Cross-layer-based modeling for quality of service guarantees in mobile wireless networks

In this article we propose a cross-layer approach to investigate the impact of the physical-layer infrastructure on the data-link-layer QoS performance in mobile wireless networks. At the physical layer, we take the MIMO diversity schemes as well its AMC into account. At the data-link layer, our focus is on how this physical-layer infrastructure influences the real-time multimedia QoS provisioning performance such as delay-bound violation and buffer-overflow probabilities. To achieve this goal, we first model the physical-layer service process as a finite state Markov chain. Based on this FSMC model, we then characterize the QoS performance at the data-link layer using the effective capacity approach, which turns out to be critically important for the statistical QoS guarantees in mobile wireless networks. The numerical and simulation results obtained demonstrate that the proposed cross-layer model can efficiently characterize the interaction between the physical layer infrastructure and upper layer protocols' QoS provisioning performance.     

Deterministic loss ratio quality of service guarantees for highspeed networks

Current research for the provision of deterministic quality of service guarantees in both IP networks and high speed networks involve only bounded delay guarantees, In this letter, loss ratio is considered. We propose constraints on the service function in order to provide not only deterministic bounded loss ratio under a given buffer capacity but also bounded delay. Network operation can be easily managed by existing service-function-based scheduling algorithms     

Quality of service guarantees in virtual circuit switched networks

We review some recent results regarding the problem of providing deterministic quality of service guarantees in slot-based virtual circuit switched networks. The concept of a service curve is used to partially characterize the service that virtual circuit connections receive. We find that service curves provide a convenient framework for managing the allocation of performance guarantees. In particular, bounds on end-to-end performance measures can be simply obtained in terms of service curves and burstiness constraints on arriving traffic. Service curves can be allocated to the connections, and we consider scheduling algorithms that can support the allocated service curves. Such an approach provides the required degree of isolation between the connections in order to support performance guarantees, without precluding statistical multiplexing. Finally, we examine the problem of enforcing burstiness constraints in slot-based networks     

Deterministic service guarantees in IEEE 802.12 networks .I. Thesingle-hub case

We study the problem of allocating resources in single-hub and cascaded 802.12 networks. We show that the use of the 802.12 high-priority access mechanism, when combined with admission control, allows the network to provide small deterministic delay bounds in large cascaded network topologies with potentially many hundreds of hosts. The first part of this work is to analyze relevant 802.12 network performance parameters. In the second part, we describe the scheduling model and define the admission control conditions. Experimental results received with a UNIX kernel-based implementation in a standard 802.12 test network confirm our theoretical results for network parameters, throughput, and delay bounds. In this paper, the single-hub topology is analyzed     

Dynamic resource allocation with service guarantees over large scale optical networks

The lack of effective contention resolution mechanisms in the optical domain presents dynamic optical switching architectures with a hard dilemma between high loss (when adopting one-way reservations) and high delay (when using two-way reservations). In this work we evaluate an alternative hierarchical network architecture, which achieves a satisfactory compromise by partitioning the network into a number of geographically limited domains operating in slot and frame synchronous mode where two-way reservations are effective.     

Matrix extensions of the filtering theory for deterministic trafficregulation and service guarantees

We extend the filtering theory, presented in a previous paper, for deterministic traffic regulation and service guarantees to the matrix setting. Such an extension enables us to model telecommunication networks as linear systems with multiple inputs and multiple outputs under the (min,+)-algebra. Analogous to the scalar setting, there is an associated calculus in the matrix setting, including feedback, concatenation, “filter bank summation”, and performance bounds. As an application of the calculus, we derive service guarantees for networks with nested window flow control. In particular, service guarantees for networks with tandem flow control can be solved explicitly by the Gauss elimination     

Migrating sockets-end system support for networking with quality ofservice guarantees

We present an end system architecture designed to support networking with quality of service (QoS) guarantees. The protocol processing component of the architecture, called migrating sockets, has been designed with minimal hidden scheduling which enables accurate determination of the rate requirement of a user application. The end system provides QoS guarantees using: 1) an adaptive rate-controlled scheduler; 2) rate-based flow control on the send side for access to reserved-rate network connections; and 3) a constant overhead active demultiplexing mechanism on the receive side which can be transparently enabled in wide-area TCP/IP internetworking (although it is not restricted to TCP/IP). To achieve efficiency, migrating sockets lets user applications manage network endpoints with minimal system intervention, provides user level protocols read-only access to routing information, and integrates kernel level support previously built for efficient data movement. Migrating sockets is backward compatible with Unix semantics and Berkeley sockets. It has been used to implement Internet protocols such as TCP, UDP, and IP (including IP multicast), and run existing applications such as vic. Migrating sockets has been implemented in Solaris 2.5.1. We discuss our implementation experience, and present performance results of our system running on Sun Sparc and Ultra workstations, as well as Pentium-II desktops     

