Polling Mechanism Research Articles

Polling mechanisms and the demand revelation problem

We consider a revelation mechanism for the production of public goods. A sample of consumers is drawn at random. Each member of the sample is asked to reveal her(his) preferences; agents are subjected to transfers of the Groves class; and any surplus of taxes collected on sampled agents is redistributed to non-sampled agents. This polling mechanism is non-parametric, revealing in dominant strategies, budget balanced, and approximately efficient if the consumer population is large. When applied to a public good with exclusion, this mechanism, in combination with consumer free mobility, yields approximately optimal allocations.

QoS support for integrated services over CATV

Cable TV has emerged as a promising access network infrastructure for the delivery of voice, video, and high-speed data traffic. A central issue in the design of protocols for CATV networks is to support different levels of QoS for diverse user applications. While CATV service providers and equipment have standardized, in the so-called MCNS protocol, the basic network architecture and interfaces, issues in the MAC layer for QoS support are likely to be left for differentiation in vendor products. This article first presents an overview of the basic CATV network architectural assumptions and the set of QoS requirements for supporting integrated services over CATV. It then discusses a MAC layer scheduling protocol that can efficiently multiplex constant bit rate traffic, such as voice over IP with guaranteed delay bound, and best-effort traffic, such as data services with minimum bit rate guarantee, while achieving fairness on any excess available bandwidth. The performance of this algorithm is illustrated by simulation results using Opnet. We also discuss a dynamic polling mechanism that enhances the link utilization while preserving delay bounds for latency-critical traffic.

Performance analysis of RAID for different communication mechanism between RAID controller and string controllers

A Stochastic Petri Nets (SPN) model of the orthogonal RAID is constructed. After analyzing the performance of the system we can see that the performance of the system has the relationship with the choice of communication mechanism, which is the polling mechanism or interrupt mechanism, between the RAID controller and the string controllers. The faster the rate of the Go to Communication transition in the SPN, the higher the average utilization of the string controller, and the better the performance of RAID. The rate is larger under the polling mechanism than that under the interrupt mechanism in RAID. Thus, the polling mechanism between the RAID controller and the string controllers should be adopted to improve the performance of RAID.

Static and dynamic polling mechanisms for fieldbus networks

Real-time local area networks like Fieldbus have to handle two types ofdata transfer, synchronous and asynchronous. The synchronous data is generated periodically and has to be transmitted before fixed deadlines. Asynchronous messages are generated by unforeseen events and thus cannot be predicted. The data transfer is handled in two different phases or time---windows. In this paper, we apply different algorithms that are known from the real-time schedluing discipline for real-time communication networks. Simplifications are made with respect to frame lengths and the resulting error is shown to be negligible for the type of data transfer considered. The algorithms generate the correct polling sequence for the data transfer automatically respecting the periodic deadlines. We also introduce dynamic mechanisms to extend time-windows and utilize the network bandwidth more efficiently. These algorithms are computed during the real-time operation of the network.

Analysis of polling protocols for fieldbus networks

Roll-call polling mechanisms are considered for fieldbus networks. Based on a producer/consumer communication model, two different protocols are presented, namely the standardized FIP (Factory Instrumentation Protocol) and a modified FIP protocol that we propose here. The modified protocol uses redundancy to eliminate local timers used by the FIP protocol. The two protocols are analyzed for efficiency, jitter and robustness. We compare the two protocols based on implementation and analytical results. Practical aspects concerning: clock precision; computing time; and hard real-time constraints are also discussed. The results show that: (1) the original FIP protocol is fractionally more efficient with respect to its execution time than the modified one; (2) the modifications proposed, however, reduce the jitter and improve the robustness considerably; (3) the slot time of the original FIP protocol has theoretical upper bound but the modified protocol has no such limitations.

Multiqueue Systems with Nonexhaustive Cyclic Service

Queuing models with cyclic-type service are applicable for performance studies of polling mechanisms in data communication and switching systems or cyclic scheduling algorithms in real time computers. This paper provides an approximate analysis of the multiqueue system M[x]/G/1 with batch Poisson input, general service times, general overhead (switchover) times, and a single server operating under a cyclic strategy with nonexhaustive service of queues. Based on a new concept of conditional cycle times, the generating function of the stationary probabilities of state, the Laplace-Stieltjes transforms of the delay distributions, and the mean waiting times are derived explicitly for each queue through an imbedded Markov chain approach and an independence assumption. The approximate analytic results are validated by computer simulations. Besides this analysis, a stability criterion is derived for the general case of GI/G/1 systems with cyclic priority service. The paper concludes with a number of studies of the behavior of cyclic queues discovering interesting properties such as the dependence of cycle times and waiting times on the arrival and service process types and on the efficiency of cyclic priorities.

Evaluation of UMTS RLC Parameters for MPEG-4 Video Streaming

Universal Mobile Telecommunication Systems (UMTS) known as Third Generation (3G) mobile phone systems using Wideband Code Division Multiple Access (WCDMA) standard aim to provide a high bit rate of services to enable a high quality of multimedia communications. The 3G specification entity, 3GPP, has defined a reliable link layer protocol, Radio Link Control (RLC), for hiding transmission errors from upper layers. Due to the complexity of the protocol and the a number of parameter configurations available, there are many ways that can degrade a system performance, such as incorrect parameters configuration, buffer missmanagement, protocol stalling, etc. MPEG-4 is widely used for video stream services due to its good video quality at low bit rate. In this paper, we have studied on the impacts of RLC parameters, especially RLC timer and polling mechanism, for MPEG-4 video stream transmission by using a computer simulation. Our simulation results provide some suggestions value to optimize such parameters, e.g. RLC time and polling.

America Faces the War: A Study in Public Opinion

The author, social psychologist at Princeton University, is Director of the Princeton Public Opinion Research Project. Since the outbrcak of war, the Project, under a grant from the Rockefeller Foundation, has been charting the course of American opinion through the polling mechanism of the American Institute of Public Opinion. In this article, Dr. Cantril presents a cross-section picture of American opinion in connection with the war as of the end of July, traces opinion trends since the spring of 1939, describes the patterns of opinion which have been discovered and the characteristics of people holding these opinions, and offers some interpretations of public opinion as recorded to date.