QoS Control Research Articles

Power optimization for dynamic configuration in heterogeneous web server clusters

To reduce the environmental impact, it is essential to make data centers green, by turning off servers and tuning their speeds for the instantaneous load offered, that is, determining the dynamic configuration in web server clusters. We model the problem of selecting the servers that will be on and finding their speeds through mixed integer programming; we also show how to combine such solutions with control theory. For proof of concept, we implemented this dynamic configuration scheme in a web server cluster running Linux, with soft real-time requirements and QoS control, in order to guarantee both energy-efficiency and good user experience. In this paper, we show the performance of our scheme compared to other schemes, a comparison of a centralized and a distributed approach for QoS control, and a comparison of schemes for choosing speeds of servers.

A Method Based on the Degree of Object Attributes Attention for Transmission QoS Control

In Distributed Virtual Environment,it is an important issue that how to manage the distribution of 3D geometry.Instead of downloading the whole virtual world objects into the clients' machines,on-demand method is to copy only objects that the user needs-partial replication of a virtual world rather than full replication.Therefore,a key aspect is how to efficiently replicate the required data in real-time.To solve this problem,a QoS transmission control method and a QoS Management Model,which are based on the degree of object attributes attention,are given in this paper.This method extends the traditional geometry-based model transmission control method.Non-geometric attributes and geometric attributes are integrated together and regarded as QoS parameters.Because real-time property is the most important requirements in distributed virtual environment and it can be affected by network bandwidth during the run time,a dynamic negotiation algorithm,which combines the idea of dynamic QoS management,is given in this paper.Experimental results show that the method is able to reflect user's level of concern about virtual objects in virtual environment comprehensively,and it can gain better transmission results while ensuring the prerequisite of real-time with the changing of the network bandwidth.

종단간 QoS 지원을 위해 Bottom-half 메커니즘을 이용한 우선순위 및 예산 기반의 네트워크 프로토콜 처리

종단 호스트에서의 전통적인 네트워크 프로토콜 처리 기법은 인터럽트 기반의 선착순 처리 방식을 사용함으로써 다음과 같은 두 가지 문제점을 가진다. 첫째, 인터럽트가 가장 높은 우선순위로 처리되기 때문에 네트워크 패킷과 응용 프로세스간에 우선순위 역전현상이 발생할 수 있다. 둘째, 네트워크 패킷 처리가 선착순으로 진행되기 때문에 패킷과 패킷간에 우선순위 역전현상이 발생할 수 있다. 이러한 문제는 우선순위에 기반한 프로토콜 처리 방법으로 해결이 가능한 것으로 알려져 있지만, 기본적으로 우선순위 기반의 해법은 기아(starvation)라는 부작용을 가지고 있으며 각각의 네트워크 흐름에 대하여 QoS 격리 및 조절이 불가능하기 때문에 네트워크 흐름마다 상이한 QoS가 요구되는 환경에 적용하기 어렵다는 문제점을 가지고 있다. 본 논문에서는 우선순위와 예산(budget) 개념에 기반하여 bottom-half 메커니즘을 이용한 프로토콜 처리 기법을 제안한다. 제안하는 방법을 사용하면 우선순위 기반의 프로토콜 처리 방법이 가지고 있는 기아 현상을 해결함은 물론 각각의 네트워크 연결이 요구하는 QoS의 격리(isolation)가 가능하다. 이러한 특성으로 인해 패킷 처리 시간을 상한 (upper-bound)시키는 것이 가능해지며, 본 논문에서는 그 최대값을 계산해내는 방법을 함께 제안한다. 마지막으로, 실험을 통해 제안하는 방법이 네트워크 흐름간 QoS를 효과적으로 격리 및 조절할 수 있음을 확인할 수 있었다. The traditional interrupt-based protocol processing at end hosts has two priority-inversion problems. First, low-priority packets may interrupt and delay high-priority process executionssince interrupts have the highest priority in most operating systems. Second, low-priority packet may delay high priority packets when they arrive almost simultaneously since interrupt processing is performed in a FCFS (first come, first served) order. These problems can be solved by a priority-based protocol processing policy and implementation. However, general priority-based schemes commonly have the problem of starvation and cannot support the each network flow requiring the mutually exclusive QoS since the packets are processed in the FCFS order. Therefore, the priority-based schemes are not appropriate for different QoS-demanding applications. In this paper, we present a bottom-half-based approach that relies on priority- and budget-based processing. The proposed approach allows us to solve both the starvation and priority-inversion problems, and further enables effective QoS isolation between different network connections. This feature also enables bounding the protocol processing time at an end host. We finally show through experiments that the proposed approach achieves QoS isolation and control.

