Search

Background: The flexible boundaries of special districts allow for overlaps with each other that generate various specialized service bundles on a territorial basis. The combined overlapping boundaries may reveal willingness to have more services at additional costs as the special districts generally provide services selectively to those who reside within their boundaries. Objective: This study aims to investigate whether overlapping special districts sort citizens by income level as reflected by the Tiebout model. Methods: This study utilizes a cross‐sectional block group data of Ventura County in California, taking numbers of vertices of special districts as independent variable and household income as dependent variable. Results: Estimation result demonstrates that a greater number of specialized services is associated with higher income levels and varies by service type. Conclusion: Findings of this study imply that income segregation could be predetermined by jurisdictional boundary, and that other subjects of urban segregation may have similar pattern. [ABSTRACT FROM AUTHOR]

Using various offset times to separate differential services is the most common form of service differentiation in optical burst switching networks. In this approach, a larger offset time is given to a higher priority burst, but it causes this burst to have a longer delay. One solution to this problem is to adjust the burst assembly time so that the buffering delay of the higher priority burst is always shorter than that of the lower priority burst. However, this adjustment causes another problem, called delay unfairness, for bursts with differential priorities that share the same path to their destination. This article proposes a new solution for delay fairness using the burst assembly. [ABSTRACT FROM AUTHOR]

Workload demands in e‐commerce applications are very dynamic in nature, therefore it is essential for internet service providers to manage server resources effectively to maximize total revenue in server overloading situations. In this paper, a data mining technique is applied to a typical e‐commerce application model for identification of composite association rules that capture user navigation patterns. Two algorithms are then developed based on the derived rules for admission control, service differentiation, and priority scheduling. Our approach takes the following aspects into consideration: (a) only final purchase requests result in company revenue; (b) any other request can potentially lead to final purchase, depending upon the likelihood of the navigation sequence that starts from current request and leads to final purchase; (c) service differentiation and priority assignment are based on aggregated confidence and average support of the composite association rules. As identification of composite association rules and computation of confidence and support of the rules can be pre‐computed offline, the proposed approach incurs minimum performance overheads. The evaluation results suggest that the proposed approach is effective in terms of request management for revenue maximization. This article is categorized under: Application Areas > Science and Technology Algorithmic Development > Association Rules Algorithmic Development > Web Mining [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) are the most commonly deployed technology in smart grid environments owing to their advantages including low cost and successful adoption in various harsh smart grid environments. However, providing the quality of service (QoS) requirements of smart grid applications with WSNs is difficult because of the power constraints of sensor nodes and unreliable wireless links. In order to meet the QoS requirements of smart grid applications using WSNs, in this paper, we first propose a QoS-aware omnidirectional antenna-based medium access control (QODA-MAC). Then, in order to investigate the impact of using sectored antennas on meeting QoS requirements, we also propose another QoS-aware four-sectored antenna-based MAC protocol (QFSA-MAC). The aim of the proposed approaches is to increase channel utilization with efficient service differentiation considering traffic flows with different requirements as well as providing reliable and fast delivery of data. We measure the performance of QODA-MAC and QFSA-MAC by making extensive simulations and compare them with each other. The results show that QFSA-MAC outperforms the QODA-MAC protocol and satisfies QoS requirements of smart grid applications by achieving significant improvement in terms of latency, energy consumption and data delivery. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Variable weight optical code division multiple access system (VW‐OCDMA) is developed to provide service differentiation in optical metro networks where different applications demand for different quality of services. In VW‐OCDMA, different number of wavelengths carries the data for different services. Hence, the fibre impairment effects vary for different services. In this study, the performance of a VW‐OCDMA is analysed under the impact of fibre impairments including chromatic dispersion, self‐phase modulation, four wave mixing and stimulated Brillouin scattering. It is shown that how higher weights which are supposed to deliver higher quality are more affected by fibre impairments. At last, the experimental results of three users with different weights are demonstrated. [ABSTRACT FROM AUTHOR]

Because of the highly dynamic topology and the unstable service status of nodes, services in vehicular ad hoc networks (VANETs) are not always reliable enough for users. Nodes in such a VANET incline to be selfish, which will even enhance this situation. In this work, we present an incentive model for VANETs to support more reliable services in network. We model the situation of service request and response in VANETs by using game theory. We consider the competitive and cooperative relationship between the nodes to formulate the game for VANETs. A contribution measurement is given in order to encourage cooperation during the game. Nodes are encouraged to provide more services to their neighbors in order to acquire more services from other nodes in our model. We also conduct a simulation for the proposed model and give detailed analysis in this work. From the results of the simulation, we argue that we could enable a VANET to support more reliable service by configuring suitable parameters for it. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequencydivision multiplexing passive optical network (OFDMPON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization. [ABSTRACT FROM AUTHOR]

SUMMARY Congestion in the ubiquitous sensor network occurs when traffic load exceeds available capacity at any point in a network. Congestion causes overall channel quality to degrade and loss rates to rise, leads to buffer drops and increases latencies. Therefore, congestion and latency have effects on energy efficiency, memory size, buffer size, and throughput. This paper proposes a new method, called TCCP (Tournament-based Congestion Control Protocol), to minimize congestion in the ubiquitous sensor network. In this paper, the winner is the stream with the highest importance level in the competition of ubiquitous sensor network. In general, there are a lot of congestion and delay in the continuous streaming of multimedia streams with lower importance level. The proposed method consists of three parts: tournament decision, best-fit control strategy and service differentiation. The final winner in the tournament controls congestion effectively, minimizes packet loss due to congestion, decreases energy consumption, and improves QoS. The simulation result shows that the proposed method is more effective and has better performance compared with those of CCF (congestion control and fairness), PCCP (priority based congestion control protocol), and CODA (congestion detection and avoidance). Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we depart from our previously proposed Non-Congestive Queuing (NCQ) mechanism and propose a new scheduling discipline that allows for efficient interoperation of dedicated systems (such as sensor and voice networks) with the Internet. More precisely, our approach provides delay guarantees to applications that do not contribute noticeably to congestion because of their tiny packet sizes and low transmission rates. In addition, our approach uses a second level of prioritization that conditionally favors, in terms of delay, applications with slightly longer packets as well. Based on the NCQ concept, Non-Congestive Queuing Plus (NCQ+) promotes applications that require comparatively small service times, as long as their total service times cause insignificant delays to other packets in the queue. Therefore, we prioritize packets, and in turn corresponding flows, according to their impact on total delay. We evaluate NCQ+ using ns-2-based experiments. Results show that whenever prioritization buffer resources are sufficient, NCQ+ can provide non-detectable delays to sensor applications and conditionally improve the performance of VoIP applications, while maintaining the impact on the performance of the other flows insignificant. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper proposes a multi-dimensional Markov model to analyse the performance of the IEEE 802.11e EDCF MAC protocol. Based on this model, we present extensive performance evaluation in terms of throughput, throughput ratios, and access delay of flows of distinct priorities under RTS/CTS mode. We also provide quantitative analysis of the impact of prioritized parameters, i.e. Arbitration InterFrame Space (AIFS), Contention Window (CW) on Quality of Service (QoS) differentiation. The accuracy of the proposed model is verified by means of comparing the numerical results obtained from both analytical model and simulations. Our research can be used as a guideline for the prediction of how flows belonging to a certain Traffic Category (TC) perform with their TC-specific parameters, as well as designing EDCF-based WLANs and tuning the parameters to achieve the desirable di .erentiated QoS objectives. [ABSTRACT FROM AUTHOR]