Raúl Aquino

Open-WiSe: A Solar Powered Wireless Sensor Network Platform

Because battery-powered nodes are required in wireless sensor networks and energy consumption represents an important design consideration, alternate energy sources are needed to provide more effective and optimal function. The main goal of this work is to present an energy harvesting wireless sensor network platform, the Open Wireless Sensor node (WiSe). The design and implementation of the solar powered wireless platform is described including the hardware architecture, firmware, and a POSIX Real-Time Kernel. A sleep and wake up strategy was implemented to prolong the lifetime of the wireless sensor network. This platform was developed as a tool for researchers investigating Wireless sensor network or system integrators.

Formal Specification and Design Techniques for Wireless Sensor and Actuator Networks

A current trend in the development and implementation of industrial applications is to use wireless networks to communicate the system nodes, mainly to increase application flexibility, reliability and portability, as well as to reduce the implementation cost. However, the nondeterministic and concurrent behavior of distributed systems makes their analysis and design complex, often resulting in less than satisfactory performance in simulation and test bed scenarios, which is caused by using imprecise models to analyze, validate and design these systems. Moreover, there are some simulation platforms that do not support these models. This paper presents a design and validation method for Wireless Sensor and Actuator Networks (WSAN) which is supported on a minimal set of wireless components represented in Colored Petri Nets (CPN). In summary, the model presented allows users to verify the design properties and structural behavior of the system.

PlaIMoS: A Remote Mobile Healthcare Platform to Monitor Cardiovascular and Respiratory Variables

The number of elderly and chronically ill patients has grown significantly over the past few decades as life expectancy has increased worldwide, leading to increased demands on the health care system and significantly taxing traditional health care practices. Consequently, there is an urgent need to use technology to innovate and more constantly and intensely monitor, report and analyze critical patient physiological parameters beyond conventional clinical settings in a more efficient and cost effective manner. This paper presents a technological platform called PlaIMoS which consists of wearable sensors, a fixed measurement station, a network infrastructure that employs IEEE 802.15.4 and IEEE 802.11 to transmit data with security mechanisms, a server to analyze all information collected and apps for iOS, Android and Windows 10 mobile operating systems to provide real-time measurements. The developed architecture, designed primarily to record and report electrocardiogram and heart rate data, also monitors parameters associated with chronic respiratory illnesses, including patient blood oxygen saturation and respiration rate, body temperature, fall detection and galvanic resistance.

μDDS: A Middleware for Real-time Wireless Embedded Systems

A Real-Time Wireless Distributed Embedded System (RTWDES) is formed by a large quantity of small devices with certain computing power, wireless communication and sensing/actuators capabilities. These types of networks have become popular as they have been developed for applications which can carry out a vast quantity of tasks, including home and building monitoring, object tracking, precision agriculture, military applications, disaster recovery, industry applications, among others. For this type of applications a middleware is used in software systems to bridge the gap between the application and the underlying operating system and networks. As a result, a middleware system can facilitate the development of applications and is designed to provide common services to the applications. The development of a middleware for sensor networks presents several challenges due to the limited computational resources and energy of the different nodes. This work is related with the design, implementation and test of a micro middleware for RTWDES; the proposal incorporates characteristics of a message oriented middleware thus allowing the applications to communicate by employing the publish/subscribe model. Experimental evaluation shows that the proposed middleware provides a stable and timely service to support different Quality of Service (QoS) levels.

Performance optimization of the initialization process of IEEE 802.16 mesh networks

The IEEE 802.16–2004 standard defines a medium access control (MAC) layer for a mesh network topology. In these networks, wide scale power outages can cause serious disruptions to digital services when centralized scheduling is used. This results in very long service recovery times for all mesh nodes. In this paper we propose a new recovery scheme and study the performance of the initialization process due to service disruption of IEEE 802.16–2004 mesh networks. We implemented an OPNET simulation model of the scheme. Results show that the recovery times obtained with the proposed scheme can be reduced by up to 98% compared with the default mechanism.

Performance Evaluation of Five New Adaptive Contention Slot Allocators for IEEE 802.16 Based Systems

A reservation based medium access control (MAC) protocol has been adopted by the IEEE 802.16 standard as the basic protocol for data communication within the upstream channel. In this paper, we propose the following five new contention slot allocators (CSA) for the IEEE 802.16 MAC protocol: Forced-CSA, Variable-CSA, Multicast-CSA, Collision Free-CSA and CDMA-CSA. The new techniques dynamically fit the number of contention slots needed to solve collisions according to the current traffic load, considerably improving overall system performance. The CSAs introduced in this paper indicate that the mean access delay could be reduced up to 75% compared with the currently adopted method by the IEEE 802.16 MAC protocol, called simple-CSA. A performance evaluation of our five CSA schemes is presented and compared with previous CSA schemes, simple-CSA and IEEE 802.14-CSA. Obtained results turned out to be closer to the maximum estimated throughput than currently used methods.

A methodology to develop mobile robots based on a feature model

This paper presents a methodology to develop mobile robots by means of a feature model. A feature model is a compact representation of all the products of a software product line in terms of their features, which is based on a feature metamodel. Although feature models are used to develop software product lines, we use this approach to development a mobile robot product line; i.e. our feature model was used to develop several MORTREDs (mobile robots for research and development). We have configured our feature model; since it is selected an instance of the MORTED Feature Model (employing user-specific data selected) and we have implemented it through the development of a specific mobile robot. The proposed feature model permits users to create a series of modified functional versions that build upon each other to meet their specific study or developmental needs.

Performance analysis of best effort support in broadband IEEE 802.16 networks

This paper presents a performance analysis of best effort support over the MAC protocol proposed in the IEEE 802.16 standard. We focus on the uplink channel since it is the critical element for efficient delivery of services on demand to individual users (i.e., Best Effort service). We describe a modeling approach and derive the resulting analytical model. Such a model allows us to efficiently compute network throughput. We test this model by means of computer simulations which are also reported in this paper. Simulation results and theoretical computations showed a close agreement, thus validating the model.