A Link Loss Model for the On-body Propagation Channel for Binaural Hearing Aids

Binaural hearing aids communicate with each other through a wireless link for synchronization. A propagation model is needed to estimate the ear-to-ear link loss for such binaural hearing aids. The link loss is a critical parameter in a link budget to decide the sensitivity of the transceiver. In this paper, we have presented a model for the deterministic component of the ear-to-ear link loss. The model takes into account the dominant paths having most of the power of the creeping wave from the transceiver in one ear to the transceiver in other ear and the effect of the protruding part of the outer ear called pinna. Simulations are done to validate the model using in-the-ear (ITE) placement of antennas at 2.45 GHz on two heterogeneous phantoms of different age-group and body size. The model agrees with the simulations. The ear-to-ear link loss between the antennas for the binaural hearing aids in the homogeneous SAM phantom is compared with a heterogeneous phantom. It is found that the absence of the pinna and the lossless shell in the SAM phantom underestimate the link loss. This is verified by the measurements on a phantom where we have included the pinnas fabricated by 3D-printing

An Analytical Link Loss Model for On-Body Propagation Around the Body Based on Elliptical Approximation of the Torso with Arms' Influence Included

An analytical model for estimating the link loss for the on-body wave propagation around the torso is presented. The model is based on the attenuation of the creeping waves over an elliptical approximation of the human torso and includes the influence of the arms. The importance of including the arms' effect for a proper estimation of the link loss is discussed. The model is validated by the full-wave electromagnetic simulations on a numerical phantom

Miniaturized antennas for link between binaural hearing aids

We have investigated the possibility of using the 2.45 GHz ISM band for communication between binaural hearing aids. The small size of a modern hearing aid makes it necessary to miniaturize the antennas to make this feasible. Two different types of hearing aid placements have been investigated: in the outer ear and in the ear canal. Both put strict demands on the size of the antenna, which have been miniaturized by applying disc loads and high permittivity materials. The investigations have been done by FDTD simulation of a modified SAM phantom head, where we have included a simple model of the ear canal. Simulations show that the outer ear placement is better, as it gives a total link loss of 48 dB. The placement in the ear canal gives a total link loss of 92 dB

An Approach to Analyze the Movements of the Arms while Walking using Wearable Wireless Devices

Abstract—Rhythmic movement of the arms while walking is an important feature of human gait. In this paper, we present an approach to analyze the movements of the arms while walking by using three wearable wireless devices placed around the torso. One of the devices is transmitter placed at the back and the other two are symmetrically placed receivers that record the power variation due to movements of the arms while walking. We show that the power received by the receivers will have symmetrical variation if the arms’ swing is symmetrical. An analytical model has been used to calculate the position of the receivers. Full wave simulations on a walking phantom are done to confirm the results

Dielectric Characterization of Soil Samples by Microwave Measurements

Northern high-latitude wetlands are well known to seasonally emit methane gas into the atmosphere, and therefore contribute to greenhouse effects. While these gas emissions are well documented, their causes are not well understood. The method described in this work can be used to analyze the changes happening in the soil during gas emissions, and therefore help the understanding of the sub-surface gas dynamics. We have monitored a sample of peat soil through an artificial freezing and thawing cycle, using both a gas detector to measure the methane flux at the soil surface and a vector network analyzer to measure the transmission of microwaves through the soil. It was observed that the results from the two measurement approaches had a very good match under specific microwave signal conditions. In addition, from the microwave measured data, the dielectric properties of the soil and the volumetric fractions of its constituents were also calculated based on a dielectric mixing model

Internet of Buoys: An Internet of Things Implementation at Sea

Internet of Things (IoT) applications are emerging in many different areas, including maritime environments. One of the applications in this area is the monitoring of buoys at sea. To realize wireless tracking of buoys, an accurate prediction of the path loss in an open-sea environment is essential. So far, channel measurements at sea have mainly been conducted with antennas placed a couple of meters above the sea surface, which is higher than the buoys themselves. Therefore, we investigated the validity of the published channel models at sea by means of path loss measurements using a LoRa link with a transmitter antenna height of 0.35 m and a base station antenna height of 2.65 m and 5.2 m. Our results show that the round earth loss model is not accurate at these antenna heights. The ITU-R P.2001-3 model and a model by Bullington show a better agreement with our measurements. However, the difference between our two measurement campaigns shows that more investigation is needed on the dependence of the path loss on the sea state. Additionally, the availability of Sigfox, Narrowband Internet of Things (NB-IoT), and The Things Network at sea has been explored. We found that NB-IoT and Sigfox can be used for IoT applications in the tested area at low antenna heights

On the modeling of tensile index from larger data sets

The objective of this study is to analyze and foresee potential outliers in pulp and handsheet properties for larger data sets. The method is divided into two parts comprising a generalized Extreme Studentized Deviate (ESD) procedure for laboratory data followed by an analysis of the findings using a multivariable model based on internal variables (i. e. process variables like consistency and fiber residence time inside the refiner) as predictors. The process data used in this has been obtained from CD-82 refiners and from a laboratory test program perspective, the test series were extensive. In the procedure more than 290 samples were analyzed to get a stable outlier detection. Note, this set was obtained from pulp at one specific operating condition. When comparing such "secured data sets" with process data it is shown that an extended procedure must be performed to get data sets which cover different operating points. Here 100 pulp samples at different process conditions were analyzed. It is shown that only about 60 percent of all tensile index measurements were accepted in the procedure which indicates the need to oversample when performing extensive trials to get reliable pulp and handsheet properties in TMP and CTMP processes

Control Problems at the European Spallation Source

A background on the Europan Spallation Source is given, and our work on three control problems important for the design of its linear accelerator are presented

Constant net-time headway as key mechanism behind pedestrian flow dynamics

We show that keeping a constant lower limit on the net-time headway is the key mechanism behind the dynamics of pedestrian streams. There is a large variety in flow and speed as functions of density for empirical data of pedestrian streams, obtained from studies in different countries. The net-time headway however, stays approximately constant over all these different data sets. By using this fact, we demonstrate how the underlying dynamics of pedestrian crowds, naturally follows from local interactions. This means that there is no need to come up with an arbitrary fit function (with arbitrary fit parameters) as has traditionally been done. Further, by using not only the average density values, but the variance as well, we show how the recently reported stop-and-go waves [Helbing et al., Physical Review E, 75, 046109] emerge when local density variations take values exceeding a certain maximum global (average) density, which makes pedestrians stop.Comment: 7 pages, 7 figure

A measurement-based fading model for wireless personal area networks

Personal area networks (PANs) are wireless communications systems with high data rates but small coverage area. PAN propagation channels differ from the well-explored propagation channels of wide-area networks due to several reasons: (i) the distances are typically very small, (ii) the antenna arrangements can be quite different, and (iii) the influence from human presence in the environment is different. The current paper presents results of a channel measurement campaign, where measurements are conducted over distances of 1-10 m using several multi-antenna devices, combined to create different PAN scenarios. For each measured Tx-Rx separation, channel realizations are obtained by small spatial movements of the antenna devices, and by rotating the persons holding the devices. From the results, we draw two main conclusions: (i) The small-scale amplitude statistics, analyzed as the variations over a small sampling area and frequency subchannels, cannot be described in a satisfactory way using only the Rayleigh or Ricean distributions, rather a mixed distribution, the generalized gamma distribution, is more suitable; (ii) it is advantageous to distinguish between two types of large-scale fading: body shadowing (due to the orientation of the person holding the device) and shadowing due to surrounding objects (lateral movement). We also define and parameterize a complete statistical model for all fading