networks such as those used in aircraft and spacecraft control, process control and factory communications. The token passing systems consist of N stations, each of which has (K+1) priority queues. The highest priority queues can transmit a message whenever the token arrives. A lower priority queue can transmit a message if the token rotation time (which was reset and restarted at the previous token arrival instant) is not expired when the token arrives. An analytical model is developed based on the independent and identically distributed random variables of conditional effective service times (time interval between two consecutive instants at which a priority queue has an opportunity to transmit a message) of each priority queue. The condition is assigned on the basis of the contribution of message transmission time to the effective service time. The approximate mean waiting time for each priority queue is determined using the well-known results from Kuehn (1979), who first introduced the conditional cycle time. The approximate analytical model is validated by comparison with the simulation results  相似文献   

14.
为了验证服务质量在解决网络带宽不足方面的作用,采用DynamipsGUI搭建网络环境,配置优先级队列,模拟了relnet以及大小为15000字节的数据从路由器转发时,路由器根据优先级队列将数据报文从不同队列转发的过程。实验表明,服务质量能够在一定程度上解决网络带宽不足的问题。  相似文献   

15.
杨明  许瑞琛  蒋挺 《通信技术》2011,44(12):69-71
在研究现有网络数据传递拥塞控制问题的基础上,提出了一种基于路由器缓冲区队列长度的网络拥塞预测机制,并以该预测机制为基础提出了一种计费策略(PPBC,Per-Packet Billing Control)来控制网络拥塞.在拥塞控制模式中,将路由器缓冲区队列长度作为拥塞指标,通过马尔可夫链建模预测网络拥塞度.在服务器终端和数据发送方之间建立反馈机制,利用网络拥塞度,通过数据包计费方式控制网络拥塞.最后采用NS2仿真软件对PPBC性能进行仿真测评,仿真结果表明:PPBC不仅能够有效缓解网络拥塞,还能够使网络保持较低的丢包率.  相似文献   

16.
The interaction of congestion control with the partitioning of source information into components of varying importance for variable-bit-rate packet voice and packet video is investigated. High-priority transport for the more important signal components results in substantially increased objective service quality. Using a Markov chain voice source model with simple PCM speech encoding and a priority queue, simulation results show a signal-to-noise ratio improvement of 45 dB with two priorities over an unprioritized system. Performance is sensitive to the fraction of traffic placed in each priority, and the optimal partition depends on network loss conditions. When this partition is optimized dynamically, quality degrades gracefully over a wide range of load values. Results with DCT encoded speech and video samples show similar behavior. Variations are investigated such as further partition of low-priority information into multiple priorities. A simulation with delay added to represent other network nodes shows general insensitivity to delay of network feedback information. A comparison is made between dropping packets on buffer overflow and timeout based on service requirements  相似文献   

17.
In this paper, we propose queueing strategies employing the service interval-based priority (sip) which can provide delay-bounded, and loss-free services, while maximizing bandwidth utilization in the atm network. We also describe a variation of the sip, the residual service interval-based priority (rsip) which can achieve almost full utilization by assigning priorities dynamically on the basis of the residual service interval. We store the realtime cells belonging to different connections in logically separated queues, and for each queue, we set a parameter called service interval, during which only one cell is allowed to be transmitted. The sip server takes and transmits the head-of-line (hol) cell of the queue which has the smallest service interval, while the rsip server selects the queue with the smallest residual service interval. When there is no eligible real-time cell, it transmits non-real-time cell, thus enabling a maximized bandwidth utilization. Employing the above queueing strategies, we analyze the delay characteristics deterministically with the leaky bucket bounded input traffic and then dimension the optimal service interval. In dimensioning the service interval and buffer space of each real-time service queue, we consider burstiness of traffic in conjunction with delay constraints, so that bandwidth utilization can get maximized. In addition, we consider the issues of protection from malicious users, average bandwidth utilization, and coupling between the delay bound and the bandwidth allocation granularity.  相似文献   

18.
针对相控阵预警雷达,给出一种基于多级队列混合优先级和雷达事件时间配额的调度策略,通过对队列优先级和事件截止期的分析得到一组执行序列。并且根据上帧中各队列事件的实际用时,自适应地调整下一帧中波束请求或雷达事件所占的时间配额。  相似文献   

19.
对于多站(多队列)循环服务系统,本文提出一种可动态调整服务量的分级复合型新策略,以适应站点负荷非均衡系统。文章讨论的主要内容有:(1)新策略简介;(2)新策略系统排队服务模型特点;(3)新策略系统在队列容量有限时的队列状态转移规律;(4)队列状态转移概率算法;(5)队列状态概率的非常规算法。  相似文献   

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