Eduardo Cerqueira

An overview of quality of experience measurement challenges for video applications in IP networks

The increase in multimedia content on the Internet has created a renewed interest in quality assessment. There is however a main difference from the traditional quality assessment approaches, as now, the focus relies on the user perceived quality, opposed to the network centered approach classically proposed. In this paper we overview the most relevant challenges to perform Quality of Experience (QoE) assessment in IP networks and highlight the particular considerations necessary when compared to alternative mechanisms, already deployed, such as Quality of Service (QoS). To assist on the handling of such challenges we first discuss the different approaches to Quality of Experience assessment along with the most relevant QoE metrics, and then we discuss how they are used to provide objective results about user satisfaction.

Towards software-defined VANET: Architecture and services

Vehicular Ad Hoc Networks (VANETs) have in recent years been viewed as one of the enabling technologies to provide a wide variety of services, such as vehicle road safety, enhanced traffic and travel efficiency, and convenience and comfort for passengers and drivers. However, current VANET architectures lack in flexibility and make the deployment of services/protocols in large-scale a hard task. In this paper, we demonstrate how Software-Defined Networking (SDN), an emerging network paradigm, can be used to provide the flexibility and programmability to networks and introduces new services and features to todays VANETs. We take the concept of SDN, which has mainly been designed for wired infrastructures, especially in the data center space, and propose SDN-based VANET architecture and its operational mode to adapt SDN to VANET environments. We also discuss benefits of a Software-Defined VANET and the services that can be provided. We demonstrate in simulation the feasibility of a Software-Defined VANET by comparing SDN-based routing with traditional MANET/VANET routing protocols. We also show in simulation fallback mechanisms that must be provided to apply the SDN concept into mobile wireless scenarios, and demonstrate one of the possible services that can be provided by a Software-Defined VANET.

Control of Multiple Packet Schedulers for Improving QoS on OpenFlow/SDN Networking

Packet scheduling is essential to properly support applications on Software-Defined Networking (SDN) model. However, on OpenFlow/SDN, QoS is only performed with bandwidth guarantees and by a well-known FIFO scheduling. Facing this limitation, this paper presents the QoSFlow proposal, which controls multiple packet schedulers of Linux kernel and improve the flexibility of QoS control. The paper assesses QoSFlow performance, by analysing response time of packet scheduler operations running on datapath level, maximum bandwidth capacity, hardware resource utilization rate, bandwidth isolation and QoE. Our outcomes show an increase more than 48% on PSNR value of QoE by using SFQ scheduling.

A routing protocol based on energy and link quality for Internet of Things applications.

The Internet of Things (IoT) is attracting considerable attention from the universities, industries, citizens and governments for applications, such as healthcare, environmental monitoring and smart buildings. IoT enables network connectivity between smart devices at all times, everywhere, and about everything. In this context, Wireless Sensor Networks (WSNs) play an important role in increasing the ubiquity of networks with smart devices that are low-cost and easy to deploy. However, sensor nodes are restricted in terms of energy, processing and memory. Additionally, low-power radios are very sensitive to noise, interference and multipath distortions. In this context, this article proposes a routing protocol based on Routing by Energy and Link quality (REL) for IoT applications. To increase reliability and energy-efficiency, REL selects routes on the basis of a proposed end-to-end link quality estimator mechanism, residual energy and hop count. Furthermore, REL proposes an event-driven mechanism to provide load balancing and avoid the premature energy depletion of nodes/networks. Performance evaluations were carried out using simulation and testbed experiments to show the impact and benefits of REL in small and large-scale networks. The results show that REL increases the network lifetime and services availability, as well as the quality of service of IoT applications. It also provides an even distribution of scarce network resources and reduces the packet loss rate, compared with the performance of well-known protocols.

Framework for the integrated video quality assessment

Through years of development Content Networks (CN) have become more sophisticated and more technically diverse. Modern CN are designed to be more adaptive to communication environment, devices and user requirements. However, one open issue is the still fluctuating quality of service provision. As a result user experience can be negatively affected. In order to maintain a satisfactory level of user experience it is crucial to develop a feasible solution to measure the extent to which video services meet users’ expectation. Assessing video quality with respect to users’ subjective opinions is a complex task. In this paper we address challenges of this task and design an integrated framework using a number of comprehensive functional modules. Our framework integrates objective quality assessment models of Artifacts Measurement (AM) and Quality of Delivery (QoD) approaches. Only the fittest models are activated by the framework considering requirements of individual evaluation tasks. We also introduce our recent work of realising key functional modules of the framework. Joint subjective experiments between two institutes have also been carried out for the purpose of model implementation and evaluation. Results from experiments verify the concept of an integrated framework and show the effectiveness of its key modules in estimating the quality level of video services.

