Price‐coupled scheduling for differentiated services: Gcµ versus GPS

We present an integrated approach to pricing and scheduling for services that are differentiated in terms of throughput, delay and loss specifications. The key building block to the model are quality value curves that specify a user's value of higher quality levels. From the analysis emerges a pricing rule that charges based on rate and quality grade, and a dynamic scheduling rule, called the Gcµ rule. The analysis also derives the economically optimal probabilistic quality of service (QoS) guarantee parameters. We compare our model to the deterministic approach of QoS guarantees using burstiness constraints and fair scheduling rules. The scheduling that arises from such a deterministic approach is the well‐known Generalized Processor Sharing (GPS). A comparative analysis inspires the fair Gcµ‐PS rule as the scheduling rule that combines the unique strengths of GPS and Gcµ. This Gcµ‐PS rule is proposed as a tailored scheduling solution for both the expedited forwarding class and the four assured forwarding classes in the IETF's differentiated services. Copyright © 2002 John Wiley & Sons, Ltd.     

Smoothing and transporting video in QoS IP networks

Real‐time traffic such as voice and video, when transported over the Internet, demand stringent quality of service (QoS) requirements. The current Internet as of today is still used as a best effort environment with no quality guarantees. An IP‐based Internet that supports different QoS requirements for different applications has been evolving for the past few years. Video streams are bursty in nature due to the instant variability of the video content being encoded. To help mitigate the transport of bursty video streams with minimal loss of information, rate‐adaptive shapers (RASs) are usually being used to reduce the burstiness and therefore help preserve the desired quality. When transporting video over a QoS IP network, each stream is classified under a specific traffic profile to which it must conform, to avoid packet loss and picture quality degradation. In this paper we study, evaluate and propose RASs for the transport of video over a QoS IP network. We utilize the encoding video parameters for choosing the appropriate configuration needed to support the real‐time transport of Variable Bit Rate (VBR) encoded video streams. The performance evaluation of the different RASs is based on the transport of MPEG‐4 video streams encoded as VBR. The performance is studied based on looking at the effect of various parameters associated with the RASs on the effectiveness of smoothing out the burstiness of video and minimizing the probability of packet loss. Copyright © 2005 John Wiley & Sons, Ltd.     

Evaluating the expedited forwarding of voice traffic in a differentiated services network

The Differentiated Services architecture offers a scalable alternative to provide Quality of Service (QoS) to the new multimedia applications in the Internet. This paper aims at evaluating the delay and jitter experienced by voice traffic when handled by the Expedited Forwarding (EF) scheme. The analysis includes the effects of different packet scheduling mechanisms implementing EF and of the voice packet size. We also evaluate how efficiently each type of traffic uses an extra allocated bandwidth and the impact of traffic shaping. The results show that increasing the service rate share allocated to the EF aggregate does not significantly affect the competing best effort (BE) traffic. This holds as long as the BE traffic can use the bandwidth left unused by the EF traffic in idle periods. Copyright © 2002 John Wiley & Sons, Ltd.     

A framework for delivering fine granularity and fair service discrimination in DiffServ networks

In order to achieve a quality of service (QoS) capable of satisfying an ever increasing range of user requirements, differentiated services (DiffServ) have been introduced as a scalable solution that emerges ‘naturally’ from today's best effort service approach. Mapping the packet treatment into a small number of per hop behaviours (PHBs) is the key idea behind the scalability of DiffServ but this comes at the cost of loosing some behavioural differentiation and some fairness between flows multiplexed into the same aggregated traffic. The paper proposes a novel simple and effective DiffServ approach, the ‘Simple Weighted Integration of diFferentiated Traffic’ (SWIFT), and uses it in a series of simulations covering a relatively wide range of local network conditions. Measured voice and video traffic traces and computer generated self‐similar background traffic were used in simulations performed at various congestion levels and for in‐profile and out‐of‐profile source behaviour. The resulted throughput, mean delay, maximum delay and jitter are used to asses SWIFT's capabilities—isolation of the in‐profile traffic from congestion effects, treatment differentiation, increased resource utilization, fairness in treatment under congestion, and incentivity for nice behaviour. Comparisons with other approaches employing traffic control are also provided. Copyright © 2003 John Wiley & Sons, Ltd.     

