Peio Lopez Iturri

Performance Analysis of IEEE 802.15.4 Compliant Wireless Devices for Heterogeneous Indoor Home Automation Environments

The influence of topology as well as morphology of complex indoor scenarios in the deployment of wireless sensor networks and wireless systems applied to home and building automation systems is analyzed. The existence of loss mechanisms such as material absorption (walls, furniture, etc.) and strong multipath components as well as the increase in the number of wireless sensors within indoor scenarios increases the relevance in the configuration of the heterogeneous wireless systems. Simulation results by means of empirical-based models are compared with an in-house 3D ray launching code as well as measurement results from wireless sensor networks illustrate the strong influence of the indoor scenario in the overall performance. The use of adequate radioplanning strategies lead to optimal wireless network deployments in terms of capacity, quality of service, and reduced power consumption.

Impact of High Power Interference Sources in Planning and Deployment of Wireless Sensor Networks and Devices in the 2.4 GHz Frequency Band in Heterogeneous Environments

In this work, the impact of radiofrequency radiation leakage from microwave ovens and its effect on 802.15.4 ZigBee-compliant wireless sensor networks operating in the 2.4 GHz Industrial Scientific Medical (ISM) band is analyzed. By means of a novel radioplanning approach, based on electromagnetic field simulation of a microwave oven and determination of equivalent radiation sources applied to an in-house developed 3D ray launching algorithm, estimation of the microwave ovens power leakage is obtained for the complete volume of an indoor scenario. The magnitude and the variable nature of the interference is analyzed and the impact in the radio link quality in operating wireless sensors is estimated and compared with radio channel measurements as well as packet measurements. The measurement results reveal the importance of selecting an adequate 802.15.4 channel, as well as the Wireless Sensor Network deployment strategy within this type of environment, in order to optimize energy consumption and increase the overall network performance. The proposed method enables one to estimate potential interference effects in devices operating within the 2.4 GHz band in the complete scenario, prior to wireless sensor network deployment, which can aid in achieving the most optimal network topology.

Evaluation of Electromagnetic Interference and Exposure Assessment from s-Health Solutions Based on Wi-Fi Devices

In the last decade the number of wireless devices operating at the frequency band of 2.4 GHz has increased in several settings, such as healthcare, occupational, and household. In this work, the emissions from Wi-Fi transceivers applicable to context aware scenarios are analyzed in terms of potential interference and assessment on exposure guideline compliance. Near field measurement results as well as deterministic simulation results on realistic indoor environments are presented, providing insight on the interaction between the Wi-Fi transceiver and implantable/body area network devices as well as other transceivers operating within an indoor environment, exhibiting topological and morphological complexity. By following approaches (near field estimation/deterministic estimation), colocated body situations as well as large indoor emissions can be determined. The results show in general compliance with exposure levels and the impact of overall network deployment, which can be optimized in order to reduce overall interference levels while maximizing system performance.

Analysis of estimation of electromagnetic dosimetric values from non-ionizing radiofrequency fields in conventional road vehicle environments

Abstract A high number of wireless technologies can be found operating in vehicular environments with the aim of offering different services. The dosimetric evaluation of this kind of scenarios must be performed in order to assess their compatibility with current exposure limits. In this work, a dosimetric evaluation inside a conventional car is performed, with the aid of an in-house 3D Ray Launching computational code, which has been compared with measurement results of wireless sensor networks located inside the vehicle. These results can aid in an adequate assessment of human exposure to non-ionizing radiofrequency fields, taking into account the impact of the morphology and the topology of the vehicle for current as well as for future exposure limits.

Characterization of Wireless Channel Impact on Wireless Sensor Network Performance in Public Transportation Buses

Wireless communications systems have been rapidly growing during the last two decades, and they are gaining a significant role for multiple communication tasks within public transportation buses. In this paper, the impact of topology and morphology of different types of urban buses is analyzed with the aid of an in-house developed 3D ray launching code and compared with onboard measurements of a deployed wireless sensor network (WSN). The presence of human beings has been taken into account, showing a significant influence in the signal attenuation in the case of considering persons. In addition, the statistical analysis of simulation results considering both large- and small-scale fading has been performed, providing good agreement with statistics for typical indoor environments. In addition, a WSN has been programmed and deployed within the buses in order to analyze topological impact with overall system performance, with the aim of minimizing the energy consumption as well as nondesired interference levels. The use of deterministic techniques destined to consider the inherent complexity of the buses can aid in wireless system planning in order to minimize power consumption and increase overall system capacity.

