Adaptive call admission control for QoS provisioning in multimedia wireless networks

An important quality-of-service (QoS) issue in wireless multimedia networks is how to control handoff drops. We propose admission-control algorithms that adaptively control the admission threshold in each cell in order to keep the handoff-dropping probability below a predefined level. The admission threshold is dynamically adjusted based on handoff-dropping events. We first present a simple admission-control scheme that brings out an important performance evaluation criterion - intercell fairness - and serves as a reference point. We then investigate the intercell unfairness problem and develop two enhanced schemes to overcome this problem. The performance of these protocols is benchmarked and compared with other competitive schemes. The results indicate that our schemes perform very well while, in addition, achieving significantly reduced complexity and signaling load.

The Quality of Service (QoS) support for multimedia multi-user sessions is essential to the success of fourth generation mobile networks. However, it requires the QoS control for those sessions independently of the movement of users, QoS model, and link capacity supported by wired and wireless networks in the end-to-end session path. This paper presents the Multi-user Session Control (MUSC) mechanism to provide QoS mapping and QoS adaptation of multi-user sessions over heterogeneous and mobile networks. The coordination of the QoS mapping and QoS adaptation controllers allows the adaptation of the session to the current network conditions and the dynamic selection of the most suitable network service class to map the session. The MUSC control is based on the session requirements, existing services class and their available bandwidth. Performance evaluation shows the impact of the MUSC proposal by analysing its convergence time, as well as the one-way delay and throughput of multi-user sessions in a QoS-aware mobile scenario.

The evolution of the World Wide Web service has incorporated new distributed multimedia conference applications, powering a new generation of e-learning development and allowing improved interactivity and prohuman relations. Groupware applications are increasingly representative in the Internet home applications market, however, the Quality of Service (QoS) provided by the network is still a limitation impairing their performance. Such applications have found, in multicast technology, an ally contributing for their efficient implementation and scalability. Additionally, considering QoS as a design goal at the application level becomes crucial for groupware development, enabling QoS productivity to applications. The applications’ ability to adapt themselves dynamically according to the resources availability can be considered a quality factor. Tolerant real-time applications, such as video conferences, are in the frontline to benefit from QoS adaptation. However, not all include adaptive technology able to provide both end-system and network quality awareness. Adaptation, in these cases, can be achieved by introducing a multiplatform middleware layer responsible for tutoring the applications’ resources (enabling adjudication or limitation) based on the available processing and networking capabilities. Congregating these technological contributions, an adaptive platform has been developed integrating public domain multicast tools, applied to a Web-based distance learning system. The system is user-centered (e-student), aiming at good pedagogical practices and proactive usability for multimedia and network resources. The services provided, including QoS adapted interactive multimedia multicast conferences (MMC), are fully integrated and transparent to end-users. QoS adaptation, when treated systematically in tolerant real-time applications, denotes advantages in group scalability and QoS sustainability in heterogeneous and unpredictable environments such as the Internet.

The emerging IEEE 802.11e standard for wireless local area networks (WLANs) has been proposed to support quality of service (QoS) by assigning different channel access parameters (CAPs) to different access categories (ACs). As an important part of QoS, an admission control scheme is required to maximally utilize the wireless medium resources and to efficiently admit the upcoming real time traffic while not compromising the QoS of existing traffic. In this paper, we propose a novel admission and congestion control scheme which obtains the admission control parameters through existing analytical model and traffic QoS requirements. It then dynamically updates the CAPs based on periodical monitoring of current channel conditions. Through numerical analysis and extensive simulation, results show that such a scheme could provide the guaranteed QoS for admitted real-time traffic in terms of guaranteed throughput achievement, bounded maximum delay and bounded maximum dropping rate while maintaining good channel utilization

Next generation wireless networks target to provide quality of service (QoS) for multimedia applications. In this paper, the system supports two QoS criteria, i.e., the system should keep the handoff dropping probability always less than a predefined QoS bound, while maintaining the relative priorities of different traffic classes in terms of blocking probability. To achieve this goal, a dynamic multiple-threshold bandwidth reservation scheme is proposed, which is capable of granting differential priorities to different traffic class and to new ad handoff traffic for each class by dynamically adjusting bandwidth reservation thresholds. Moreover, in times of network congestion, a preventive measure by use of throttling new connection acceptance is taken. Another contribution of this paper is to generalize the concept of relative priority, hence giving the network operator more flexibility to adjust admission control policy by incorporating some dynamic factors such as offered load. The elaborate simulation is conducted to verify the performance of the scheme.