宽带CDMA IP网中实现区分服务的QoS结构

3G CDMA网提供高速无线IP服务,其业务主要包括数据、语音互式多媒体。为了能保证这些异构业务的QoS,并提供业务区分,将有线IP网的分区服务（DIFFSERV）QoS模型引入3G CDMA网络。针对无线网络的终端移动性、高丢失率、更低的网络带宽等特点,对原有的DIFFSERV结构进行了修改,给出了基于DIFFSERV的无线QoS结构,并简单描述了实现协议。还给出了有效带宽的录入控制策略和资源预留策略来实现QoS。通过仿真,研究了各种策略的性能。     

Expedited forwarding end‐to‐end delay and jitter in DiffServ

The scheduling disciplines and active buffer management represent the main components employed in the differentiated services (DiffServ) data plane, which provide qualitative per‐hop behaviors corresponding to the QoS required by supported traffic classes. In the first part of this paper, we compute the per‐hop delay bound that should be guaranteed by the different multiservice scheduling disciplines, so that the end‐to‐end (e2e) delay required by expedited forwarding (EF) traffic can be guaranteed. Consequently, we derive the e2e delay bound of EF traffic served by priority queuing–weighted fair queuing (PQ–WFQ) at every hop along its routing path. Although real‐time flows are principally offered EF service class, some simulations on DiffServ‐enabled network show that these flows suffer from delay jitter and they are negatively impacted by lower priority traffic. In the second part of this paper, we clarify the passive impact of delay jitter on EF traffic, where EF flows are represented by renewal periodic ON–OFF flows, and the background (BG) flows are characterized by the Poisson process. We analyze through different scenarios the jitter effects of these BG flows on EF flow patterns when they are served by a single class scheduling discipline, such as first‐input first‐output, and a multiclass or multiservice scheduling discipline, such as static priority service discipline. As a result, we have found out that the EF per‐hop behaviors (PHBs) configuration according to RFCs 2598 and 3246 (IETF RFC 2598, June 1999; RFC 3246, IETF, March 2002) cannot stand alone in guaranteeing the delay jitter required by EF flows. Therefore, playout buffers must be added to DiffServ‐enabled networks for handling delay jitter problem that suffers from EF flows. Copyright © 2008 John Wiley & Sons, Ltd.     

An optimal bandwidth allocation and data droppage scheme for differentiated services in a wireless network

This paper presents an optimal proportional bandwidth allocation and data droppage scheme to provide differentiated services (DiffServ) for downlink pre‐orchestrated multimedia data in a single‐hop wireless network. The proposed resource allocation scheme finds the optimal bandwidth allocation and data drop rates under minimum quality‐of‐service (QoS) constraints. It combines the desirable attributes of relative DiffServ and absolute DiffServ approaches. In contrast to relative DiffServ approach, the proposed scheme guarantees the minimum amount of bandwidth provided to each user without dropping any data at the base‐station, when the network has sufficient resources. If the network does not have sufficient resources to provide minimum bandwidth guarantees to all users without dropping data, the proportional data dropper finds the optimal data drop rates within acceptable levels of QoS and thus avoids the inflexibility of absolute DiffServ approach. The optimal bandwidth allocation and data droppage problems are formulated as constrained nonlinear optimization problems and solved using efficient techniques. Simulations are performed to show that the proposed scheme exhibits the desirable features of absolute and relative DiffServ. Copyright © 2009 John Wiley & Sons, Ltd.     

Proportional delay differentiation provision by bandwidth adaptation of class‐based queue scheduling

Supporting quality of service (QoS) over the Internet is a very important issue and many mechanisms have already been devised or are under way towards achieving this goal. One of the most important approaches is the so‐called Differentiated Services (DiffServ) architecture, which provides a scalable mechanism for QoS support in a TCP/IP network. The main concept underlying DiffServ is the aggregation of traffic flows at an ingress (or egress) point of a network and the marking of the IP packets of each traffic flow according to several classification criteria. Diffserv is classified under two taxonomies: the absolute and the relative. In absolute DiffServ architecture, an admission control scheme is utilized to provide QoS as absolute bounds of specific QoS parameters. The relative DiffServ model offers also QoS guarantees per class but in reference to the guarantees given to the other classes defined. In this paper, relative proportional delay differentiation is achieved based on class‐based queueing (CBQ) scheduler. Specifically, the service rates allocated to the classes of a CBQ scheduler are frequently adjusted in order to obtain relative delay spacing among them. The model presented can also be exploited in order to meet absolute delay constraints in conjunction with relative delay differentiation provision. Simulation experiments verify that our model can attain relative as well as absolute delay differentiation provided that the preconditions posed are satisfied. Copyright © 2004 John Wiley & Sons, Ltd.     

