A ray-based channel model for MIMO troposcatter communications

Abstract

Troposcatter communications provide a good alternative for beyond-Line-of-Sight (b-LoS) communication because it can provide reliable high data rate applications with the advancement in the modem and high power amplifiers. The employment of the high data rate applications with troposcatter communications requires the investigation of the troposcatter channels. However, available channel models for the troposcatter communications are not able to take the non-homogeneities of the air turbulence into account. Therefore, the main motivation of this paper is to develop a ray-based MIMO troposcatter channel model in which the beamwidths of the antennas are divided to small parts and, the associated delay and power of the rays are calculated in order to consider the non-homogeneities and time variations of the channel. Also, in order to show the time varying behaviour of the channel this paper provides the simulation results for the maximum data rate of the channel by using real world measurements first time in the literature.

A Nonuniform Spatial Rain Attenuation Model for Troposcatter Communication Links

“…In the ray-based approach, path length and power of each ray is calculated separately to form power delay spectrum (PDS) [2]. In this way, each ray is subjected to different conditions according to its own path.…”

“…is the polarization mismatch factor. σ V is the differential scattering cross-section which is modeled with the Rayleigh scattering approximation [2], [12]. a rain is the rain attenuation which is introduced in this paper.…”

“…Unlike scattering particles (1 − 10 µm ), sizes of rain droplets can vary 1 µm up to 1 mm. Since size of rain droplets and wavelength of signals become comparable especially for high carrier frequencies between 10 − 15 GHz, the effect of rain droplets cannot be modeled by Rayleigh scattering approximation as in [2]. To this end, in the presence of rain, path loss calculations require a correction factor (S) for the Rayleigh scattering approximation when carrier frequency is higher than 10 GHz and, this correction factor in dB is given as […”

“…N is the noise power (modeled as thermal noise N = kBT ), T is the temperature in K, B is the bandwidth and k is the Boltzmann constant. Our ray-based method [2] utilizes the real-world water vapor mixing ratio measurements [15]. Therefore, this approach can model fluctuations in the channel.…”

“…We utilize available rain models [9], [10] to generate synthetic rain distribution. We simulate the proposed rain attenuation model by modifying our previously introduced ray-based troposcatter channel modeling approach [2] to predict rain loss and maximum data rates in the presence of rain for the first time.…”