The paper proposes an adaptive admission control (AC) policy, that reduces call dropping probability, resorting to rate adaptation in accordance with the instantaneous connection configurations. We describe the philosophy of the proposed adaptive scheme and analyze the effective call dropping probability when considering a single cell UMTS scenario with an additive white Gaussian noise (AWGN) channel. Our simulations demonstrate that, by employing the proposed scheme, the network performance can be extremely increased while the quality of service (QoS) requested is respected.

Wireless multimedia services have to rely on strict quality of service (QoS) requirements to reach the feasibility, including guaranteed available bandwidth, tight delay constraint, and hard jitter tolerance. WiMAX has emerged as one of the most promising broadband wireless access technologies to support these types of services. To guarantee the QoS of connections, CAC (Call Admission Control) can grant a new call only while the required bandwidth is available. With concern about connection capacity, the CAC seems rigid and turns into an obstacle instead while the bandwidth of some connections could be stolen temporarily. Thus, adaptive admission control, differing from the conventional CAC, can flexibly increase connection capacity by stealing bandwidth based on user streaming buffer (USB). A connection in sufficient USB state implies that the undergoing streaming application can perform smoothly even if its bandwidth is stolen temporarily. Therefore, how to determine the USB state of each connection is the most important topic in this study. In order to effectively decrease the risk of system overuse arising from stealing bandwidth, the adaptive admission control is extended by means of an intelligent mechanism to decide the USB states. The simulation results show the proposed intelligent mechanism utilizing fuzzy neural network (FNN) really outperforms than the adaptive admission control in terms of controlling the probability of poor application performance. With approximate connection capacity (or call blocking probability), the intelligent resource management indeed decreases the risk of system overuse.

An integrated bandwidth allocation and admission control framework for the support of heterogeneous real-time traffic in class-based IP networks

Admission control is a key management function in wireless networks, particularly wireless mesh networks (WMNs), in order to support multimedia applications that require quality of service (QoS) guarantees. Even using state of the art schemes to provide QoS, if the amount of traffic in the network is allowed to increase in an uncontrolled manner, network performance will deteriorate significantly degrading the QoS for all network traffic. With admission control, a new flow is admitted only if the QoS requirements of all flows in the network still can be met after the new flow begins. This paper introduces a distributed admission control scheme, called RCAC (routing on cliques admission control) for WMNs. We propose an analytical model that enables computing the appropriate admission ratio to guarantee that the loss rate in the network does not exceed a target value; the model also allows computing end-to-end delay necessary to process flow requests with delay constraints. RCAC achieves scalability since it partitions the network into cliques; only clique heads are involved in the admission control procedure. Simulations, using ns-2, demonstrate that RCAC accepts new incoming flows only when the network target loss rate and end-to-end delay are satisfied and maintains relatively high resource utilization in a dynamic traffic load environment.

Quality of Service (QoS) has been widely used to support dynamic Web Service (WS) selection and composition. Due to the volatile nature of QoS parameters, QoS prediction has been put forward to understand the trend of QoS data volatility and estimate QoS values in dynamic environments. In order to provide adaptive and effective QoS prediction, we propose a WS QoS prediction approach, named WS-QoSP, based on the technique of forecast combination. Different from the existing QoS prediction approaches that choose a most feasible forecasting model and predict relying on this "best" model, WS-QoSP selects multiple potential forecasting models, combines the results of the selected models to optimize the overall forecast accuracy. Results of real data experiments demonstrate the diversified forecast accuracy gains by using WS-QoSP.

