Papers by Pedro S Rodríguez-Hernández
Characterization of blocking time in real-time systems with dynamic priority ceilings
Proceedings Ninth Euromicro Workshop on Real Time Systems
ABSTRACT In a single processor real time system, scheduled via the Earliest Deadline First algori... more ABSTRACT In a single processor real time system, scheduled via the Earliest Deadline First algorithm (EDF), we have accurately characterized the blocking time that each task can encounter when accesses to shared resources are regulated via the Dynamic Priority Ceiling Protocol (DPCP). It is shown that worst case blocking times do not always reach the total duration of the critical sections which produce them. Our characterization allows the real time system designer to attain a higher processor utilization factor while the tasks meet all their deadlines
A preemptive priority-based disk I/O subsystem for the management of hard real-time disk traffic
Proceedings Ninth Euromicro Workshop on Real Time Systems, 1997
We present the design and implementation of a disk I/O subsystem appropriated for the management ... more We present the design and implementation of a disk I/O subsystem appropriated for the management of hard real time disk traffic. The proposed disk I/O subsystem allows the invocation of preemptive priority based disk I/O operations, both for non contiguous and contiguous data layouts. Disk I/O requests are scheduled in a common layer upon the disk driver, where access to
A Study for Self-adapting Urban Traffic Control
Lecture Notes in Computer Science, 2016
Nowadays, managing traffic in cities is a complex problem involving considerable physical and eco... more Nowadays, managing traffic in cities is a complex problem involving considerable physical and economical resources. However, traffic can be simulated by multi-agent systems (MAS), since cars and traffic lights can be modeled as agents that interact to obtain an overall goal: to reduce the average waiting times for the traffic users. In this paper, we present a self-organizing solution to efficiently manage urban traffic. We compare our proposal with other classical and alternative self-organizing approaches, observing that ours provides better results. Then, we present the main contributions of the paper that analyze the effects of different traffic conditions over our cheap and easy-to-implement method for self-organizing urban traffic management. We consider several scenarios where we explore the effects of dynamic traffic density, a reduction in the percentage of sensors needed to support the traffic management system, and the possibility of using communication among cross-points.
Agent model of C2C communications in urban environments
2008 IEEE International Symposium on Industrial Electronics, 2008
... Enrique Costa-Montenegro, Felipe Gil-Castineira, Cristina López-Bravo, Juan Carlos Burguillo... more ... Enrique Costa-Montenegro, Felipe Gil-Castineira, Cristina López-Bravo, Juan Carlos Burguillo-Rial, Pedro Rodrıguez-Hernández and Francisco Javier González-Castano Departamento de Ingenierıa Telemática Universidad de Vigo, Spain {kike, xil, clbravo, jrial, pedro, ...
Computing and informatics, 2009
Managing traffic in cities is nowadays a complex problem involving considerable physical and econ... more Managing traffic in cities is nowadays a complex problem involving considerable physical and economical resources. Multi-agent Systems (MAS) consist of a set of distributed, usually cooperating , agents that act autonomously. The traffic in a city can be simulated by a MAS with different agents, cars and traffic lights, that interact to obtain an overall goal: to reduce average waiting times for the traffic users. In this paper, we describe an agent-based simulator to model traffic in cities. Using this simulator, we present a self-organizing solution to efficiently manage urban traffic. We compare our proposal with recent approaches, providing better results than classical and alternative self-organizing methods, with lower resources and investments.
Distributed and centralized algorithms for large-scale IEEE 802.11b infrastructure planning
Proceedings. ISCC 2004. Ninth International Symposium on Computers And Communications (IEEE Cat. No.04TH8769)
... E. Costa-Montenegro, FJ GonzBlez-CastaHo, UM Garcia-Palomares, M. Vilas-Paz, PS Rodriguez-Her... more ... E. Costa-Montenegro, FJ GonzBlez-CastaHo, UM Garcia-Palomares, M. Vilas-Paz, PS Rodriguez-HernBndez Dept. Ingenieria TelemBtica, Universidad de Vigo ETSI Telecomunicaci6n, Campus, 36200 Vigo, Spain. { kike,javier,ubaldo,mvilas,pedro} @ det.uvigo.es Abstract ...
