Quality Of Service Mechanisms Research Articles

Dynamic address resolution for enhanced configurability in packet-based TDMA GPONs

Packet-oriented PONs will offer an efficient way to transfer IP traffic, providing at the same time flexible Quality of Service mechanisms to support a great variety of services. To allow provisioning of connections from customer sites to ISP sub-networks across packet-based PONs, it is necessary to correlate the Ethernet MAC address used in the customer terminals to the ISP interfaces and the MAC addresses used in the shared PON system. Automatic address resolution mechanisms are needed to allow for automatic dynamic reconfiguration without manual intervention. The address resolution mechanism impacts on the design of the MAC local address since it should allow for identification of the client interfaces on both ends of the PON. This paper investigates the relevant issues and proposes a solution extending the widely used address resolution protocol.

Special Issue on Voice Over IP—Theory and Practice

Special Issue on Voice Over IP—Theory and Practice

Prioritized support of different traffic classes in IEEE 802.11e wireless LANs

IEEE 802.11e is an amendment to the popular 802.11 standard that defines quality of service mechanisms to support sensitive applications, such as voice and video. An important component of these mechanisms is the traffic scheduler, an entity that decides on the channel allocation among different stations. This paper proposes a scheduling algorithm for IEEE 802.11e, referred to as P-ARROW (Prioritized and Adaptive Resource Reservation over Wireless), that effectively handles multimedia traffic by utilizing the formal specification of each traffic stream. Using a single ''priority factor'' parameter, the scheduling can vary between strict prioritization and purely deadline-driven allocation. Performance evaluation results extracted from an advanced simulation model, show that P-ARROW is very efficient in supporting the desired level of service differentiation and prioritization among different traffic classes.

Statistical Identification of Major Event Days: An Application to Continuity of Supply Regulation in Italy

The Italian regulatory mechanism for quality of service in electricity distribution links the tariff to the SAIDI indicator of the average duration of interruptions per consumer. In order to separate major interruption events data from normal operation data, the regulator introduced, in the year 2000, a criterion based on a given definition of force majeure . For the new regulatory period, beginning in 2004, the authors studied the possibility of substituting this criterion with one based on a statistical definition of major event days. The statistical two-step methodology illustrated here was tested using real data and proposed to interested parties in the consultation process; it was found to be at the same time equitable, unambiguous, and simple to implement. This criterion was thus adopted in the new regulatory framework.

A method to efficiently integrate Internet Telephony call signaling with dynamic resource negotiation

Internet Telephony imposes Quality of Service (QoS) requirements in terms of delay, jitter and loss ratio to provide reliable, high-quality multimedia services. While the Internet has historically offered a best effort service, it is hard to satisfy the required QoS of multimedia applications. In order to provide a tight QoS guarantee to telephony services, priority must be offered to real-time flows. Dynamic resource negotiations are required at the beginning of sessions besides long term service contracts. Most of the researchers propose to integrate call signaling with resource negotiation in a sequential manner [G. Camarillo, W. Marshall, J. Rosenberg, Integration of Resource Management and SIP, IETF RFC 3312, October 2002; P. Goyal et al., Integration of call signaling and resource management for IP telephony. IEEE Network, 13(3) (1999) 24-32; H. Schulzrinne, J. Rosenberg, J. Lennox, Interaction of call setup and resource reservation protocols in Internet Telephony. Technical Report, Columbia University and Bell Laboratories, June, 1999. Available from: http:// www.cs.columbia.edu/~hgs/sip/drafts/resource.pdf]. This method can provide QoS at the highest level, but it results in high call setup delay and high probability of connection failure. Parallel integration is an alternative method that can mitigate these drawbacks. In this paper, we proposed a detail solution based on the parallel approach to establish resource negotiation simultaneously with call signaling. This approach can apply to different QoS models and mechanisms such as Integrated Services (IntServ), Differentiated Services (DiffServ) and Multi-Protocol Label Switching (MPLS). This paper presents the architecture and system design of the parallel signaling approach. Threshold quality control scheme is applied to guarantee that the service is above the acceptable level before a telephone session begins.

GMPLS-based service differentiation for scalable QoS support in all-optical Grid applications

In the forthcoming new era of truly distributed computing, industry, businesses, and home users are placing complex and challenging demands on the transport network, now powered by the emerging photonic technologies, about Quality-of-Service (QoS) assurances that are required for new real-time computing and storage service applications geographically distributed worldwide according to the Grid model. There is the need to devise mechanisms for QoS provisioning in IP over WDM networks that must consider the physical characteristics and limitations of the optical domain to ensure the proper treatment of service classes when passing from the electrical switching to the optical domain and back. In addition, these mechanisms should be directly accessible to Grid applications to make them able to request and release network resources as they need. A (G)MPLS-based control plane combined with a wavelength-routed optical network is seen as a very promising approach for the realization of transport infrastructures for the future ''photonic empowered'' Grid computing paradigm, since it allows native user-controlled bandwidth resources and class-of-service provisioning, that is one of the strongest requirements for truly distributed computing. Considering this, we propose a general framework for providing differentiated services QoS to Grid applications in wavelength-routed photonic networks, built on the strengths of GMPLS for dynamic path selection and wavelength assignment. This framework makes it technically and economically viable to think of a set of computing, storage or combined computing storage nodes coupled through a high-performance optical network as one large computational and storage device.

