Seminars take place in the "Auditório do DSI" at the Azurém Campus of University of Minho in Guimarães
Speaker: Rui L. Aguiar
This talk will address the problems on the design of mobility management systems. The currents trends from standardization bodies (IETF/3GPP/IEEE) will be discussed. The talk will address the separation between local and global domains, and will present the different mobility models that future networks will have to support: user, device, session – and associated technologies.
Speaker: Rui L. Aguiar
Current network design is based on the Internet paradigm. The basic IP-design considerations have been long been challenged by issues as mobility, QoS, multimedia, security and multicast. As a consequence, the IP deficiencies are well-known. Recently, some advocates of a refunding of networking principles have been presenting a radical change on networking design, the so-called clean-slate design. The talk will address the major challenges being tackled by these novel approaches.
Speaker: Petia Georgieva
Neural networks (NN) is a computational and engineering methodology whose design is based on models taken from neurobiology and on the notion of learning, in particular, the brain's massively parallel and learning aspects. The use of neural networks is becoming increasingly widespread, with applications in many areas. The objective of this lecture is to introduce the PhD students to the research area of NNs and to some of their most successful applications as in signal processing, modeling and control. The lecture is going to consider typical NN architectures (Feedforward NN, Radial Basis NN, Recurrent NN) and associated computational algorithms for accomplishing learning (error correction learning, Hebbian learning, competitive learning). Supervised, unsupervised and reinforcement learning paradigms are also going to be discussed.
Speaker: Orlando Belo
All over the world we have been assisting to a strong increase of the telecommunication systems usage. People are faced day after day with strong marketing campaigns trying to get their attention to new telecommunication products and services. Telecommunication companies try surviving in a high competitive business arena. It seems that their efforts were well done, because customers are adopting strongly the new trends and use (and abuse) systematically communication services in their quotidian. Although fraud situations are rare, they are increasing and they correspond to a large amount of money that telecommunication companies lose every year. In this talk, we will present and discuss the problem of fraud detection in telecommunication systems, especially the super-imposed ones, providing an anomaly-based technique, supported by a signature schema, for getting closer fraud situations.
Speaker: Susana Sargento
The goal of this seminar on New Trends on Mobile Networking is to provide an overview of cutting-edge research on emerging networks and paradigms, focusing on the self-organized and mobile aspects and trends of these networks, addressing mainly wireless ad-hoc and mesh networks and their integration in the infrastructure network. The new network paradigms require the support of different, distributed protocols for the network operation. This seminar will span a specific range of topics with a focus on the mobile self-organization paradigm, covering important research results from the past and promising new directions. Topics that will be covered include: - Paradigms of self-configuration - Ad-hoc networks: application and usage scenarios, main challenges and significant approaches with respect to trust, congestion control, QoS and mobility - Mesh networks: community concept in the mesh networking, emerging standards (IEEE 802.11s, IEEE 802.16 mesh), main challenges and significant approaches with respect to trust, congestion control, QoS and mobility - Autonomic communication: autonomic paradigm, collaboration and trust.
Speaker: Susana Sargento
With the current evolution of network technologies we envision that, in a near future, there will be a heterogeneous landscape of different technologies such as WLAN, WiMAX, UMTS/MBMS and DVB, providing ubiquitous network access to users. Also, networks such as ad-hoc and moving networks are also expected to be integrated in a next generation network. Regarding network providers, multi-technology and multi-network availability can and should be used to enhance user experience aiming at the always-best-connected paradigm. This ubiquitous network access requires an architecture that homogeneously integrates the heterogeneous access technologies for seamless movement of the users throughout the available technologies. This seminar will comprise a specific range of topics with a focus on the integration of heterogeneous networks, covering important research results on mobility, multihoming, QoS from the past and promising new directions. Topics that will be covered include: - Heterogeneity of access technologies: local area technologies, cellular technologies and broadcast distribution technologies - Integration of heterogeneous technologies - Challenges for networks integration: - Mobility: new fast mobility approaches and media independent, multihoming - QoS: architectures for QoS support (efficiency and scalability) and integration with mobility - Support for the integration of ad-hoc, mesh, vehiculars and moving networks
Speaker: José Carlos Pedro
This Talk aims at presenting a broad overview on some of the new applications of digital signal processing techniques for achieving the reconfigurability of wireless transmitters. The Talk starts with a review of the limitations imposed on power added efficiency and spectrum efficiency by conventional analogue transmitters, to then show how they can be overcome with some emerging technologies as the polar transmitter. Then it discusses how this alternative wireless transmitter architecture is especially amenable for the transfer of many traditional analog blocks into the digital domain, enabling, this way, the desired reconfigurability of the transmitter by software.
