多级门限服务轮询系统MAC离散时间控制协议模型分析

 本文提出了一种新的多级门限服务轮询系统MAC控制协议的分析模型.采用嵌入马尔可夫链理论,对离散时间的多级门限服务轮询系统进行了分析,获得了轮询时刻系统队长的概率母函数,精确解析了系统的平均排队队长、平均循环周期、信息分组的平均等待时延.通过对多级门限服务轮询系统的控制机理研究,分析获得了m控制参数的有效控制取值大小和系统的相关特性.多级门限服务轮询系统综合了基本门限服务轮询系统和完全服务轮询系统,在轮询系统的MAC控制协议的应用方面更为有效.     

离散时间闸门式多级门限服务的两级优先级轮询排队系统分析

本文提出了一种基于闸门式多级门限服务的两级优先级轮询系统.论文先构建了系统的排队分析模型,然后把模型中各个站点内的等待顾客数合起来设定为系统状态变量,对系统状态变量的概率母函数求二阶偏导后组成迭代方程组,联立求解后得到了站点的平均排队队长、顾客平均等待时间以及服务器查询周期等关键指标的完整数学解析表达式.最后,对该模型进行了仿真实验分析,实验结果与理论结果相一致.系统性能分析表明该轮询系统满足了周期性系统服务资源分配过程中业务多样性和弹性服务的发展需求,使得轮询控制策略应用方面更为广泛.     

离散时间并行优化门限服务轮询系统排队特性解析

针对周期式查询门限服务中流水线式调度效率低的问题，本文提出了一种并行优化门限服务轮询控制的系统服务资源调度策略.论文构建了轮询排队系统及其数学模型，先对系统状态变量的概率母函数求偏导得到一阶和二阶特性参数方程组，联立求解后推导出各个系统参数的完整数学解析表达式.仿真实验结果和理论计算值相一致.系统性能分析表明，该系统的队长和时延特性均得到了较大的提高，能够更好的适应密集数据环境下时延敏感性数据的服务需求.     

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.     

移动Ad hoc网络轮询接入控制协议

该文对Ad hoc网络的MAC层协议进行了研究,通过对无线令牌环协议(WTRP)进行改进,提出了一种新的具有QoS保障的无竞争的分布式并行无线轮询访问协议(DPWPAP),并采用嵌入Markov链和概率母函数的分析方法,用限定服务规则进行了系统建模,在系统模型的基础上得到了系统的平均排队队长以及平均等待时间的解析结果.理论分析和仿真结果是一致的,表明该协议的排队等待延迟和平均等待队列长度均比WTRP有很大降低,稳定性大大增强,更加适用于对时延要求较高的业务.     

并行调度两级轮询控制系统分析研究

为了保证系统公平性不受损害,文中提出中心站点采用门限服务,普通站点采用并行调度完全服务的两级优先级轮询控制系统模型。通过马尔科夫链与概率母函数相结合的方法对模型的平均排队队长、平均等待时间等重要参数进行解析。经仿真得出,模拟仿真值与理论值误差较小,近似相等,表明模型理论分析合理正确。数值结果对比表明,模型区分网络业务高低优先级的性能优良,且普通站点工作效率得以提高,从而保证了系统公平性。     

优先级控制轮询在变电站通信网络中的应用

变电站通信网络是变电站实现综合自动化的前提,变电站内部设备可划分成3个层次,其中第二层的数据和控制信息传送到与远方调度中心通信的站级PC机,该过程属于计算机通信网络的范畴,针对变电站通信网络的这个特点,将两级优先级控制轮询系统用在变电站通信网络中。提出了在站级PC通信接口(主节点)采用完全服务的轮询方式,第二层设备通信接口内部的数据缓冲区(子节点)采用门限服务的轮询方式的新模型。完全服务的优先级比门限服务的高,对新模型进行了仿真和理论计算,得出新系统的平均时延和平均排队队长与负载之间的关系、平均时延和平均排队队长与子节点数之间的关系,这些参数对于提高变电站通信网络的性能至关重要。     

