Periódicos, Publicação

A real-time video quality estimator for emerging wireless multimedia systems

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Wireless Mesh Networks (WMNs) are increasingly deployed to enable thousands of users to share, create, and access live video streaming with different characteristics and content, such as video surveillance and football matches. In this context, there is a need for new mechanisms for assessing the quality level of videos because operators are seeking to control their delivery process and optimize their network resources, while increasing the user’s satisfaction. However, the development of in-service and non-intrusive Quality of Experience assessment schemes for real-time Internet videos with different complexity and motion levels, Group of Picture lengths, and characteristics, remains a significant challenge. To address this issue, this article proposes a non-intrusive parametric real-time video quality estimator, called MultiQoE that correlates wireless networks’ impairments, videos’ characteristics, and users’ perception into a predicted Mean Opinion Score. An instance of MultiQoE was implemented in WMNs and performance evaluation results demonstrate the efficiency and accuracy of MultiQoE in predicting the user’s perception of live video streaming services when compared to subjective, objective, and well-known parametric solutions.

Periódicos, Publicação

Management of Caching Policies and Redundancy over Unreliable Channels

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Caching plays a central role in networked systems, reducing the load on servers and the delay experienced by users. Despite their relevance, networked caching systems still pose a number of challenges pertaining their long term behavior. In this paper, we formally show and experimentally evidence conditions under which networked caches tend to synchronize over time. Such synchronization, in turn, leads to performance degradation and aging, motivating the monitoring of caching systems for eventual rejuvenation, as well as the deployment of diverse cache replacement policies across caches to promote diversity and preclude synchronization and its aging effects. Based on trace-driven simulations with real workloads, we show how hit probability is sensitive to varying channel reliability, cache sizes, and cache separation, indicating that the mix of simple policies, such as Least Recently Used (LRU) and Least Frequently Used (LFU), provide competitive performance against state-of-art policies. Indeed, our results suggest that diversity in cache replacement policies, rejuvenation and intentional dropping of requests are strategies that build diversity across caches, preventing or mitigating performance degradation due to caching aging.

Artigos de Conferência, Publicação

Building an infrastructure for experimentation between Brazil and Europe to enhance research collaboration in future Internet

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This paper describes the experience of RNP, the Brazilian research and education network, in creating a large scale research facility for experimentation on Future Internet as a member of the FIBRE (Future Internet testbeds experimentation between BRazil and Europe) project. Its main goal is to create common space between Brazil and EU for Future Internet experimental research into network infrastructure and distributed applications, by building and operating a federated EU-Brazil Future Internet experimental facility. The FIBRE testbed is currently composed by a federation of 13 local testbeds (a.k.a. experimental islands), located in different R&E organizations. The FIBRE infrastructure combines heterogeneous physical resources and different technologies, including OpenFlow, wireless and optical communications. We also present the architecture of FIBRE, which allows users to access the testbed through an integrated interface for either experimental or control planes, and provides a common access to the different underlying Control and Monitoring Frameworks (CMFs) for Future Internet experimentation.

Artigos de Conferência, Publicação

Fibre-an international testbed for future internet experimentation

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This paper describes the FIBRE testbed, a large-scale research facility for experimentation on Future Internet. The current testbed is a federation of 13 local testbeds (aka experimental islands), located in different R&E organizations. The FIBRE infrastructure combines heterogeneous physical resources and different technologies, including OpenFlow, wireless and optical communications. This paper discusses the architecture of FIBRE, which includes different Control Management Frameworks, and describes how the testbed can be used in research and education to experiment with networking and distributed systems.

Artigos de Conferência, Publicação

Data Aggregation for group communication in Machine-to-Machine environments

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The energy resources of Machine-to-Machine (M2M) devices need to last as much as possible. Data aggregation is a suitable solution to prolong the network lifetime, since it allows the devices to reduce the amount of data traffic. In M2M systems, the M2M platform and the Constrained Application Protocol (CoAP) enable multiple entities to send concurrent data-requests to the same capillary network. For example, in a Smart Metering scenario, there are devices measuring the electricity consumption of an entire building. The supplier company requests all devices to send the data updates every 1800 seconds (i.e., 30 minutes). On the other hand, a resident requests his/her devices to communicate every 600 seconds (i.e., 10 minutes). These concurrent data-requests create heterogeneous groups over the same capillary network, since each group might be able to execute different in-network functions and to have a unique temporal-frequency of communication. However, the traditional data aggregation solutions designed for periodic monitoring assume the execution of a single static data-request during all network lifetime. This makes the traditional data aggregation solutions not suitable for M2M environments. To fill this gap, this paper presents Data Aggregation for Multiple Groups (DAMiG), which is designed to provide Data Aggregation for heterogeneous and concurrent sets of CoAP data-requests. DAMiG explores the group communication periodicity to perform internal and external-group traffic aggregation. To achieve that, DAMiG computes a suitable aggregation structure and applies statistical and merger aggregation functions along the path. DAMiG is able to reduce the energy consumption in scenarios with single or several concurrent CoAP data-requests. Moreover, the selection of internal and external-group paths takes into account the residual energy of the nodes, avoiding the paths with low residual energy.

