Management of Multimedia Networks and Services

In this paper, we define a new performance parameter, named

PPT

, for 802.11 DCF, which binds successful transmission probability and saturation throughput together. An expression of optimal minimum contention windows (

CW

min

)

is obtained analytically for maximizing PPT. For simplicity, we give a name DCF-PPT to the 802.11 DCF that sets its

CW

min

according this expression. The simulation results indicate that, compared to 802.11 DCF, DCF-PPT can significantly increase the PPT and successful transmission probability (about 0.95) in condition that the saturation throughput is not decreased.

Wireless sensor networks are composed of a large number of sensors densely deployed in inhospitable physical environments. How to disseminate information energy efficiently throughout such a network is still a challenge. Although energy efficiency is a key concern in wireless sensor networks, it often introduces additional delay. In this work, we first propose an Energy*Delay efficient routing scheme called

C

2

E

2

S

(Cluster and Chain based Energy*Delay Efficient Routing Scheme) for wireless sensor networks. This scheme is a combination of cluster-based and chain-based approaches. Next, we propose (1) an Energy*Delay-aware routing algorithm for sensors within each

k

-hop cluster, (2) an Energy-efficient chain construction algorithm for clusterheads. We also consider the network lifetime as an important factor as opposed to other approaches. The simulation results show that

C

2

E

2

S

consumes less energy, balances the energy and delay metrics, as well as extends the network lifetime compared with other approaches.

We present feedback control techniques to intelligently support priorities of soft handoff calls during call admission control (CAC) in power-controlled DS-CDMA multicellular networks. We design a classic proportional controller to dynamically solve resource management problems, which arise during run-time adaptation, via continuously monitoring real-time system performance to adjust system parameters accordingly. Performance evaluation reveals that the solution not only has excellent stability behavior, but also meets zero steady state error and settling time requirements.

We determine the gain that can be achieved by incorporating movement prediction information in the session admission control process in mobile cellular networks. The gain is obtained by evaluating the performance of optimal policies achieved with and without the predictive information, while taking into account possible prediction errors. We evaluate the impact of predicting only incoming handovers, only outgoing or both types together. The prediction agent is able to determine the handover instants both stochastically and deterministically.Two different approaches to compute the optimal admission policy were studied: dynamic programming and reinforcement learning. Numerical results show significant performance gains when the predictive information is used in the admission process, and that higher gains are obtained when deterministic handover instants can be determined.

We propose a novel adaptive reservation scheme designed to operate in association with the well-known Multiple Guard Channel (MGC) admission control policy. The scheme adjusts the MGC configuration parameters by continuously tracking the Quality of Service (QoS) perceived by users, adapting to any mix of aggregated traffic and enforcing a differentiated treatment among services during underload and overload episodes. The performance evaluation study confirms that the QoS objective is met with an excellent precision and that it converges rapidly to new operating conditions. These features along with its simplicity make our scheme superior to previous proposals and justify that it can satisfactorily deal with the non-stationary nature of an operating network.

Recent trends in computing have been driving the demand for mobile multimedia applications, specifically distributed virtual environments (DVEs). These applications must deal with the variable resource availability of both connection and client device in order to achieve real-time event communication. Relevance-based event filtering is used to explore event stream adaptation in response to variable QoS. Results show that the performance gains from such adaptation are inconsistent due to the irregular nature of event communication. Increased reliability is proposed through dynamic consideration of the resource requirements of the various adapted event stream solutions.

A mobile network is a set of IP subnets connected to the Internet through one or more mobile routers. When a mobile router moves into or out of a subnet, it suffers from the same handover problems as a mobile node does in the Mobile IP. A seamless handover scheme with dual mobile routers is proposed for a large and fast moving network such as trains. Each of the dual mobile routers is located at each end of the moving network for space diversity, but they perform a handover as one logical mobile router. Since one of the two mobile routers can continuously receive packets from its home agent, the proposed scheme can provide no service disruption time resulting in no packet losses during handovers. Performance evaluation showed that the proposed scheme can provide excellent performance for realtime service, compared with existing schemes.

