Toufik Ahmed

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.

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.

Adaptive Distributed Gateway Discovery in Hybrid Wireless Networks

An ever-growing demand for coverage extension, higher data-rates and improved connectivity has motivated the interconnection of mobile ad-hoc networks to fixed IP networks, to form a Hybrid Wireless Network (HWN). The convergence of ad- hoc and infrastructure network is also attractive in real-world scenarios due to its practicality and usefulness. In HWNs, gateways are generally used as an interconnection point for the integrated network. In order to improve the overall performance of HWN, an efficient gateway discovery and route maintenance scheme is indispensable. In this paper, we present a novel adaptive gateway discovery scheme called ADD (Adaptive Distributed gateway Discovery), in which the adaptation is done in a fully distributed manner. Simulation results show that the distributed adaptation capabilities of our proposed scheme facilitate outperforming the existing gateway discovery mechanisms in terms of control overhead, packet delivery and delay.

SDN/NFV-enabled satellite communications networks

In the context of next generation 5G networks, the satellite industry is clearly committed to revisit and revamp the role of satellite communications. As major drivers in the evolution of (terrestrial) fixed and mobile networks, Software Defined Networking (SDN) and Network Function Virtualisation (NFV) technologies are also being positioned as central technology enablers towards improved and more flexible integration of satellite and terrestrial segments, providing satellite network further service innovation and business agility by advanced network resources management techniques. Through the analysis of scenarios and use cases, this paper provides a description of the benefits that SDN/NFV technologies can bring into satellite communications towards 5G. Three scenarios are presented and analysed to delineate different potential improvement areas pursued through the introduction of SDN/NFV technologies in the satellite ground segment domain. Within each scenario, a number of use cases are developed to gain further insight into specific capabilities and to identify the technical challenges stemming from them.

Cellular software defined networking: a framework

Todays mobile customers desire to remain connected anywhere, at any time, and using any device. This phenomenon has encouraged mobile network operators to build complex network architectures by incorporating new features and extensions, which are harder to manage and operate. In this article we propose a novel and simplified architecture for mobile networks. The proposed architecture, which we call CSDN (Cellular SDN), leverages software defined networking (SDN) and network functions virtualization (NFV). SDN abstracts the network and separates the control plane from the data plane; NFV decouples logical network functions from the underlying hardware, for dynamic resource orchestration. Furthermore, we argue that dynamic resource orchestration and optimal control need real-time context data analyses to make intelligent decisions. Thus, in the proposed architecture we exploit the capability of the mobile edge networks to gather information related to the network as well as the users. This information can be used to optimize network utilization and application performance, and to enhance the user experience. In addition, the gathered data can be shared with third party service providers, enabling the realization of innovative services.

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.

Challenges, opportunities, and solutions for converged satellite and terrestrial networks

The current trend in telecommunications services provisioning is shifting toward global ubiquitous networking and unified service architecture. Given the diversity of access technologies, this global ubiquitous networking cannot be possible without efficient interworking between the different access players. This leads to the necessity of defining, implementing, and deploying common services control architecture, able to support a wide variety of services for users in a variety of roles (consumer, producer, or manager of communication and media). This article defines some issues related to the interworking operation between the satellite and terrestrial domains. It suggests some solutions and discusses their potential.

Adaptive Packet Video Streaming Over P2P Networks Using Active Measurements

In this paper we consider the problem of real-time streaming of IP packet video over Peer-to-Peer networks (P2P) from multiple senders to a single receiver. P2P networks are characterized by a potentially large and highly dynamic population of hosts that join and leave the network frequently. We present the design and evaluation of a quality adaptation streaming mechanism in a multi-source streaming to a single receiver. Multimedia streaming is a real time application so, the main challenges in the design of this mechanism are (1) selection of senders peers nodes; (2) stream switching among the peers; (3) optimizing video quality by active measurements of links; and (4) enhancing the overall Quality of Service (QoS). Our key technique to provide quality adaptation is based on active measurements of network links and selection of sender peers to enhance the overall throughput. We used video traffic organized as MDC (Multiple Description Coding) layers, which provides high error resilient. Our simulations results using ns2 show that our solution allows to efficiently utilize available network bandwidth of sending peers and allow maximizing streaming qualities at the reception peer.

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.

A metric for no-reference video quality assessment for HD TV delivery based on saliency maps

This paper contributes to objective video quality assessment of broadcasted HDTV content without reference. In this context we present a new No-Reference video quality metric taking into account the behavior of Human Visual System. This new metric called WMBER is based on macro-blocks error detection weighted by saliency maps computed at the decoder side. Moreover, both macro-block error detection and saliency maps processing require only partial decoding allowing real-time performance. A subjective experiment has been carried out to evaluate the performances of the proposed metric. The results are compared to the Full Reference metric MSE. The evaluation of the results shows that the proposed method provides a very good prediction of subjective measures.