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Featured researches published by Alexandre Santos.


international conference on software, telecommunications and computer networks | 2013

Security architecture for mobile e-health applications in medication control

Fabio Goncalves; Joaquim Macedo; M. João Nicolau; Alexandre Santos

The use of Radio Frequency Identification technology (RFID) in medical context enables not only drug identification, but also a rapid and precise identification of patients, physicians, nurses or any other health caregiver. The combination of RFID tag identification with structured and secured Internet of Things (IoT) solutions enables ubiquitous and easy access to medical related records, while providing control and security to all interactions. This paper defines a basic security architecture, easily deployable on mobile platforms, which would allow to establish and manage a medication prescription service in mobility context making use of electronic Personal Health Records. This security architecture is aimed to be used with a mobile e-health application (m-health) through a simple and intuitive interface, supported by RFID technology. This architecture, able to support secured and authenticated interactions, will enable an easy deployment of m-health applications. The special case of drug administration and ubiquitous medication control system, along with the corresponding Internet of Things context, is presented. The security architecture and its protocols, along with a general Ambient Assisted Living secure service for medication control, is then analyzed in the context of the Internet of Things.


international conference on communications | 2003

A distributed admission control model for CoS networks using QoS and SLS monitoring

Solange Rito Lima; Paulo Carvalho; Alexandre Santos; Vasco Freitas

Achieving an admission control strategy for CoS networks covering both intra-domain and end-to-end operation is still an open issue. This paper discusses how AC can be carried out without adding significant complexity to the network control plane and proposes a distributed service-oriented AC model for these networks. The model only involves the network edge nodes leaving the network core unchanged. Ingress nodes perform implicit or explicit service-dependent AC based on both QoS and SLSs utilization metrics, obtained through edge-to-edge online monitoring performed at egress nodes. From an end-to-end perspective, the flow request is used both for AC and available service computation. Relevant aspects of the model interrelated areas and implementation key points are also discussed.


new technologies, mobility and security | 2008

Efficiency of PRI and WRR DiffServ Scheduling Mechanisms for Real-Time Services on UMTS Environment

Nuno Vasco Lopes; Maria João Nicolau; Alexandre Santos

The next generation of mobile phones will be probably all-IP based enabling users to access Internet services. In order to make this possible a satisfactory quality of service, at least equal to the fixed Internet, must be ensured. To achieve this goal an end-to-end QoS system must be constructed. Another fact is the dominance of IP over other technologies due, in large measure, to its characteristic of working with heterogeneous technologies. Consequently, being IP the common denominator on a heterogeneous environment, it is important to develop end-to-end IP QoS guarantees for the different applications over distinct access technologies. This is particularly important for cellular wireless networks due to the ever growing expansion of mobile phone users. One way to contribute to this goal is to apply DiffServ QoS mechanisms to UMTS technology in order to model an End-to-End QoS communication system. A mapping of DiffServ CodePoints into UMTS classes can be applied in order to get efficient PHB configurations. This paper proposes an architecture to support end-to-end quality of service to several application services running on mobile UMTS user agents and communicating with servers located in a wired internet. The proposed architecture is based on a DiffServ model, where QoS parameters are set either by the user agent or by the SGSN. In particular, RED queue management and PRI or WRR scheduling policies are enforced. Different UMTS traffic classes are mapped into different DiffServ parameters. The performance of this architecture has been evaluated by simulation using NS, assuming different network load scenarios. In particular, the delay and packet loss experienced by VoIP, Video, FTP and HTTP traffic are evaluated in the cases of PRI and WRR scheduling policies, and compared to those measured when DiffServ is not implemented. Finally, a revenue function to estimate the profits that an ISP could expect by using a DiffServ implementation on IP UMTS core routers is proposed.


international conference on conceptual structures | 2002

A distributed admission control model for class-based networks using edge-to-edge QoS and SLS monitoring

Solange Rito Lima; Paulo Carvalho; Alexandre Santos; Vasco Freitas

The advent of class-based networks has brought new needs for network traffic control in order to assure a certain QoS level. Despite the existing proposals, achieving a generic admission control (AC) strategy for traffic entering these networks is still an open issue. This paper provides new insights on how AC shall be accomplished proposing an encompassing AC model for multi-service class-based networks, which covers both intra-domain and end-to-end operation, without requiring changes in the network core and complex AC signaling. For each service type, AC is distributed and based on both on-line edge-to-edge monitoring of relevant QoS parameters and SLSs utilization. Service monitoring, performed at egress nodes, provides adequate metrics to ingress nodes which take implicit or explicit AC decisions based on service-de pendent criteria. Although being oriented to flow AC. the model can easily be applied to SLS AC. SLS auditing and SLS traffic conditioning are tasks also covered.


intelligent distributed computing | 2016

A Geographic Opportunistic Forwarding Strategy for Vehicular Named Data Networking

Xuejie Liu; M. João Nicolau; António Costa; Joaquim Macedo; Alexandre Santos

Recent advanced intelligent devices enable vehicles to retrieve information while they are traveling along a road. The store-carry-and-forward paradigm has a better performance than traditional communication due to the tolerance to intermittent connectivity in vehicular networks. Named Data Networking is an alternative to IP-based networks for data retrieval. On account of most vehicular applications taking interest in geographic location related information, this paper propose a Geographical Opportunistic Forwarding Protocol (GOFP) to support geo-tagged name based information retrieval in Vehicle Named Data Networking (V-NDN). The proposed protocol adopts the opportunistic forwarding strategy, and the position of interest and trajectories of vehicles are used in forwarding decision. Then the ONE simulator is extended to support GOFP and simulation results show that GOFP has a better performance when compared to other similar protocols in V-NDN.


