Search results for "quality of service"
showing 10 items of 194 documents
Accounting for service quality to customers in the efficiency of water companies: evidence from England and Wales
2015
This paper investigates the role of service quality to customers in the efficiency assessment of water companies in England and Wales. To achieve this, data envelopment analysis techniques are employed to compute the technical efficiency of the water companies following two approaches: (i) traditional assessment based on quantity variables (without the inclusion of service quality variables) and (ii) alternative assessment considering quantity and service quality variables as undesirable outputs. The analysis covers 22 water and sewerage companies and water only companies providing drinking water services. The results indicate that the traditional efficiency assessment reveals a high level …
Is Admission-Controlled Traffic Self-Similar?
2002
It is widely recognized that the maximum number of heavy-tailed flows that can be admitted to a network link, while meeting QoS targets, can be much lower than in the case of markovian flows. In fact, the superposition of heavy-tailed flows shows long range dependence (self-similarity), which has a detrimental impact on network performance. In this paper, we show that long range dependence is significantly reduced when traffic is controlled by a Measurement-Based Admission Control (MBAC) algorithm. Our results appear to suggest that MBAC is a value added tool to improve performance in the presence of self-similar traffic, rather than a mere approximation for traditional (parameter-based) ad…
Transport service for session initiation protocol in SIP-T scenarios
2005
The traditional telephone service has undergone deep changes in the years concerning the techniques of commutation and signaling. Today, public switched telecom networks (PSTNs) and private integrated services networks (PINSs) are strongly directed to adopt IP-based backbone. If it is possible to transfer the voice on packet switching network, in such reliable way, using voice over IP (VoIP) techniques, there is not still a valid alternative to the signaling systems, reliable and unfailing, like signaling system n.7 (SST). Session initiation protocol (SIP) seems to be the best candidate. SIP is an application layer signaling protocol and the problem remains still opened for what it concerns…
Analysis and Simulation of the Signaling Protocols for the DiffServ Framework
2006
This paper considers signaling protocols for the DiffServ QoS framework. Originally, DiffServ had no standardized signaling solution, which resulted in the static configuration for the DiffServ domain. However, the dynamic allocation of resources within the domain allows to ensure the per-flow QoS guarantees and achieve better performance. At the moment, several signaling solutions for DiffServ framework are available. Thus, it is crucial to analyse these solutions and interconnections between them. In particular, the RSVP, aggregated RSVP, GIST, COPS, and SIP protocols will be considered. The simulation comprises several scenarios that present that the dynamic allocation of resource within…
The simulation and analysis of the revenue critierion based adaptive WFQ
2003
This paper presents the simulation and analysis of the adaptive resource allocation model, which was proposed and theoretically considered in our previous works. It relies upon the Weighted Fair Queueing (WFQ) service policy and uses the revenue criterion to adjust weights. The purpose of the proposed model is to maximize a provider's revenue and, at the same time, ensure the required Quality-of-Service (QoS) for end-users. Our previous works provided the theoretical evaluation of the proposed model and considered the single-node case only. This paper presents more realistic network scenario, which includes a set of clients and several intermediate switching nodes with the proposed model. T…
A Simulation Software for the Evaluation of Vulnerabilities in Reputation Management Systems
2019
Multi-agent distributed systems are characterized by autonomous entities that interact with each other to provide, and/or request, different kinds of services. In several contexts, especially when a reward is offered according to the quality of service, individual agents (or coordinated groups) may act in a selfish way. To prevent such behaviours, distributed Reputation Management Systems (RMSs) provide every agent with the capability of computing the reputation of the others according to direct past interactions, as well as indirect opinions reported by their neighbourhood. This last point introduces a weakness on gossiped information that makes RMSs vulnerable to malicious agents’ intent …
QoS-Aware Fault Detection in Wireless Sensor Networks
2013
Wireless sensor networks (WSNs) are a fundamental building block of many pervasive applications. Nevertheless the use of such technology raises new challenges regarding the development of reliable and fault-tolerant systems. One of the most critical issues is the detection of corrupted readings amidst the huge amount of gathered sensory data. Indeed, such readings could significantly affect the quality of service (QoS) of the WSN, and thus it is highly desirable to automatically discard them. This issue is usually addressed through “fault detection” algorithms that classify readings by exploiting temporal and spatial correlations. Generally, these algorithms do not take into account QoS re…
Reputation Management for Distributed Service-Oriented Architectures
2010
Nowadays, several network applications require that consumer nodes acquire distributed services from unknown service providers on the Internet. The main goal of consumer nodes is the selection of the best services among the huge multitude provided by the network. As basic criteria for this choice, service cost and Quality-of-Service (QoS) can be considered, provided that the underlying Service-Oriented Architecture (SOA) be augmented in order to support the declaration of this information. The correct behavior of such new SOA platforms, however, will depend on the presence of some mechanisms that allow consumer nodes to evaluate trustworthiness of service providers. This work proposes a new…
Non-cooperative Aerial Base Station Placement via Stochastic Optimization
2019
Autonomous unmanned aerial vehicles (UAVs) with on-board base station equipment can potentially provide connectivity in areas where the terrestrial infrastructure is overloaded, damaged, or absent. Use cases comprise emergency response, wildfire suppression, surveillance, and cellular communications in crowded events to name a few. A central problem to enable this technology is to place such aerial base stations (AirBSs) in locations that approximately optimize the relevant communication metrics. To alleviate the limitations of existing algorithms, which require intensive and reliable communications among AirBSs or between the AirBSs and a central controller, this paper leverages stochastic…
Network-Assisted Resource Allocation with Quality and Conflict Constraints for V2V Communications
2018
The 3rd Generation Partnership Project (3GPP) has recently established in Rel. 14 a network-assisted resource allocation scheme for vehicular broadcast communications. Such novel paradigm is known as vehicle--to--vehicle (V2V) \textit{mode-3} and consists in eNodeBs engaging only in the distribution of sidelink subchannels among vehicles in coverage. Thereupon, without further intervention of the former, vehicles will broadcast their respective signals directly to their counterparts. Because the allotment of subchannels takes place intermittently to reduce signaling, it must primarily be conflict-free in order not to jeopardize the reception of signals. We have identified four pivotal types…