Papers by Juan Carlos Ortega Sanchez
Computer Communications, 2007
The case in which the same information or events need to be sent from a single sensor node to mul... more The case in which the same information or events need to be sent from a single sensor node to multiple actuator nodes, is very common in many applications of Sensor and Actuator Networks (SANET). Sensors have very limited resources in terms of energy, bandwidth, and computational power. Thus, routing messages preserving energy and network bandwidth is a challenging requirement of paramount importance. In this paper we present a novel energy-efficient multicast routing protocol called GMREE which is specifically designed to achieve that goal. Our protocol builds multicast trees based on a greedy algorithm using local information. The heuristic we use is based in the concept of cost over progress metric and it is specially designed to minimize the total energy used by the multicast tree. GMREE incorporates a relay selection function which selects nodes from a node's neighborhood taking into account not only the minimization of the energy but also the number of relays selected. Nodes only select relays based on a locally built and energy-efficient underlying graph reduction such as Gabriel graph, enclosure graph or a local shortest path tree. Thus, the topology of the resulting multicast trees really takes advantage of the benefit of sending a single message to multiple destinations through the relays which provide best energy paths. Our simulation results show that our proposed protocol outperforms the traditional energy-efficient multiunicast routing over a variety of network densities and number of receivers. In addition, for dense networks, the performance approximates the one achieved using the centralized shortest weighted path tree (computed by Dijkstra's algorithm).
IEEE Transactions on Electron Devices, 2021
Technology computer-aided design (TCAD) semiconductor device simulators solve partial differentia... more Technology computer-aided design (TCAD) semiconductor device simulators solve partial differential equations (PDE) using the finite volume method (FVM), or related methods. While this approach has been in use over several decades, its methods continue to be extended, and are still applicable for investigating novel devices. In this paper, we present an element edge based (EEB) FVM discretization approach suitable for capturing vector-field effects. Drawing from a 2D approach in the literature, we have extended this method to 3D. We implemented this method in a TCAD semiconductor device simulator, which uses a generalized PDE (GPDE) approach to simulate devices with the FVM. We describe how our EEB method is compatible with the GPDE approach, allowing the modeling of vector effects using scripting. This method is applied to solve polarization effects in a 3D ferro capacitor, and a 2D ferroelectric field-effect transistor. An example for fielddependent mobility in a 3D MOSFET is also presented.
DEVSIM is a technology computer aided design (TCAD) simulation soft- ware. It is released under a... more DEVSIM is a technology computer aided design (TCAD) simulation soft- ware. It is released under an open source license. The software solves user defined partial differential equations (PDEs) on 1D, 2D, and 3D meshes. It is implemented in C++ using custom code and a collection of open source libraries. The Python scripting interface enables users to setup and control their simulations. In this chapter, we present an overview of the tool. This is followed with a bipolar junction transistor (BJT) design and characterization example. A collection of open source tools were used to create a simulation mesh, and visualize results
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Papers by Juan Carlos Ortega Sanchez