A Service-specific Overlay Network (SSON) is a virtualization concept proposed for customized media delivery in the Ambient Networks architecture [1]. The service specific media delivery network has to be constructed dynamically without prior knowledge of the underlying physical network. This process must consider unique properties, such as routing the media flow through strategic locations that provide special media processing capabilities (for example, media transcoding, caching and synchronization) inside the network. In today’s dynamic and mobile network environments establishing an optimal SSON with a reasonable time and message/traffic complexity is challenging. This paper proposes a pattern-based methodology to establish the SSONs. This scheme enables setting up SSONs on demand without prior knowledge of the network topology and where the media processing capabilities are located in the underlying network. A new pattern referred to as

path-directed

search pattern is devised and applied to search for potential overlay nodes and to configure their media processing functions accordingly. The scheme is implemented on a pattern simulation tool and the result shows that SSONs of high quality can be built with a reasonable time and message/traffic complexity.

Multimedia applications, such as videoconferences, require an efficient management of the Quality of Service (QoS) and consist of a great number of participants which requires the use of multicast routing protocol. Unlike unicast protocol, multicast protocol handles a great number of users while minimizing both network overhead and bandwidth consumption. However, combining multicast routing and QoS guarantee is a hard challenging task, known as the delay and delay variation multicast problem. This problem is considered as an NP-complete problem, and is resolved only by heuristic solutions. In this paper, we propose a scalable multicast algorithm that tackle the delay and delay variation by exploiting the Hierarchic Tree construction concepts. In fact, the proposal algorithm guarantees QoS by: (i) reducing the network charge; (ii) decreasing the multicast delay variation. We compare the performance of our algorithm against the DDVCA (Delay and Delay Variation Constraint Algorithm) scheme and demonstrate lower multicast delay variation and efficient bandwidth utilization while maintaining lower time complexity.

This paper proposes a semi-reliable multicast protocol that aims to increase the quality of video streams transmitted in large-scale systems without overloading the video source and the communications network. This protocol, which is based on the IP multicast protocol and the MPEG standard, evaluates the necessity of retransmitting lost packets taking into account the capacity of the corresponding MPEG frames to improve the quality of the video stream. The proposed protocol relies on the neighboring receivers for retransmitting lost packets, resulting in much faster recovery, which is vital in order to receive retransmitted packets in time to be exhibited. Besides, this strategy avoids overloading the video source, making it more scalable than the traditional approach of retransmitting from the source.

New requirements of service-oriented fault management are analyzed and a framework MDFM (Multi-Domain Fault Manager) is proposed in this paper to solve the service fault localization problem in multi-domain context. Different from current solutions, our approach decomposes SLS (Service Level Specification) based on network capability, and monitor service performance in each domain along the end-to-end path. As a result, MDFM can localize the approximate domain rapidly on which the root cause resides, therefore causative region is narrowed down and computation cost for fault analysis is reduced. Faults on both server and client sides are considered in MDFM. A prototype has been implemented to prove the feasibility and efficiency of our service fault management framework.

The quality of audio in IP telephony is significantly influenced by the impact of packet loss rate, burstiness and distribution on a specific audio compression technique. In this paper, we propose a novel statistical-based on-line audio quality assessment framework, Audio Genome, that can deduce the audio quality of an on-going Internet audio for many different codecs under any network loss condition at real-time. Our approach is superior to proposed learning-based techniques in terms of computational speed and ease of deployment. Our extensive evaluation experiments, that include large simulation scenarios, show that our approach is accurate and viable for adaptive real-time audio mechanisms. Finally, we show a deployment of Audio Genome as an integral part of an adaptive rate control mechanism.

The telecommunications landscape is undergoing a period of dramatic change. A near term next generation network (NGN) is emerging characterized by a rich set of services and a dynamic and competitive marketplace where innovation and time to market will be critical success factors. Changing consumer-provider relationships, competitive pressures and new e-commerce technologies will accelerate the use of real time payment and prepayment techniques. This will increase the demand for real-time processing of charging data. Powerful, new, charging support systems will be needed to enable real time charging of these new services. Policy based management appears to offer potential solutions.

New deployment scenarios tend to consider the requirement of session continuity for service provisioning, especially multimedia streaming, to limited heterogeneous portable devices roaming among wireless localities. In particular, multimedia streaming should not experience any interruption while clients roam in wired-wireless integrated networks based on the standard best-effort Internet. The paper proposes an application-level middleware approach to proactively overcome Wi-Fi handoff and maintain multimedia session continuity in the wireless Internet by exploiting mobile proxies running on the wired network. Mobile middleware proxies locally support resource-limited clients, avoid packet losses during handoffs, pre-fetch local buffers with multimedia contents before handoff occurrence, and possibly reconfigure/renegotiate ongoing sessions after handoffs. Experimental results show that, notwithstanding the application-level implementation, mobile proxies can avoid streaming discontinuities with good efficiency in wireless-wired integrated networks even if their pro-activity is based on simple and lightweight handoff prediction techniques.