完全服务和门限服务两级轮询系统E(x)特性分析

本文基于区分业务的优先级和提高系统的公平性,提出了普通站点队列采用完全服务、中心站点采用门限服务策略的完全-门限服务两级轮询系统模型,该模型既能满足区分业务优先级的服务需求,又能兼顾系统的公平性。然后,应用嵌入式马尔科夫链和概率母函数建立了系统的数学模型,并精确解析了系统平均排队队长、平均查询周期等E(x)特性。通过理论计算与仿真实验结果的对比,说明了二者的一致性,新的系统通过始终优先查询中心站点实现了区分优先级的控制,同时普通站点采用完全服务,在服务策略上得到较好的服务,使系统有更好的公平性。     

周期查询式限定服务排队系统研究

本文采用嵌入马尔可夫链理论和概率母函数的方法,在离散时间状态下对周期查询式限定(K=1)服务排队系统进行了分析,讨论了报文的平均排队队长和平均等待时间的特性,改进了H。Tagai(1985)的分析结果。     

离散时间的完全服务并行优化轮询排队系统特性分析

轮询是一种依次有序服务的系统资源动态调度机制.针对服务器在站点间查询、服务和转移过程中的流水线作业方式导致了系统整体服务效率较低的问题,本文提出了完全服务的并行优化轮询系统.首先,构建了系统的单服务器多队列排队模型和相应的系统状态方程,并精确解析出系统特性参数的完整数学解析表达式.此外,还提出了一种系统状态稳定性的判定方法,对不同负载状态下的系统稳定性进行了定量分析.计算机仿真的统计分析结果与理论计算值相一致.最后,系统性能分析表明,在保持周期性、无冲突服务的基础上,系统的队长、时延特性和稳定状态下负载能力均得到了较大的提高.     

Packet Delay Analysis of Symmetric Gated Polling System for DBA Scheme in an EPON

In this paper, we analyze the mean packet delay of a dynamic bandwidth allocation (DBA) scheme in an Ethernet passive optical network (EPON). We propose the interleaved polling system with a gated service discipline and a two-stage queue in order to investigate the delay performance of DBA scheme in an EPON. We assume that input packets arrive at an optical network unit (ONU) according to a Poisson process from several types of users. We use a continuous time queueing model in order to find the mean packet delay and the mean cycle time of an arbitrary packet. We obtain the closed form solution for the mean packet delay of the proposed gated polling system with a two-stage queue. We obtain another result on the mean packet delay by solving a system of linear equations derived from the moments of the queue length distribution. We give some numerical results to investigate the delay performances for the symmetric polling system with statistically identical stations. In addition, we compare numerical results on the closed form solution with numerical results on a system of linear equations.     

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。     

Performance evaluation of polling systems for wireless localcommunication networks

This paper evaluates the performance of different polling systems used in wireless local networks where the transmission channel exhibits a nonstationary behavior. Many spatially dispersed data user terminals have been assumed to share a common short-range radio uplink channel to access a hub station. We have specifically considered cyclic polling systems with M queues (terminals), having the same general packet arrival process and general switchover period. The gated and exhaustive disciplines have been considered in ordering the transmission of the packets buffered at each terminal. By appropriately modeling the uplink channel, we propose analytical approaches to derive the average packet waiting time and the average cycle length for gated polling systems, combined with stop-and-wait (SW) and go-back-N (GBN) automatic repeat request (ARQ) techniques to control errors. A gated cyclic polling scheme combined with the selective-repeated (SR) stutter ARQ technique as well as an exhaustive cyclic polling scheme combined with SW, GBN, or SR stutter ARQ techniques, respectively, have also been considered In order to give an in-depth knowledge of the behavior of suitable polling alternatives for applications in wireless local communication networks     

Polling systems with simultaneous arrivals

The authors analyze polling systems with multiple types of simultaneous arrivals, namely, batches of customers may arrive at the different queues at an arrival epoch. The authors consider cyclic polling systems with N queues, general service time distribution in each queue, and general switchover times. For both the exhaustive and the gated service disciplines the authors derive the necessary equations for computing the N expected waiting time figures. A pseudo conservation law for these system is also derived. The authors compare several special cases of the correlated arrivals polling system, discuss the computational aspects of the numerical method, and examine the applicability of the analysis to other polling systems     