On providing blocking probability and throughput guarantees in a multi‐service environment

As the Internet evolves from a packet network supporting a single best effort service class towards an integrated infrastructure supporting several service classes—some with QoS guarantees—there is a growing interest in the introduction of admission control and in devising bandwidth sharing strategies, which meet the diverse needs of QoS‐assured and elastic services. In this paper we show that the extension of the classical multi‐rate loss model is possible in a way that makes it useful in the performance analysis of a future admission control based Internet that supports traffic with peak rate guarantee as well as elastic traffic. After introducing the model, it is applied for the analysis of a single link, where it sheds light on the trade‐off between blocking probability and throughput. For the investigation of this trade‐off, we introduce the throughput‐threshold constraint, which bounds the probability that the throughput of a traffic flow drops below a predefined threshold. Finally, we use the model to determine the optimal parameter set of the popular partial overlap link allocation policy: we propose a computationally efficient algorithm that provides blocking probability‐ and throughput guarantees. We conclude that the model and the numerical results provide important insights in traffic engineering in the Internet. Copyright © 2002 John Wiley & Sons, Ltd.     

Exploitation of DWDM for optical packet switching with quality ofservice guarantees

This paper addresses the problem of building optical packet switches that are able to effectively cope with variable length packet traffic and quality of service management, therefore able to support IP traffic. The paper aims at showing that the availability of dense wavelength division multiplexing is crucial. By suitably exploiting the wavelength dimension a multistage fiber delay line buffer can be implemented, with fine granularity and long delay with an architecture of limited complexity. This is necessary to fulfill the buffering requirements of variable length packets. Furthermore, the wavelength domain is proved to be more effective than the time domain to manage different levels of quality of service. Algorithms are presented that are peculiarly designed for this environment showing that they can effectively differentiate the packet loss probability between three priority classes     

A min, + system theory for constrained traffic regulation and dynamic service guarantees

By extending the system theory under the (min, +) algebra to the time-varying setting, we solve the problem of constrained traffic regulation and develop a calculus for dynamic service guarantees. For a constrained traffic-regulation problem with maximum tolerable delay d and maximum buffer size q, the optimal regulator that generates the output traffic conforming to a subadditive envelope f and minimizes the number of discarded packets is a concatenation of the g-clipper with g(t) = min[f(t+ d), f (t)+q] and the maximal f-regulator. The g-clipper is a bufferless device, which optimally drops packets as necessary in order that its output be conformant to an envelope g. The maximal f-regulator is a buffered device that delays packets as necessary in order that its output be conformant to an envelope f. The maximal f-regulator is a linear time-invariant filter with impulse response f, under the (min, +) algebra. To provide dynamic service guarantees in a network, we develop the concept of a dynamic server as a basic network element. Dynamic servers can be joined by concatenation, "filter bank summation," and feedback to form a composite dynamic server. We also show that dynamic service guarantees for multiple input streams sharing a work-conserving link can be achieved by a dynamic service curve earliest deadline scheduling algorithm, if an appropriate admission control is enforced.     

Virtual path control for ATM networks with call level quality ofservice guarantees

The configuration of virtual path (VP) connection services is expected to play an important role in the operation of large-scale asynchronous transfer mode (ATM) networks. A major research challenge is to understand the fundamental tradeoff between the network call throughput and the processing load on the signaling system and to provide an algorithm for VP capacity allocation that achieves an optimal network operating point while guaranteeing quality of service (QoS) at the call level and satisfies a priori bounds on the processing load of the call processors. We present a taxonomy of previous approaches to the problem and identify their strengths and weaknesses. Based on these observations, we provide an algorithm for the VP capacity allocation problem that satisfies nodal constraints on the call processing load and blocking constraints for each source-destination (SD) pair. The algorithm maximizes the network revenue under the above set of constraints and is parameterized by the number of traffic classes in the network, the method of presentation of networking resources, the admission control policy used in every link and VP, and the network routing scheme. Finally, we apply the algorithm to three sample networks and study several of its performance characteristics. In one case, we applied the calculated VP distribution to the Xunet ATM testbed and verified experimentally the predicted performance     