Artigos de Conferência, Publicação

Efficient and secure M2M communications for smart metering

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Machine-to-Machine technology supports several application scenarios, such as smart metering, automotive, healthcare and city monitoring. Smart metering applications have attracted the interest of companies and governments since these applications bring many benefits (e.g. costs reduction and increased reliability) for production, monitoring and distribution of utilities, such as gas, water and electricity. Multi-hop wireless communication is a cost-effective technology for smart metering applications because it extends the wireless range and enables fast deployment. Smart metering data communicated via wireless multi-hop approaches needs mechanisms that makes the communication less vulnerable to security threats and saves the device resources. Data encryption and data aggregation mechanisms emerge as potential solutions to fulfill these requirements. However, the simultaneous execution of data encryption and data aggregation mechanisms is not a trivial task. This is because the data encryption prevents the data aggregation mechanism to summarize the data along the path. Another challenge is to manage both mechanisms according to the concurrent Machine-to-Machine (M2M) applications interests. In this context, we present sMeter, which is a framework that deals with multiple applications interests, avoiding interest conflicts of concurrent users and supporting the management of data aggregation and data encryption. sMeter is implemented using low-cost hardware in an indoor environment. The communication is performed via a wireless multi-hop technology, and the performance of this communication is evaluated in terms of delay, data reception ratio and received signal strength indication.

Artigos de Conferência, Publicação

Model of organization and distribution of applications for software defined networks: SDNrepo

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One way to provide more flexibility for computer networks is through software defined networks (SDN). This paradigm supports network applications, whose behavior is defined by the controllers. However, management applications SDN is a solution under explored, such applications are scattered in various repositories codes on-line, or are still embedded in the factory switches. This article proposes a model of organization and distribution of applications, called SDNrepo, may specify and model all the way that applications must do to reach the end user, in this case the controllers.

Artigos de Conferência, Publicação

RepoSDN: An repository organization and coordination method of software defined networks applications

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This paper describes the experience of RNP, the Brazilian research and education network, in creating a large scale research facility for experimentation on Future Internet as a member of the FIBRE (Future Internet testbeds experimentation between BRazil and Europe) project. Its main goal is to create common space between Brazil and EU for Future Internet experimental research into network infrastructure and distributed applications, by building and operating a federated EU-Brazil Future Internet experimental facility. The FIBRE testbed is currently composed by a federation of 13 local testbeds (a.k.a. experimental islands), located in different R&E organizations. The FIBRE infrastructure combines heterogeneous physical resources and different technologies, including OpenFlow, wireless and optical communications. We also present the architecture of FIBRE, which allows users to access the testbed through an integrated interface for either experimental or control planes, and provides a common access to the different underlying Control and Monitoring Frameworks (CMFs) for Future Internet experimentation

Artigos de Conferência, Publicação

Context-aware adaptation mechanism for video dissemination over Flying Ad-Hoc Networks

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The user experience on watching live video sequences transmitted over a Flying Ad-Hoc Networks (FANETs) must be considered to drop packets in overloaded queues, in scenarios with high buffer overflow and packet loss rate. In this paper, we introduce a context-aware adaptation mechanism to manage overloaded buffers. More specifically, we propose a utility function to compute the dropping probability of each packet in overloaded queues based on video context information, such as frame importance, packet deadline, and sensing relevance. In this way, the proposed mechanism drops the packet that adds the minimum video distortion. Simulation evaluation shows that the proposed adaptation mechanism provides real-time multimedia dissemination with QoE support in a multi-hop, multi-flow, and mobile network environments.

Artigos de Conferência, Publicação

Additions to the ETArch control plane to support multimedia QoS-guaranteed content transport over OpenFlow-enabled SDN future internet systems

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The Future Internet approach requires new solutions to support novel usage scenarios driven by the technological evolution and the new service demands. However, this paradigm shift requires deeper changes in the existing systems, which makes Internet providers reluctant in deploying the full transformation required for the Future Internet. The Entity Title Architecture (ETArch) is a holistic clean-slate Future Internet system embedding new services for these scenarios leveraging the Software Defined Networking (SDN) concept materialized by the OpenFlow. However, legacy ETArch deploys a fully per-flow approach to provision the same transport model for all sessions (equivalent to the Internet best-effort), while suffering with performance drawbacks and lacking Quality of Service (QoS) control. To that, we evolved ETArch with SMART (Support of Mobile Sessions with High Transport Network Resource Demand) QoS control approach, which coordinates admission control and dynamic control of super-dimensioned resources to accommodate multimedia sessions with QoS-guaranteed over time, while keeping scalability/performance and users with full Quality of Experience (QoE). The SMART-enabled ETArch system evaluation was carried out using a real Testbed of the OFELIA Brazilian Island, confirming its benefits in both data and control planes over the legacy ETArch.

Artigos de Conferência, Publicação

Filling the gap between Software Defined Networking and Wireless Mesh Networks

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Software Defined Networking (SDN) has emerged as a new paradigm that highly increase the network management flexibility through simple but powerful abstractions. The key idea is decoupling the control plane, which makes the forward decisions, from the data plane, which effectively makes the forward. However, the OpenFlow, the main SDN enabler, is designed mainly by wired networks characteristics. As consequence, Wireless Mesh Networks (WMNs) is not suitable for operating as control plane and many wireless networks features are neglected in the OpenFlow, e.g.: power control and network ID. In addition, there are few effort research to extend SDN to wireless networks and these existing works focus on very specific issues of this integration. In this paper, we propose an architecture to extent the OpenFlow functionalities in order to proper deal with wireless networks, including an approach for transporting the control plane over wireless multihop networks. The extensions include new rules, actions, and commands, which bring the network management flexibility to the wireless context. We validated our proposal by implementing and testing some extensions in a small real world testbed. As a proof of concept, we illustrate the OpenFlow capability of isolation between research and production traffics in a wireless backhaul.