Ahmed Mehaoua

Adaptive packet video streaming over IP networks: a cross-layer approach

There is an increasing demand for supporting real-time audiovisual services over next-generation wired and wireless networks. Various link/network characteristics make the deployment of such demanding services more challenging than traditional data applications like e-mail and the Web. These audiovisual applications are bandwidth adaptive but have stringent delay, jitter, and packet loss requirements. Consequently, one of the major requirements for the successful and wide deployment of such services is the efficient transmission of sensitive content (audio, video, image) over a broad range of bandwidth-constrained access networks. These media will be typically compressed according to the emerging ISO/IEC MPEG-4 standard to achieve high bandwidth efficiency and content-based interactivity. MPEG-4 provides an integrated object-oriented representation and coding of natural and synthetic audiovisual content for its manipulation and transport over a broad range of communication infrastructures. In This work, we leverage the characteristics of MPEG-4 and Internet protocol (IP) differentiated service frameworks, to propose an innovative cross-layer content delivery architecture that is capable of receiving information from the network and adaptively tune transport parameters, bit rates, and QoS mechanisms according to the underlying network conditions. This service-aware IP transport architecture is composed of: 1) an automatic content-level audiovisual object classification model; 2) a reliable application level framing protocol with fine-grained TCP-Friendly rate control and adaptive unequal error protection; and 3) a service-level QoS matching/packet tagging algorithm for seamless IP differentiated service delivery. The obtained results demonstrate, that breaking the OSI protocol layer isolation paradigm and injecting content-level semantic and service-level requirements within the transport and traffic control protocols, lead to intelligent and efficient support of multimedia services over complex network architectures.

Sliding contention window (SCW): towards backoff range-based service differentiation over IEEE 802.11 wireless LAN networks

A number of works have tried to adjust the contention window in order to provide differentiated quality of service in IEEE 802.11-based wireless networks. By giving different service classes different CWs, the distribution of backoff intervals (chosen randomly, on the interval [O, CW]) will reflect the desired service classes. However, these protocols cannot deliver firm service guarantees while maintaining high network utilization, particularly under congested network conditions. In this article we propose a new MAC protocol featuring a sliding CW (SCW) for each network flow. The SCW dynamically adjusts to changing network conditions, but remains within a per-class predefined range in order to maintain a separation between different service classes. Each flows SCW reacts based on the degree to which class-defined QoS metrics are satisfied. Simulation results show that compared to the enhanced distributed coordination function (EDCF) scheme of 802.11e, SCW consistently excels, in terms of network utilization, strict service separation, and service-level fairness.

Encapsulation and marking of MPEG-4 video over IP differentiated services

Traditional IP networks offer users best-effort service. In this model, all user packets compete equally for network resources. Much attention is being given to developing IP QoS (quality of service), which allows network operators to offer differing levels of treatment to user packets. In this article, we investigate QoS interaction provisioning between MPEG-4 video applications and IP DiffServ networks. QoS interaction is performed through intelligent encapsulation and marking of MPEG-4 elementary streams (video, audio, signaling, scenes and object descriptors) on IP Diffservs AF/EF per hop behavior. Our contribution to this issue is twofold: first, we analyze the different proposals for MPEG-4 encapsulation protocols over RTP/IP; and second, we propose and evaluate a video-oriented marking mechanism for IP Diffserv edge routers. A performance evaluation is carried through simulation using ns2.

FAFC: fast adaptive fuzzy AQM controller for TCP/IP networks

Recently, many active queue management (AQM) algorithms have been proposed to address performance degradations of end-to-end congestion control. However, these AQM algorithms present weaknesses for stabilizing delays in heavily loaded networks. In this paper, we describe a novel adaptive fuzzy control algorithm to improve best effort TCP/IP networks performance. Compared to traditional AQM algorithms (RED, PID and others), our proposal avoids buffer overflows/underflows, and minimizes packet dropping. We propose an on-line adaptation mechanism that captures fluctuating network conditions, while classical AQM algorithms require static tuning. The algorithm stability is mathematically proven. Simulation results show that for the same link utilization, our fast adaptive fuzzy controller provides better performance than RED and PID.

Performance analysis of cell discarding techniques for best effort video communications over ATM networks

Abstract With increasing interest in the transmission of audio–visual applications over ATM best effort services, efficient video-oriented control mechanisms for improving the video quality in the presence of loss have to be designed. In this paper, we propose and evaluate two new slice-based discard schemes for use with available bit rate and guaranteed frame rate services (e.g. formerly UBR+). The schemes adaptively and selectively adjust the discard level to switch buffer occupancy and video cell payload types. To improve their performance, we also introduce a dynamic frame-level priority data partition technique based on MPEG data structure and feedback from the network. To support these mechanisms, enhancements to the ATM adaptation layer 5 and a new MPEG-2 encapsulation strategy are also proposed. The presented quality of picture (QoP) control framework is evaluated using simulation and actual MPEG video data. The overall aim of the framework is double. First, ensuring a graceful picture quality degradation by minimizing cell loss probability for critical video data, and second optimizing the network effective throughput by reducing transmission of non useful data. In comparison to previous approaches, the performance evaluation have shown a significant reduction of the bad throughput and minimization of losses of intra- and predictive-coded frames at both cell and slice layers.

