NEC Europe Laboratories

Heidelberg, Germany

NEC Europe Laboratories

Heidelberg, Germany
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Garfias P.,Polytechnic University of Catalonia | Sallent S.,Polytechnic University of Catalonia | Gutierrez L.,Polytechnic University of Catalonia | Mur D.C.,NEC Europe Laboratories
National Fiber Optic Engineers Conference, NFOEC 2012 | Year: 2012

This paper proposes an improved scheduling algorithm that optimizes the allocation of the real-time services and elastic flows in EPON by spreading the real-time service periods lowering the delay and thus fulfilling the QoS requirements. © 2012 OSA.


Papageorgiou A.,NEC Europe Laboratories | Schatke M.,Blue Moon | Schulte S.,Vienna University of Technology | Steinmetz R.,TU Darmstadt
International Journal of Web Services Research | Year: 2012

Reducing the size of the wirelessly transmitted data during the invocation of third-party Web services is a worthwhile goal of many mobile application developers. Among many adaptation mechanisms that can be used for the mediation of such Web service invocations, the automated enhancement of caching mechanisms is a promising approach that can spare the re-transmission of entire content fields of the exchanged messages. However, it is usually impeded by technological constraints and by various other factors, such as the inherent risk of using responses that are not fresh, i.e., are not up-to-date. This paper presents the roadmap, the most important technical and algorithmic details, and a thorough evaluation of the first solution for generically and automatically enriching the communication with any third-party Web service in a way that cached responses can be exploited while a freshness of 100% is maintained. Copyright © 2012, IGI Global.


Mur D.C.,NEC Europe Laboratories | Perez-Costa X.,NEC Europe Laboratories | Marchenko V.,RWTH Aachen | Ribes S.S.,Polytechnic University of Catalonia
Wireless Communications and Mobile Computing | Year: 2012

Wireless LAN is becoming a pervasive wireless access technology that can be found in almost any mobile device such as laptops, PDAs, portable game consoles and mobile phones. Each of these groups of devices have a different set of requirements according to their intended use and applications but most of them share two main requirements: QoS support to satisfy applications' demands and power saving functionality to achieve an operating time according to users' expectations. IEEE 802.11e defines two centralized solutions in order to address these problems: Hybrid Coordination Channel Access (HCCA) for QoS and Scheduled Automatic Power Save Delivery (S-APSD) for power saving. The focus of our work in this paper is the analysis and evaluation of a proposed centralized scheduler that makes use of both aforementioned IEEE 802.11e QoS and power saving solutions. Our contributions are as follows: (i) Design and analytical modeling of a proposed centralized scheduler (DRA) that maximizes the minimum distance between the resource allocations with pseudo-polynomial complexity, (ii) Extensive performance evaluation of the QoS and power saving benefits of the Distribution proposal (DRA) as compared to a generic Grouping one (GRA), and (iii) Evaluation of the complexity and scalability of the proposal to assess its feasibility in practice. Copyright © 2010 John Wiley & Sons, Ltd.

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