QoS control in the 3GPP evolved packet system

In this article we describe the QoS concept of the evolved packet system, which was standardized in 3GPP Release 8. The concept provides access network operators and service operators with a set of tools to enable service and subscriber differentiation. Such tools are becoming increasingly important as operators are moving from a single to a multi-service offering at the same time as both the number of mobile broadband subscribers and the traffic volume per subscriber is rapidly increasing. The "bearer" is a central element of the EPS QoS concept and is the level of granularity for bearer-level QoS control. The network-initiated QoS control paradigm specified in EPS is a set of signaling procedures for managing bearers and controlling their QoS assigned by the network. The EPS QoS concept is class-based, where each bearer is assigned one and only one QoS class identifier by the network. The QCI is a scalar that is used within the access network as a reference to node-specific parameters that control packet forwarding treatment. This class-based approach, together with the network-initiated QoS control paradigm, gives network operators full control over the QoS provided for its offered services for each of its subscriber groups.

1A2-A14 高専-豊橋技科大間における遠隔制御システムを用いた体験型学習

In this Paper, collaboration and education system for students of National College of Technology (NCT) based on Tele-Control system has been proposed. In the proposed system, Toyohashi University of Technology (TUT) provides experimental apparatuses for tele-control system as a server site, and the client system is constructed by using 1 DOF paddle system with haptic feedback for student's use in a client site at NCT. Several control experiments have conducted between TUT and 9 NCTs respectively. Moreover, experimental contents have proposed and improvement for communication environment using QoS control has evaluated through the experiments.

音声・ビデオストリーミングＩＰ伝送におけるＱｏＥを考慮したＷＦＱスケジューラの配置

We propose an effective arrangement of packet schedulers (WFQ and FIFO) that can enhance the QoE of an audio-video streaming transmission over IP networks (typified by IPTV). Previously, the authors examined the relationship between the arrangement of WFQ and application-level QoS and observed that WFQ for all or both edge nodes leads to a high application-level QoS. Now, we have assessed the arrangement in terms of the QoE in addition to application-level QoS. The results show that WFQ on the receiver-side edge in the network satisfactorily enhances the QoE as well as the WFQ on both edges and the WFQ on all nodes. This implies that QoS control in the access network dominates QoE.

A QoS Control Mechanism to Provide Service Differentiation and Overload Protection to Internet Scalable Servers

Nowadays, enterprises providing services through Internet often require online services supplied by other enterprises. This entails the cooperation of enterprise servers using Web services technology. The service exchange between enterprises must be carried out with a determined level of quality, which is usually established in a service level agreement (SLA). However, the fulfilment of SLAs is not an easy task and requires equipping the servers with special control mechanisms which control the quality of the services supplied. The first contribution of this research work is the analysis and definition of the main requirements that these control mechanisms must fulfil. The second contribution is the design of a control mechanism which fulfils these requirements and overcomes numerous deficiencies posed by previous mechanisms. The designed mechanism provides differentiation between distinct categories of service consumers as well as protection against server overloads. Furthermore, it scales in a cluster and does not require any modification to the system software of the host server, or to its application logic.