Speaker: José Carlos Pedro
Wireless transmitter linearization consists on finding an auxiliary circuit capable of generating a distortion that cancels the one originally created in the transmitter nonlinearities. Therefore, the success of this linearization strongly depends on an accurate behavioral model of its nonlinear distortion. This is particularly important in digital predistortion, DPD, where the linearizer must be a very good approximation of the PA model pre-inverse. This Talk starts by identifying the main sources of wireless transmitter nonlinearity and its impact on the quality of service, to then derive general conditions for the transmitter behavioral model identification. Then, the Talk will address the theoretical inversion of this transmitter model to end up discussing methods of DPD identification.
Speaker: Nuno Borges Carvalho
This talk is dedicated to present an overview of measurement systems used for wireless circuits and system evaluation, in that respect some basic concepts of Digital Oscilloscopes, Spectrum Analysers, Network Analyzers and more advanced instrumentation as vector signal analyzers will be presented. The basic concepts of those type of instrumentation, and the explanation of its building blocks will be addressed throughout the seminar. The presentation will also include some information on RF system design and wireless figures of merit evaluation. Special attention will also be given to measurements instrumentation for nonlinear distortion in wireless systems, including figures of merit for co-channel and adjacent channel distortion.
Speaker: Nuno Borges Carvalho
This talk is aimed at the explanation of location and positioning technologies for indoor environments. In the seminar some techniques for location systems, as angle of arrival, time of flight, differential time of flight, and RF fingerprinting, will be addressed and explained. It is expected to be able to make an overview of the most used schemes for this type of systems, and present some practical solutions for location in indoor environments. The main problems associated with these schemes will also be addressed as some proposals for error minimization, in the path for this explanations basic concepts as system modeling using nonlinear approximants will also be addressed, specially neural networks modeling approaches for location schemes.
Speaker: Carlos Lima
A smart antenna system combines multiple antenna elements with a signal-processing capability to optimize its radiation and/or reception pattern automatically in response to the signal environment. A wide range of wireless communication systems may benefit from spatial processing, including high-mobility cellular systems, low-mobility short-range systems, wireless local loop applications, satellite communications, and wireless LAN. By employing an array of antennas, it is possible to multiplex channels in the spatial dimension just as in the frequency and time dimensions. To increase system capacity, spatially selective transmission as well as spatially selective reception must be achieved. Adaptive arrays utilize sophisticated signal-processing algorithms to continuously distinguish between desired signals, multipath, and interfering signals as well as calculate their directions of arrival. This approach continuously updates its transmit strategy based on changes in both the desired and interfering signal locations. The ability to track users smoothly with main lobes and interferers with nulls ensures that the link budget is constantly maximized because there are neither microsectors nor predefined patterns. The flexibility of adaptive smart antenna technology allows for the creation of new value-added products and services that give operators a significant competitive advantage. Adaptive smart antennas are not restricted to any particular modulation format or air-interface protocol. They are compatible with all current air-interface modulation schemes. The main purpose of this tutorial is to present the most relevant algorithms in array signal processing and the current research directions, especially concerning to DoA algorithms for arbitrary geometry arrays.
Speaker: Joaquim José dos Santos Esteves Neves
By definition, the Global Information Infrastructure (GII) will be an infrastructure which facilitates the development, implementation and interoperability of existing and future information services and applications within and across the telecommunications, information technology, consumer electronics and content provision industries. This infrastructure will consist of interactive, broadcast and other multimedia delivery mechanisms coupled with capabilities for individuals to securely share, use and manage information, anytime and anywhere, with security and privacy protection, and with levels of acceptable cost and quality. Taking into consideration the extraordinary expansion of digital traffic, and the need to converge and optimise the operating networks, several study groups are developing global standards for Next Generation Networks (NGN) at the International Telecommunication Union (ITU ), which will establish the convergence of telecommunications network and IP network technologies. By other side, TISPAN (Telecommunication and Internet converged Services and Protocols for Advanced Networking) is the European Telecommunications Standards Institute (ETSI) core competence centre for fixed networks and for migration from switched circuit networks to packet-based networks with an architecture that can serve in both to create the Next Generation Networks. A Next Generation Network is a packet-based network able to provide Telecommunication Services to users and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent of the underlying transport-related technologies. It enables unfettered access for users to networks and to competing service providers and services of their choice. It supports generalised mobility which will allow consistent and ubiquitous provision of services to users. The proposed 2 hours session of the MAP-Tele Seminar Curricular Unit, will focus on the recent activities of the Next Generation Networks - Global Standards Initiative (NGN-GSI), that are being held at ITU.
