Networks and Multimedia Communications Group


Group objectives 2003-2007

In 2003-2007 the group aimed at addressing the following topics:
Network Dimensioning and Routing Optimization - To develop modelling and solving techniques for optimization problems that arise in telecommunications both on network dimensioning and traffic routing, which include not only efficient mathematical programming models but also heuristic and meta-heuristic algorithms to find good solutions in short computing times.
Traffic statistical characterization, modeling and measurements - To gain a better understanding of the behavior of Internet traffic and users, by developing (i) traffic models that incorporate long range dependence and multi-fractal characteristics and (ii) statistical methods to classify Internet users and detect Internet applications based on traffic characteristics. To develop models to predict the network performance when the input traffic profile changes. To develop methods to infer network characteristics from end-to-end measurements. To develop a network monitoring platform with a p2p architecture.
Network architectures and protocols for novel networks - To research on new paradigms for networks, with special focus on mobile environments. This includes paradigms as user-centric networks, heterogeneous networks for mobile environments, ad-hoc and mesh structures, post-IP architectures, considering both always best connected and disconnected operations. Multiple aspects of networks are considered here, including aspects as mobility, QoS, security and multimedia, with the overall ambition of devising the best integrated compromises between some (all) of these aspects leading to an integrated solution for future communications.
Advanced service platforms - To research on the service support for novel networks, including aspects such as service deployment, composition, context awareness and customer profiling, both at the network-level services and added value services. This also includes evolutions on standardized platforms, such as the IMS or MBMS, or home network triple-play platforms.
Experimental infrastructures - To Implement and maintain an advanced network laboratory to support research in the network areas being addressed by the group.

Main achievements 2003-2007

Network Dimensioning and Routing Optimization - In MPLS and MPLS/WDM, considered hop constrained routing with survivability and proposed ILP models for realistic problem instances and efficient heuristics based on decompositions of the ILP models. In OSPF, proposed an ILP model, an exact solving technique and, for large networks, meta-heuristics with better performance than previous known techniques. In Ethernet with Multiple Spanning Trees, proposed meta-heuristics for link load optimization.
Traffic statistical characterization, modeling and measurements - Fitting procedures for MMPPs, dBMAPs and L-Systems to model the packet arrival and size processes. Methodologies for the classification of Internet users and identification of Internet applications based on discriminant analysis and neural networks. Methodology to estimate the capacity and the cross-traffic of all links in a path based on end-to-end measurements. A network model to predict the QoS based only on measurements of the inbound/outbound traffic. A Java version of the OWAMP protocol and a distributed traffic monitoring tool with a p2p architecture.
Network architectures and protocols for novel networks - A NGN architecture, integrating QoS, mobility, and security (including novel privacy concepts) in multi-mode communications, supporting ad-hoc, mesh, and infrastructure communications, and using optimum mechanisms for data transfer, switching from multicast to unicast modes. A user-centric wireless architecture, based on self-organized concepts, cross-layer cooperation and user incentives. A security architecture for LANs that introduces an effective security in local configuration protocols, such as DHCP and ARP. A communication platform, developed to Portuguese Navy, for TCP/IP services over HF military systems optimised for web browsing and email.
Advanced service platforms - Contributed to the development of standardization of 3GPP-based infrastructures, with new MBMS-advanced concepts, merging IMS and MBMS platforms, and with contributions to all-IP visions of IMS++ platforms. Researched on grid platforms and its interoperation with the network. Developed optimum mechanisms for triple-play environments, for home networks. Experimental infrastructures - Implemented a state-of-the-art network laboratory used as testbed for several European funded research projects, including C-Mobile (on MBMS evolutions); Daidalos (on NGN) and AMORA (on home networks).