Papers by Pablo Villa Rodriguez
From its conception the Internet has been a communication network and therefore its development h... more From its conception the Internet has been a communication network and therefore its development has been largely driven by the overarch- ing assumption that connections and data transfers are sensitive to delay. Therefore, spatial optimization, in the form of routing, has been the main tool for improving the services ofiered by the network. Temporal opti- mization, in the form of scheduling, has been limited to millisecond-second scales, to be aligned with the requirements of interactive, delay sensitive tra-c. In late years, however, the network has been progressively sifting from communication to content dissemination. Unlike communication, content dissemination can sometimes tolerate much larger delays, e.g., in the order of hours. Such higher tolerance to delay allows scheduling to go beyond congestion avoidance. In this short note we exemplify how to use store-and-forward scheduling to service bulk data transfers that are impossible, or too expensive under current pricing schem...
Is it possible to have a unique, recognizable style in soccer nowadays? We address this question ... more Is it possible to have a unique, recognizable style in soccer nowadays? We address this question by proposing a method to quantify the motif characteristics of soccer teams based on their pass networks. We introduce the the concept of "flow motifs" to characterize the statistically significant pass sequence patterns. It extends the idea of the network motifs, highly significant subgraphs that usually consists of three or four nodes. The analysis of the motifs in the pass networks allows us to compare and differentiate the styles of different teams. Although most teams tend to apply homogenous style, surprisingly, a unique strategy of soccer exists. Specifically, FC Barcelona's famous tiki-taka does not consist of uncountable random passes but rather has a precise, finely constructed structure.
Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064), 2000
Popular documents are frequently mirrored on multiple sites in an effort to share the load and re... more Popular documents are frequently mirrored on multiple sites in an effort to share the load and reduce clients' retrieval latencies. However, choosing the best mirror site is a non-trivial task and a bad choice may give an poor performance. We propose a scheme in which clients access multiple mirror sites in parallel to speedup document downloads while eliminating the problem of server selection. In our scheme, clients connect to mirror sites using unicast TCP and dynamically request different pieces of a document from different sites, thus, adapting to changing network/server conditions. A dynamic parallel-access can be easily implemented in the current Internet, and does not require any modifications at the mirror sites. Using dynamic parallel-access all clients experience dramatic speedups in downloading documents, and the load is shared among servers without the need for a server selection mechanism. Even in a situation where clients are connected through modem lines, dynamic parallel-access offers transmission rates at least as high as the fastest server.
Medicina Intensiva
1. Med Clin (Barc). 2012 Jul 27. [Epub ahead of print] [Utilization of the extracorporeal membran... more 1. Med Clin (Barc). 2012 Jul 27. [Epub ahead of print] [Utilization of the extracorporeal membrane oxygenator in myocarditis with refractory cardiogenic shock: preliminary results from a Spanish pioneering experience.]. [Article in Spanish]. Gordón M, Gimeno R, Pérez-Esteban F, Fuset MP. Servicio de Medicina Intensiva, Hospital Universitario y Politécnico La Fe, Valencia, España. PMID: 22841466 [PubMed - as supplied by publisher]. Publication Types: LETTER.
We have developed a first of its kind methodology for deriving bandwidth prices for premium direc... more We have developed a first of its kind methodology for deriving bandwidth prices for premium direct peering between Access ISPs (A-ISPs) and Content and Service Providers (CSPs) that want to deliver content and services in premium quality. Our methodology establishes a direct link between service profitability, e.g., from advertising, user- and subscriber-loyalty, interconnection costs, and finally bandwidth price for peering. Unlike existing work in both the networking and economics literature, our resulting computational model built around Nash bargaining, can be used for deriving quantitative results comparable to actual market prices. We analyze the US market and derive prices for video that compare favorably with existing prices for transit and paid peering. We also observe that the fair prices returned by the model for high-profit/low-volume services such as search, are orders of magnitude higher than current bandwidth prices. This implies that resolving existing (fierce) inter...
BitTorrent (BT) is currently the main P2P protocol used for sharing large files over the Internet... more BitTorrent (BT) is currently the main P2P protocol used for sharing large files over the Internet. It is therefore important to understand the performance characteristics of existing real-world BT implementations (clients). In this work, we measure the download speed of over 10 million BT users over one month. Surprisingly, our measurements show that the two most famous BT clients, namely uTorrent and Vuze (Azureus), achieve different download speeds for the same set of torrents. In particular, we observe that uTorrent users achieve 16% faster download speed than users of Vuze in our data set. To shed light to the cause of this difference, we reverse engineer the two clients to infer their individual design choices. Our study shows that the two clients differ in two important areas: (a) how they manage their neighborhood, and (b) how they distribute their upload capacity to their peers. We speculate that the cause of the mismatch in download speeds can be attribute to these differen...
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Papers by Pablo Villa Rodriguez