IP增值业务网络中的问题及其解决方案

ＩＰ增值网络系统凭借先进的多媒体通信技术支撑及强大的市场竞争力迅速发展。解决其在发展中所面临的一些问题的关键就是要有一套完整的ＩＰ网络解决方案,以实现一个具有网管系统、帐务清算系统、计费系统、认证系统、业务运营系统等一整套功能体系的ＩＰ增值业务网络系统,以便为ＩＰ网络运营商创造更具市场活力和产品兼容性的网络运营环境。     

QoS provisioning for multiple non‐real‐time services in cellular wireless networks

Future mobile services are expected to include various non‐voice oriented services. One important category of non‐voice oriented mobile services is non‐real‐time services. When a mobile user establishes a connection to access non‐real‐time service, the mobile user usually cares about whether the total time to complete its data transfer is within its time tolerance. In addition, different mobile users may have different bandwidth requirements and different tolerances in the total completion time. It is essential for wireless systems to provide various mobile users with different total completion times. In this paper, two quality‐of‐service (QoS) metrics, called stretch ratio and eligibility percentage, are employed at a connection level to present the degree of the length of the total completion time. We devise a measurement based call admission control scheme that provides multiple QoSs for various mobile users which have different requirements of stretch ratios, eligibility percentages, and bandwidths. Extensive simulation results show that the measurement based call admission control scheme not only provides various satisfactory QoSs for mobile users but also produces high throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

On the performance of proximity‐based services

Proximity‐based services (PBS) are a subclass of location‐based services that aim to detect the closest point of interest by comparing relative position of a mobile user with a set of entities to be detected. Traditionally, the performances of PBS are measured on the basis of the norm of the estimation error. Although this performance criterion is suitable for location‐based services that aim tracking applications, it does not give enough information about the performance of PBS. This paper provides a novel framework quantifying the system performance of PBS by making use of spatially quantized decision regions that are determined according to service properties. The detection problem in PBS is modeled by an M‐ary hypothesis test, and analytical expressions for correct detection, false alarm, and missed detection rates are derived. A relation between location estimation accuracy requirements that are mandated by regulatory organizations and the performance metrics of PBS is given. Additionally, a flexible cost expression that can be used to design high‐performance PBS is provided. A system deployment scenario is considered to demonstrate the results. By using this framework, PBS designers can improve their command on the services’ behavior and estimate service performance before deployment. Copyright © 2011 John Wiley & Sons, Ltd.     

Robust design of communication systems: The case of expedited forwarding of voice traffic in differentiated services networks

Design of experiments (DOE) is gaining acceptance in the community of telecommunication researchers, especially during the past several years. In this paper, a state‐of‐the‐art review on the use of DOE in the field of communication networks is presented, and the need for introducing a systematic robust design methodology to network simulations or testbed experiments is identified in ensuring robust behaviours of a network against uncontrollable sources of variation. Then, the Taguchi robust design methodology is applied for optimizing the expedited forwarding (EF) of voice traffic in a differentiated services network, and its step‐by‐step procedures are described in detail. The experimental data are collected using the ns‐2 simulator, and the SN ratio, a robustness measure, is analysed to determine an optimal design condition for each performance characteristic. The analysis results show that ‘type of queue scheduling schemes’ is a major control factor for ensuring robust behaviours of one‐way delay and jitter while ‘EF queue size’ is for throughput and loss rate. Finally, a compromised optimal design condition is identified using a desirability function approach adapted to multi‐characteristic robust design problems. Copyright © 2007 John Wiley & Sons, Ltd.     