Resource Optimization in Communications Systems: An Information Theoretic-Estimation Theoretic Approach
Speaker: Miguel Rodrigues
A large body of optimization problems abound in the telecommunications field, particularly enticing ones relating to resource optimization in communication systems. In this talk, we will concentrate on power allocation optimization problems in so-called multiple input-multiple output Gaussian channels with arbitrary inputs, that represent a very large number of relevant communications scenarios such as multiple antenna systems, code division multiple access (CDMA) systems or digital subscriber line (DSL) systems. In this context, we will resort to a key information theoretic-estimation theoretic mathematical framework to tackle this kind of problems in an effective manner. Initially, we will review some basic principles of unconstrained and constrained optimization theory, with a particular emphasis on convex optimization problems. We will introduce a number of key concepts including the first-order or Karush-Kuhn-Tucker (KKT) optimality conditions that yield the various critical points (maxima, minima and saddle-points) to a particular optimization problem. We will then consider a number of classic power allocation problems in communications systems, namely power allocation in parallel independent Gaussian channels with Gaussian inputs as well as parallel independent Gaussian channels with arbitrary inputs. In this context, we will review the conventional waterfilling and mercury-waterfilling graphical interpretations that illustrate the optimal power allocation policy that maximizes the system mutual information (or system information rate). We will later consider power allocation in multiple input-multiple output Gaussian channels with arbitrary inputs. Here, we will exploit the information theoretic-estimation theoretic framework to determine the power allocation strategy that maximizes the information rate between the input and the output of the system. We will also put forth a novel mercury-waterfilling interpretation of the optimal power allocation procedure that generalizes the conventional waterfilling and mercury-waterfilling interpretations. We will also exploit this same mathematical framework to specialize the optimal power allocation strategy to asymptotic regimes, namely the low- and high-power regimes. Of particular relevance, we will demonstrate that in the high-power regime the power allocation strategy that maximizes mutual information also maximizes the minimum distance of the output lattice, hence minimizes the error probability. We will also extrapolate these results to optimal precoding policies. This represents joint work with Prof. Fernando Perez-Cruz and Prof. Sergio Verdú from the Department of Electrical Engineering, Princeton University, U.S.A.
Speaker: Helena Rodrigues
Pervasive Computing has been emerging as a new paradigm for computing systems, and essentially corresponds to a vision where computation is embedded into everyday objects, where everything communicates with everything else, and where virtual and physical environments are closely interconnected. Smart Spaces have become a particularly active topic of research in the Pervasive Computing research community, with the ultimate goal being the creation of a meta-operating system for physical environments. Such software infrastructure should be able to transparently manage the relevant resources and provide an integrated execution environment in which applications, seen here as orchestrated collections of services, could be executed in association with the corresponding physical environment. A considerable number of middleware architectures have been proposed that aim to provide the necessary glue to integrate an open, diverse and a priori unknown set of services into a functioning system. Typical issues include the architectural approach, the discovery, selection and spontaneous interaction between entities, naming, event notification, and the ability to enable cooperation between entities even if separated in time and space. These systems provide some type of programming model that application developers can use to create new applications without having to consider the details of the underlying infrastructure. Research in the area of middleware for Smart Spaces has been in progress for the last few years, both in academia and industry, and it is now possible to study and compare a diverse number of approaches and their accomplishments. The goal of this seminar is to introduce students into the key design approaches of software infrastructures for Smart Spaces. Reference case studies will be used to guide the study of the most commonly used approaches and issues. This seminar will focus on the limitations of existent approaches and present to students some new directions to system support for smart spaces based on the properties of gradual evolution and sustainability.