A single-server queue with vacations and gated time-limited service

An M/G/1 queue with server vacations and gated time-limited service is analyzed. At each visit, the server serves the queue up to a fixed amount of time. When the time expires or after all candidate customers have been served, whichever occurs first, the server takes a vacation. The service policy is gated, since only those customers present at the beginning of a server visit (poling instant) are candidates for service during that visit; subsequent arrivals are deferred until the next visit. A functional equation which characterizes the amount of work, U_p, at a polling instant is derived. To solve the equation, a numerical technique is utilized in which the complementary cumulative function for U_p is closely approximated by a weighted sum of Laguerre functions with unknown coefficients. The equation is then transformed into a set of linear equations from which the coefficients can be computed. By the stochastic decomposition and Poisson-arrivals-see-time-averages properties, the average customer response time can be related to the average amount of work found by an arrival. Several numerical examples are included. The model studied is applicable to communication and computer systems where timers are used to allocate service to customers     

Approximate Delay Analysis and Results for Asymmetric Token-Passing and Polling Networks

Notwithstanding much effort, explicit analytical results for average message delays for asymmetric token rings are currently unavailable. We develop an excellent and relatively simple analytic approximation which readily demonstrates the effects of the many system parameters on delay-throughput performance. The approximation applies to any cyclically served network (including rings, polling networks, and unidirectional fiber optic broadcast networks) with independent time-slot arrivals and gated service. The approximation becomes exact for symmetric loading. An equation for the moment-generating function of the joint terminal service times is obtained via an imbedded Markov chain. Two matrix equations are then derived, one for the mean terminal service times of theNqueues and another for the joint second central moments. A two-dimensional difference equation for the second central moments is then obtained. This difference equation together with Kleinrock's conservation law is used to approximate the mean delay at each queue. The peak approximation error is typically a few percent for various loading distributions including heavy or highly asymmetric loading, even if the statistics for message arrivals, message lengths, or walk times vary among the queues. Actual delay-throughput results are presented for various terminal loadings. Also included is a procedure to upperbound the error of our approximation for any message and walk time statistics, given the terminal utilizations.     

Predictive multicast polling for wireless networks with multipacket reception and queuing

In this paper, we propose the predictive multicast polling scheme for medium access control in wireless networks with multipacket reception capability. We concentrate on the case in which the packet arrival process is general and the maximum queue size is finite but larger than one. We derive both analytical results and simulation results. We use the theory of discrete-time Markov chain to analyze the evolution of the system state. In addition, we propose to use Markov reward processes to calculate the exact value of the network throughput. Furthermore, we obtain the average system size, the packet blocking probability, and the average packet delay. We show that our numerical results are consistent with simulation results. We also use simulation results to justify the usage of the proposed approach. Our study shows that the system performance can be significantly improved with a few additional buffers in the queues.     

Queue-aware uplink bandwidth allocation and rate control for polling service in IEEE 802.16 broadband wireless networks

IEEE 802.16 standard defines the air interface specifications for broadband access in wireless metropolitan area networks. Although the medium access control signaling has been well-defined in the IEEE 802.16 specifications, resource management and scheduling, which are crucial components to guarantee quality of service performances, still remain as open issues. In this paper, we propose adaptive queue-aware uplink bandwidth allocation and rate control mechanisms in a subscriber station for polling service in IEEE 802.16 broadband wireless networks. While the bandwidth allocation mechanism adaptively allocates bandwidth for polling service in the presence of higher priority unsolicited grant service, the rate control mechanism dynamically limits the transmission rate for the connections under polling service. Both of these schemes exploit the queue status information to guarantee the desired quality of service (QoS) performance for polling service. We present a queuing analytical framework to analyze the proposed resource management model from which various performance measures for polling service in both steady and transient states can be obtained. We also analyze the performance of best-effort service in the presence of unsolicited grant service and polling service. The proposed analytical model would be useful for performance evaluation and engineering of radio resource management alternatives in a subscriber station so that the desired quality of service performances for polling service can be achieved. Analytical results are validated by simulations and typical numerical results are presented.