this paper, we present the design, implementation, and evaluation of the INSIGNIA QOS Framework that supports the delivery of adaptive services in mobile ad hoc networks. A key component of our QOS framework is the INSIGNIA signaling system, an in-band signaling system that supports fast reservation, restoration, and adaptation algorithms that are specifically designed to deliver adaptive service. The signaling system is designed to be lightweight and highly responsive to changes in network topology, node connectivity, and end-to-end quality of service conditions. The structure of the paper is as follows. We discuss our framework in the context of the related work and present the main design considerations that have influenced our thinking in Sections 2 and 3, respectively. Section 4 presents an overview of the INSIGNIA QOS framework. The detailed design of the INSIGNIA signaling system is given in Section 5. We evaluate our QOS framework in Section 6, paying particular attention to the performance of the signaling system under a variety of network conditions. Our simulation results show the benefit of the INSIGNIA QOS framework under diverse mobility, traffic, and channel conditions in support of fast reservation, restoration, and adaptation. Finally, we present our conclusion in Section 7

The specification and management of Quality of Service (QoS) is important in networks and distributed computing systems, particularly to support multimedia applications. The advent of portable lap-top computers, palmtops and Personal Digital Assistants with integrated communication capabilities facilitates mobile computing. This paper is a survey of QoS concepts and techniques for mobile distributed computing environments. The QoS attributes typically specified and negotiated for general communication systems are described as well as some QoS models. A brief overview is given of some practical systems described in the literature. The design issues relating to both mobile and nomadic computing are explained and then the specific QoS issues related to mobile and nomadic systems are discussed. The conclusion summarises the important issues relating to supporting QoS for mobile systems. Keywords Mobile systems, nomadic systems, quality of service, multimedia Quality of Service in Mobile...

By trading off temporal and spatial quality with available bandwidth, or manipulating the playout time of continuous media in response to variation in delay, audio and video flows can be made to adapt to fluctuating network conditions with minimal perceptual distortion. In this article the authors describe the implementation of an adaptive transport system that incorporates a QoS-oriented API and a range of QoS mechanisms that best assist multimedia applications in adapting to fluctuations in the delivered network QoS. The system, which is an instantiation of the transport and network layers of a QoS architecture, is implemented in a multi-ATM switch network environment with Linux-based PC end systems and continuous media file servers. A performance evaluation of the system configured to support a video-ondemand application scenario is presented and discussed. A novel aspect of the system is the implementation of a "QoS adaptation" algorithm which allows applications to del...

Display characteristics, network Quality of Service, and the user's current task all exhibit a wide range of variation when users interact with mobile and ubiquitous devices. It is desirable to enable applications to adapt to these variations. The user's experience in interacting with the application can be significantly enhanced by adapting the data presented. However, we find that naive degradation of data can quickly result in an unacceptable presentation.

We introduce a scalable application-level QoS adaptation service for roaming between wireless networks that are based on different technologies (‘inter-tech’ roaming). The service is part of a platform that supports the distribution of multimedia streams (e.g., a streamed TV channel) to mobile clients operating in a heterogeneous environment. Central to our approach is the notion of a service class, which is a domain-specific perceptual QoS level. Each domain in a wireless infrastructure must support a limited number of these service classes. Our adaptation service handles inter-tech roaming by handing a client off from one service class to another. In this paper, we focus on the design of the adaptation service’s client-side components. They combine the loss characteristics of the client’s network interfaces with configurable policies to decide when to initiate a handoff to a target service class and when to complete it. We conclude with some experimental resuults. 1.

A major trend in the Internet today is the push for ubiquitous access to rich multimedia content. Achieving this goal requires the incorporation of adaptation techniques, which will transform the media into various formats, suitable for a variety of devices with diverse communication and presentation capabilities. In this survey, we present the categories of adaptation techniques focusing on their characteristics and potential. We analyze various schemes in order to evaluate their effectiveness, performance, complexity, and applicability. We then describe the adaptation policies, methods and mechanisms that they use, along with the supporting mechanisms that aim in increasing the efficiency of the adaptation process. Finally, we present several case studies, commercial approaches and current trends in the area of ubiquitous access to Internet multimedia content. 1.

live multimedia broadcasts (e.g., for applications such as TV, radio, or e-cinema) to a potentially large number of mobile hosts that roam about in a wireless internet with hotspots. We take a user-oriented approach based on an application-level delivery infrastructure consisting of and managed by (value-added) service providers. The service providers are mobility-aware and offer broadcasts in configurations that are optimized for wireless links and mobile hosts. In hotspots, mobile hosts may be able to simultaneously reach several localized service providers through different interfaces. Within this context, we present the design of a lightweight application-level protocol that enables mobile hosts to select a service provider from which they want to receive a broadcast. Mobile hosts use the protocol to begin receiving a broadcast and to remain connected to the same logical broadcast as they move across subnets. The protocol is independent of the actual stream control protocol (e.g., RTSP) that service providers might use. We show how our protocol can be realized with the existing protocols SIP and SDP. The realization uses SIP in combination with SDP's offer-answer model in a new way.

Abstract. In this paper, we present ongoing work on an application-level platform that assists in broadcasting multimedia streams in heterogeneous mobile systems. Our work revolves around the notion of a technology domain, which is a set of resources that serve mobile clients connecting to the mobile system through a specific wireless technology. We consider the policies that technology domains use to (a) manage the availability of content channels and their perceptual quality levels, and (b) to manage the adaptation strategy that clients must follow in switching between quality levels. We discuss our future work in these areas, which will focus on adaptation as a result of clients roaming between different technology domains. 1.

Active Networks (AN) are investigated since several years, attempting to satisfy the increasing needs for highly customizable protocol mechanisms in an era where the Internet is threatened to become immutable due to its huge installed base. AN seem to be particularly useful in the context of QoS support. This paper investigates AN for On-demand QoS routing and proposes an approach called AQR. Simulation experiments are reported which show the (varying) benefits of AQR under various network conditions and traffic characteristics.

This thesis contributes toward the design of a new adaptive quality of service (QOS) paradigm for wireless ad hoc networks. We address some of the key performance problems in the broader realm of wireless ad hoc networks, including mobile ad hoc networks and emerging wireless ad hoc sensor networks. Wireless ad hoc networks represent autonomous distributed systems that are infrastructureless, fully distributed, and multi-hop in nature. Over the last several years, wireless ad hoc networks have attracted considerable research attention in the general networking and performance community. This has been fueled by recent technological advances in the development of multifunctional and low-cost wireless communication devices. Wireless ad hoc networks have diverse applications spanning several domains, including military, commercial, medical, and home networks. The results of all this research activity the wireless ad hoc networks are starting to move from the research domain into the real world and are being gradually integrated into our daily lives. Projections indicate that this will accelerate later in the decade, to the point where some analysts predict that these types of self-organizing