A voice over IP quality monitoring architecture based on the development of the VQuality library is described. VQuality implements the E-model and its extensions for objective voice quality measurement. The library also supports generation of a customized voice quality CDR with extensions that permit transfer of call quality parameters measured over different instants of time, besides interacting with a RADIUS server for data collection. The framework is exemplified in the context of the fone@RNP VoIP service and VoIP clients incorporating the new functionality are shown.

Providing Quality of Service(QoS) in distributed networks, such as multimedia ad hoc wireless network, also requires well defined scheduling schemes. However, due to the distributed nature of ad hoc networks, nodes may not be able to determine the next packet to transmit as in the centralized networks. Thus, it is a non-trivial issue to provide bounded delay guarantee, with fair share of resources. In this paper, we implement a scheduling scheme named delay guaranteed fair queueing (DGFQ) in a multimedia ad hoc wireless network with distributed manner. According to the performance evaluation results, both average and maximum delay could be controlled with varying

service differentiation coefficient

. In summary our new scheme can manages the delay performance of multimedia traffic in the distributed network environment.

Index terms:

Fair queueing, Ad hoc network, Quality of Service (QoS), Multimedia network.

The paper describes a management-oriented model for cost-effective ‘data connectivity’ provisioning between the end-point entities of networked multimedia applications. The ‘connectivity’ service provider (SP) may maintain multiple policy-based protocol mechanisms that differ in the bandwidth allocation strategies exercised on transport networks and the extent of QoS guarantees enforced for application-level data flows. The required QoS is prescribed through a service interface, with the SP instantiating one of the policy modules with appropriate parameters to meet the QoS requirements. The model allows dynamic switching from one policy module to another, based on a

cost

associated with bandwidth usage by the network infrastructure for a given QoS offering. The management functions of SP monitor the changes and/or outages in network bandwidth in a dynamic setting, and map them onto connectivity costs incurred by the selected policy mechanism. To accommodate this end-to-end connectivity management, the SP employs an extended form of ’diffserv’-style traffic classification for flow aggregation purposes and ’intserv’-style resource control for bandwidth allocation purposes.

This paper proposes to integrate security parameters into the Service Level Specification (SLS) template proposed in the Tequila project to improve SLA-based management of QoS [8], [21]. Integrating those parameters in the QoS part of the Service Level Agreement (SLA) specification is essential in particular for secure multimedia services since the QoS is negotiated when the multimedia service is deployed. Security mechanisms need to be negotiated at deployment time when sensible multimedia information is exchanged. In this paper we show that including security parameters in the SLA specification improves the SLA-based management of QoS and therefore the negotiation, deployment and use of the secure multimedia service. The parameters this paper proposes to integrate have the advantage to be understandable by both the end-users and service providers.

This paper presents an application-layer middleware that applies a microeconomic model to help multimedia applications utilize available bandwidth in a way that maximizes the user’s net benefit. The key components are a bandwidth broker that puts the supply of available bandwidth on a virtual market residing inside the application, and utility functions for each media, which are used to calculate their relative gain to the user at each bandwidth level. Basic supply and demand principles are used where the broker raises a virtual price if the total demand from all media exceeds the available supply, or lowers the price if demand is lower than the available supply. The advantage of the middleware is that it allows problems related to network management (usually affecting the supply) and human computer interaction (usually affecting demand) to be researched and integrated separately into an application and combined to leverage bandwidth in the best possible way. As a proof of concept, a prototype has been built by integrating the middleware into Marratech Pro, a commercially available e-meeting application. The paper presents experimental results using this prototype.

SNMP-based network management is simple but lacks scalability and efficiency of processing the management data as the number of agents increases. XML-based network management is a new paradigm developed to overcome these limitations. One of the main challenges is how to distribute the management tasks to achieve efficiency and scalability. In this paper, we propose a framework using JPVM to distribute the management tasks among multiple gateways. We compare the performance of three approaches, namely the static weighted load balancing approach, the equal work non-weighted load balancing approach, and the single gateway approach. The first approach provides better communication time between the XML-based manager and the SNMP agents. It takes advantage of the XML, DOM, and Java servlets.