New algorithms for QoS performance improvement in high speed networks

In this paper is addressed the issue how to provide QoS control and improve performance in high speed Optical Burst Switching (OBS) networks. In order to provide better proportional differentiated ...

Outsourcing automated QoS control of home routers for a better online game experience

Consumer network access links can become bottlenecks when faced with heterogeneous network traffic where real-time traffic from network games finds itself competing with nongame traffic for access to bandwidth. We would like to prioritize network game traffic over these bandwidth restricted links. However, the limited resources of consumer access devices make this problematic. We propose a solution whereby the classification of flows is outsourced to an ISP-based system. The access device is then notified of flow classifications and can apply a simple flow prioritization rule. We have developed a prototype of this system and found it viable in terms of functionality, timeliness of classification, and scalability.

Reconfigurable Service Composition and Categorization for Power-Aware Mobile Computing

The requirement of agile adaptation to varying resource constraints in mobile systems motivates the use of a service-oriented architecture (SOA), which can support the composition of two or more services to form a complex service. In this paper, we propose SOA-based middleware to support QoS control of mobile applications and to configure an energy-efficient service composition graph. We categorize services into two layers: functionality-centric services, which are connected to create a complex service to meet the user's intentions, and resource-centric services, which undertake distributed functionality-centric services in a way that increases the success rate of service composition while reducing contention at specific service nodes. We also present a service routing algorithm to balance the resource consumption of service providers on a service-overlay network. Through simulation of power-aware service composition using a realistic model based on ns-2 and traced data, we demonstrate that our approach can help both the mobile devices and the servers in a service-overlay network to reduce energy consumption without an increase in response time.

Scalable Video Streaming Adaptive to Time-Varying IEEE 802.11 MAC Parameters

This letter proposes a QoS control method for video streaming service over wireless networks. Based on statistical analysis, the time-varying MAC parameters highly related to channel condition are selected to predict available bitrate. Adaptive bitrate control of scalably-encoded video guarantees continuity in streaming service even if the channel condition changes abruptly.

Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs

Supporting telephone services using wireless LAN as the access network is an important application nowadays. The SIP and IEEE 802.1 1e are the two most promising protocols to support such services. In this paper, we show how to integrate SIP and 802. lie to conduct call admission control and resource reservation to support VoIP's QoS in IEEE 802. lie WLANs. Besides, we also suggest some adjustments and MAC enhancements to 802.1 1e to facilitate VoIP traffics over WLANs.

Proportional and Deterministic Differentiation Methods of Multi-Class QoS in IEEE 802.11e Wireless LAN

Recently, wireless LAN is achieving remarkable growth and maturity. On the other hand, by the advance of the Internet, the demand for multimedia communication services which include video and voice will be expected to grow. Therefore, in the future, the mechanism of QoS guarantee must be realized even in wireless LAN environment. So far, IEEE 802.11e EDCF has been proposed, which is a contention based channel access method to achieve the QoS guarantee in wireless LAN. However, this cannot realize the desired throughput ratio or deterministic target throughput in principle. In this paper, we expand the EDCF to solve such QoS issues and enable more flexible QoS control. Moreover, we show the effectiveness of our proposal by computer simulation.