TIP's performance quality of service

The author presents a transport performance quality of service (QoS) parameter set, which enables applications to describe their required performance properties and guarantees appropriately. The performance QoS is provided at the service interface of the Transport and Internetworking Package (TIP), which is an adaptive transport system based on an object-oriented and modular architecture     

Service quality in TINA: quality of service trading in open networkarchitecture

Enterprise-level QoS issues are discussed, from which QoS evolution paths are derived. Service-level QoS issues are identified, and they have been studied as a part of service quality issues in TINA service architecture. TINA stream binding and its role in the TINA QoS framework are presented. Soft guarantee of stream quality is proposed, which does not require strict resource reservation. The soft guarantee concept combined with TINA stream binding architecture supports progressive evolution of service quality     

Measuring the internet quality of service in AQUILA

This paper is focussed on design concepts and experiences of the Distributed Measurement Architecture (DMA) used for scalable intra-domain Quality of Service (QoS) monitoring in the framework of the AQUILA DiffServ project. AQUILA DMA consists of QoS measurement tools and methodologies for passive and active QoS monitoring including distributed agents, QoS database, management stations for QoS aggregation and correlation, generation of application traffic classes. The development of such a complex system needs systematic tests to validate the architecture. Therefore application like load generators are used to test the system under different load conditions. For MBAC the admission control agents measure the effective bandwidth consumed by the accepted active IP flows to estimate the unused bandwidth at this access point.     

An introduction to quality of service

Quality of service (QoS) is like ‘life’ — a dictionary may define the word but it does not help us understand its meaning. This paper defines what is meant by QoS in the context of packet networks. It discusses the drivers that lead to the development of QoS for IP networks in the context of the history of packet communications. The paper then presents the basic packet QoS taxonomy using the simple analogy of the postal system. It also briefly looks at potential future developments, while discussing general QoS issues throughout.     

Restorable dynamic quality of service routing

The focus of quality-of-service routing has been on the routing of a single path satisfying specified QoS constraints. Upon failure of a node or link on the path, a new path satisfying the constraints has to be established. However, resources needed to satisfy the QoS requirements are not guaranteed to be available at the rerouting instant, so QoS is not guaranteed upon failure. Restorable QoS routing, where active and backup paths must be simultaneously set up, has been previously studied. This is mostly motivated by the incorporation of mechanisms to establish QoS guaranteed paths with failure protection in multiprotocol label switching networks. This article describes some previously developed algorithms for dynamic routing of restorable QoS guaranteed paths     

局域网IP电话的QoS策略

本文论述了影响IP网上语音服务质量的主要因素,并提出了基于局域网VoIP相应的解决方案。着重分析了局域网中的保证语音QoS(Quality of Service)的机制,提出了在园区网及骨干接入中的QoS保证策略。     

Management of quality of service enabled VPNs

New emerging IP services based on differentiated services and the IP security architecture offer the level of communication support that corporate Internet applications need nowadays. However, these services add an additional degree of complexity to IP networks which will require sophisticated management support. The management of enhanced IP services for their customers is thus an emerging important task for Internet service providers. This article describes a potential management architecture service providers will need for that task, considering problems such as multiprovider services and service automation. We focus on a quality-enhanced virtual private network service which is particularly useful for corporate internetworking     

基于光GMPLS接入网中区分服务的QoS研究

通过配置区分服务体系实现基于光GMPLS环状网络的QoS测量,涉及到不同的实时多媒体服务.讨论并分析区分服务结构的三种服务级别的特性.仿真结果表明,在网络过载的情况下,快速转发类和保证转发类都有很好的保护作用.加速转发类适合于实时服务,而最大努力类对任何类型的服务}生能都非常低,同时保证转发非常适合于视频流.     

国外电信服务质量监管机制

我国政府及电信行业管制部门对电信服务质量的监管给予了高度重视。电信服务质量不仅是电信企业生存和参与竞争的根本,而且与广大电信消费者息息相关,涉及到电信消费者的切身利益,因此提高电信服务质量是电信企业,电信消费者和电信管制机构共同的目标和愿望。电信服务监管机制就是实现上述三者利益最大化的游戏规则,同时三方利益又相互制约,共同促成了电信服务质量的提升和发展。介绍了国外几种主要的电信服务质量监管机制,并对其利弊进行了分析,旨在为我国电信服务质量的监管提供参考。