A survey of envelope processes and their applications in quality of service provisioning

Provisioning of quality of service (QoS) guarantees has become an increasingly important and challenging topic in the design of the current and the next-generation Internet. The class of envelope processes (EPs) is one of the key elements for many QoS provisioning mechanisms. An arrival EP A(τ) (or a service curve) bounds the cumulative traffic of a flow (or the cumulative service a flow receives) over any interval of length τ. Such bounds can be deterministic or probabilistic, and can be used for provisioning of deterministic or statistical service guarantees. In this article we provide a survey on arrival EPs and service curves. We provide an overview of various EPs proposed in the literature during the last 15 years and discuss their applications and performance in QoS provisioning. We aim to provide a big picture of the existing work. There is considerable research effort addressing QoS issues in resource-constrained access networks (such as wireless networks) and in the new multiprotocol label switching (MPLS) and peer-to-peer (P2P) networking paradigms. We aim to provide a comprehensive survey of existing work, which can yield useful insights, and help the development of new QoS metrics, mechanisms, and architectures for emerging network environments.

A framework for end-to-end RSVP context transfer in mobile IPv6

Providing Quality-of-Service (QoS) guarantees and mobility support for Internet devices has become a hot research topic in the Next Generation Internet research, since mobile computing is getting widespread. Context transfers allow better node mobility support, and avoid re-initiation of signaling to and from a Mobile Node (MN). However, Context Transfer Protocol (CTP) [1] proposed by IETF can not meet the need of end-to-end QoS mechanisms because contexts are only transferred between Access Routers (ARs). This paper presents a framework for end-to-end QoS context transfer based on the architecture of F-HMIPv6, which may provide an end-to-end QoS context transfer for real-time applications, therefore they can get promptly the same forwarding process, minimize the handover service disruption, and avoid initiating the end-to-end QoS signaling from scratch after an MN performs handovers. The Context Transfer Data message containing the QoS context information, a hop-by-hop extension IPv6 option header, is sent from the previous access router (PAR) to the next access router (NAR) via the Mobility Anchor Point (MAP) where old path and new path meet each other. The QoS entities in the nodes between MAP and NAR will be required to check the QoS context information and reserve appropriate resources for MN’s sessions and update the new path data in the QoS entities. After successful context transfers, the resources reserved for MN’s sessions will be released on the old path. Our scheme may also reduce the signaling overhead and handover latencies by adopting the F-HMIPv6 [2] architecture.

Providing Throughput Guarantees in 802.11e WLAN Through a Dynamic Priority Assignment Mechanism

Supporting real-time and interactive traffic in addition to traditional data traffic with a best-effort nature represents a constantly rising need in any kind of telecommunications environment. The IEEE 802.11 based WLAN (Wireless Local Area Network) environment does not represent an exception. This is why at different protocol layers, and primarily at the MAC layer, many efforts are being put by both the research community and the standardization bodies to design effective mechanisms for user QoS (Quality of Service) differentiation. Although early results are coming into sight, such as, for example, the IEEE 802.11e standard release, still a thorough research activity is required. Aim of the present paper is to contribute to the cited research issue by proposing an improvement to the "static" traffic prioritisation mechanism foreseen by the IEEE 802.11e MAC (Medium Access Control) protocol. This latter shows a twofold drawback. First, there is no certainty that QoS requirements relevant to a given application are always fulfilled by the "statically" associated priority. Second, resource requests of the applications are not adapted to the (usually highly) variable traffic conditions of a distributed WLAN environment. The algorithm we propose is specifically tailored to "dynamically" assign 802.11e MAC priorities, depending on both application QoS requirements and observed network congestion conditions. It is carefully designed, implemented into a system simulation tool, and its highly effective behaviour assessed under variable traffic and system conditions.