On sequential and parallel non-monotone derivative-free algorithms for box constrained optimization
Optimization Methods and Software, 2012
ABSTRACT This paper proposes a space decomposition scheme for non-monotone (NM) derivative-free p... more ABSTRACT This paper proposes a space decomposition scheme for non-monotone (NM) derivative-free parallel and sequential algorithms for solving the box-constrained optimization problem (BCOP). Convergence to Karush Kuhn Tucker points is proved under the same conditions for NM and monotone algorithms for solving unconstrained and BCOPs. The parallel algorithm has two unique features: all processors exchange information on discrete quasi-minimal points, and are able to sample function values on the whole set of directions that conform to non-negative spanning sets for each decomposed subspace. The parallel algorithm has a high degree of fault tolerance: convergence prevails even if only one processor remains running. Preliminary results are encouraging for solving small-and medium-sized problems.
IEEE Communications Letters, 2000
Input-buffered asynchronous transfer mode (ATM) packet switches are simpler than output-buffered ... more Input-buffered asynchronous transfer mode (ATM) packet switches are simpler than output-buffered switches. However, due to HOL blocking, their throughput is poor. Neural schedulers represent a promising solution for high throughput inputbuffered switching, but their response time variance is too high for realistic hard real-time constraints. To overcome this problem, in this paper we formulate and evaluate a new neural scheduler with bounded response time.
Neural scheduler with bounded response time and its application for real-time switches
Electronics Letters, 1999
ABSTRACT
Stochastic neural scheduler for real-time input-buffered packet switching
Electronics Letters, 1999
ABSTRACT
Unified approach for solving box-constrained models with continuous or discrete variables by non monotone direct search methods
Optimization Letters
Sensors, 2015
Smart cities are expected to improve the quality of life of citizens by relying on new paradigms,... more Smart cities are expected to improve the quality of life of citizens by relying on new paradigms, such as the Internet of Things (IoT) and its capacity to manage and interconnect thousands of sensors and actuators scattered across the city. At the same time, mobile devices widely assist professional and personal everyday activities. A very good example of the potential of these devices for smart cities is their powerful support for intuitive service interfaces (such as those based on augmented reality (AR)) for non-expert users. In our work, we consider a scenario that combines IoT and AR within a smart city maintenance service to improve the accessibility of sensor and actuator devices in the field, where responsiveness is crucial. In it, depending on the location and needs of each service, data and commands will be transported by an urban communications network or consulted on the spot. Direct AR interaction with urban objects has already been described; it usually relies on 2D visual codes to deliver object identifiers (IDs) to the rendering device to identify object resources. These IDs allow information about the objects to be retrieved from a remote server. In this work, we present a novel solution that replaces static AR markers with dynamic markers based on LED communication, which can be decoded through cameras Sensors 2015, 15 16084 embedded in smartphones. These dynamic markers can directly deliver sensor information to the rendering device, on top of the object ID, without further network interaction.
In this paper we present SinCity, a pedagogical testbed to compare multi-agent learning strategie... more In this paper we present SinCity, a pedagogical testbed to compare multi-agent learning strategies. SinCity has been developed in NetLogo and it can be considered as an extension of the simple predator-prey pursuit problem. In our case, we model a police/thief pursuit in an urban grid environment where several elements (cars, traffic lights, etc.) may interact with the agents in the simulation. SinCity allows to model, in a graphical friendly environment, different strategies for both, the Police and the thief, also implying coordination and communication among the agent set. SinCity is oriented mainly as a pedagogical testbed for learning techniques. The main contributions of the paper are a graphical simulating environment in NetLogo (distributed as open source), a pedagogical testbed for simulating multiagent learning strategies, and the results concerning the simulations performed.
Transactions on Emerging Telecommunications Technologies, 2012
Multihop wireless systems outperform single-hop ones in terms of coverage and capacity. The IEEE ... more Multihop wireless systems outperform single-hop ones in terms of coverage and capacity. The IEEE 802.16 standard, also known as Worldwide Interoperability for Microwave Access (WiMAX), is one of the latest broadband wireless access technologies over long distances. Mobile multihop relay (MMR) WiMAX networks introduce relay stations (RS) to improve range and performance at low cost. Providing multimedia capabilities to groups defined by node proximity is an interesting feature in tactical communications, which MMR WiMAX networks may support. This paper presents a dynamic group management scheme at the Medium Access Control (MAC) layer based on RS position, with dynamic RS selection, suitable for military environments where communications between close nodes are prioritary. The proposal is evaluated analytically and by simulations.