Speaker: Paulo Cortez
TCP/IP traffic prediction has gained recent attention from the computer networks community. By improving this task, network providers can optimize resources, allowing for better quality of service. We propose a novel NN forecasting approach based on fast heuristic procedures and compare the results with other methods (e.g. Holt-winters, Arima). The predictions are analyzed at different time scales/lookahead horizons and experiments in real-world datasets (e.g. UKERNA), have shown competitive results. Also, we developed a multivariate approach based in a novel heuristic that uses the Open Shortest Path First (OSPF) protocol and Dijkstra algorithm to select the most probable neighbor that is expected to influence the predicted link. Regarding the univariate versus multivariate comparison, better results were achieved by the latter for the core to subnetwork links.
Speaker: Rui José
The promise of anywhere and anytime has been an important driver for the Telecommunications industry. The overall idea is that the wide availability of a vast range of network technologies and services would enable a continuous access to information services and applications. The underlying assumption, which is also prevalent in mobile computing in general, is that we should be able to provide users and applications with a seamless service in which the infrastructural details would be irrelevant. Regardless of the merits of this approach, entirely new ways of looking at this problem have been emerging with Ubiquitous Computing and Ambient Intelligence. Physical proximity and the respective location of reference suddenly become crucial in how we access services. Infrastructural seams, such as access points, suddenly become key elements in system design. Additionally, we realised that there are several types of infrastructural limitations with consequences that we cannot hide, and in those cases it is often better to expose that ambiguity to users and let them deal with them. This seminar is going to introduce ubiquitous computing and ambient intelligence, and in that context is going to present some case studies in which the discontinuities and limitations of the infrastructure are explored as seams to support the integration between physical and virtual environments.
Speaker: Paulo Mendes
In the most recent years, we have assisted to an increasing popularity of peer-to-peer applications, social networks and wireless technologies. Such tendency is still bound to increase, as shown by the support that wireless is currently offering to support human interaction in the information era. There are however serious limitations to this growth given that wireless networks are unreliable due to signal fading and bandwidth limitations. Solutions to the current limitations are being worked out on different OSI Layers. For instance, solutions may rely on multimedia coding, trying to increase the reliability of communications and quality of multimedia content. At the network level, cooperation models are strongly emerging, in particular due to the sharing possibilities that the wireless media offers. For instance, communication where the user is actively involved in the provider chain, user-provided models, are emerging (e.g. FON, Wisher). These new models have as main factor cooperation, as have other networking methods that are capable of intelligently forming cooperative entities, creating a user-centric approach to improve the efficiency of wireless communications. This seminar will be presented in the context of the MAP-TELE optional course ""Cooperative Networking"", which will be dedicated to the analysis of emerging cooperation networking models and technologies. Special attention will be given to the course three main topics: i) cooperative communication models and market potential; ii) cooperation techniques; iii) and security in cooperative environments.
Speaker: Rute Sofia
Within the context of packet-switched networking and specifically within the context of the Internet, forwarding relies on the store-and-forward concept. Specifically, nodes keep forwarding state about the possible location (or direction) of destinations and compute paths based on such information. For instance, in OSI Layer 3 the optimal path in unicast scenarios is the shortest path between two points in terms of traversed number of hops. In OSI Layer 2 and considering the case of Ethernet forwarding behavior, the optimal path between two nodes relates to the min cumulative path cost. In the Internet, forwarding strategies are therefore dependent upon the way that link costs are defined. While still efficient, most of the metrics that are the basis to today's Internet routing were though having in mind static topologies, fix end-nodes, and providing support to the client-server service models. Those parameters were capable of providing robustness while keeping a much desired feature of IP: its connectionless facet. This seminar has as main purpose to delve into the changes that the Internet is going through, specifically focusing on forwarding and routing aspects. The content to be presented gives a small perspective on the optional MAP-TELE course “Advanced Forwarding and Routing”. The seminar will go through the course content and present the three modules to be held during the second semester: Ethernet forwarding on large scale networks (carrier-grade Ethernet forwarding); new routing approaches; routing in Delay Tolerant Networking (DTN).
Speaker: Luis Ribeiro
This seminar will address a number of RF and telematic technologies which can be used to help VIPs in their daily life. We'll discuss examples such as radio-transceiver solutions for navigation within buildings; client-server applications such as midiChat; RF case-finder; alternative (low-cost) cane designs for blind-people.