Transversal fading analysis in straight tunnels at 2.4 GHz

Abstract

In tunnel-like environments the electromagnetic waves propagate differently in comparison to free space and urban scenarios. This is because, depending on the working frequency, tunnels can act as waveguides. As a consequence of this some specific phenomena occur, such as fast and slow fadings, caused by the constructive and destructive interference due to the multi path propagation. Fadings along the longitudinal dimension of tunnels have been widely studied under different geometric conditions, antenna polarization and working frequen cies. Nevertheless, fadings also take place in the transversal dimension or cross-section. This issue has been poorly treated in the literature. In this context, our research group has been investigating navigation algorithms for multi-robot teams in tunnel-like environments under communication constraints. As fadings affect the communication among robots, a study about this phenomenon is necessary. In this work we present a complete study about transversal fadings in the Somport tunnel at 2.4 GHz. Results after carrying out a measuring campaign are presented and compared to modal theory based calculations, showing that fadings present a similar behavior in each transversal half of the tunnel (with the same period and phase, and with a phase delay between both halves) but different in the center, where although no deep fadings appear, the mean value of the signal power is lower compared to the fadings maximums. This led us to define a comfort-zone for communications for robot navigation in tunnels.

A Methodology for Localization in Tunnels Based on Periodic RF Signal Fadings

“…The transversal fadings analysis (i.e. the effects of moving in the cross section of the tunnel) have been studied in [9].…”

“…In our previous works we have studied the wireless signal propagation in tunnels, noticing that the communication range in a transmitter-receiver setup can be extended in comparison to free space, but the signal suffers from strong fading phenomena (see [7]- [9]). Fadings in these confined environments are unavoidable and are usually considered a serious problem for communication purposes.…”

“…Fadings in these confined environments are unavoidable and are usually considered a serious problem for communication purposes. However, an appropriate choice of the antenna positions allows the generation and detection of somewhat 'ad-hoc', known-geometry fading structures, useful for the elaboration of coverage maps and navigation inside tunnels (see [9], [10]), and as we are proposing here, for localization.…”

Ground robotics in tunnels: Keys and lessons learned after 10 years of research and experiments

“…The paper will address the aspects of communication, localization in large settings, and autonomous navigation found during our long‐term research in the tunnels and other confined environments. The goal of this study paper is that the reader not only understands the solutions, but also what led to the choice of those solutions over others, supported by a 10‐year research project that produced over 40 field experiments and more than 20 publications, some of the most relevant coping with the challenges of real‐time communication (Tardioli & Villarroel, ), radio signal propagation (Rizzo, Lera, & Villarroel, a, b), localization based on topological information (Romeo & Montano, ; Tardioli & Villarroel, ), communication‐aware navigation (Rizzo, Tardioli, et al, ; Tardioli et al, ), cooperative navigation (Urcola, Riazuelo, Lazaro, & Montano, ), and robotics intervention system where those proposals are put together (Tardioli et al, , 2016a).…”

Power Characteristics of Wireless Charging for Sensor Networks in Tunnels

“…Chahé Nerguizian [11] placed the transmitting antenna at different locations during the narrowband measurement procedure and analyzed the path loss. Carlos Rizzo [12] presented a complete study about transversal fading in the Somport tunnel at 2.4 GHz. The fading behavior was similar in each transversal half of the tunnel but different in the center.…”