Provide Quality Of Service Guarantees Research Articles

An efficient bandwidth reservation and call admission control scheme for wireless mobile networks

With increasing use of mobile units for various applications, it has become imperative to provide services with quality of service (QoS) guarantees. Efficient utilization of the available bandwidth is an important issue in any QoS provisioning scheme. To this end, we propose techniques for bandwidth reservation and call admission control for wireless mobile networks. Our proposed techniques utilize the available bandwidth efficiently to provide QoS guarantee with reduced new call rejection and handoff call blocking. We have analyzed the performance of our scheme through extensive simulation studies. The results appear promising.

Providing deterministic quality-of-service guarantees on WDM optical networks

A major challenge in the design of future generation high-speed networks is the provision of guaranteed quality-of-service (QoS) for a wide variety of multimedia applications. In this paper we investigate the problem of providing QoS guarantees to real-time variable length messages (e.g., IP packets) in wavelength division multiplexing (WDM) optical networks. In particular, we propose a systematic mechanism comprised of admission control, traffic regulation, and message scheduling that provide guaranteed performance service for real-time application streams made up of variable-length messages. We formulate an analytical model based on the theory of max-plus algebra to evaluate the deterministic bounded message delay in a WDM network environment using our proposed QoS guarantee mechanism to determine the "schedulability conditions" of multimedia application streams, We also conduct a series of discrete-event and trace-driven simulations to verify the accuracy of the analytical model. The simulation results demonstrate that the analytic delay bound we obtained for our WDM optical network is valid and accurate.

Buffered fixed routing: a routing protocol for real-time transport in grid networks

We propose a new routing protocol called buffered fixed routing (BFR) for real-time applications on grid networks. While previous routing protocols for grid networks have been designed to improve network throughput, the BFR scheme is proposed to guarantee the end-to-end packet delay and sequencing without loss by using finite buffers at each node. Thus the proposed scheme can satisfy quality-of-service (QoS) requirements of real-time applications. The BFR scheme uses the token on the row ring to provide QoS guarantees. The performance of the BFR scheme is analyzed by using the Geom/Geom/1 queueing system under uniform traffic. In the simulation, the BFR scheme shows the zero-loss, high-throughput performance with the minimum delay variation compared to other routing protocols such as store and forward routing, deflection routing and vertical routing. In addition, it has shown the smallest average delay at intermediate and heavy loads.

An Approach to Quality of Service Management in Distributed Multimedia Application: Design and an Implementation

Most work related to quality of service (QoS) is concerned with individual system components, such as the operating system or the network. However, to support distributed multimedia applications, the entire distributed system must participate in providing the guaranteed performance levels. In recognition of this, a number of QoS architectures have been proposed to provide QoS guarantees. The mechanisms and schemes proposed by those architectures are used in a rather static manner since the involved entities, e.g., the network, sender and receiver, are known before the connection (call) set-up phase. In contrast to these architectures, we propose a general QoS management framework which supports the dynamic choice of a configuration of system components to support the QoS requirements for the user of a specific application. We consider different possible system configurations and select the most appropriate one depending on the desired QoS and the available resources. In this paper we present an overview of this general frameworks especially, we concentrate on QoS negotiation and adaptation mechanisms. To show the feasibility of this approach, we designed and implemented a QoS manager for distributed multimedia presentational applications, such as news-on-demand. The negotiation and adaptation mechanisms which are supported by the QoS manager are specializations of the general framework. The proposed framework allows to improve the utilization of system resources, and thus to increase the system availability; it also allows to recover automatically, if this is possible, from QoS degradations. Furthermore, it provides the flexibility to incorporate different resource reservation schemes and scheduling policies, and to accommodate new system component technologies.

