Showing papers by "Francisco J. González-Castaño published in 2002"

Bluetooth location networks

Abstract: We propose a Bluetooth location network (BLN) for location-aware or context-driven mobile networks, such as m-commerce networks or e-museums. We assume that, in any of those scenarios, there exist service servers that need to know user location in real-time, to send context-oriented information to user handhelds when necessary. The BLN transmits position information to the service servers, without user participation. It is not subject to line-of-sight constraints and is supported by existing commercial handhelds. BLN users carry either a Bluetooth-enabled handheld or any mobile data terminal and a Bluetooth badge. The BLN is composed of small, wireless Bluetooth nodes, which establish a spontaneous network topology at system initialization. The BLN can coexist with Bluetooth devices that are not part of the location system, such as printers or headphones.

Condor grid computing from mobile handheld devices

Abstract: In this paper, we propose a hierarchical design methodology for grid access from handheld devices. After determining all user interactions required and technologies available, they are arranged in layers. All functions in a layer are also supported by all underlying layers. By doing so, the designer is less conditioned by the constraints of a specific, out-of-context platform. Additionally, in a stratified modular design, many software components can be re-used. We present a prototype to access Condor from two neighbor layers: PDAs and cell phones.

Real-time interception systems for the GSM protocol

Abstract: A GSM protocol interceptor is a device located in a (possibly) closed area that listens to information exchanged between base stations (BSs) and mobile stations (MSs). This paper presents three new interception systems for security purposes. The first one (detector) forces all idle MSs nearby to generate activity, which can be used to activate an alarm of MS presence. The second one (selective interceptor) monitors information exchange between MS and BS and, in case of MS activity, (1) extracts messages containing MS identifiers and (2) checks identifiers in a local cache to decide if an external jamming unit should block individual calls (either incoming or outgoing). The third system (enhanced selective interceptor) combines the previous two systems to improve blocking performance. We analyze transactions of the GSM protocol that are relevant to interception system operation. Those transactions impose real-time constraints that we quantify. We present real tests and simulations that address the feasibility of the systems.

A New Transcoding Technique for PDA Browsers, Based on Content Hierarchy

Abstract: This paper presents a new transcoding technique for WWW navigation on small display devices: Hierarchical Atomic Navigation Unlike previous techniques, Hierarchical Atomic Navigation keeps all original information in a readable way, without imposing the use of a specific browser To achieve this goal, a navigator page is used to represent original contents in a symbolic way A set of representative icons replaces unreadable elements These icons are linked to actual individual contents, as a set of atomic pages Hierarchical Atomic Navigation can be used on any PDA, regardless of OS and browser choice, since both navigator and atomic pages use widely supported standard formats (eg XML, HTML)

Cellular Network for Real-Time Mobile Auction

Abstract: Auctions are an ancient form of economic activity and, as such, have evolved with technology. However, some forms of traditional auction have survived unchanged, even in areas of great economic interest, until modern regulations imposed a change. We present the design of a specialized cellular network that has recently replaced traditional fish auctions in Galicia (Spain).

Heuristic-Driven Test Case Selection from Formal Specifications. A Case Study

Abstract: We propose an approach to testing that combines formal methods with practical criteria, close to the testing engineer's experience. It can be seen as a framework to evaluate and select test suites using formal methods, assisted by informal heuristics. This proposal is illustrated with a practical case study: the testing of a protocol for mobile auctions in a distributed, wireless environment.

Pushing Web Pages into Personal Digital Assistants: Need, Tools and Solutions

Abstract: In this paper, we analyze the problem of pushing Web contents into Personal Digital Assistants (PDAs), withminim um client participation. Typical HTTP or Javascript implementations require periodic client reloads, which impose an inefficient network utilization. We justify the existence of this problem, review existing alternatives, and propose a market-oriented implementation for wireless iPAQ Pocket PCs.

Real-time 3G UMTS terminal detection

Abstract: The authors study the feasibility of a real-time 3G UMTS terminal detector to be located in a restricted area. All idle terminals entering the restricted area are forced to emit signaling information which can be captured. The authors analyze the detector protocol settings and response time. They also determine the conditions it would impose on UMTS operators.

Neural parallel-hierarchical-matching scheduler for input-buffered packet switches

Abstract: Input-buffered packet switches boosted with high-performance schedulers achieve near-100% throughput. Several authors have proposed the use of neural schedulers. These schedulers have a fast theoretical convergence, but the standard deviation of the number of iterations required can be arbitrarily large. In a previous paper, the authors proposed a hybrid digital-neural scheduler, HBRTNS, with bounded response time: O(N) clock steps. As an evolution of that concept, the authors present a two-stage neural Parallel-Hierarchical-Matching scheduler (nPHM), which generates high quality solutions in few clock steps. We present numerical comparisons with diverse state-of-the-art algorithms and the ideal output-buffered case.