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Publications

Publications by Manuel Ricardo

2005

Dynamic and automatic interworking between personal area networks using composition

Authors
Campos, R; Pinho, C; Ricardo, M; Ruela, J; Pöyhönen, P; Kappler, C;

Publication
Proceedings of the IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, Berlin, Germany, September 11-14, 2005

Abstract
Next generation communication networks will be characterized by the coexistence of multiple technologies and user devices in an integrated fashion. The increasing number of devices owned by a single user will lead to a new communication paradigm: users owning multiple devices that form cooperative networks, and networks of different users that communicate with each other, e.g., acquiring Internet access through each other. In this communication scenario no user intervention should be required and technology should seamlessly adapt to the user's context, preferences, and needs. In this paper we address one of those scenarios, interworking between Personal Area Networks, using legacy technologies and the Ambient Network and Network Composition concepts, herein explained. We argue that new functionalities should be introduced to enable effortless use of legacy technologies in such dynamic and heterogeneous environments. © 2005 IEEE.

2011

Network infrastructure extension using 802.1D-based wireless mesh networks

Authors
Campos, R; Duarte, R; Sousa, F; Ricardo, M; Ruela, J;

Publication
WIRELESS COMMUNICATIONS & MOBILE COMPUTING

Abstract
Ubiquitous Internet access is becoming a major requirement for end-users due to the increasing number of services and applications supported over the Internet. Extending the coverage of current Wi-Fi infrastructures installed in companies, universities and cities, has been considered a solution to help in fulfilling this requirement, namely when it comes to wireless and nomadic Internet access. This paper describes and analyses a new and simple solution, called Wi-Fi network Infrastructure eXtension (WiFIX), aimed at extending current Wi-Fi infrastructures. WiFIX is based on standard IEEE 802.1D bridges and a single-message protocol that is able to self-organize the network, and it only requires software changes in IEEE 802.11 access points (APs); no changes to IEEE 802.11 stations are needed. Overhead analysis and experimental results show both the higher efficiency of the solution compared to the IEEE 802.11s draft standard and its good performance as far as data throughput, delay and packet loss are concerned. Copyright (C) 2010 John Wiley & Sons, Ltd.

2002

Support of IP QoS over UMTS networks

Authors
Ricardo, M; Dias, J; Carneiro, G; Ruela, J;

Publication
13TH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOL 1-5, PROCEEDINGS: SAILING THE WAVES OF THE WIRELESS OCEANS

Abstract
The paper presents an end-to-end Quality of Service (QoS) architecture suitable for IP communications scenarios that include UMTS access networks. The rationale for the architecture is justified and its main features are described, notably the QoS management functions on the terminal equipment, the mapping between IP and UMTS QoS parameters and the negotiation of these parameters.

2002

IP traffic control on UNITS terminal equipment

Authors
Ricardo, M; Soares, R; Dias, J; Ruela, J;

Publication
MULTIACCESS, MOBILITY AND TELETRAFFIC FOR WIRELESS COMMUNICATIONS, VOLUME 6

Abstract
The paper presents the architecture of an UNITS terminal equipment optimised for IP based communications and describes the traffic control mechanisms required for supporting emerging 3G services.

2004

Cross-layer design in 4G wireless terminals

Authors
Carneiro, G; Ruela, J; Ricardo, M;

Publication
IEEE WIRELESS COMMUNICATIONS

Abstract
The classical TCP/IP layered protocol architecture is beginning to show signs of age. In order to cope with problems such as the poor performance of wireless links and mobile terminals, including the high error rate of wireless network interfaces, power saving requirements, quality of service, and an increasingly dynamic network environment, a protocol architecture that considers cross-layer interactions seems to be required. This article describes a framework for further enhancements of the traditional IP-based protocol stack to meet current and future requirements. Known problems associated with the strictly layered protocol architecture are summarized and classified, and a first, solution involving cross-layer design is proposed.

2023

UAV-Assisted Wireless Communications: An Experimental Analysis of A2G and G2A Channels

Authors
Shafafi, K; Almeida, EN; Coelho, A; Fontes, H; Ricardo, M; Campos, R;

Publication
Simulation Tools and Techniques - 15th EAI International Conference, SIMUtools 2023, Seville, Spain, December 14-15, 2023, Proceedings

Abstract
Unmanned Aerial Vehicles (UAVs) offer promising potential as communications node carriers, providing on-demand wireless connectivity to users. While existing literature presents various wireless channel models, it often overlooks the impact of UAV heading. This paper provides an experimental characterization of the Air-to-Ground (A2G) and Ground-to-Air (G2A) wireless channels in an open environment with no obstacles nor interference, considering the distance and the UAV heading. We analyze the received signal strength indicator and the TCP throughput between a ground user and a UAV, covering distances between 50 m and 500 m, and considering different UAV headings. Additionally, we characterize the antenna’s radiation pattern based on UAV headings. The paper provides valuable perspectives on the capabilities of UAVs in offering on-demand and dynamic wireless connectivity, as well as highlights the significance of considering UAV heading and antenna configurations in real-world scenarios.

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