ZigBee Radio Channel Analysis in a Complex Vehicular Environment [Wireless Corner]

In this paper, the influence of the topology and morphology of a particularly complex scenario on the deployment of ZigBee wireless sensor networks is analyzed. This complex scenario is a car. The existence of loss mechanisms, such as material absorption (seats, dashboard, etc.), and strong multipath components due to the great number of obstacles and the metallic environment (bodywork), as well as the growing demand for wireless systems within a vehicle, emphasize the importance of the configuration of heterogeneous intra-car wireless systems. Measurement results, as well as simulation results by means of an in-house three-dimensional ray-launching algorithm, illustrate the strong influence of this complex scenario on the overall performance of the intra-car wireless sensor network. Results also show that ZigBee is a viable technology for successfully deploying intra-car wireless sensor networks.

Estimation of wireless coverage in complex cave environments for speleology applications

Summary form only given. Wireless communication systems can be found in a wide variety of environments such as industrial, scientific, home and building automation, vehicles and outdoor environments, mainly due to the development of smaller and cheaper devices and the increasing operational lifetime. In this paper, the feasibility of the deployment of a wireless communication system inside caves is presented. Specifically, a Wireless Sensor Network (WSN) at 868 MHz, 2.4 GHz and 5 GHz bands is studied. WSN in cave environments have great potential because communication systems for speleology and potholing are wired, including the systems used by emergency and rescue teams such as firefighters. In order to perform the radio propagation analysis, an in-house 3D Ray Launching simulation code has been employed, which provides accurate estimations of received power level for full complex indoor scenarios, as it takes into account the topology and the morphology of the scenario, including material properties. Fig. 1a shows the schematic representation of the considered scenario for this work, which corresponds to the dimensions of a real cave placed in Navarre. The estimated received power level for a height of 1.5m inside the cave is represented in Fig. 1b. Results confirm that there is a great dependence of network performance with the topology of the scenario. Therefore, an overall increase system efficiency can be achieved with the aid of this deterministic simulation method.

Assessment of electromagnetic dosimetric values from non-ionizing radiofrequency sources in a conventional road vehicle

The use of different wireless communication systems operating in vehicular environments is growing rapidly. Most of these systems have been focused on providing comfort and security, and low consumption wireless technologies offered the possibility of implantation of intra-vehicular networks using ZigBee or Bluetooth, which coexist with long distance communication systems like mobile telephony systems (GSM, UMTS, HSPA, etc.) or location systems such as GPS inside the vehicle. Most works have been written about interferences among wireless systems inside cars, but few speak about dosimetry. These last studies have been usually done theoretically using simulation tools, calculating electric field and hence, Specific Absorption Rate values. In this work, a dosimetric evaluation inside a conventional car is performed in order to assess the compatibility with current exposure limits. The electric field produced by three wireless communication systems (ZigBee, GSM and UMTS) has been estimated using an in-house developed 3D ray launching code, and then measurements have been taken by means of a spectrum analyzer and a dosimeter. The ICNIRP has developed the most authoritative guidelines in order to regulate the exposure conditions to electromagnetic sources. Although the obtained values are below the ICNIRP limits, nowadays no definitive knowledge has been obtained about the effect of long-term low-level exposure to wireless technologies, so this 3D ray launching algorithm can aid in an adequate assessment of human exposure to nonionizing radiofrequency fields, obtaining the estimations of the E-field (see Fig. 1), specific regions of higher amplitudes or hot spots identification.

Topological dependence in the performance of deterministic wireless channel estimation

The evolution of wireless communication systems, with the use of high level modulation schemes in order to implement high capacity microcells and femtocells for 4G systems, requires in depth radio analysis in order to perform adequate coverage/capacity estimations. In addition, indoor coverage is gaining more relevance, with complex scenarios given in terms of diversity of materials as well as by the presence of furniture, walls and persons. In this framework, deterministic methods, such as Ray Tracing and Ray Launching algorithms play a fundamental role, since they provide an adequate trade-off between accuracy and computational cost. In large scenarios, however, convergence issues arise as a function of the distance of the launched rays from the equivalent transmitter source, as well as with the employed mesh element size. In this work, the performance of the in-house implemented 3D ray launching algorithm is analyzed for a large scenario in terms of volumetric ray launching resolution, number of reflection until extinction and cuboid size (as depicted in Figure 1). The results give a direct dependence of the transmitter-receiver distance and the employed cuboid size, which leads to the need of implementing dynamic meshing strategies in order to optimize overall simulation performance.