Polling systems with server timeouts and their application to tokenpassing networks

Polling systems have long been the subject of study and are of particular interest in the analysis of high-speed communications networks. There are many options for the scheduling policies that can be used at each polling station (exhaustive, gated, customer limited, etc.). In addition, one can impose an upper bound on the total service time delivered to customers at a station per server visit. In the most common case the upper bound is a constant for each polling station, and the resulting system model is not Markovian even when service times and interarrival times are exponential. In the paper, a comprehensive solution is developed for the major scheduling policies with time limits for each polling station. The approach is based on studying the embedded Markov chain defined at the sequence of epochs when the server arrives at each polling station. The computation of transition probabilities for the embedded chain requires transient analysis of the Markov process describing the system evolution between epochs. Uniformization methods are used to develop efficient algorithms for the transition probabilities and for system performance measures. Example problems are solved using the techniques developed to illustrate the utility of the results     

A new measure for time-dependent queueing systems with statistically dependent arrivals

This paper studies a first-come, first-served, queueing system wherein statistically dependent arrivals can occur only at the imaginary transition marks and statistically independent departures can occur at any point of time. Both intertransition times and service times are following the exponential distribution. Probability of exact number of arrivals and departures are obtained explicitly by solving the difference equations iteratively. Particular cases of interest are also derived therefrom.     

Discrete-time buffers with variable-length train arrivals

An infinite capacity single server queueing system is considered, to which messages consisting of a variable number of fixed-length packets arrive at the rate of one packet per slot (`train arrivals'). Assuming geometrically distributed message lengths. An exact closed-form expression for the probability generating function (pgf) of the buffer contents is obtained     

Polling as ritual

In contemporary U.S. politics, the practice of consulting the latest poll has become a ritual like consulting the oracle was to the ancient Greeks. In this essay I argue that polling is not just an instrumental means to manipulate or reflect public attitudes, but is also a cultural form that sustains and affirms deeply held founding mythologies about community, democracy, and vox populi. By appropriating and controlling the terms of dissent, polling ritual enables the national congregation to affirm its unity in spite of difference. Thus, what is constructed through polling ritual is social solidarity rather than public policy.     

Reliability of 3-state device systems with simultaneous failures

This work is concerned with computing the reliability of redundant systems of three-state (e.g., good, failed-open or failed-short) devices. Allowing for multiple failures, formulas are presented for calculating the reliability of a parallel-series system or a series-parallel system which is formed from three-state, non-DFM (dual failure-mode) devices, and which might require multiple paths to function. The words series and parallel are used in the layout-diagram sense. The formulation encompasses cases which have been analyzed by complex methods in numerous papers on the reliability of three-state DFM device systems. The effects of dominant failure-modes on the relationship between reliability of a series system and that of a parallel system, and on the relationship between the reliability of a parallel-series system and that of series-parallel system are presented     

查询式完全服务排队模型分析

本文对查询式完全服务队系统，采用嵌入马乐可夫链理论和概率母了函数的分析方法进行了研究，给出了报文的平均延迟计算公式和有关的参数值。最后通过计算机模拟实验，给出了查询式完全服务排队系统的模拟数值的结果。理论计算与模拟结果相一致。     

Polling deregistration for unlicensed PCS

The FCC has allocated the spectrum between 1850-1910 and 1930-1990 MHz for licensed personal communications services (PCS) and the band between 1920-1930 MHz for unlicensed PCS (UPCS). This paper describes a polling deregistration protocol for a wireless access communications network which would support interoperability between licensed personal communications services (PCS) and unlicensed-PCS (UPCS). We show how the protocol can be efficiently implemented in the personal access communications system (PACS) for licensed PCS and in the PACS-Unlicensed Version B (PACS-UB). An analytical model is proposed to analyze the performance of the polling protocol. A cost function is derived, which can be used to estimate the optimal polling frequency     

On Adaptive Tree Polling Algorithms

This paper proposes three different algorithms for polling a finite set of users to determine the binary state of each user. The states are assumed to be described by i.i.d. Bernoulli random variables with parameterp. The algorithms differ in the responses offered by the users to queries and how the responses from several users are combined by the channel to produce a composite feedback signal which is received by all users. For each algorithm, the average number of transmissions required to determine the states of all users is determined as a function of the parameterp.     

Experimental studies of direction of arrivals using a smart antenna testbed in wireless communication systems

This paper presents some preliminary results from experimental studies on space‐division‐multiple‐access (SDMA) for wireless communications. A smart antenna system utilizing direction‐of‐arrival (DOA)‐based beamforming techniques can enhance signal quality by reducing co‐channel interference from mobiles located at angles spatially distinct from the base station. Adopting both smart uplink and downlink beamforming, a communication system with an antenna array can increase the cell coverage of a base station and significantly boost capacity compared with conventional antenna systems. However, successful implementation of DOA‐based beamforming techniques depends on the DOA characteristics. This paper presented the feasibility of direction finding and DOA variation with respect to frequency. Furthermore, the angle spread was studied for selected environments. The results demonstrate the feasibility of applying proposed smart antenna system utilizing DOA‐based beamforming algorithm for increasing channel capacity and improving system performance in frequency‐division‐duplex (FDD) wireless communication systems. Copyright © 2003 John Wiley & Sons, Ltd.     

