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Publicações

Publicações por Manuel Ricardo

2011

Evaluating Location Fingerprinting Methods for Underground GSM Networks deployed over Leaky Feeder

Autores
Pereira, F; Theis, C; Moreira, A; Ricardo, M;

Publicação
2011 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION

Abstract
Accurate localization techniques have long been of major importance for safety systems and a lot of research has been conducted in the distributed computing field regarding its functionality and reliability. In the specific scenario of long yet narrow tunnels existing at CERN, localization methods will enable a number of applications and processes to substantially reduce human intervention. In this paper we evaluate the use of Fingerprinting techniques with GSM signal available throughout the LHC tunnel via a radiating cable and compare some methods to estimate the location. The existing GSM infrastructure and tunnel conditions seem to be favorable to the adoption of these Fingerprinting methods. Nevertheless significant variations in the signal have been observed which might be traced back to different operational states of accelerator equipment. These effects and their sources will be analyzed in more detail in order to improve the applied techniques and their accuracy under such challenging conditions.

2011

Media Independent Handover Management in Heterogeneous Access Networks - An Empirical Evaluation

Autores
Cardoso, T; Neves, P; Ricardo, M; Sargento, S;

Publicação
Proceedings of the 73rd IEEE Vehicular Technology Conference, VTC Spring 2011, 15-18 May 2011, Budapest, Hungary

Abstract
The growth of available broadband access technologies has brought an enormous challenge for operators wanting to ensure seamless mobility to its customers in heterogeneous environments. In this paper we present an enhanced Mobility Management entity focused on a real heterogeneous environments and based on IEEE802.21 standard. This entity is capable to perform terminal and handover management regardless the access technology used. This entity was deployed in a real heterogeneous environment with Wi-Fi, WiMAX and HSPA using an Android smartphone. In order to provide Layer 3 mobility support it was integrated with a modified version of MIPv6. The results show not only the impact of a centralized entity to manage vertical handovers, but also the performance of IEEE802.21 protocol in a real scenario with a real implementation. ©2011 IEEE © 2011 IEEE.© 2011 IEEE.

2010

Using Directional Antennas on Stub Wireless Mesh Networks: Impact on Throughput, Delay, and Fairness

Autores
Kandasamy, S; Campos, RL; Morla, R; Ricardo, M;

Publicação
Proceedings of the 19th International Conference on Computer Communications and Networks, IEEE ICCCN 2010, Zürich, Switzerland, August 2-5, 2010

Abstract
Wireless Mesh Networks (WMNs), which feature infrastructureless broadband network configurations, are attracting attention as an elemental technology when it comes to the extension of current WLAN infrastructures. State of the art solutions addressing WMNs usually assume the use of omnidirectional antennas. In this paper we evaluate the performance improvements obtained when using directional antennas. By using simulations, we analyze the gains in terms of throughput, delay and fairness, considering a grid network topology used to extend an infrastructure network. Simulation results show that by changing the type of antenna in use from omnidirectional to directional, the average throughput of a WMN can increase about 56% and the average network delay can be reduced by approximately 40%, without compromising fairness. © 2010 IEEE.

2010

Improving P2P video streaming in wireless mesh networks

Autores
Salta, N; Morla, R; Ricardo, M;

Publicação
The 9th IFIP Annual Mediterranean Ad Hoc Networking Workshop, Med-Hoc-Net 2010, Juan Les Pins, France, 23-25 June, 2010

Abstract
P2P Video Streaming has become a reliable and efficient solution for distributing video on the Internet. Similarly to regular P2P file-sharing, all the participating nodes exchange information. Wireless Mesh Networks, in turn, can be seen as a cost-effective solution to extend Internet access networks. In this paper we propose improvements to P2P Video Streaming. These improvements can provide gains in scenarios where the service is deployed over Wireless Mesh Networks and the nodes are simultaneously peers and packet forwarders. By using cross-layer interactions between application and network layers, we show that the proposed improvements reduce substantially the amount of traffic in the network. ©2010 IEEE.

2010

WiMetroNet A Scalable Wireless Network for Metropolitan Transports

Autores
Ricardo, M; Carneiro, G; Fortuna, P; Abrantes, F; Dias, J;

Publicação
Sixth Advanced International Conference on Telecommunications, AICT 2010, 9-15 May 2010, Barcelona, Spain

Abstract
This paper addresses Wireless Networks for Metropolitan Transports (WNMT), a class of moving or vehicle-to-infrastructure networks that may be used by public transportation systems to provide broadband access to their vehicles, stops, and passengers. We propose the WiMetroNet, a WNMT that is auto-configurable and scalable. It is based on a new Ad hoc routing protocol, the Wireless Metropolitan Routing Protocol (WMRP), which, coupled with data plane optimizations, was designed to be scalable to thousands of nodes. © 2010 IEEE.

2006

Dynamic and automatic connection of personal area networks to the global internet

Autores
Campos, R; Ricardo, M;

Publicação
Proceedings of the International Conference on Wireless Communications and Mobile Computing, IWCMC 2006, Vancouver, British Columbia, Canada, July 3-6, 2006

Abstract
In the Next Generation Networks (NGNs) users will carry multiple devices forming cooperative networks known as Personal Area Networks (PANs). Some existing technologies enable this type of networks, such as Bluetooth or IEEE 802.15.4, but a unified framework capable of self-organizing them dynamically in a full heterogeneous environment populated by these and other technologies still has to be defined. Also, these networks are envisioned to be connecting dynamically to the Internet, and may use two IP versions and their autoconfiguration mechanisms. In this paper we propose a new framework, the Autoconfiguration and Self-management of Personal Area Networks (ASPAN), which enables the automatic and dynamic deployment of PANs in the heterogeneous environments envisioned for NGNs and handles the automatic and dynamic connection of a PAN to the global Internet. Copyright 2006 ACM.

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