Fast Fading Characterization for Body Area Networks in Circular Metallic Indoor Environments

Abstract

With the increasing development of 5G and Body Area Network based systems being implemented in unusual environments, propagation inside metallic structures is a key aspect to characterize propagation effects inside ships and other similar environments, mostly composed of metallic walls. In this paper, indoor propagation inside circular metallic structures is addressed and fast fading statistical distributions parameters are obtained from simulation, being assessed with measurements at 2.45 GHz in a passenger ferry discotheque with an 8 m diameter circular shape. It is observed that, in this kind of environments, second order reflections are particularly relevant due to the walls' high reflective nature. Globally, it is concluded that the Rayleigh distribution can be used to characterize fast fading effects with no significant loss of accuracy compared to the Rice one, since a low value of the Rice parameter is observed, being below 3.1 dB, even under Line-of-Sight conditions. Moreover, it is observed that, from the fast fading viewpoint, the best transmitter position is at the circle center. INDEX TERMS Body area networks, fading characterization, metallic structures, propagation modelling.

A Wideband Channel Model for Body Area Networks in Circular Metallic Indoor Environments

“…The signal at the Rx can be described by the sum of the LoS component with the reflected ones; many reflections are observed, their importance decreasing for an increasing reflection order, due to the increasing path length and the corresponding increasing attenuation. Regions with a given number of reflections are defined as catacaustic zones [18], [19, p. 183-186], Figure 2 showing the catacaustic regions for different Rx positions, when 1 st and 2 nd order reflections are considered: 2 or 4 reflections are observed for 1 st order reflections, while for 2 nd order ones, one can see that there are up to 8, [14]. When analyzing the sum of the reflection components, one can consider up to Nr order reflections, with reflected rays in each one, hence, the signal at the Rx is described by [14],…”

“…Moreover, among other aspects, the scenario dynamics, namely due to the presence of people and obstacles, the use of different types of antennas/polarizations and the user's body movement (causing antennas misalignment), will also have an impact on results. Still, among all these limitations, the proposed model allows to reasonably match the results from measurements for the conditions under study [14]. The three-dimensional approach is left for future work.…”

“…As far as the authors are aware of, the first research on BAN radio channels in metallic environments has been described in [13]. In [14], propagation inside circular metallic structures is addressed and a channel model was proposed and assessed with measurements at 2.45 GHz in a passenger ferry discotheque with an 8 m diameter circular shape. The measurement campaign focused on system loss measurements in the link between a transmitting antenna (Tx) located on the body in different locations and a receiving one (Rx) positioned off-body.…”

“…In the current paper, the model in [14] is used to address the temporal characteristics of the propagation channel as a function of the radius of the circular environment, and an analytical model for the dependence of mean delay and average delay spread on the radius, the working frequency and the distance between an Access Point (AP) and a Mobile Terminal (MT) is proposed (obviously, either can serve as both Tx and Rx). One should remember that the circular shape has some specific characteristics (catacaustic regions) not found in usual environments with other geometries, namely rectangular ones, such as rooms and corridors, its analysis being one of the novelties of this paper.…”

“…Given the two-dimensional approach to the problem, the position of the antennas on the body is not relevant. As mentioned in [14], the objective is to keep the model as simple as possible, while still being accurate enough to describe reality and keeping the deviation from measurements within an acceptable margin. Naturally, this simple model has limitations, namely when different antennas heights are considered.…”