Time-Variant Radio Channel Characterization and Modelling of Vegetation Media at Millimeter-Wave Frequency

Abstract

Results of an extensive measurement campaign to characterize and model dynamic effects on the radio channel in vegetation media at 40 GHz, are presented. Using two small trees in an anechoic chamber, narrowband fast-fading measurements, utilizing co-polarized signals, were conducted to obtain radio channel characterization. This was performed as a function of the bi-static scattering angle, wind speed, wind incidence, and tree species. Furthermore, a modelling methodology is investigated and assessed as to its feasibility as a means to model vegetation dynamics effects on propagation. A radio channel model based on a simplified set of Markovian parameters, is proposed. The model is representative of the radio signal in the three main identified propagation regions around a vegetation volume as a mean to satisfactorily model highly time-variant radio signals. The propagation regions considered are receiver angular sections (in the azimuth plane) around the tree, where the received signal behaves distinctly for each region. Model validation results are presented using one of the tree species.

Channel Characterization and Finite-State Markov Channel Modeling for Time-Varying Plasma Sheath Surrounding Hypersonic Vehicles

“…Since the effects of the plasma sheath are time-varying, the corresponding channel model must be expressed in terms of statistical averages and probability densities. The finite- state Markov channel (FMSC) model, which was firstly proposed by Gilbert and Elliott at Bell Labs, has attracted quite some attention due to its usefulness to represent such time-varying characteristics [24][25][26][27]. In this section, we will partition the power levels of the received signal into a finite number of states and construct the FSMC model of different scenarios, which could enable us to simulate the time-varying effects on electromagnetic wave propagation through plasma sheath with low complexity.…”

“…In order to determine the parameters of the FMSC model, the data processing and parameter extraction procedures are given as following steps [26,27],…”

Modeling and inferring the attenuation induced by vegetation barriers at 2G/3G/4G cellular bands using Artificial Neural Networks

“…A second goal to accomplish within this paper is to provide a general model for the attenuation of a vegetation barrier, instead of focusing only in the scattering phenomena [8][9] or in some other specific physical parameters [10]. The model framework presented herein aims at predicting the excess attenuation due to vegetation at all cellular phone frequency bands by means of an ANN.…”

“…Afterwards, values conforming the representation are obtained by equations(4)to(9), where m is the number of attenuation samples available for each case under study, is the median attenuation value, and ai , aj , ak represent the value of the attenuation for the ordered sample i, j and k, respectively. To compare the measurement outcomes of our study, we will mainly focus on median attenuation values and on the attenuation scattering or IQR.…”

Wireless Communications in a Tree Canopy

“…Therefore, the frequencies of operation are 2.45 GHz and 5.2 GHz, the ISM band whose is license free and a number of RF modules are available in the market. Although there are a number of works related to effect of vegetation on propagation channel as aforementioned and in [19][20][21][22], most of them are focused on propagation channel through the tree canopies. There is a lack of knowledge for propagation in a tree canopy.…”