Catálogo de publicaciones - libros

For designing and testing embedded software, simulation tools have been used to keep pace with the rapid development of customized hardware parts. SID is a framework for building computer system simulations and SID is made for debugging, testing and verifying embedded software. Though, it is difficult for developers to use SID for their work. In this work, we developed an integrated virtual platform environment based SID simulation framework for a simulator engine and Eclipse for development platform. The proposed system avoids users to manually write the configuration file, and aids loading and connecting components on the fly. We also developed an image file builder and an automation tool for running SID simulation with GDB debugger. Furthermore, users can also monitor/probe the status of all the active components in the target virtual platform during the simulation

Wireless sensor networks are subject to sensor node and link failures due to various reasons. This paper proposes an energy-efficient, -disjoint-path routing algorithm that adaptively varies the number of disjoint paths () according to changing data patterns and a target-delivery ratio of critical events. The proposed algorithm sends packets through a single path (=1) under no occurrence of critical events, whereas it sends through disjoint paths (>1) under the occurrence of critical events, where is computed from a well-defined fault model and the target delivery ratio. Note that the proposed algorithm detects the occurrence of critical events by monitoring changing data patterns. Our simulations reveal that the proposed algorithm not only guarantees the target delivery ratio as much as a multi-path routing algorithm, but also makes energy consumption and average delay as low as a single-path routing algorithm.

The increasing success of mobile-enabled embedded devices is stressing the need for software architectures facing mobility-related issues. This paper proposes a simple yet effective mobility management scheme to ease the development of mobile ubiquitous applications. The scheme seamlessly handles handoff events and provides ubiquitous applications with both location-awareness and mobility prediction support. An implementation prototype has been developed on real-world Bluetooth enabled devices. Experimental results are then obtained from the prototype, showing the effectiveness of the proposed scheme.

In this paper we propose event-driven power management techniques for wireless sensor networks. To accomplish this we model a sensor network application as a set of application-specific events that the application may contain. Events are first classified into scheduled and non-scheduled events. These events are further classified according to the size and the locality of the data, and the real-time characteristics of the event. For scheduled events we propose schedule-driven power control and global coordination. For non-scheduled events we propose source-driven and sink-driven power control for both lower energy consumption and higher performance. Experimentation results confirm that the event driven power management can substantially save energy compared to existing low energy sensor network protocols while it can meet the performance required by the application.

In most sensor network applications, events are time stamped with node’s local time. However, energy is highly constrained resource in sensor networks. The purpose of this paper is to present a time- synchronization algorithm for sensor networks that aims at reducing the computation and communication energy expended by the algorithm. We use MAC-layer time stamping and estimate the clock drift rate and the offset in order to obtain high precision performance. Our algorithm works in two steps. In the first step, a spanning tree is built in the sensor network. In the second step, all nodes in the network synchronize their clocks to their parent nodes. We analyze and implement our time synchronization algorithm on Berkeley MicaZ platform and show that it can synchronize a pair of neighboring motes to an average accuracy of around one microsecond with communication complexity of .

Network Simulators are important tools in network research. As the selected topology often influences the outcome of the simulation, realistic topologies are required to produce realistic simulation results. The topology generator presented in this document, GenSeN, was created based on the authors’ knowledge from several experiences. GenSeN is a tool capable of generating realistic topologies of wireless sensor networks and, additionally, auto-configuring important characteristics of sensor nodes, such as energy parameters. The tool was validated by comparison with real deployment strategies and experiences.

Wireless sensor networks (WSNs) are comprised of energy constrained nodes. This limitation has led to the crucial need for energy-aware protocols to produce an efficient network. In this paper, we propose an energy aware geographical multipath routing scheme for WSNs. The distance to the destination location, remaining battery capacity, and queue size of candidate sensor nodes in the local communication range are taken into consideration for next hop relay node selection, and Analytical Hierarchy Process (AHP) is applied for decision making. Simulation results show that this scheme can extend the network lifetime longer than the original geographical routing scheme which only considers distance to the destination location. Moreover, the proposed scheme can reduce the packet loss rate and link failure rate since the buffer capacity is considered.

Accurate real-time monitoring of structural health can result in significant safety improvements, while providing data that can be used to improve design and construction practices. For bridges, monitoring of water level, tilt, displacement, strain, and vibration can provide snapshots of the state of the structure. Real-time measurement and communication of this information can be invaluable in guiding decisions regarding the safety and remaining fatigue life of a bridge.

This paper describes the real-time data acquisition, communication, and alerting capabilities of the Flood Frog, an autonomous wireless system for remote monitoring. Battery power and utilization of the GSM cellular network result in a completely wireless system. Coupled with the low cost of the device, the elimination of cables allows deployment in locations where autonomous monitoring is hindered by cost or infeasibility of installation. The first prototype of the system was deployed in Osage Beach, MO in November 2006.

The distributed denial of service (DDoS) attack that is one of the most threatening attacks in the wired network has been already extended in the wireless mobile network, owing to the appearance of DDoS attack tool against mobile phone. In the future, the latent threats for the converged form of DDoS attack should be resolved for the induction of successful convergence network. However, because of the current problems in defending against converged DDoS attacks on convergence network, such as the absence of a converged defense, research on cooperation architecture between defense processes is critical. In this paper, we analyze possible converged attacks, thus we propose a scalable and dynamic notification architecture based on overlay routing against DDoS attacks in consideration of the capacity of each node. A main feature of this architecture is the speedy notification of attack detection to each highest defense system in the network of the attack agents as well as in the victims. Thus it makes it possible not only to fast defense at the network of victims but also to identify attack agents. We analyzed the overhead for constructing our hierarchical overlay, simulated the transmission rate and speed of detection notification, and found a marked improvement using our defense compared to general routes.

Recently more embedded terminals have begun to use a general-purpose OS such as Linux. These terminals can perform various functions, such as downloading applications. Since these applications maybe malicious, it is necessary to protect terminals against them and to ensure stability of services provided by the terminals. We have proposed a security enhanced middleware model for embedded terminals based on Linux (SEMMETL). The SEMMETL offers client identification, access control for each application and resource control for each application. The security enhanced X server (SEN XServer) is an example of our proposed SEMMETL. By applying the SEMMETL to middleware, we can enhance the security of embedded terminals and ensure stability.