Alessandro Floris

On adding the social dimension to the Internet of Vehicles: Friendship and middleware

In this paper, we analyze the combination of Vehicular Ad-hoc NETworks (VANETs) with the Social Internet of Things (SIoT), i.e., the Social Internet of Vehicles (SIoV). In the SIoV every vehicle is capable of establishing social relationships with other vehicles in an autonomous way with the intent of creating an overlay social network that can be exploited for information search and dissemination in VANET applications. The contribution of this paper is two-fold: firstly, we define some relationships which can be established between the vehicles and between the vehicles and the road side units (RSUs); secondly, we propose a SIoV middleware which extends the functionalities of the Intelligent Transportation Systems Station Architecture (ITS SA), defined by ISO and ETSI standards, to take into account the elements needed to integrate VANETs in the SIoT. Additionally, we present results of software simulations analyzing realistic vehicular mobility trace in order to study the characteristics of the resulting social network structure.

QoE assessment of multimedia video consumption on tablet devices

In this paper we present a study aimed at assessing the Quality of Experience in video streaming when the user is employing a tablet devices. The study has been conducted on a database containing subjective assessment scores relative to 216 streaming sessions of video sequences encoded with H.264/AVC and corrupted by typical wireless channel transmission errors. Four 20sec-long video sequences at Common Intermediate Format (CIF) spatial resolution have been corrupted with 54 combinations of key parameters for the reference application: bitrate, packet loss rate, playout delay and transmission interruption. Subjective evaluations have been collected in compliance with ITU-T Recommendation P.910 through singlestimulus Absolute Category Rating (ACR) from 40 subjects. The videos were reproduced on two different tablet devices: on an Apple iPad 2 and on a Samsung Galaxy Tab GT-P1000. Subjective observations include the perceived quality considering all aspects of the fruition chain, from the coding to the environment and device specific issues. The evaluation results also provided several remarks that can be helpful in designing systems and applications for multimedia contents played back on tablets. The results show a good correlation between subjective observations and some impairments so that a simple QoE index is proposed. A correlation study between subjective assessment and objective metrics is also provided.

QoE-centric service delivery

The provisioning of the quality to end users is a major objective for the successful deployment of multimedia services over the Internet. It is more and more evident from past research and service deployments that such an objective often requires a collaboration among the different parties that are involved in the delivery of the service. This paper specifically focuses on the cooperation between the Over-The-Top (OTTs) and the Internet Service Providers (ISPs) and proposes a novel service delivery approach that is purely driven by the Quality of Experience (QoE) provided to the final common users. Initially, we identify the need of the collaboration among the OTTs and the ISPs where we not only highlight some of the enterprise level motivations (revenue generation) but also the technical aspects which require collaboration. Later, we provide a reference architecture with the required modules and vertical interfaces for the interaction among the OTTs and the ISPs. Then, we provide a collaboration model where we focus on the modeling of the revenue, whose maximization drives the collaboration. The revenue is considered to be dependent on the user churn, which in turn is affected by the QoE and is modeled using the Sigmoid function. We illustrate simulation results based on our proposed collaboration approach which highlight how the proposed strategy increases the revenue generation and QoE for the OTTs and the ISPs hence providing a ground for ISP to join the loop of revenue generation between OTTs and users.

Quality of Experience in the Multimedia Internet of Things: Definition and practical use-cases

In this paper, a first approach for evaluating the Quality of Experience (QoE) for IoT (Internet of Things) applications is presented. Firstly, a layered IoT architecture is analysed to understand which QoE influence factors have to be considered in relevant application scenarios. Secondly, we introduce the concept of Multimedia IoT (MIoT) and define a layered QoE model aimed at evaluating and combining the contributions of each influence factor to estimate the overall QoE in MIoT applications. Finally, we present a vehicular MIoT application that has been used to conduct subjective quality assessments to verify the performance of the proposed approach.

Streaming video over wireless channels: Exploiting reduced-reference quality estimation at the user-side

We propose a source rate control scheme for streaming video sequences over wireless channels by resorting on a reduced-reference (RR) quality estimation approach. It works as follows: the server extracts important features of the original video, which are coded and sent through the channel along with the video sequence and then exploited at the decoder to compute the actual quality; the observed quality is analyzed to obtain information on the impact of the source rate at the given system configuration; at the receiver, decisions are taken on the optimal source rate to be applied next at the encoder to maximize the quality as perceived at the user-side. The rate is adjusted on a per-window basis to compensate low-throughput periods with high-throughput periods so as to avoid abrupt video quality changes, which can be caused by sudden variations in the channel throughput. The use of the RR quality estimation represents the main novelty of the proposed work. This has the advantage of allowing the rate control to optimize the user-perceived video quality after all the streaming system impairments have affected the signal, including actual channel errors, playback buffer starvation occurrences and error concealment. This approach is new in this context, since in the past proposals video models are used to predict the relationships of the quality with the coding rate, channel errors and starvation occurrences. Numerical simulations show how the proposed approach is able to achieve results similar to those obtained with model-based approaches, but with the significant benefit of not requiring any knowledge on the signal and channel characteristics.