Some network management trends are currently analysing the application of several generic technologies that include Web Services and Ontologies. Web Services can provide an interface to access to managed resources. On the other hand, ontologies provide a way to represent management information. Web Services interfaces can be defined using OWL-S, an ontology of services that semantically describes the set of operations a Web Service provides. This can be useful in configuration management, where each network resource defines the way it can be configured. This paper presents a proposal to describe with the OWL Service ontology the management interfaces based on Web Services. To illustrate this approach, an example is provided in which OWL-S is used to specify the processes needed to configure a resource.

The tasks of operating and managing diverse network devices from multiple vendors are getting more difficult and complicated. For that reason, IETF Netconf Working Group has been standardizing network configuration management. The Netconf protocol is an output of that standardization and can be used to effectively manage various devices on a network. However, it is still problematic for the manager to discover and manage configurable parameters in various devices. This paper proposes a method that can quickly discover devices and their parameters as well as methods to manipulate the configuration information on them. We present the architecture for XCMS-WS which meets this mechanism. Using the Web Services technologies, we have develioed a more powerful and flexible system than our previous XCMS. For validation, we have applied XCMS-WS for the configuration management of NG-MON, a distributed, real-time Internet traffic monitoring and analysis system.

This paper presents a Java agent application framework and shows its example through the implementation of an agent application service. This framework comprised of agent, agent system, agent master and agent manager components. Each component is connected to others via an agent interface, and messages are passed through these interface points. By using this framework, it is possible to deploy a new agent application service with simple and efficient operation. Herein, we implemented the agent application service network using a Java agent application framework. Specifically, the implemented network was a contents distribution network using an agent service, and the network was both controlled and managed with the agent framework interface. In our test, the network service decreased network traffic while preserving reasonable quality through the adequate deployment and management of agent components.

In recent years, a wide variety of wireless access networks that support multimedia services have been emerging with different characteristics. The service areas of many of these networks overlap so that a mobile user from an overlapped service area can access any network that supports the user’s application. A mobile user can take advantage of the availability of such heterogeneous multimedia networks only when the user terminal is equipped with a mechanism that can select an optimal network for the application. This paper proposes a novel analytical framework of such a mechanism. For this purpose we define the user-centric performance and user-centric cost, and derive their expressions. The user-centric performance, which is also a measure of the user-perceived quality of service (QoS), relates the requirements of user applications with the parameters of network services. The user-centric cost is measured by the user’s willingness to pay the price and allow for the consumption of the mobile terminal’s resources for accessing the network services. Based on the performance and cost analyses, we describe a network selection mechanism and discuss its implementation issues. We then present an example system to numerically elaborate the functioning of the proposed mechanism.

Content Distribution Network (CDN) technology has been proposed to deliver content from content nodes placed at strategic locations on the Internet. However, only companies or organizations, who can pay for the services of CDNs, have the privilege of using CDNs to distribute their content. Individual users (peers) have to resort to more economical peer-to-peer (P2P) technologies to distribute their content. Although P2P technologies have demonstrated tremendous successes, they have inherent problems such as the instability and the limited bandwidth of peers. In this paper, we propose a new approach to build bandwidth bounded data distribution trees inside a CDN so that external peers can leverage the power of a CDN’s infrastructure for distributing their content. Our performance evaluation shows that, with some limited help from a CDN, the content distribution time among peers can be speeded up from 1.5 to 3 times.

Incompatibility of different QoS (Quality of Service) mechanisms and heterogeneity of different vendors’ network devices are the major obstacles for providing end-to-end QoS in IP network. Inspired by Java, we propose an end-to-end QoS solution in this paper, i.e. QoSJava, which decouples QoS requirements from network details. By QoS Mechanisms Adapter and Device Driver, which act as “Java Virtual Machine”, QoSJava enables interoperation between different QoS mechanisms and cooperation of dissimilar network devices. A prototype of QoSJava has been implemented, and the experimental results prove that network devices can be configured automatically to provide an end-to-end QoS. Moreover, QoSJava is not only compatible with current QoS mechanisms and devices, but open to new QoS solutions and advanced devices in the future.

Video streaming over peer-to-peer networks has attracted a lot of interest recently. However most of the research on streaming in peer-to-peer networks focused on schemes where all the clients have the whole movie. In this paper we propose schemes where clients store only partial movie after viewing the movie. We propose cooperative schemes where replication is done in a way that maximizes a global function and uncooperative schemes where each node makes replication decision independently. We evaluate both schemes using extensive simulation. Simulation results show that cooperative schemes perform better but they are harder to implement and maintain. Uncooperative schemes are simpler, based on a distributed algorithm but they suffer from lower performance.