유비쿼터스 컴퓨팅에서 분산 멀티미디어 서비스를 위한 하이브리드 QoS 관리 모델

유비쿼터스 컴퓨팅은 컴퓨터 시스템의 물리적인 공간을 확장시켰으며, 보다 동적인 분산 시스템으로 이끌었다. 이러한 환경에서는 다양한 디바이스와 자원 그리고 사용자 요구사항에 대한 새로운 QoS 파라미터가 요구되고 있다. 본 논문에서는 유비쿼터스 컴퓨팅 환경에 적합한 정적 QoS 파라미터와 동적 QoS 파라미터를 정의한 새로운 하이브리드 QoS 관리 모델을 제안하였다. 제안한 시스템 구성은 분산된 형태로 종단간 QoS 제어 및 관리할 수 있도록 클라이언트 측에는 QoS 제어 관리를 위한 모듈(QoS CMM), 서버 측에 QoS 관리 모듈(QoS MM), 그리고 중앙형 QoS 제어 및 관리를 위한 자원 QoS 관리 모듈(RQoS MM)을 구성하였다. 정적 QoS 파라미터는 자원 QoS 관리 모듈에서 처리하며, 동적 QoS 파라미터에 대한 전체적인 QoS 제어는 QoS CMM에 의해 다자간 통신의 경우에 서버 측의 부담을 최소화 시킬 수 있도록 하였다. 끝으로, 그래픽 사용자 인터페이스를 통해 위치 기반 애플리케이션으로 클라이언트 단말형태인 데스크탑 PC, 노트북, PDA에 따른 멀티미디어 서비스 수행 결과 화면을 보였다. Ubiquitous computing has extended the computer system into the whole physical space and has ushered the emergence of more dynamic distributed systems. This environment require unique QoS parameters for various devices, resources and user requirements. In this paper, we propose a new hybrid QoS management model which defines a static-dynamic QoS parameter that is more appropriate to the ubiquitous computing environment. This model consists of the QoS Control Management Module(QoS CMM) in the client side and the Resource QoS Management Module (RQoS MM) in the server side. The RQoS MM deals with the static QoS parameters and the whole QoS control of the distributed control(QoS CMM) in order to minimize server load in cases of multiple communication. Finally, we present the experimental result of our location based application using a graphical user interface that shows the multimedia service execution of selected client device types such as desktop PC, notebook and PDA.

Feasibility of QoS control based on QoS mapping over IP networks

This paper proposes a method for testing feasibility of QoS control based on QoS mapping. In multimedia applications over IP networks, it is important to investigate how we enhance user-level QoS of audio–video transmission. As one of the methods, we can control QoS at lower levels so that user-level QoS keeps high according to a result of QoS mapping. However, there is no guarantee that a given scheme of QoS control at lower levels can give desirable user-level QoS. Therefore, we must examine the feasibility of the QoS control. In order to test it, we introduce concepts of the feasibility space and the decision boundary, which are obtained by the QoS mapping with multiple regression analysis. To show the effectiveness of our method, as an illustration, we utilize the simulation results in a previous work by the authors’ research group. The simulation treats EDCA of IEEE 802.11e and VTR media synchronization control as node-level QoS control and application-level one, respectively.

에이전트 기반 화상회의 시스템에서 협조 프로토콜의 확장 및 평가

본 논문에서는 에이전트 기반 화상회의 시스템에 있어서 QoS의 자율적 조정 기능을 실현하기 위한 협조 프로토콜의 확장을 제안하고, 실장 및 실험을 통하여 그 유효성을 확인한다. 에이전트 기반 화상회의 시스템의 자율적 조정이란, 화상회의 중에 발생하는 이용자의 요구 및 시스템의 자원 상황의 변화에 대하여 시스템 내 기능 및 성능을 조정하는 것에 의해서 대처하는 구조이다. 기존 협조 프로토콜은 에이전트간의 긴밀한 협조 동작을 실행하기 위해서 그 기능이 부족하고 시스템내 자원의 효과적 활용이 충분하지 않았다. 따라서 기존의 협조 프로토콜에 대하여 협조 상태를 도입하고, 퍼포먼스의 확장, 타협 레벨의 도입을 시도하여 실장 및 실험 평가를 수행하였다. 그 결과 에이전트간에서 더욱 더 고도한 협조 동작이 가능하게 되어 기존보다 시스템의 유연성이 향상되었음을 확인하였다. In this paper, we propose the extension of cooperation protocol which realizes the autonomous control of QoS and show its effectiveness with implementation and experiments of our agent-based videoconference system. The autonomous QoS control in the agent-based videoconference system means the framework of adjusting its functions/abilities by itself to cope with the changes of user requirements and system resource situations. But, the original cooperation protocol used by the agent-based videoconference system is not enough to perform cooperation closely to use the limited resources effectively. In our proposal, the cooperation protocol is offended in the following points: (1) introducing a cooperation states, (2) extension of performatives, (3) introducing compromise levels. We embedded the proposed protocol to the agent-based videoconference system and experimented the behavior of the system. According to the experiments on this prototype system, we confirmed that the flexibility of the system is improved.