Quality-of-service provisioning system for multimedia transmission in IEEE 802.11 wireless LANs

IEEE 802.11, the standard of wireless local area networks (WLANs), allows the coexistence of asynchronous and time-bounded traffic using the distributed coordination function (DCF) and point coordination function (PCF) modes of operations, respectively. In spite of its increasing popularity in real-world applications, the protocol suffers from the lack of any priority and access control policy to cope with various types of multimedia traffic, as well as user mobility. To expand support for applications with quality-of-service (QoS) requirements, the 802.11E task group was formed to enhance the original IEEE 802.11 medium access control (MAC) protocol. However, the problem of choosing the right set of MAC parameters and QoS mechanism to provide predictable QoS in IEEE 802.11 networks remains unsolved. In this paper, we propose a polling with nonpreemptive priority-based access control scheme for the IEEE 802.11 protocol. Under such a scheme, modifying the DCF access method in the contention period supports multiple levels of priorities such that user handoff calls can be supported in wireless LANs. The proposed transmit-permission policy and adaptive bandwidth allocation scheme derive sufficient conditions such that all the time-bounded traffic sources satisfy their time constraints to provide various QoS guarantees in the contention free period, while maintaining efficient bandwidth utilization at the same time. In addition, our proposed scheme is provably optimal for voice traffic in that it gives minimum average waiting time for voice packets. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design indeed provides a good performance in the IEEE 802.11 WLAN's environment, and can be easily incorporated into the hybrid coordination function (HCF) access scheme in the IEEE 802.11e standard.

Practical limitations of ethernet-based inhouse multimedia distribution

100 Mbit/s Ethernet seems to be suited for an integrated digital home network combining PC interconnection and audiovisual entertainment devices. The MAC procedure 100 Mbit/s Ethernet lacks QoS (quality of service) in collision domains. This paper presents a proposal of an easy to implement, reliable and compatible MAC based QoS mechanism that fills this gap. Measurements with respect to the QoS parameters show the performance of our proposal. These measurements also exhibit, that 100 Mbit/s Ethernet easily meets QoS specifications for audio and video if proper network equipment is selected.

Economics and scalability of QoS solutions

The paper presents an analysis of the factors which affect the scaling of quality of service (QoS) solutions. This includes analysis of the sources of variance in traffic forecasts and how these contribute to a probability that a network resource will be unable to meet the capacity load placed upon it. While the analysis is general and could be applied to a wide variety of QoS mechanisms, this paper is focused on the scalability of ‘edge connection acceptance control with DiffServ core’ networks for real-time services and concludes that this scaling of such networks is remarkably poor. One way of addressing this poor scalability is for operators to lease from other operators what is for them ‘virtual infrastructure’ in order to construct a network with short topology.

Internet Multicast Video Delivery

Internet video delivery has been motivating research in multicast routing, quality of service (QoS), and the service model of the Internet itself for the last 15 years. Multicast delivery has the potential to deliver a large amount of content that currently cannot be delivered through broadcast. IP and overlay multicast are two architectures proposed to provide multicast support. A large body of research has been done with IP multicast and QoS mechanisms for IP multicast since the late 1980s. In the past five years, overlay multicast research has gained momentum with a vision to accomplish ubiquitous multicast delivery that is efficient and scales in the dimensions of the number of groups, number of receivers, and number of senders. This work presents an overview of the issues facing both IP and overlay multicast and the approaches that researchers are taking to solve them. Many of these approaches take advantage of a rich interface, beyond a single rate video stream, between the coding and delivery mechanisms. The semantics of this interface is an important question for future research and we discuss this with insight from experience on delivery technologies.

Performance Evaluation of the Impact of QoS Mechanisms in an IPv6 Network for IPv6-Capable Real-Time Applications

This paper describes a Quality of Service (QoS) service on an IPv6 domain that aims to service aggregates of real-time traffic with minimum delay, jitter, and packet loss. It contains results from the tests that were performed in order to configure and evaluate the QoS mechanisms. As an actual example of real-time traffic, we have used the OpenH323 project, an open source H.323 implementation that has been ported to IPv6. The QoS mechanisms in IPv6 networks is still a field that has not been researched adequately, and we therefore present the results from the experiments in our IPv6 network that took advantage of the QoS mechanisms. This QoS service uses the Modular QoS CLI (MQC) mechanism and especially the Low Latency Queue feature (LLQ) in order to treat packets from real-time applications.

Quality of service for SIP sessions in 3GPP-based networks

This letter addresses how quality of service (QoS) for Session Initiation Protocol (SIP)-based multimedia sessions can be realized within the 3rd Generation Partnership Project (3GPP) architecture. It discusses a scenario for voice over IP (VoIP) to illustrate how relevant QoS mechanisms and signaling protocols such as SIP, Media Gateway Control Protocol (H.248/Megaco), and the Common Open Policy Service (COPS) interact. Related aspects of the Universal Mobile Telecommunications System (UMTS) access network and the IP Multimedia Subsystem (IMS) are explained.