Emerging networked multimedia applications in the Internet require special supports from the underlying network such as real-time treatment, guaranteed service, and different levels of network service quality. However, the current Internet having the same-service-for-all paradigm is not suitable for these multimedia communications. In this paper, firstly we introduce a scalable and adaptive quality of service (QoS) mapping framework over the differentiated services (DiffServ, or DS) network. The framework is composed of the functionalities of proactive and reactive QoS mapping controls to provide reliable and consistent end-to-end service guarantee. On this framework, we propose a network-adaptive QoS control to have a feedback of instantaneous network fluctuation. The main idea of our proposal is to employ explicit congestion notification (ECN) mechanism in conjunction with the proactive QoS mapping control at the ingress of a DiffServ domain. It is possible not only that the status of network classes is notified to the end-host applications but also that a reactive QoS adjustment is triggered at the ingress side. Our simulation results illustrate how to enhance the QoS performance of streaming video in the under-provisioned network.

QoS management is nowadays a mandatory feature in current broadband residential gateways developments. The interconnection between different QoS domains has to be treated into different steps in order to provide a reliable end-to-end QoS solution. The scenario analyzed in this paper is the mapping between QoS requirements in residential users connected to a broadband access network across a multiservice broadband access gateway. Different approaches to provide QoS in the access network are discussed as well as their impact in the design of a residential gateway. An architecture of a gateway based on IMS (IP Multimedia Subsystem) as SIP-based signaling domain for multimedia services is presented with the corresponding adaptation to a broadband fixed access scenario according to Next Generation Networks (NGN) standardization. Finally, the implementation of a prototype of the QoS-enabled gateway, based on the Click! modular router [1], is described to demonstrate end-to-end QoS provisioning for multimedia services. This prototype allows us the demonstration of (1) an innovative way of extending gateway device functionalities using Click! and (2) the feasibility of residential gateway architecture proposed. The work presented in this paper has been developed within the framework of the 6

th

Framework Programme IST MUSE [2] project.

In order to improve the scalability of the IETF’s PBM architecture, we previously proposed an extension to this architecture. The aim of our proposal was to facilitate the support of on-demand resource allocation in stateless IP networks. The proposed schema distribute part of the decision making process but keeps centralized the bandwidth brokerage operation as this latter uses a critical resources (traffic matrix). Our current work aims to render the PBM architecture completely distributed by designing a scalable scheme for bandwidth brokerage. To that end, we propose using a proactive two-tier scheme in order to improve the scalability of the resource management procedures. In this paper, we present the proposed scheme, its design features and the set of experimentations we realized in order to demonstrate its performances.

With the growth of bandwidth, real-time video streaming service becomes popular. Such application is also considered a future killer application on Internet. Recent research efforts have demonstrated the promising potential of building cost-effective video streaming systems on top of peer-to-peer (P2P) networks. Since the peers have limited capacity, such as upstream bandwidth, each streaming session may involve multiple supplying peers. In this paper, we propose a novel strategy to retrieve a long-duration video from multiple peers which have arbitrary and restricted upstream bandwidth, such that the waiting time is minimized. In comparison with the previous work [13], our strategy can greatly improve the waiting time. In the arbitrary given examples, our strategy can improve the waiting time by 67%. To take into account the popular compressed video with variable bit rate, we also show how to apply our strategy readily to the VBR videos.

The growing heterogeneity and scalability of Internet services has complicated, beyond human capabilities, the management of network devices. Therefore, a new paradigm called autonomic networking is being introduced to control, in an efficient and automatic manner, this complex environment. This approach aims to enhance network elements with capabilities that allow them to choose their own behavior for achieving high-level directives. This so called autonomic network element should be able to optimize its configuration, ensure its protection, detect/repair unpredicted conflicts between services requirements and coordinate its behavior with other network elements.

In this paper, we present a research activity that investigates this new concept, and applies it to facilitate the configuration and the optimization of a multi-services IP network. This approach is a first step toward building a self-configured and self-optimized IP network that automatically supports the QoS requirements of heterogeneous applications without any external intervention. Different paradigms have been explored in order to model this behavior and to render network equipment autonomic. A laboratory prototype has been developed to highlight the autonomic behavior of the network to achieve heterogeneous QoS requirements of multimedia and data applications.