Sensors, 2014
Large-scale wireless sensor networks have not achieved market impact, so far. Nevertheless, this ... more Large-scale wireless sensor networks have not achieved market impact, so far. Nevertheless, this technology may be applied successfully to small-scale niche markets. Shipyards are hazardous working environments with many potential risks to worker safety. Toxic gases generated in soldering processes in enclosed spaces (e.g., cargo holds) are one such risk. The dynamic environment of a ship under construction makes it very difficult to plan gas detection fixed infrastructures connected to external monitoring stations via wired links. While portable devices with gas level indicators exist, they require workers to monitor measurements, often in situations where they are focused on other tasks for relatively long periods. In this work, we present a wireless multihop remote gas monitoring system for shipyard environments that has been tested in a real ship under construction. Using this system, we validate IEEE 802.15.4/Zigbee wireless networks as a suitable technology to connect gas detectors to control stations outside the ships. These networks have the added benefit that they reconfigure themselves dynamically in case of network failure or redeployment, for example when a relay is moved to a new location. Performance measurements include round trip time (which determines the alert response time for safety teams) and link quality indicator and packet error rate (which determine communication robustness).
Electronics and Electrical Engineering, 2012
At this moment, the importance of computers in all the areas of knowledge is undeniable. Students... more At this moment, the importance of computers in all the areas of knowledge is undeniable. Students must acquire competencies in computer use during their primary and secondary studies. Later on, during college education they must learn to use basic computer science tools used in their respective disciplines. On many occasions the professor is the person who designs the lab setup , and also sets the configuration, installs and maintains all the computers. These tasks, especially the maintenance of the software and hardware environment, are not simple because, among other reasons, the design of a laboratory determines who uses it and how. Besides, those tasks are very important, as shown by all the research in the literature. In this paper we present a tool that simplifies this work in a very noteworthy way. That tool centralizes the installation, configuration and maintenance of the applications in a remote single server. Ill. 4, bibl. 15 (in English; abstracts in English and Lithuanian).
Simple Linux-based devices bring real networking features to a system that runs over power lines.... more Simple Linux-based devices bring real networking features to a system that runs over power lines. Power line communication (PLC) technology allows you to transmit data by way of the electric grid's low-and medium-voltage power lines. Any device in a building thus may access a LAN to share resources. Figure 1 shows the Ovislink HomePlug Ethernet Bridges we currently are using.
Peer to Peer (P2P) computer networks rely on direct connections between participants instead of c... more Peer to Peer (P2P) computer networks rely on direct connections between participants instead of conventional centralized resources. These networks are useful for many purposes, but the killer application nowadays is file sharing. BitTorrent is a very popular protocol for this matter. In this paper, we use a multi-agent model of a BitTorrent network. In it, each BitTorrent client is an agent that interacts with other agents and reacts autonomously, following the same decision algorithms as real clients. Their goals are downloading contents in the shortest possible time and sharing them with other agents. The use of this multi-agent model allows us to introduce modifications to the protocol. We have modified this model to use fountain codes, also known as rateless erasure codes, a class of codes in which the original source symbols can be recovered from any subset of the encoding symbols. We evaluated how BitTorrent performs using these codes and compared with its normal behavior.
2012 Seventh International Conference on P2P, Parallel, Grid, Cloud and Internet Computing, 2012
Peer to Peer (P2P) computer networks rely on direct connections between participants instead of c... more Peer to Peer (P2P) computer networks rely on direct connections between participants instead of conventional centralized resources. These networks are useful for many purposes, but the killer application nowadays is file sharing. BitTorrent is a very popular protocol for this matter.
Agent model of C2C communications in urban environments
2008 IEEE International Symposium on Industrial Electronics, 2008
... Enrique Costa-Montenegro, Felipe Gil-Castineira, Cristina López-Bravo, Juan Carlos Burguillo... more ... Enrique Costa-Montenegro, Felipe Gil-Castineira, Cristina López-Bravo, Juan Carlos Burguillo-Rial, Pedro Rodrıguez-Hernández and Francisco Javier González-Castano Departamento de Ingenierıa Telemática Universidad de Vigo, Spain {kike, xil, clbravo, jrial, pedro, ...
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Papers by Pedro S Rodríguez-Hernández