Measurement‐based admission control scheme with priority and service classes for application in wireless IP networks

Wireless IP networks will provide voice and data services using IP protocols over the wireless channel. But current IP is unsuitable to provide delay or loss bounds and insufficient to support diverse quality of service, both required by real‐time applications. In order to support real‐time applications in wireless IP networks, in this paper a measurement‐based admission control (MBAC) with priority criteria and service classes is considered. First we have shown the suitability of MBAC in wireless IP networks by comparing its performance with a parameter‐based scheme. Next, we have investigated the performance of strictly policy‐based MBAC and policy plus traffic characteristic‐based MBAC schemes in terms of (1) increasing the user mobility, (2) changing traffic parameters and (3) the presence of greedy users. The efficiency and fairness of each scheme are measured in terms of lower class new and handoff traffic performance. Copyright © 2003 John Wiley & Sons, Ltd.     

IP VPN业务管理中可重用管理组件的划分和应用

IP VPN(基于IP的虚拟专用网)业务管理面临的主要难题是,TMN(电信管理网)管理层次模型中业务管理层不断扩展的业务需求,可重用业务管理组件是降低动态变化的业务需求带来的业务管理复杂度、灵活地定制和提供IP VPN业务的有效途径.本文首先分析了IP VPN的基本业务需求,提出了IP VPN业务属性的概念.在此基础上,从IP VPN业务属性的视点对IP VPN业务管理功能进行了划分,形成可重用的业务管理组件.最后,本文给出了一个业务管理功能向业务管理组件映射的实例.     

Protection Management for Guaranteed User‐Driven Virtual Circuit Services in Dynamic Multi‐domain Environments: Design Issues and Challenges

Fault management of virtualized network environments using user‐driven network provisioning systems (NPSs) is crucial for guaranteeing seamless virtual network services irrespective of physical infrastructure impairment. The network service interface (NSI) of the Open Grid Forum reflects the need for a common standard management API for the reservation and provisioning of user‐driven virtual circuits (VCs) across global networks. NSI‐based NPSs (that is, network service agents) can be used to compose user‐driven VCs for mission‐critical applications in a dynamic multi‐domain. In this article, we first attempt to outline the design issues and challenges faced when attempting to provide mission‐critical applications using dynamic VCs with a protection that is both user‐driven and trustworthy in a dynamic multi‐domain environment, to motivate work in this area of research. We also survey representative works that address inter‐domain VC protection and qualitatively evaluate them and current NSI against the issues and challenges.     

IP网络传输话音和TDM业务的新技术-TDMoIP

介绍3TDMoIP的实现过程，主要对Ingress方向的上数据处理过程进行描述，在IP网络上实现数据处理业务。与传统网络相比，IP网络组网更简单经济，传送数据、图像、声音质量更好，与VOIP相比时延更小。     

蜂窝重叠情况下移动IP切换延时分析

从理论上首次对移动 IP 切换过程中的切换延时和乱序分组进行了建模和分析,分别得到了各自的概率分布公式。并且根据这个结果,优化了重叠区域的半径。结果表明:本模型准确地描述了移动 IP 的切换行为,它对于评价移动 IP 的切换性能非常有用。     

一种基于层次模型的USB2.0接口芯片IP核固件的设计与实现

在对USB2．0设备端接口芯片IP核进行分析的基础上,提出了一种基于层次模型的IP核固件的设计实现方案,并给出了一个大容量存储设备USB接口IP核固件的设计实例,实验结果验证了本设计的先进性和合理性。     

New Framework and Mechanisms of Context‐Aware Service Composition in the Future Internet

The ongoing proliferation of new services, applications, and contents is leading the Internet to an architectural crisis owing to its inability to provide efficient solutions to new requirements. Clean‐slate architectures for the future Internet offer a new approach to tackle current and future challenges. This proposal introduces a novel clean‐slate architecture in which the TCP/IP protocol stack is decoupled in basic functionalities, that is, atomic services (ASs). A negotiation protocol, which enables context‐aware service discovery for providing adapted communications, is also specified. Then, we present how ASs can be discovered and composed according to requesters' requirements. In addition, a media service provisioning use case shows the benefits of our framework. Finally, a proof‐of‐concept implementation of the framework is described and analyzed. This paper describes the first clean‐slate architecture aligned with the work done within the ISO/IEC Future Network working group.