Luis Amaral Lopes

A Proposal for Dynamic Frequency Sharing in Wireless Networks

Wireless networks are today employed as complementary access technology, implemented on the last hop towards the Internet end-user. The shared media that wireless deployments provide and which is relevant to interconnect multiple users has a limited technical design, as only one device can be served per unit of time, design aspect that limits the potential applicability of wireless in dense environments. This paper proposes and evaluates a novel MAC-layer mechanism that extends current wireless networks with the possibility to perform downstream transmission to multiple devices within a single transmission time-frame, resulting in improved fairness for all devices. The mechanism, which is software-defined, is backward-compatible with current wireless standards and does not require any hardware changes. The solution has been validated in a realistic testbed, and the paper provides details concerning the computational aspects of our solution; a description of the implementation; and results extracted under different realistic scenarios in terms of throughput, packet loss, as well as jitter.

A Proposal for Elastic Spectrum Management in Wireless Local Area Networks

The last hop of the Internet towards the end-user is mostly supported by wireless technologies and thus interconnects multiple users, that should, ideally, be served simultaneously. The shared media capability of such last hop is, however, underused, asthe principle behind wireless technologies implies that only one user can be served at an instant in time. Aiming at allowing multiuser transmission within a specific time-frame, this technological demonstration goes over a novel wireless extension mechanism explaining how it can be applied to current wireless networks while keeping backward compatibility.

Trust as a Fairness Parameter for Quality of Experience in Wireless Networks

This paper addresses the applicability of trust metrics as a fairness parameter in call admission control within the context of user-centric networks. The paper explains how trust can assist in improving user Quality of Experience in wireless networks, by taking into consideration not only channel conditions, but also trust levels derived from the interaction that users have in the context of Internet shared services.

NSense: A people-centric, non-intrusive opportunistic sensing tool for contextualizing nearness

In the context of social well-being and context awareness several eHealth applications have been focused on tracking activities, such as sleep or specific fitness habits, with the purpose of promoting physical well-being with increasing success. Sensing technology can, however, be applied to improve social well-being, in addition to physical well-being. This paper addresses NSense, a tool that has been developed to capture and to infer social interaction patterns aiming to assist in the promotion of social well-being. Experiments carried out under realistic settings validate the NSense performance in terms of its capability to infer social interaction context based on our proposed computational utility functions. Traces obtained during the experiments are available via the CRAWDAD international trace repository.