周期查询式门限服务排队系统中信息分组的延迟分析

本文采用嵌入马尔可夫链理论和概率母函数的方法，对在离散时间状态下的周期查询式门限服务排队系统进行了分析，推导出信息分组的平均等待时间公式，改进了文献［３］中的计算结果。     

服务器个数随机可变的轮询系统分析

前人关于轮询系统的大量研究均以服务器无故障为前提。本文提出了一种容许服务器个数随机可变的多服务器轮询模型。同时考虑排队延迟与服务器故障／修复的影响，获得了顾客等待时间的平均值公式。     

5G切片架构下具有重传机制的轮询系统研究

面对海量应用场景及客户需求,传统的轮询系统方案不能满足轮询系统中每个站点所需要的服务质量要求。为降低系统时延,适应更大的网络规模,提出基于5G网络切片的轮询方案。将5G网络切片划分为增强型移动带宽切片、海量机器通信切片和高可靠低时延通信切片,再将这3类切片各自划分出N个更低层子切片,构建3个独立的具有重传机制的完全服务轮询模型。信息分组按照先进先出的规则进入各子切片,由通用服务器进行统一发送。在此基础上,采用概率母函数及马尔可夫链建立非理想信道环境下基于5G网络切片架构的轮询系统数学模型,推导系统平均排队队长和平均等待时间的精确表达式,进行信息分组出错概率和重传阈值与轮询系统性能之间的定量关系分析。基于Matlab的仿真实验结果证明了该模型的正确性,其较重传门限服务时延更少,能够为非理想信道环境下基于5G网络切片架构的轮询系统分析提供一种快速评估机制。     

Learning automata-based solutions to the optimal web polling problem modelled as a nonlinear fractional knapsack problem

We consider the problem of polling web pages as a strategy for monitoring the world wide web. The problem consists of repeatedly polling a selection of web pages so that changes that occur over time are detected. In particular, we consider the case where we are constrained to poll a maximum number of web pages per unit of time, and this constraint is typically dictated by the governing communication bandwidth, and by the speed limitations associated with the processing. Since only a fraction of the web pages can be polled within a given unit of time, the issue at stake is one of determining which web pages are to be polled, and we attempt to do it in a manner that maximizes the number of changes detected. We solve the problem by first modelling it as a stochastic nonlinear fractional knapsack problem. We then present an online learning automata (LA) system, namely, the hierarchy of twofold resource allocation automata (H-TRAA), whose primitive component is a twofold resource allocation automaton (TRAA). Both the TRAA and the H-TRAA have been proven to be asymptotically optimal. Finally, we demonstrate empirically that the H-TRAA provides orders of magnitude faster convergence compared to the learning automata knapsack game (LAKG) which represents the state-of-the-art for this problem. Further, in contrast to the LAKG, the H-TRAA scales sub-linearly. Based on these results, we believe that the H-TRAA has also tremendous potential to handle demanding real-world applications, particularly those which deal with the world wide web.     

网页实时防篡改系统研究

为了解决网页篡改的问题,并对发生问题的web页面进行自动恢复．本文基于时间轮询技术与核心内嵌技术,设计并实现了一种网页防篡改系统．该系统能够实时的检测网页被篡改并进行实时阻断及后台恢复;系统能定时的对网站的文件进行扫描,并根据不同的扫描结果进行相应的处理．采用时间轮询技术与核心内嵌技术有效的弥补了采用一种技术带来的缺陷,保证网页的完整性及安全性,并且使网页的防护达到了实时性．     

Seamless handover supported by parallel polling and dynamic multicast group in connected WLAN micro-cells system

WLAN (Wireless Local Area Network) has been seen to be one of the promising access technologies that adapts to 4G cellular network systems in providing very high speed connection with QoS guarantee through the polling function. However, when the handover happens, the contention-based medium access mechanism which is mainly used in WLAN is invoked and introduces unbounded transmission delay due to idle time periods and retransmission because of collision during the handover. If this technique is expanded to use in a microcellular network such as connected WLAN micro-cells, contention-based mechanism, therefore, should not be used to handle the MT’s handover, especially for vehicular users who change access point every few seconds. To overcome these difficulties in handover, we introduce parallel polling scheme in dynamic LMC (Logical Macro Cell) which can reduce delays much and remove packet loss rate. LMC is a virtual single macro cell which is built on a multicast group of adjacent micro-cells. In the same LMC, polling signals are sent from every BS (base station) to give MT (mobile terminal) permission to access one of these BSs. Instead of wasting much time to contend for resources of a new BS during handover, the MT answers the polling as an acknowledgment to connect to that new BS. The polling response is controlled to multicast to all BSs of the same LMC via the core network to synchronize for the next polling cycle. LMC is controlled to dynamically change when the MT comes in a new BS to make polling signals be continuous in a new LMC. Through analytical and simulation results, we show that the parallel polling scheme can achieve no handover latency, no packet loss and maintain mobile users’ throughput stably in the high traffic load condition though it causes overhead on the neighboring cells in both of wired and wireless sections. At speeds of up to70 m/s, the MT can still maintain its stable connection. OMNeT++ simulator with INET project is used to evaluate our proposal.     

基于WinCE Wavedev2驱动的音频通道切换算法

为了在资源有限的设备上实时切换数据传输通道,研究了Wavedev2驱动,在驱动双DMA(直接内存存取)数据传输框架下,提出了中断轮询通道切换算法。结合中断探测的准确性和循环探测的实时性,实现了空闲时不占用CPU的数据通道切换功能,并把它应用于录音回放通道切换和耳机探测问题中。算法分析及实验对比结果表明,该算法在实用性上优于通用的循环探测算法和IST(中断服务线程)探测算法。     

基于Linux的高速网络包捕获技术研究

论文首先分析了Linux数据包捕获机制,指出了在高速流量的网络环境中,频繁的网卡中断是系统接受数据包能力瓶颈。然后讨论了基于Linux系统中采用中断和轮询相结合的数据包捕获技术NAPI。测试实验结果证明了NAPI技术能有效地提高数据包捕获效率。     

基于Web的嵌入式网络管理系统

介绍嵌入式网络管理技术及其应用，该系统采用基于Web的方式，继承了Web服务的优点，将传统的陷阱报告和轮询方式结合起来实现故障管理，用图形化配置方式给用户呈现了设备各接口实时状态示意图。采用Web服务任务内处理方式实现用户管理，从而提高了运行效率同时在一定程度上保证了网络的安全性。     

连续时间完全服务与门限服务两级轮询系统性能研究

在信息分组以连续时间规律到达系统的基础上，对于轮询系统中不同优先级的业务问题，提出区分优先级的两级轮询服务模型。首先，在该模型中，低优先级站点采用门限服务，高优先级站点采用完全服务；然后，在高优先级转低优先级时，将传输服务与转移查询并行处理来降低服务器在查询转换期间所耗费的时间，提高轮询系统的效率；最后，运用马尔可夫链和概率母函数的方法建立了系统的数学模型，通过对数学模型精确解析，得到了连续时间两级服务系统每个站点的平均排队队长和平均等待时间的表达式，精确解析出平均排队队长和平均等待时间的值。仿真实验结果表明：理论计算值与实验仿真值近似相等，说明理论分析正确合理。该模型既能保障低优先级站点服务质量，又能为高优先级站点提供优质服务。