Providing Service Differentiation for Optical-Burst-Switched Networks

This paper proposes a service differentiation scheme called preemptive wavelength reservation protocol (PWRP) to provide proportional quality of service (QoS) for optical-burst-switched (OBS) networks. In the context of service differentiation, traffic is divided into different service classes based on traffic characteristics. A service differentiation scheme then provides different degrees of resource assurance to different classes of traffic in proportion to their service classes. Unlike existing approaches, which may degrade to classless schemes or which may suffer from low wavelength utilization, the mechanism in this paper is robust and efficient and supports an incremental deployment of QoS support. A usage profile for each class is maintained at the router, and a preemptive wavelength reservation mechanism is implemented to ensure QoS. An analytical model is derived and simulations are conducted to evaluate the performance. The results show that the approach described in this paper performs better than existing mechanisms in terms of lower blocking probability and higher resource utilization, making it an excellent QoS mechanism for OBS networks.

A unified bandwidth reservation and admission control mechanism for QoS provisioning in cellular networks

AbstractWe propose a unified framework consisting of a differential bandwidth reservation (DBR) algorithm and a Quality of Service (QoS)‐aware admission control scheme to provide QoS guarantees to on‐going connections in cellular networks. The differential bandwidth reservation policy uses a sector of cells in making the bandwidth reservation for accepting a new call. Based on the distance of the target cells in the sectors, two different bandwidth reservation policies are applied to optimize the connection dropping rate (CDR), while maintaining a competitive connection blocking rate (CBR). In addition, two possible mobile terminal (MT) movements are analyzed using the DBR mechanism. In the first case, no knowledge of an MT's moving path is assumed to be known, while in the second case, prior knowledge of a user profile is used in bandwidth reservation, and it is called user profile‐based DBR (UPDBR) algorithm. Using the DBR scheme, we propose an admission control algorithm that uses varying number of cells in a sector to meet admission decisions. Extensive simulation is performed to evaluate our methodology. Comparison of the proposed scheme with two prior schemes shows that our approach is not only capable of providing better QoS guarantees, but is also flexible in terms of using varying number of cells in satisfying the high‐level QoS requirements. Copyright © 2004 John Wiley & Sons, Ltd.

Admission control by implicit signaling in support of voice over IP over ADSL

Voice over DSL (VoDSL) is a technology that enables the transport of data and multiple voice calls over a single copper-pair. Voice over ATM (VoATM) and Voice over IP (VoIP) are the two main alternatives for carrying voice over DSL. ATM is currently the preferred technology, since it offers the advantage of ATM’s built-in Quality of Service (QoS) mechanisms. IP QoS mechanisms have been maturing only in recent years. However, if VoIP can achieve comparable performance to that of VoATM in the access networks, it would facilitate end-to-end IP telephony and could result in major cost savings. In this paper, we propose a VoIP-based VoDSL architecture that provides QoS guarantees comparable to those offered by ATM in the DSL access network. Our QoS architecture supports Premium and Regular service categories for voice traffic and the Best-Effort service category for data traffic. The Weighted Fair Queuing algorithm is used to schedule voice and data packets for transmission over the bottleneck link. Fragmentation of large data packets reduces the waiting time for voice packets in the link. We also propose a new admission control mechanism called Admission Control by Implicit Signaling. This mechanism takes advantage of application layer signaling by mapping it to the IP header. We evaluate the performance of our QoS architecture by means of a simulation study. Our results show that our VoIP architecture can provide QoS comparable to that provided by the VoATM architecture.

Distributed mechanisms for quality of service in wireless LANs

Wireless local area networks are gaining popularity at an unprecedented rate, at home, at work, and in public hot spot locations. As these networks become ubiquitous and an integral part of the infrastructure, they will increasingly be used for multimedia applications. There is limited QoS support in WLANs, which will become an impediment in deploying multimedia applications. We present a tutorial on QoS support in IEEE 802.11 WLANs with a focus on the distributed MAC protocol of 802.11. Most QoS support mechanisms proposed for 802.11 use well-known techniques such as priority assignment and fair scheduling, and map QoS metrics into some existing 802.11 MAC parameter, thereby avoiding a redesign of the MAC protocol. We provide a taxonomy of the mechanisms and describe the essential concepts, problems, and advantages of each mechanism. From our study, we conclude that choosing the right set of MAC parameters and the QoS mechanism itself to provide predictable QoS in 802.11 networks is still an open problem.

Towards efficient resource on-demand in Grid Computing

The essence of Grid Computing is to provide efficient Resource on Demand (RoD). This paper addresses this challenge from the perspective of network, the living platform of Grid, by providing effective Quality of Service (QoS) mechanisms (both IntServ and DiffServ) inside the Grid networking environment. Specifically, the efficiency of this QoS mechanism is maximized by policy-based management taking care of the flexible control of QoS parameters/components and active networks technology looking after the fast delivery of various QoS configurations. The first experiment exemplified the current implementation status.