Experimental Study on the Impact of Antenna Characteristics on Non-Stationary V2I Channel Parameters in Tunnels

Abstract

This paper analyses the experimentally-assessed dual-polarized (DP) mobile channel in a tunnel environment at 1.35 GHz under traffic conditions. We investigate the impact of antenna polarization and radiation pattern on the non-stationary vehicle-to-infrastructure (V2I) channel. Basic channel evaluation metrics are examined including path gain, co-polarization ratio (CPR), and cross-polarization discrimination (XPD). In addition, the stationarity region is estimated using the channel correlation function approach, and used to calculate the time-varying delay and Doppler power profiles. Statistical models are presented for parameters like CPR, XPD, RMS delay and Doppler spreads, where the lognormal distribution provides the best fit. The polarization and the opening angle of the antennas into the propagation channel are found to strongly influence the observed non-stationarity of the channel. They impact the degree of multipath richness that is captured, thus providing different path gain, delay and Doppler spreads. Based on our analysis, the directional antenna with vertical polarization provides the longest stationarity time of 400 ms at 90 km/h, as well as the highest path gain and lowest dispersion. Furthermore, the DP channel capacity is calculated and its dependence on different normalization approaches is investigated. We propose a more accurate normalization for the DP channels that takes the conservation of energy into account. Moreover, the subchannels correlation coefficients are determined. While the condition number is found to be low on average, the correlation results show high correlation among the DP subchannels. As conclusion, we show how the CPR and XPD play the main role in providing multiplexing gain for DP tunnel channels.

Vehicle Localization Using Doppler Shift and Time of Arrival Measurements in a Tunnel Environment

“…On the other hand, analytical stochastic models that are obtained from measurements in real traffic conditions describe the specific environment with less computational cost [ 9 ]. As the propagation is influenced by many factors (e.g., tunnel geometry, obstacles, nodes setup, traffic), measurements in practical scenarios are required to characterize and model the propagation in tunnels [ 10 ].…”

“…When it comes to the localization topic, propagation path losses and fadings, specifically generation and detection of the known-geometry fading structures are useful for elaboration of coverage maps, localization, and navigation inside tunnels [ 11 , 12 , 13 , 14 ]. An appropriate choice of the antenna positions and periodic patterns, regarding fading over distance, can enable one-dimensional localization by detecting the changes in the slope of the received signal fadings, precisely by having the number of maxima and minima encountered on the received signal wavelength [ 10 , 11 , 12 , 14 ]. However, the traffic condition disturbs the propagating modes, making the pseudo-periods less clear than in empty tunnels [ 10 ], and this causes localization errors.…”

“…An appropriate choice of the antenna positions and periodic patterns, regarding fading over distance, can enable one-dimensional localization by detecting the changes in the slope of the received signal fadings, precisely by having the number of maxima and minima encountered on the received signal wavelength [ 10 , 11 , 12 , 14 ]. However, the traffic condition disturbs the propagating modes, making the pseudo-periods less clear than in empty tunnels [ 10 ], and this causes localization errors. The presence of traffic, the number and size of vehicles increase the signal attenuation and fluctuations too, especially close to vehicles [ 15 ].…”

“…Moreover, this approach adds the need for compatibility between different standards and technologies and causes different delays, dependencies, problems, and uncertainties [ 40 , 41 ]. Thus, in this work, we use our previous studies and analysis on the non-stationary V2I channel in the frequency band of LTE-V [ 10 ] to address vehicle localization in tunnels and to show preliminary results on this matter.…”

Evaluation of a Switched Combining Based Distributed Antenna System (DAS) for Pedestrian-to-Vehicle Communications

“…Over the last few decades, a number of studies have been conducted which investigate the characteristics of V2X communication channels (including P2V communication channels) with the aim of developing V2X based wireless systems [8][9][10][11][12][13]. Also, to this end, a number of antenna diversity techniques have been studied with the aim of increasing signal reliability in the context of vehicle-to-vehicle (V2V) and vehicle-toinfrastructure (V2I) communications [14][15][16][17][18][19][20]. In contrast, there are comparatively few results on the use of spatial diversity techniques in the context of P2V communications presented in the open literature [21], [22].…”