The design of the TAO real-time object request broker

Many real-time application domains can benefit from flexible and open distributed architectures, such as those defined by the CORBA specification. CORBA is an architecture for distributed object computing being standardized by the OMG. Although CORBA is well-suited for conventional request/response applications, CORBA implementations are not yet suited for real-time applications due to the lack of key quality of service (QoS) features and performance optimizations. This paper makes three contributions to the design of real-time CORBA systems. First, the paper describes the design of TAO, which is our high-performance, real-time CORBA 2.0-compliant implementation that runs on a range of OS platforms with real-time features including VxWorks, Chorus, Solaris 2.x, and Windows NT. Second, it presents TAO's real-time scheduling service that can provide QoS guarantees for deterministic real-time CORBA applications. Finally, the paper presents performance measurements that demonstrate the effects of priority inversion and non-determinism in conventional CORBA implementations and how these hazards are avoided in TAO.

An adaptive bandwidth reservation scheme for high-speed multimedia wireless networks

In the next generation high-speed wireless networks, it is important to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. This paper proposes an admission control scheme based on adaptive bandwidth reservation to provide QoS guarantees for multimedia traffic carried in high-speed wireless cellular networks. The proposed scheme allocates bandwidth to a connection in the cell where the connection request originates and reserves bandwidth in all neighboring cells. When a user moves to a new cell and a handoff occurs, bandwidth is allocated in the new cell, bandwidth is reserved in the new cell's neighboring cells, and reserved bandwidth in more distant cells is released. The amount of bandwidth to reserve is dynamically adjusted, reflecting the current network conditions. The performance of the proposed scheme is evaluated through simulations of realistic cellular environments. The simulated network consists of a large number of cells, mobile users with various movement patterns are assumed, and a variety of multimedia applications (e.g., audio phone, video conference, video on demand, file transfer, etc.) is considered. It is shown that the proposed scheme provides small handoff dropping probability (i.e., the probability that handoff connections are dropped due to a lack of bandwidth) and achieves high bandwidth utilization.

Achievable QoS and scheduling policies for integrated services wireless networks

In Integrated Services Wireless Networks transmission resources are shared among geographically disperse applications with diverse Quality of Service (QoS) requirements and traffic characteristics. To provide QoS guarantees and use the bandwidth efficiently, call admission and scheduling functions are necessary. These functions should ensure the delivery of the target QoS to the supported applications while achieving statistical multiplexing gains, without explicit and continuous exchange of information between sources and scheduler. In this dissertation, call admission and transmission scheduling policies are studied for a TDMA system. Variable bit rate (VBR) applications with distinct QoS requirements and traffic characteristics are considered. In this environment, packets which cannot be transmitted over the frame following their arrival may be dropped (due to delay violations) or may be delayed to compete for service in the next frame, depending on the QoS requirements. The focus of the research is to determine the region of achievable multi-dimensional (non-degenerate) QoS vectors for heterogeneous VBR applications in this shared resource environment. Determining the region of achievable QoS is central to the admission control problem. For example, if with the addition of the new source, the new multi-dimensional target QoS vector is in the region of achievable QoS, then the call can be admitted. The problem of determining the region of achievable QoS vectors is formulated in a manner that makes it possible to investigate by employing polytope/convex space and game theory. As a result, the region of achievable QoS for heterogeneous applications in a interference/resource-limited wireless network is precisely described. In addition, it is possible to identify simple policies which deliver any given QoS vector within the region, by proving properties associated with the extreme points of the region. Together, call admission and scheduling are shown to ensure that the target QoS is delivered to each application. Finally, the impact that channel quality has on the region of achievable QoS is studied. In a wireless environment, packets are dropped not only due to the competition for the transmission resources, but also due to channel induced errors (interference). Thus, the physical channel can affect the region of achievable QoS as well. As a consequence, the region of achievable QoS vectors is shaped by the packet discarding process at both the transmitter and the receiver due to resource and interference limitations, respectively.

Open issues and challenges in providing quality of service guarantees in high-speed networks

In this paper we identify the challenges and open issues involved in providing quality-of-service (QOS) guarantees to sessions in a high-speed wide area network and briefly survey research in this area. Four approaches towards providing QOS guarantees are described and discussed: the tightly controlled approach, the approximate approach, the bounding approach, and the observation-based approach.