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。     

非对称周期查询限定服务系统解析

本文利用嵌入马尔可夫链理论和概率母函数的方法,对局域网络中离散时间状态下,有限缓冲器的非对称周期查询限定(k=1)服务系统 ∑ N i G_i/ ∑ N i G_i/1( ∑ N i G_i)/ ∑ N i S_i(FCFS)模型进行了解析,获得了系统第i队列的查询周期、信息分组平均队长、信息分组平均延时和信息分组丢失率的数学解析表达式.计算机模拟的结果表明了仿真与理论的一致性.     

A queueing problem with random memory arrivals and heterogeneous servers

This paper studies the steady state behaviour in discrete time of a limited space queueing problem with random memory arrivals wherein service is accomplished through S-heterogeneous parallel channels. The arrivals at two consecutive time marks depend upon a random variable which takes values one and zero with probabilities p and q respectively according to whether the arrivals at two consecutive time marks are correlated or uncorrelated. The explicit probabilities for the number of units in the system have been worked out. Some special cases of interest have also been derived.     

KVM技术在全专业综合监控轮询管理系统中的应用

在简要介绍KVM技术及其优点的基础上,就全业务运营的新形势下,电信运营商如何运用KVM技术,优化整合现全专业综合监控轮询系统,解决运营商网管系统多、机房空间不足等问题,以达到提高网络监控质量和管理效率及降低成本的目的。     

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。     

Polling Best Effort Traffic in Bluetooth

Bluetooth [1] is a wireless access technology where polling is used to sharebandwidth among the nodes. We have introduced a new poller named PredictiveFair Poller (PFP) in [2, 3]. In this paper we explain the operation of thePredictive Fair Poller and compare it with the conventional Round Robin pollerand the Fair Exhaustive Poller (FEP) [4] for two Best Effort trafficscenarios. We show through simulations that the Predictive Fair Poller is ableto divide bandwidth in a fair and efficient manner.     

Performance Optimization with Efficient Polling Mechanism in IEEE 802.16 Networks with Cross-Layer Consideration

IEEE 802.16 standard suite defines a reservation-based bandwidth allocation mechanism. A SS (Subscriber Station) has to be polled to request bandwidth reservation before transmits uplink data to a BS (Base Station). In this mechanism exist two main polling modes: the unicast polling mode and the contention-based polling mode. The different polling operations in MAC (Medium Access Control) result in different PHY (PHYsical layer) frame structure that deeply affect the performance. Therefore, there should be an optimal scheme to adopt these two polling modes in order to optimize the performance. Although the standard defines five service classes to adaptively use the polling modes to fit the QoS (Quality of Service) requirements of different applications, it does not specify exactly a scheme to adopt these two polling modes efficiently and fairly during the polling process. In~this paper, we investigate the polling mechanisms in IEEE 802.16 networks, and focus the attention on the performance caused by different adoption schemes. We also propose a simple but efficient polling mechanism to optimize the performance. The simulation results verify that the performance is conditioned to the fulfillment of the polling mechanisms and our proposed optimal polling scheme can allocate bandwidth more efficient and achieve better performance.     

Modeling of simultaneous switching noise in high speed systems

Simultaneous switching noise (SSN) has become a major bottleneck in high speed digital design. For future systems, modeling SSN can be complex: due to the thousands of interconnects that need to be analyzed. This is because a system level modeling approach is necessary that combines the chip, package and board level interactions. This paper presents an efficient method to model the SSN for high speed systems by developing circuit models for the planes and interconnections that can be combined using superposition theory. This approximation is valid at frequencies where skin effect is dominant. Simulation results are compared with the measurements on a test vehicle, verifying the validity of the method. In addition a system has been simulated to compute SSN, showing the application of this method for complex systems     

A note on the conservation law for queues with batch arrivals

The conservation law formula for work-conserving queues with batch arrivals is derived for when the arrival instants of customers are assumed to constitute an arrivals see time averages (ASTA) process. The derivation is based on the analysis of the corresponding first-in first-out (FIFO) multiclass queue and its steady state. Hence, the mean work load in the queue at an arbitrary time instant can be equated with the mean time that an arbitrary customer has to wait in the FIFO queue     

两级优先级控制轮询系统研究

 本文基于区分业务优先级服务的应用需求,提出了两级优先级控制的轮询系统,采用门限服务和完全服务的不同服务策略方式实现了基于优先级的控制.然后,应用马尔可夫链和概率母函数的方法建立了系统模型,并精确解析了系统的平均排队队长和信息分组的平均等待时间关键特性,理论计算和仿真实验的对比分析说明了理论分析与实验的一致性,新的轮询系统实现了优先级的控制并提高了系统性能.