next generation internet | 2005

A new path probing strategy for inter-domain multicast routing

António Costa; Maria João Nicolau; Alexandre Santos; Vasco Freitas

Many already in use applications require the provision of QoS services from the underlying network infra-structure. This is particularly true for multicast, since it involves many participants at very sparse locations usually aiming to receive or send multimedia real-time streams. One way to provide QoS is through routing, since QoS aware multicast routing protocols can find feasible multicast trees. In this paper an inter-domain QoS multicast routing protocol is presented, specifically designed for the hierarchical inter-domain scenario, where requirements like intra-domain independency and policy awareness should be met. Emphasis is given to the path probing mechanism used to connect new members to the multicast tree, stressing how it differs from others. Simulation results show that despite using a less aggressive and simplified probing mechanism-more suitable for inter-domain scenarios-the proposed routing strategy can build multicast trees with metrics similar to those build by more aggressive techniques, with considerable less effort.


ad hoc networks | 2015

A Probabilistic Interest Forwarding Protocol for Named Data Delay Tolerant Networks

Paulo Duarte; Joaquim Macedo; António Costa; Maria João Nicolau; Alexandre Santos

Delay Tolerant Networks (DTN) were designed to allow delayed communications in mobile wireless scenarios where direct end-to-end connectivity is not possible. Nodes store and carry packets, deciding whether to forward them or not on each opportunistic contact they eventually establish in the near future. Recently, Named Data Networking (NDN) have emerged as a completely new paradigm for future networks. Instead of being treated as source or destination identifiers, nodes are viewed as consumers that express interests on information or producers that provide information. Current research is carried on the combination of these two concepts, by applying data-centric approach in DTN scenarios. In this paper, a new routing protocol called PIFP (Probabilistic Interest Forwarding Protocol) is proposed, that explores the frequency of opportunistic contacts, not between the nodes themselves, but between the nodes and the information, in order to compute a delivery probability for interest and data packets in a Named Data Delay Tolerant network (ND-DTN) scenario. The protocol design and a prototype implementation for The ONE Simulator are both described. Simulation results show that PIFP presents significant improvements in terms of interest satisfaction, average delay and total cost, when compared to other ND-DTN approaches recently proposed.


international conference on ultra modern telecommunications | 2009

QoS-aware architecture for FHMIP micromobility

Nuno Vasco Lopes; Maria João Nicolau; Alexandre Santos

Wireless networks will certainly run applications with strict QoS requirements and so, micro-mobility protocols such as fast hierarchical mobile IPv6 (FHMIP) are useful tools to accomplish this new feature. The FHMIP is an effective scheme to reduce Mobile IPv6 handover disruption, however it does not support applications QoS requirements. Therefore, in order to provide QoS guarantees for real-time applications it is necessary to develop new traffic management schemes; this implies the optimization of network mobility support and also some network congestion control. A traffic management scheme of this type should take into account the QoS requirements of handover users and should implement a resource management (RM) scheme in order to achieve this. In this paper, a new RM scheme for the DiffServ QoS model is proposed. This new scheme is implemented by access routers as an extension to FHMIP micromobility protocol. In order to prevent QoS degradation of the existing traffic, access routers should evaluate the impact of admitting a new mobile node (MN), previously to the handover. This evaluation and sequent decision on wether admitting or refusing MNs traffic is based on a measurement-based admission control (MBAC) algorithm. This architecture, that has been implemented and tested using ns-2, includes a simple signaling protocol, a traffic descriptor and exhibits an adaptive behavior to traffic QoS requirements. All the necessary measurements are aggregated by class-of-service, thus avoiding maintaining state on the individual flows.


international ifip tc networking conference | 2002

Long-Range Dependence of Internet Traffic Aggregates

Solange Rito Lima; Magda Silva; Paulo Carvalho; Alexandre Santos; Vasco Freitas

This paper studies and discusses the presence of LRD in network traffic after classifying flows into traffic aggregates. Following DiffServ architecture principles, generic QoS application requirements and the transport protocolin use, a classification criterion of Internet traffic is established. Using fractal theory, the resulting traffic classes are analysed. The Hurst parameter is estimated and used as a measure of traffic burstiness and LRD in each traffic class. The traffic volume per class and per interface is also measured. The study uses real traffic traces collected at a University of Minho major backbone router in different periods of network activity.


international conference on networks | 2002

Internet network services management framework

Bruno Dias; Alexandre Santos; Fernando Boavida

This document presents a new approach to Internet network management without changing the basic rules of the interface and encapsulation mechanisms of standard management transport protocols. The Internet network services management framework (INSMF) tries to overcome the most important limitations of the Internet network management framework (INMF) by adding a new extension-model to it, using a network service management distributed architecture that provides services management functions with any desired level of functionality. The specification of a generic domain name service (DNS) management service is presented, as a way to illustrate the capabilities and potential of the proposed framework.

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