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Publications

Publications by José Manuel Oliveira

2008

Dynamic generation of SMIL-based multimedia interfaces

Authors
Oliveira, JM; Carrapatoso, E;

Publication
Journal of Multimedia

Abstract
The current heterogeneous world of networks and terminals combined with the generalized mobility of users pose telecommunications operators and service providers the challenge of dynamically adapt the services they provide. This paper presents a proposal to solve the problem of the adaptation of multimedia services in mobile contexts. The paper combines context-awareness techniques with user interface modeling and description to dynamically adapt telecommunications services to user resources, in terms of terminal and network conditions. The solution is mainly characterized by the approach used for resolving the existing dependencies among user interface variables, which is based on the constraints theory, and by the mechanism for acquiring the user context information, which uses the Parlay/OSA interfaces. The experiments and tests carried out with these techniques demonstrate a general Improvement of the adaptation of multimedia services in mobile environments, in comparison to systems that do not dynamically integrate the user context information in the adaptation process. © 2008 Academy Publisher.

2009

Unified communications: Different approaches for different types of enterprises

Authors
Almeida, F; Oliveira, J; Cruz, J;

Publication
Proceedings of the IADIS International Conference Informatics 2009, Part of the IADIS Multi Conference on Computer Science and Information Systems, MCCSIS 2009

Abstract
Unified communications (UC) have the potential to dramatically simplify and improve enterprise communications, reducing costs and improving revenue opportunities. By integrating various forms of communications, such as voice, video, instant messaging, conferencing, presence and voicemail, individuals and groups can more effectively control and manage their inbound and outbound communications sessions. However, Large Enterprises (LE) and Small & Medium Enterprises (SMEs) have a diverse perspective look of UC and different needs. In this paper we will analyze the reasons that motivate the business leaders to introduce unified communications and we will study with detail the large enterprises and SMEs approach for the implementation of a unified communications solution. © 2009 IADIS.

2009

Mitigating the Security Risks of Unified Communications

Authors
Almeida, F; Cruz, J; Oliveira, J;

Publication
PROCEEDINGS OF 2009 INTERNATIONAL CONFERENCE ON COMPUTER ENGINEERING AND APPLICATIONS

Abstract
Unified Communications (UC) have the potential to dramatically simplify and improve enterprise communications, reducing costs and improving revenue opportunities. However, these benefits do not come without risks. The introduction of an IP-based UC solution brings an array of new vulnerabilities into the enterprise, exploited by a growing number of malicious programs. This paper presents the most common of risks faced by the major dominant technologies used in unified communications solutions and an approach to mitigate them.

2002

Service provision & resource discovery in the VESPER VHE

Authors
Moura, JA; Oliveira, JM; Carrapatoso, E; Roque, R;

Publication
2002 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-5, CONFERENCE PROCEEDINGS

Abstract
In VESPER1, the concept of VHE is being implemented and validated through the provision of a VHE system and various services to make use of it. This paper describes one of these services and presents how it validates VHE architecture aspects related with service adaptation to terminals and network, connection establishment, service personalization, session continuity/mobility and service advertisement. The paper also discusses some VHE usage scenarios of the resource discovery feature, showing how it plays an important role particularly in what concerns the ubiquitous service availability through the VHE platform.

2009

A Resource Management Strategy for Interconnected WLAN and UMTS Networks based on User Mobility, Call Renegotiation, and Call Reallocation

Authors
Del Monego, HI; Oliveira, JM; Ricardo, M;

Publication
2009 6TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS (ISWCS 2009)

Abstract
The users of telecommunications services are demanding access to their subscribed services in mobile contexts. This demand leads to the development of mechanisms that enable the transference of service sessions between networks, seamlessly to the user. These mechanisms allow the operator to jointly manage its networks resources, providing a better service to its customers and, simultaneously, increasing its revenue. Starting from the UMTS and WLAN interconnection architecture defined by 3GPP, this paper presents a new strategy for joint radio resource management, suitable for contexts where these networks are interconnected. This strategy bases its decisions on criteria related to user mobility characteristics. The algorithm also introduces the possibility of renegotiating new calls and reallocating running calls from one access network to another. The new radio resource management strategy is compared with two well-known strategies, the former based on coverage area and the later based on load balancing. The comparison studies show the proposed strategy outperforms the other strategies in what concerns call blocking probability and applications QoS support. Besides, the proposed strategy tends to reduce the handoffs between networks.

2012

Impact of data collecting techniques on the performance of a Wireless Sensor Network

Authors
Abdellatif, MM; Oliveira, JM; Ricardo, M; Steenkiste, P;

Publication
2012 International Symposium on Wireless Communication Systems (ISWCS), Paris, France, August 28-31, 2012

Abstract
Wireless Sensor Networks (WSNs) consist of small devices with processing, communication and sensing capabilities. These devices interact together to carryout monitoring tasks. An example of such network is a photo-voltaic (PV) power plant where each solar panel has a sensor. The number of interconnected solar panels can become very large, and spread over a large area. Each sensor will sense the output of the panel and send this value to a central node for processing. In this paper we evaluate the performance of a wireless sensor network employing three different data collecting techniques. The study considers different networks, each with a different number of nodes and with different values for the offered load, estimating for each network size and offered load, network throughput, packet loss and end-to-end packet delay. Results show that as the size of the network grows and for higher values of the offered load, the best performance is achieved by using a polling based data collecting technique. © 2012 IEEE.

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