QoE-aware service delivery: A joint-venture approach for content and network providers

The objective of this work is the investigation of a possible collaboration between Over-The-Top (OTTs) service providers and Internet Service Providers (ISPs), which is centered around the Quality of Experience (QoE). Initially, we define a reference architecture with the required modules and interfaces for the interaction between the two providers. Then, we focus on the modeling of the revenue, whose maximization drives the collaboration. It is considered as depending on the user churn, which in turn is affected by the QoE and is modeled using the Sigmoid function. We illustrate simulation results based on our proposed collaboration approach which highlights how the proposed strategy increases the revenue generation and QoE for both players hence providing a ground for ISP to join the loop of revenue generation between OTT and users.

Managing the Quality of Experience in the Multimedia Internet of Things: A Layered-Based Approach

This paper addresses the issue of evaluating the Quality of Experience (QoE) for Internet of Things (IoT) applications, with particular attention to the case where multimedia content is involved. A layered IoT architecture is firstly analyzed to understand which QoE influence factors have to be considered in relevant application scenarios. We then introduce the concept of Multimedia IoT (MIoT) and define a layered QoE model aimed at evaluating and combining the contributions of each influence factor to estimate the overall QoE in MIoT applications. Finally, we present a use case related to the remote monitoring of vehicles during driving practices, which is used to validate the proposed layered model, and we discuss a second use case for smart surveillance, to emphasize the generality of the proposed framework. The effectiveness in evaluating classes of influence factors separately is demonstrated.

Addressing un-interoperability issues in QoE models: Is a layered modelling effective?

Un-interoperability issue is herein defined as the unfeasibility (or at least difficulty) of integrating the results of different modelling activities to broaden the range of scenarios where the integrated model can be applied. Given the huge number of parameters to be considered when defining a Quality of Experience (QoE) model, many different QoE models have been proposed in the literature. Each involves different scenarios and parameters, and specifies how such features are combined. In order to solve un-interoperability issues, we propose a layered modelling approach, which follows the well-known model for interoperable systems in the networking field. Each layer of the model is devoted to a specific quality domain and the interfaces with the other domains are well-defined in order to further simplify the combination of models related to different domains. Such model could be the reference for a general-purpose QoE management system. Experimental results for validating the proposed model are provided.

OTT-ISP joint service management: A Customer Lifetime Value based approach

In this work, we propose a QoE-aware collaboration approach between Over-The-Top providers (OTT) and Internet Service Providers (ISP) based on the maximization of the profit by considering the user churn of Most Profitable Customers (MPCs), which are classified in terms of the Customer Lifetime Value (CLV). The contribution of this work is multifold. Firstly, we investigate the different perspectives of ISPs and OTTs regarding QoE management and why they should collaborate. Secondly, we investigate the current ongoing collaboration scenarios in the multimedia industry. Thirdly, we propose the QoE-aware collaboration framework based on the CLV, which includes the interfaces for information sharing between OTTs and ISPs and the use of Content Delivery Networks (CDN) and surrogate servers. Finally, we provide simulation results aiming at demonstrating the higher profit is achieved when collaboration is introduced, by engaging more MPCs with respect to current solutions.

The impact of interactivity on the QoE: A preliminary analysis

The interactivity in multimedia services concerns the input/output process of the user with the system, as well as its cooperativity. It is an important element that affects the overall Quality of Experience (QoE), which may even mask the impact of the quality level of the (audio and visual) signal itself on the overall user perception. This work is a preliminary study aimed at evaluating the weight of the interactivity, which relies on subjective assessments that have been conducted varying the artefacts, genre and interactivity features on video streaming services evaluated by the subjects. Subjective evaluations have been collected from 25 subjects in compliance with ITU-T Recommendation P.910 through single-stimulus Absolute Category Rating (ACR). It resulted that the impact of the interactivity is influenced by the presence of other components, such as presence of buffer starvations and type of content displayed. An objective quality metric able to measure the influence of the interactivity on the QoE has also been defined, which has proved to be highly correlated with subjective results. We concluded that the interactivity feature can be successfully represented by either an additive or a multiplicative component to be added in existing quality metrics.