Nuno Filipe Coutinho

Quality of experience-based routing in multi-service wireless mesh networks

We develop an optimization framework for Quality of Experience (QoE)-based routing in multi-service Wireless Mesh Networks (WMNs). The framework takes into account the heterogeneous requirements of different services delivered over a WMN, such that the overall end-user QoE is maximized under given resource constraints. We propose a novel QoE-aware double reinforcement learning strategy for dynamically computing the most efficient routes to deliver the flows of each service type. Comprehensive NS-2-based simulations demonstrate the substantial performance gains that our approach enables over conventional routing techniques such as AODV, with significant improvement over video quality.

Multiparty Seamless Transport

The demanding requirements of new real-time and mobile multimedia group-based applications (e.g. IPTV and video-conferencing) motivates the research for novel and efficient network architectures, able to fulfil service requirements and increase user experience. Multicast, despite its scalability issues, is the most suitable network technology for the delivery of multiparty content. Context-awareness is taken as a key feature in Next Generation Networks, enabling a management framework with a more comprehensive knowledge of the network, application and user. The challenge is how to use the available knowledge towards service personalization and network efficiency. This paper presents and evaluates an architecture that aims to provide personalized session content delivery to multiple mobile users, integrating different access and transport technologies. The architecture relies on an end-to-end context-aware communication framework able to dynamically react and adapt to context changes, through session and network reconfiguration. Our focus is on the transport network part, addressing a new level of scalable multiparty content delivery through the concepts of abstract multiparty trees and overlay nodes. The results show that the concept of abstract trees reduces the network reconfiguration complexity while still guaranteeing end-to-end QoS.

On the analysis of hierarchical autonomic control of multiparty services

The increasing interest in group-based multimedia services, followed by the larger resource demands and the quest for seamless mobility support, have been propelling research on novel approaches capable of overcoming the challenges posed by future networking environments. One of those challenges is heterogeneity, which can also be leveraged in favor of more enriched services through context awareness and thus enhance user service perception. In this article we describe a context-driven framework for multiparty content delivery and discuss the rewards of employing the abstract multiparty transport concept, which provides autonomic control of personalized group-based services to users through a hierarchical strategy. Since scalability is the major concern when dealing with group-based services, we evaluated the framework and its embedded concepts regarding this feature. Herein, we describe an analytical study focused on quantifying the necessary reconfigurations in the network due to any type of context change. The outcomes of this study show that through the concept of abstract multiparty trees, we obtain considerable gains regarding link savings and consequent network control operations, thus increasing the scalability of the autonomic control architecture.

Dynamic dual-reinforcement-learning routing strategies for quality of experience-aware wireless mesh networking

The impact of transmission impairments such as loss and latency on user perceived quality (QoE) depends on the service type. In a real network, multiple service types such as audio, video, and data coexist. This makes resource management inherently complex and difficult to orchestrate. In this paper, we propose an autonomous Quality of Experience management approach for multiservice wireless mesh networks, where individual mesh nodes apply reinforcement learning methods to dynamically adjust their routing strategies in order to maximize the user perceived QoE for each flow. Within the forwarding nodes, we develop a novel packet dropping strategy that takes into account the impact on QoE. Finally, a novel source rate adaptation mechanism is designed that takes into account the expected QoE in order to match the sending rate with the available network capacity. An evaluation of our mechanisms using simulations demonstrates that our approach is superior to the standard approaches, AODV and OLSR, and effectively balances the user perceived QoE between the service flows.

