Nodos sensores inalámbricos con antenas directivas de banda simple o doble para aplicaciones en agricultura

Abstract Introduction: This paper presents the design of two wireless sensor nodes, with communications systems that integrate in one case a broadband antenna for operation in the 900MHz and 2.4GHz bands, along with a circuit that allows to select the appropriate radio for operation in some of these bands with the same antenna and the other makes use of a high gain antenna for operation in the 2.4GHz band. The proposed design offers a solution to the problem of propagation of radio frequency (RF) signals in forests and plantations for applications in smart agriculture that make use of wireless sensor networks (WSN). Objective: Design of two wireless sensor nodes, with communications systems that integrate directive antennas in one case for dual band operation (900MHz-2.4GHz) and in the other with high gain antennas (2.4GHz) for applications in smart agriculture. Method: The design of the wireless nodes makes use of the PSoC (programmable chip system) model CY8CKIT-059 5LP, which integrates temperature, humidity, inclination, distance, light intensity and movement sensors that use ZigBee as a wireless communication protocol. The antennas are designed with appropriate electromagnetic simulators and the resulting prototypes from this process are characterized in impedance by means of a vector network analyzer (VNA) and radiation patterns in an anechoic chamber. The full operation of the nodes is validated in the laboratory and in open spaces. Results: The double-band node with logarithmic antenna allows packet transfer at distances of 4.1km (915MHz) and 938m (2.44GHz), along with a switching circuit that allows one of the bands to be selected depending on the propagation characteristics of the medium where the node will be installed. On the other hand, the node with SPA antenna allows transfer of packets up to 2.5km (2.44GHz). The antenna characterization results are as follows: The logarithmic antenna has a maximum gain of 2.74dBi (915MHz) and 3.06dBi (2.44GHz) respectively, with an impedance bandwidth of 3.196:1, for an S11 <-10dB. The SPA antenna resonates at a center frequency of 2.44 GHz with a gain of 7.2 dBi; an impedance bandwidth of 16.8%, for an S11 <-10dB. Conclusions: This proposal improves the performance in wireless sensor networks since the approaches allow modularity, versatility and application in different areas including agriculture, enabling longer reaches and a more extensive coverage compared to the nodes that make use of conventional XBee antennas.Introducción: Este artículo presenta el diseño de dos nodos de sensores inalámbricos, con sistemas de comunicaciones que integran en un caso una antena de banda ancha para operación en las bandas de 900MHz y 2.4GHz, junto con un circuito que permite seleccionar el radio apropiado para operación en alguna de estas bandas con la misma antena y el otro hace uso de una antena de alta ganancia para operación en la banda de 2.4GHz. El diseño propuesto ofrece una solución al problema de propagación de señales de radio frecuencia (RF) en bosques y plantaciones para aplicaciones en agricultura inteligente que hacen uso de redes de sensores inalámbricos (WSN). Objetivo: Diseñar dos nodos de sensores inalámbricos, con sistemas de comunicaciones que integran antenas directivas en un caso para operación en doble banda (900MHz-2.4GHz) y en el otro con antenas de alta ganancia (2.4GHz) para aplicaciones en agricultura inteligente. Metodología: El diseño de los nodos inalámbricos hace uso del PSoC (sistema programable en chip) modelo CY8CKIT-059 5LP, al cual se integran sensores de temperatura, humedad, inclinación, distancia, intensidad de luz y movimiento que utilizan ZigBee como protocolo de comunicación inalámbrica. Las antenas son diseñadas con simuladores electromagnéticos apropiados y los prototipos resultantes de este proceso son caracterizados en impedancia mediante un analizador de redes (VNA) y en diagrama en una cámara anecoica. La operación integral de los nodos se valida en el laboratorio y en espacios abiertos. Resultados: El nodo de doble banda con antena logarítmica permite transferencia de paquetes a distancias de 4.1km (915MHz) y de 938m (2.44GHz), junto con un circuito de conmutación que permite seleccionar una de las bandas dependiendo de las características de propagación del medio donde se instalará el nodo. Por otra parte, el nodo con antena SPA permite transferencia de paquetes hasta 2.5Km (2.44GHz). Los resultados de la caracterización de las antenas son: La antena logarítmica presenta una ganancia máxima de 2.74dBi (915MHz) y 3.06dBi (2.44GHz) respectivamente, con un ancho de banda de impedancia de 3.196:1, para un <-10dB. La antena SPA resuena a una frecuencia central de 2.44 GHz con una ganancia de 7.2 dBi; un ancho de banda de impedancia del 16.8%, para un <-10dB. Conclusiones: La propuesta consigue mejorar el desempeño en redes inalámbricas de sensores por su modularidad, versatilidad y su aplicación en diferentes áreas incluida la agricultura, lo que permite obtener mejores alcances y cobertura más amplia cuando se compara con los nodos que hacen uso de antenas XBee convencionales

Communication range dynamics using an energy saving self-adaptive transmission power controller in a wireless sensor network

The deployment of the nodes in a Wireless Sensors and Actuators Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. And also when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects, and of course, radio irregularities. A control based self-adaptive system is a typical solution to improve the energy consumption while keeping a good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping a good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value. In addition, the worst performance shows how a bad parameters choice can create isolated islands, groups of nodes disconnected from the rest of the network

Self-adaptive strategy based on fuzzy control systems for improving performance in wireless sensors networks

The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT) and Cyber-Physical Systems (CPS) are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN) are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container), and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries

Wireless industrial monitoring and control networks: the journey so far and the road ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks

Multiradio, multiboot capable sensing systems for home area networking

The development of Wireless Sensor Networking technology to deploy in smart home environments for a variety of applications such as Home Area Networking has been the focus of commercial and academic interest for the last decade. Developers of such systems have not adopted a common standard for communications in such schemes. Many Wireless Sensor Network systems use proprietary systems so interoperability between different devices and systems can be at best difficult with various protocols (standards based and non-standards based) used (ZigBee, EnOcean, MODBUS, KNX, DALI, Powerline, etc.). This work describes the development of a novel low power consumption multiradio system incorporating 32-bit ARM-Cortex microcontroller and multiple radio interfaces - ZigBee/6LoWPAN/Bluetooth LE/868MHz platform. The multiradio sensing system lends itself to interoperability and standardization between the different technologies, which typically make up a heterogeneous network of sensors for both standards based and non-standards based systems. The configurability of the system enables energy savings, and increases the range between single points enabling the implementation of adaptive networking architectures of different configurations. The system described provides a future-proof wireless platform for Home Automation Networks with regards to the network heterogeneity in terms of hardware and protocols defined as being critical for use in the built environment. This system is the first to provide the capability to communicate in the 2.4GHz band as well as the 868MHz band as well as the feature of multiboot capability. A description of the system operation and potential for power savings through the use of such a system is provided. Using such a multiradio, multiboot capable, system can not only allow interoperability across multiple radio platforms in a Home Area Network, but can also increase battery lifetime by 20 – 25% in standard sensing applications

Performance Analysis of a Compression Scheme for Highly Dense Cluster-Based Wireless Sensor Network

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