Hybrid optimization for QoS control in IP Virtual Private Networks

A multiservice IP Virtual Private Network is considered, where Quality of Service is maintained by a DiffServ paradigm, in a domain that is supervised by a Bandwidth Broker (BB). The traffic in the network belongs to three basic categories: Expedited Forwarding (EF), Assured Forwarding (AF) and Best Effort (BE). Consistently with the DiffServ environment, the Service Provider's Core Routers (CRs) only treat aggregate flows; on the other hand, the user's Edge Routers (ERs) keep per-flow information and convey it to the BB. The latter knows at each time instant the number (and the bandwidth requirements) of flows in progress within the domain for both EF and AF traffic categories. A global strategy for admission control, bandwidth allocation and routing within the domain is introduced and discussed in the paper. The aim is to minimize blocking of the ''guaranteed'' flows (EF and AF), while at the same time providing some resources also to BE traffic. In order to apply such control actions on-line, a computational structure is sought, which allows a relatively fast implementation of the overall strategy. In particular, a mix of analytical and simulation tools is applied jointly, by alternating ''local'' decisions, based on analytical models, with flow-level simulation that determine the effect of the decisions on the whole system and provide feedback information. The convergence of the scheme (under a fixed traffic pattern) is investigated and the results of its application under different traffic loads are studied by simulation on three test networks.

Energy-Efficient Wireless Packet Scheduling with Quality of Service Control

In this paper, we study the problem of packet scheduling in a wireless environment with the objective of minimizing the average transmission energy expenditure under individual packet delay constraints. Most past studies assumed that the input arrivals followed a Poisson process or were statistically independent. However, traffic from a real source typically has strong time correlation. We model a packet scheduling and queuing system for a general input process in linear time-invariant systems. We propose an energy-efficient packet scheduling policy that takes the correlation into account. Meanwhile, a slower transmission rate implies that packets stay in the transmitter for a longer time, which may result in unexpected transmitter overload and buffer overflow. We derive the upper bounds of the maximum transmission rate under an overload probability and the upper bounds of the required buffer size under a packet drop rate. Simulation results show that the proposed scheduler improves up to 15 percent in energy savings compared with the policies that assume statistically independent input. Evaluation of the bounds in providing QoS control shows that both deadline misses and packet drops can be effectively bounded by a predefined constraint.

QoS Control in Next-Generation networks[ Guest Editorial

The three articles in this special section are devoted to quality of service control in next generation networking.

Extending QoS from Radio Access to an All-IP Core in 3G Networks: An Operator's Perspective

The convergence of wireless radio networks with all-IP networks has gained significant attention due to the ever increasing proliferation of IP technologies toward base stations as well as advances in air interfaces and wireless multimedia applications. Within standardization bodies, significant efforts are underway to address the support of QoS within the radio access network and Internet multimedia subsystem. For successful end-to-end application delivery, QoS and user profile unification are critical challenges, as is the intertwined policy enforcement between the IMS and the radio network. In this article we present a comprehensive analysis of QoS signaling over the integrated RAN and IMS domains. By using an imaginary service example, referred to as family media service, we analyze the specifics of end-to-end QoS invocation, control, and policy enforcement, including roaming scenarios. Based on laboratory measurements and simulations, we assess the call-setup delay, and recommend RAN and IMS signaling optimizations for delay reduction. We conclude the article by outlining open issues and proposing viable solutions.