Context-aware selection in multicast environments

Personalization and group communications have always been conflicting approaches. From one side, the user wants to get the services with their specific characteristics. From the other side, group communications imply the support of the same service, with the same characteristics, by a group of users. To simultaneously enable personalization and profit from the resources improvements provided by group-based communications, these groups need to be defined based on the users requirements, services and network information, which we denote as “context”. Based on this context for group definition, it is possible to adapt the content to the groups of users or even re-group them according to common features. This paper addresses the network part of the problem: based on the context information, we define an intelligent network selection, both for the access and core, respectively to efficiently choose the attachment points and the multicast trees for groups of users. This selection approach will improve the efficiency of the architecture in delivering the multiparty services. The simulation results of the proposed approach show that performing a wise network selection based on context increases overall network efficiency while still providing a personalized multiparty content delivery.

UNIT: Multicast using unicast trees

The proliferation of broadband wireless accesses has enabled the provisioning of multimedia communication services. Yet, the increasing demand for group-based multimedia services requires the development of new architectures capable of seamlessly delivering multi-party content and overcoming the prevailing heterogeneity and dynamics of current and next generation communication networks. In order to face these challenges we introduce UNIT, a solution that integrates multicast technologies for both core and access wireless mesh networks. UNIT is focused on the scalability and flexibility of the content delivery framework, adopting a hierarchical control strategy that enables seamless multi-party content transport over heterogeneous networks. Moreover, UNIT performs local reconfigurations of the content distribution tree in response to any context change, without impairing the remaining branches. The evaluation of UNIT in a real world demonstrator proves its feasibility and the efficiency of the proposed mechanisms regarding the control of the multi-party delivery trees.

A control framework for abstract multiparty transport

Abstract The increasing demand for group-based multimedia communications, personalization and seamless mobility imposes the development of novel approaches to overcome the heterogeneity and dynamics of future network environments. The study developed in this article addresses a context-aware multiparty content delivery framework, capable of providing autonomic control of personalized group-based services to users by a hierarchical strategy with the concept of Abstract Multiparty Trees (AMTs). A thorough study of the proposed concept is presented, aiming to assess the scalability and flexibility of our framework and associated procedures. An analytical study quantifies the amount of reconfigurations and resources saved in the network whenever context changes, showing how the control framework scales when the network size increases. The evaluation through simulation analyses the performance of the proposed solution, meeting the results of the analytical study and showing a good performance regarding the reconfiguration of the AMTs in terms of time and control overhead. Finally, a proof-of-concept demonstrator is also detailed, in order to prove the feasibility of the AMT concept and the good performance of its main control operations.

Enhancing abstract multiparty transport through Network Coding

In recent years there has been an increasing interest in multiparty multimedia services that, associated with the new trends in content consumption (e.g. mobility, heterogeneity, high-definition), raised novel challenges. This fact motivates the research towards new techniques that are capable of improving the user experience while simultaneously making a rational use of the network resources. Network Coding (NC) is one of those techniques. It has gained a notorious relevance due to its ability to optimize network throughput and resilience to packet losses. In this work we propose a context-driven framework for multiparty content delivery using NC to enhance the reliability of the services provided. We propose and evaluate two different approaches: a static one, where the level of redundancy remains constant, and a dynamic one, where the control framework autonomously adjusts the redundancy to the sensed quality of service, deriving coding parameters from network context information. We found that while the static scheme achieves better results in terms of recovered information, it comes at the cost of sometimes excessive redundant information. On the other hand, tuning NC with context parameters in the dynamic scheme saves more network resources with a small penalty in the recovered information.

Pervasive multiparty delivery framework for ubiquitous multimedia services

Multimedia services are rapidly growing in interest with the increase of available bandwidth on core and mobile technologies. There is a business opportunity for both adaptability and personalization of services centralized in users and their surrounding environment. Context Awareness requires the network to support mechanisms that are able to get information from the user situation as location, activity, presence, velocity, preferences, surrounding noise, etc., and triggering session modification and network control mechanisms. Context awareness provides a new trend in pervasiveness since it allows a full, but unconscious interaction between users, operators and service providers. This paper presents the results, from simulation and demonstrator implementation, of an architecture that enables context-aware and personalized multiparty multimedia content delivery, independently of the underlying access and transport technologies.