The multimedia streams over the wireless access networks has increased dramatically over the past few years. Since the wireless link is featured with restricted bandwidth and limited resources, increasing demand of real-time applications imposes challenges on wireless networks to provide Quality of Service (QoS). Plenty of schemes were proposed to provide QoS, among which the admission control is a typical method. However, admission control mechanisms only consider the case at the network entering phase. After the admission, another mechanism is needed to continue to monitor the ongoing traffic and to react to fluctuation of resource consumption during the connection. Therefore, other than only using admission control schemes, which try to restrict access to the network, schemes to control on-going best-effort background are proposed in this paper. The proposed dynamical halting and resuming schemes of background traffic provide a finer way to allocate resources for video streams. It is shown via extensive simulations that proposed schemes can provide direct and solid enhancement of Quality-of-Experience (QoE) for video subscribers, and achieve good tradeoff between video quality and bandwidth utilization.

Future wireless mobile multimedia networks are likely to adopt micro/pico cellular architectures. A consequence of using small cell sizes is the increased rate of call handoffs as mobile terminals move between cells during the holding times of the calls. In a network supporting multimedia services, the increased rate of call handoffs makes it very difficult for the network to guarantee the quality of service (QoS) promised to a call at setup. This paper describes a handoff priority scheme which reduces the probability of call handoff failures in such a mobile multimedia network. The impact of this admission control policy on packet level performance is studied analytically for a homogeneous network supporting a mix of wideband and narrowband calls.

Large scale distributed real time and embedded (DRE) applications are complex entities that are often composed of different subsystems and have stringent Quality of Service (QoS) requirements. These subsystems are often developed separately by different developers increasingly using commercial off-the shelf (COTS) middleware. Subsequently, these subsystems need to be integrated, configured to communicate with each other, and distributed. However, there is currently no standard way of supporting these requirements in existing COTS middleware. While recently emerging component-based middleware provides standardized support for packaging, assembling, and deploying, there is no standard way to provision QoS required by the DRE applications. We have previously introduced a QoS encapsulation model, qoskets, as part of our QuO middleware framework that can dynamically adapt to resource constraints. In this paper we introduce implementing these QoS behaviors as components that can be assembled with other application components. The task of ensuring QoS then becomes an assembly issue. To do so we have componentized our QuO technology instead of integrating QuO into the middleware as a service. To date, we have demonstrated our approach of QoS provisioning in MICO, CIAO, and Boeing’s Prism component middleware. We present experimental results to evaluate the overhead incurred by these QoS provisioning components in the context of CIAO CCM. We use a simulated Unmanned Aerial Vehicle (UAV) application as an illustrative DRE application for the demonstration of QoS adaptations using qosket components.

Web quality of service (QoS) control can effectively prevent a Web Server from becoming overloaded. This paper presents an adaptive controller for Web QoS, which dynamically adjusts parameters of the proportional-integral (PI) controller according to the changes of the Web server model. Different from the existing methods based on the off-line system identification, the adaptive Web QoS controller is implemented based on the online system identification through a quantum-behaved particle swarm optimization (QPSO) algorithm and a mutated version of QPSO (MuQPSO). The proposed approach for online system identification by QPSO and MuQPSO shows better performance than genetic algorithms and the particle swarm optimization algorithm on the simulation tests. Then, the performance of the adaptive controller for Web QoS is tested in three experiments and compared with that of fixed PI controller. Experimental results show that the adaptive control employing online system identification by QPSO and MuQPSO algorithms is able to control the Web server resource more effectively in case of overload and, thus, improves the Web QoS.

Reducing signaling storm in wireless networks has become a major goal in designing today’s wireless communication systems. In order to reduce signaling storm, this paper addresses the issues of scheduling the signaling resources in wireless networks subject to both quality of service (QoS) and priority constraints. The applications in wireless communication systems are divided into three types,namely always-on applications, voice applications and the other applications. For all the applications, an admission control scheme is proposed that incorporates the reconfiguration of idle resources and the QoS negotiation. The QoS negotiation usually contains the following parts, QoS reduction of the new application, QoS reduction of the applications which have accessed to the network and the resources compulsory possession. When the signaling resources are limited, the proposed admission control scheme can improve the successful access rate of voice applications and reduce the impact of signaling storm in wireless network.