A beaconless Opportunistic Routing based on a cross-layer approach for efficient video dissemination in mobile multimedia IoT applications

Mobile multimedia networks are enlarging the Internet of Things (IoT) portfolio with a huge number of multimedia services for different applications. Those services run on dynamic topologies due to device mobility or failures and wireless channel impairments, such as mobile robots or Unmanned Aerial Vehicle (UAV) environments for rescue or surveillance missions. In those scenarios, beaconless Opportunistic Routing (OR) allows increasing the robustness of systems for supporting routing decisions in a completely distributed manner. Moreover, the addition of a cross-layer scheme enhances the benefits of a beaconless OR, and also enables multimedia dissemination with Quality of Experience (QoE) support. However, existing beaconless OR approaches do not support a reliable and efficient cross-layer scheme to enable effective multimedia transmission under topology changes, increasing the packet loss rate, and thus reducing the video quality level based on the user’s experience. This article proposes a Link quality and Geographical beaconless OR protocol for efficient video dissemination for mobile multimedia IoT, called LinGO. This protocol relies on a beaconless OR approach and uses multiple metrics for routing decisions, including link quality, geographic location, and energy. A QoE/video-aware optimisation scheme allows increasing the packet delivery rate in presence of links errors, by adding redundant video packets based on the frame importance from the human’s point-of-view. Simulation results show that LinGO delivers live video flows with QoE support and robustness in mobile and dynamic topologies, as needed in future IoT environments.

A distributed beaconless routing protocol for real-time video dissemination in multimedia VANETs

We design a framework for video (and in general high data rate applications) transmission over a VANET.Our framework includes both application and routing layer design.We analyze MAC layer behavior and improve its utilization by solving the Spurious Forwarding problem.We tested our protocols on a real scenario, and considered both QoS and QoE, including MOS experiments in a real car.We grant a high data rate in ad-hoc mode, also for long distance, through our backbone beaconless approach. Vehicular Ad-Hoc Networks (VANETs) will play an important role in Smart Cities and will support the development of not only safety applications, but also car smart video surveillance services. Recent improvements in multimedia over VANETs allow drivers, passengers, and rescue teams to capture, share, and access on-road multimedia services. Vehicles can cooperate with each other to transmit live flows of traffic accidents or disasters and provide drivers, passengers, and rescue teams rich visual information about a monitored area. Since humans will watch the videos, their distribution must be done by considering the provided Quality of Experience (QoE) even in multi-hop, multi-path, and dynamic environments. This article introduces an application framework to handle this kind of services and a routing protocol, the DBD (Distributed Beaconless Dissemination), that enhances the dissemination of live video flows on multimedia highway VANETs. DBD uses a backbone-based approach to create and maintain persistent and high quality routes during the video delivery in opportunistic Vehicle to Vehicle (V2V) scenarios. It also improves the performance of the IEEE 802.11p MAC layer, by solving the Spurious Forwarding (SF) problem, while increasing the packet delivery ratio and reducing the forwarding delay. Performance evaluation results show the benefits of DBD compared to existing works in forwarding videos over VANETs, where main objective and subjective QoE results are measured.

A Resource Reservation Protocol Supporting QoS-aware Multicast Trees for Next Generation Networks

It is expected that next generation of networks will handle new types of services which are destined to large audiences and have different QoS requirements. From the transport point of view, multicast is the most suitable technology for the required group communication services, since it avoids packets duplication and saves network resources. However, QoS-aware multicast content deliver raises several problems, such as the control of QoS trees in environments with asymmetric routing. This paper presents Multi-service Resource Allocation (MIRA), a multicast-aware resource reservation protocol for class-based networks that consider routing asymmetries. MIRA controls the resources of network classes associated to multicast sessions considering the QoS characteristics of the latter and network conditions of the available classes in the source-to-receivers path. A detailed description of the functionalities of MIRA and a conceptual analysis against RSVP and RMD-QoSM are presented. Finally, the session setup time, and the signalling and state overheard in comparison with RSVP are analyzed based on simulations.

Quality evaluation in peer-to-peer IPTV services

Modern IPTV services are comprised of multiple comprehensive service elements in the entire content delivery chain to maximise the efficiency in networking. Audio-visual content may experience various types of impairments during content ingest, processing, distribution and reception. While some impairments do not cause noticeable distortions to the delivered content, many others such as the network transmission loss can be highly detrimental to the user experience in content consumption. In order to optimise service quality and to provide a benchmarking platform to evaluate the designs for future audio-visual content distribution system, a quality evaluation framework is essential. We introduce such an evaluation framework to assess video service with respect of user perception, while supporting service diagnosis to identify root-causes of any detected quality degradation. Compared with existing QoE frameworks, our solution offers an advanced but practical design for the real-time analysis of IPTV services in multiple service layers.

Video quality estimator for wireless mesh networks

As Wireless Mesh Networks (WMNs) have been increasingly deployed, where users can share, create and access videos with different characteristics, the need for new quality estimator mechanisms has become important because operators want to control the quality of video delivery and optimize their network resources, while increasing the user satisfaction. However, the development of in-service Quality of Experience (QoE) estimation schemes for Internet videos (e.g., real-time streaming and gaming) with different complexities, motions, Group of Picture (GoP) sizes and contents remains a significant challenge and is crucial for the success of wireless multimedia systems. To address this challenge, we propose a real-time quality estimator approach, HyQoE, for real-time multimedia applications. The performance evaluation in a WMN scenario demonstrates the high accuracy of HyQoE in estimating the Mean Opinion Score (MOS). Moreover, the results highlight the lack of performance of the well-known objective methods and the Pseudo-Subjective Quality Assessment (PSQA) approach.