Anomaly Detection in Medical Wireless Sensor Networks

In this paper, we propose a new framework for anomaly detection in medical wireless sensor networks, which are used for remote monitoring of patient vital signs. The proposed framework performs sequential data analysis on a mini gateway used as a base station to detect abnormal changes and to cope with unreliable measurements in collected data without prior knowledge of anomalous events or normal data patterns. The proposed approach is based on the Mahalanobis distance for spatial analysis, and a kernel density estimator for the identification of abnormal temporal patterns. Our main objective is to distinguish between faulty measurements and clinical emergencies in order to reduce false alarms triggered by faulty measurements or ill-behaved sensors. Our experimental results on both real and synthetic medical datasets show that the proposed approach can achieve good detection accuracy with a low false alarm rate (less than 5.5%). Category: Embedded computing

Service-driven inter-domain QoS monitoring system for large-scale IP and DVB networks

There is a growing synergy between well-established Service Providers (SP), Content Providers (CP), and Network Providers (NP), to propose new value-added services, and hence opening new markets to generate further revenues. Meanwhile, the explosive increasing amount of multimedia content to be offered in the Internet and the heterogeneity of the underlying networking technologies demand the provision of new QoS-enabled mechanisms and architecture to efficiently control, manage and monitor the networks. Quality of service monitoring is becoming crucial to SPs for providing quantified QoS-based services and service assurance and to NPs for managing network resources. This paper proposes a framework for large scale inter-domain QoS monitoring in heterogeneous networks including IP and DVB networks that has been developed in the IST-ENTHRONE project of European Commission. One of the main aims is actually to allow high cooperation between different providers while keeping intact the authority, confidentiality, and full control of each provider over its underlying resources. The proposed monitoring framework consists of a layered architecture with two signaling protocols namely an inter-domain monitoring signaling protocol (EQoS-RM), and an intra-domain active measurement signaling protocol (Emon). The proposed QoS monitoring system is service-driven in the sense that it aimed at providing in service verification of QoS performance guarantees for the services offered to the users by the providers. To achieve this, it uses both QoS probes that perform both active and passive monitoring at different levels of abstraction employing node and network wide measurements and application-level perceived quality meters for detecting quality degradation. As such, this framework specifies three types of QoS monitoring components operating at different levels: at network element or node, at network and at service levels. This proposed system also provides monitoring information to NPs in order to assist in managing the operational status of their networks. Design and implementation of the proposed QoS monitoring system is described in this paper. Some experimental assessments of this service-driven QoS monitoring system prove its functioning in terms of accuracy and responsiveness in providing the necessary results.

SCW: sliding contention window for efficient service differentiation in IEEE 802.11 networks

Many works have recently addressed the IEEE 802.11 QoS issues by proposing different monitoring-based contention window (CW) differentiation techniques. In network saturation, however, it is difficult to guarantee firm services differentiation while achieving high network exploitation. Particularly, most existing QoS-capable MAC protocols rely on a backoff interval sampled from a dynamic range [0 CW/sub i/]. In order to ensure more deterministic service differentiation, we propose a new MAC protocol featuring a sliding contention window (SCW) for each network flow. The different flows are now able to select backoff intervals from different (separated) CW ranges. The SCW dynamically adjusts to changing network conditions, but remains within a per-class predefined range, in order to maintain a separation between different service classes. Simulation results show that compared to the EDCA scheme of 802.11e, SCW consistently excels, in terms of network utilization, strict service separation, and service-level fairness.

Service management for end-to-end QoS multimedia content delivery in heterogeneous environment

Integrated service management aims to support efficient cooperation between various business entities, in order to offer end-to-end QoS based services to end users. This is challenging, especially in the context of heterogeneous technologies (IP, DVB-TIS, UWS, GSM/GPRS, etc.). This paper proposes a service management (SM) architecture, involving several actors such as service providers (SP), content providers (CP), network providers (NP) and content consumers (CC). The SM framework presented is an architectural component of an integrated management system (IMS), having as a prime objective the support of end-to-end QoS based services through the integrated management of content, networks and terminals in heterogeneous network contexts.

End-to-end quality of service provisioning through an integrated management system for multimedia content delivery

Next generation networks will be complex, interconnecting different technologies, and architectures (IP, DVB-T/S, UMTS, GSM/GPRS, etc.) across a multitude of software and hardware platforms for offering a large number of value-added services including multimedia, audio-visual, etc. One of the major requirements for the successful and wide deployment of such services is the efficient transmission of performance sensitive digital items (i.e., audio, video, and image) over a broad range of bandwidth-constrained wired/wireless access/core/distribution networks. This paper presents an approach to the management and provisioning of end-to-end Quality of Service (QoS) in next generation networks (IP and non-IP networks) that is being developed in the IST ENTHRONE project. The primary goal of this project is to provide a solution for seamless access to multimedia content with end-to-end QoS support through integrated management of content, networks and terminals. The adopted methodology in providing end-to-end QoS is through an integrated management in the context of MPEG-21 framework for managing services at both customer and provider levels using Service Level Agreements (SLA) concept and provisioning network resources for satisfying the customer QoS demands as well as meeting the QoS requirements of multimedia contents.